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STUDY DESIGN.: Prospective in vivo randomized study. OBJECTIVE.: To evaluate the safety and efficacy of a distraction-based magnetically controlled growing rod (MCGR) in a porcine model. SUMMARY OF BACKGROUND DATA.: A high number of complications related to frequent surgical rod lengthenings has been a generally accepted outcome in growing rod surgery for early-onset scoliosis. A potentially safer technique is a system that does not require repetitive surgery. METHODS.: Seven-month-old pigs were randomly assigned to an experiment group (EG; n = 6) and a sham group (SG; n = 3). One animal in the EG became paralyzed because of a misplaced pedicle screw and was killed per the study protocol. Therefore, a total of 8 animals completed the study. The EG underwent weekly spine distraction using the MCGR. Spinal height was assessed by vertebral unit height measurements on weekly lateral radiographs. RESULTS.: A total of 49 mm of distraction across the unfused vertebral levels was planned during a 7-week period (7 mm per wk). Radiographical analysis of the MCGR device revealed an average distraction of 39 mm (range, 32-46 mm), resulting in achievement of 80% of predicted spinal height. Prior to removal of implants, spinal height for the EG was similar to the SG. However, accelerated increase in vertebral unit height was noted in the EG during the 3-week period after implant removal, which resulted in significantly greater overall spinal height in the EG (32.2% vs. 11.7%, P ≤ 0.05). No MCGR-related complications occurred. CONCLUSION.: The MCGR provided 80% of predicted spinal height by noninvasive remote distraction in this animal model. The accelerated increase in spinal height of the experimental animals after implant removal was an unexpected finding which requires additional research to better understand the effect of distraction on spinal growth. This study establishes a foundation for future research in an attempt to use a less invasive technique in distraction-based correction of early-onset scoliosis. [ABSTRACT FROM AUTHOR]

Background: Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch., Methods: A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age., Results: The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year., Conclusions: We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The International Spine Study Group (ISSG) is funded through research grants from NuVasive, SI-Bone, DePuy Synthes Spine, K2M, Stryker, Biomet, AlloSource, and Orthofix, and individual donations. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/I191)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose: To evaluate the variability in intraoperative fluid management during adult spinal deformity (ASD) surgery, and analyze the association with complications, intensive care unit (ICU) requirement, and length of hospital stay (LOS)., Methods: Multicenter comparative cohort study. Patients ≥ 18 years old and with ASD were included. Intraoperative intravenous (IV) fluid data were collected including: crystalloids, colloids, crystalloid/colloid ratio (C/C), total IV fluid (tIVF, ml), normalized total IV fluid (nIVF, ml/kg/h), input/output ratio (IOR), input-output difference (IOD), and normalized input-output difference (nIOD, ml/kg/h). Data from different centers were compared for variability analysis, and fluid parameters were analyzed for possible associations with the outcomes., Results: Seven hundred ninety-eight patients with a median age of 65.2 were included. Among different surgical centers, tIVF, nIVF, and C/C showed significant variation (p < 0.001 for each) with differences of 4.8-fold, 3.7-fold, and 4.9-fold, respectively. Two hundred ninety-two (36.6%) patients experienced at least one in-hospital complication, and ninety-two (11.5%) were IV fluid related. Univariate analysis showed significant relations for: LOS and tIVF (ρ = 0.221, p < 0.001), IOD (ρ = 0.115, p = 0.001) and IOR (ρ = -0.138, p < 0.001); IV fluid-related complications and tIVF (p = 0.049); ICU stay and tIVF, nIVF, IOD and nIOD (p < 0.001 each); extended ICU stay and tIVF (p < 0.001), nIVF (p = 0.010) and IOD (p < 0.001). Multivariate analysis controlling for confounders showed significant relations for: LOS and tIVF (p < 0.001) and nIVF (p = 0.003); ICU stay and IOR (p = 0.002), extended ICU stay and tIVF (p = 0.004)., Conclusion: Significant variability and lack of standardization in intraoperative IV fluid management exists between different surgical centers. Excessive fluid administration was found to be correlated with negative outcomes., Level of Evidence: III., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Background: Severe sagittal plane deformity with loss of L4-S1 lordosis is disabling and can be improved through various surgical techniques. However, data are limited on the differing ability of anterior lumbar interbody fusion (ALIF), pedicle subtraction osteotomy (PSO), and transforaminal lumbar interbody fusion (TLIF) to achieve alignment goals in severely malaligned patients., Methods: Severe adult spinal deformity patients with preoperative PI-LL >20°, L4-S1 lordosis <30°, and full body radiographs and PROMs at baseline and 6-week postoperative visit were included. Patients were grouped into ALIF (1-2 level ALIF at L4-S1), PSO (L4/L5 PSO), and TLIF (1-2 level TLIF at L4-S1). Comparative analyses were performed on demographics, radiographic spinopelvic parameters, complications, and PROMs., Results: Among the 96 included patients, 40 underwent ALIF, 27 underwent PSO, and 29 underwent TLIF. At baseline, cohorts had comparable age, sex, race, Edmonton frailty scores, and radiographic spinopelvic parameters (P > 0.05). However, PSO was performed more often in revision cases (P < 0.001). Following surgery, L4-S1 lordosis correction (P = 0.001) was comparable among ALIF and PSO patients and caudal lordotic apex migration (P = 0.044) was highest among ALIF patients. PSO patients had higher intraoperative estimated blood loss (P < 0.001) and motor deficits (P = 0.049), and in-hospital ICU admission (P = 0.022) and blood products given (P = 0.004), but were otherwise comparable in terms of length of stay, blood transfusion given, and postoperative admission to rehab. Likewise, 90-day postoperative complication profiles and 6-week PROMs were comparable as well., Conclusions: ALIF can restore L4-S1 sagittal alignment as powerfully as PSO, with fewer intraoperative and in-hospital complications. When feasible, ALIF is a suitable alternative to PSO and likely superior to TLIF for correcting L4-S1 lordosis among patients with severe sagittal malalignment., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Study Design: Retrospective analysis of prospectively collected data., Objective: Evaluate the impact of correcting normative segmental lordosis values on postoperative outcomes., Background: Restoring lumbar lordosis magnitude is crucial in adult spinal deformity surgery, but the optimal location and segmental distribution remain unclear., Patients and Methods: Patients were grouped based on offset to normative segmental lordosis values, extracted from recent publications. Matched patients were within 10% of the cohort's mean offset, less than or over 10% were undercorrected and overcorrected. Surgical technique, patient-reported outcome measures, and surgical complications were compared across groups at baseline and two years., Results: In total, 510 patients with a mean age of 64.6, a mean Charlson comorbidity index 2.08, and a mean follow-up of 25 months. L4-5 was least likely to be matched (19.1%), while L4-S1 was the most likely (24.3%). More patients were overcorrected at proximal levels (T10-L2; undercorrected, U: 32.2% vs. matched, M: 21.7% vs. overcorrected, O: 46.1%) and undercorrected at distal levels (L4-S1: U: 39.0% vs. M: 24.3% vs. O: 36.8%). Postoperative Oswestry disability index was comparable across correction groups at all spinal levels except at L4-S1 and T10-L2/L4-S1, where overcorrected patients and matched were better than undercorrected (U: 32.1 vs. M: 25.4 vs. O: 26.5, P =0.005; U: 36.2 vs. M: 24.2 vs. O: 26.8, P =0.001; respectively). Patients overcorrected at T10-L2 experienced higher rates of proximal junctional failure (U: 16.0% vs. M: 15.6% vs. O: 32.8%, P <0.001) and had greater posterior inclination of the upper instrumented vertebrae (U: -9.2±9.4° vs. M: -9.6±9.1° vs. O: -12.2±10.0°, P <0.001), whereas undercorrection at these levels led to higher rates of revision for implant failure (U: 14.2% vs. M: 7.3% vs. O: 6.4%, P =0.025)., Conclusions: Patients undergoing fusion for adult spinal deformity suffer higher rates of proximal junctional failure with overcorrection and increased rates of implant failure with undercorrection based on normative segmental lordosis., Level of Evidence: Level IV., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment. Recently, personalized spine surgery has witnessed significant advancements, including 3D-printed personalized interbody implants, which are customized to the surgeon's treatment and alignment goals. This study evaluates the reliability of 3D-printed patient-specific interbody implants to achieve the planned postoperative intervertebral alignment., Methods: This is a retrospective study of 217 patients with spinal deformity or degenerative conditions. Patients were included if they received 3D-printed personalized interbody implants. The desired intervertebral lordosis (IVL) angle was prescribed into the device design for each personalized interbody (IVL goal). Standing postoperative radiographs were measured, and the IVL offset was calculated as IVL achieved minus IVL goal., Results: In this patient population, 365 personalized interbodies were implanted, including 145 anterior lumbar interbody fusions (ALIFs), 99 lateral lumbar interbody fusions (LLIFs), and 121 transforaminal lumbar interbody fusions. Among the 365 treated levels, IVL offset was 1.1° ± 4.4° (mean ± SD). IVL was achieved within 5° of the plan in 299 levels (81.9%). IVL offset depended on the approach of the lumbar interbody fusion and was achieved within 5° for 85.9% of LLIF, 82.6% of transforaminal lumbar interbody fusions and 78.6% of ALIFs. Ten levels (2.7%) missed the planned IVL by >10°. ALIF and LLIF levels in which the plan was missed by more than 5° tended to be overcorrected., Conclusions: This study supports the use of 3D-printed personalized interbody implants to achieve planned sagittal intervertebral alignment., Clinical Relevance: Personalized interbody implants can consistently achieve IVL goals and potentially impact foundational lumbar alignment., Competing Interests: Declaration of Conflicting Interests : Saeed S. Sadrameli discloses that he receives consulting fees from Carlsmed. Donald J. Blaskiewicz discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Christopher P. Ames discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Jahangir Asghar discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Gregory M. Mundis discloses that he receives consulting fees from Carlsmed. Joseph A. Osorio discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Justin S. Smith discloses that he is a shareholder and receives consulting fees from Carlsmed. Sigurd H. Berven discloses that he receives consulting fees from Carlsmed. Chun-Po Yen discloses that he is a clinical research investigator and receives consulting fees from Carlsmed. Ashvin I. Patel discloses that he is a clinical investigator and receives consulting fees from Carlsmed. Michele Temple-Wong discloses that she is an employee of Carlsmed. Rodrigo J. Nicolau discloses that he is an employee of Carlsmed. Roland S. Kent discloses that he is a clinical research investigator and receives consulting fees from Carlsmed., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2024 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

Objective: Advances in surface architecture and technology have made interbody fusion devices more bioactive, with the hope of facilitating the fusion process more successfully. The advent of these increasingly bioactive implants may reduce reliance on more expensive biologics that have previously been used to achieve high fusion rates., Methods: A retrospective review of prospectively collected data (August 2018-December 2019) was conducted of consecutively performed anterior lumbar interbody fusions in which an acid-etched, nanosurface-modulated, titanium interbody device packed only with corticocancellous allograft chips and local blood was used. Minimum follow-up was 1 year, and inclusion required available imaging and outcome metrics preoperatively and at 1 year. Fusion and subsidence were assessed via CT scans and/or dynamic radiographs. Health-related quality-of-life measures (Oswestry Disability Index [ODI], visual analog scale [VAS] back/leg) were collected pre- and postoperatively., Results: In total, 55 patients met inclusion criteria (1 year of follow-up, available imaging, and outcome metrics). A total of 69 lumbar levels were treated in these 55 patients. The mean age was 67 ± 12.1 years, with 47% female patients. Roughly one-third (35%) had previous spine surgery, and approximately one-tenth (9.1%) had prior spinal fusion. A total of 20.6% were treated at multiple levels (mean levels per patient 1.2, minimum 1, maximum 3). The mean preoperative patient-reported outcomes were as follows: ODI 39.71 ± 18.15, VAS back 6.49 ± 2.19, and VAS leg 5.41 ± 2.71. One year after surgery, the mean improvements in patient-reported outcomes (vs preoperative scores) were as follows: ODI -22.9 ± 13.08 (p < 0.001), VAS back -3.75 ± 2.03 (p < 0.001), VAS leg -3.73 ± 2.32 (p < 0.001). All levels achieved fusion at 1 year postoperatively based on CT scans (65/69 levels) or dynamic radiographs (4/69 levels, change in score < 5% on flexion-extension radiographs). Four of the 65 levels were assigned to the grade 3 category according to a CT-based grading system, meaning cranial and caudal endplate bone apposition to the implant on both surfaces with no clear intervertebral bone connection through or around the implant. Sixty-one of 65 were found to have contiguous intervertebral bone bridging and thus were assigned to grade 1 (n = 54) or grade 2 (n = 7). Low-grade graft subsidence (Marchi grade 0 or I) occurred in 9 levels (13.0%) and high-grade subsidence (Marchi grade II or III) in 4 levels (5.8%). No patients required reoperation at the level of anterior lumbar interbody fusion and no radiographic or clinical evidence of pedicle screw loosening or failure was observed., Conclusions: The combination of advances in materials science and surface technology as demonstrated with a nanotechnology titanium cage resulted in the ability to obtain lumbar interbody fusion with allograft chips and local blood alone. Achieving high fusion rates with low-cost biologics/allograft provides for an attractive pathway toward reducing the cost of reconstructive spine care, and a potential incremental benefit for healthcare economics.

Background: Anterior Column Realignment (ACR) was introduced to serve as a powerful segmental kyphosis correction technique in minimally invasive Adult Spinal Deformity (ASD) surgery. Releasing the Anterior Longitudinal Ligament (ALL) and annulus allows opening of the disc space to accommodate hyperlordotic cages. The overall safety and efficacy of ACR has been difficult to determine due to the heterogenicity of surgical techniques, complications reporting, and a paucity of published studies leading to preliminary and controversial conclusions., Purpose: To determine the efficacy and complications rates associated with ACR., Study Design: Systematic review., Methods: We queried the MEDLINE, Google Scholar, and EMBASE databases for all literature related to ACR procedure with a publication cutoff start date of January 1, 2010. This systematic review was performed utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. nonEnglish, nonhuman, case reports and review article publications were excluded., Results: A total of 298 studies were identified. Following screening of title, abstract, and full text, 16 articles were included in the review with a total 756 patients. All the studies included in this systematic review were retrospective case series with a level of evidence IV. Ten studies reported ACR-related complications, with an average rate of 27.2%. The rate of reoperations was reported in 5 studies, for which the average reoperation rate was 9.5%. Cage Subsidence (CS) occurred in 13.7%, Proximal Junctional Kyphosis (PJK) in 12.2%, neurologic injury in 7.3%, and Proximal Junctional Failure (PJF) in 2.7%. The vascular injury rate was 0.5%, with bowel perforation and ureteric injury occurring in 0.2%. For the Patient Reported Outcome Measures (PROMs) and radiological outcome analysis we excluded studies with less than 12 months follow up leaving 8 studies eligible for the analysis. There was a significant improvement of both local Motion Segment Angle (MSA) and Intra Discal Angle (IDA) with a mean segmental correction of 20° lordosis in the 3 studies that reported these parameters., Conclusion: Based on the limited data available in this systematic review, the ACR technique has significant ability to restore and, when needed, correct the local segmental intervertebral angulation and thereby influencing the overall regional and global sagittal alignment. The associated risk of vascular, bowel, and nerve injury did not seem to be significantly higher in this review than other alternative lumbar interbody fusion techniques. Additional higher quality studies, including a consensus for reporting complications is required to reach definitive conclusions regarding its possible associated risks., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Study Design: Retrospective analysis of prospectively collected data., Objective: Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction., Background: Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs., Methods: ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection., Results: Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs (P<0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=-0.22, 95%CI=-0.43--0.01, P=0.038) and C2SPi (coeff=-0.72, 95%CI=-1.36--0.07, P=0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95%CI=0.01-0.28, P=0.040) and thoracolumbar lordosis (coeff=0.22, 95%CI=0.10-0.33, P=0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs (P<0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes., Conclusions: Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection., Level of Evidence: IV., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: The evolution of MCGR technique has led to modifications in the configuration of the proximal construct to decrease the incidence of implant-related complications (IRC) and revision surgeries. However, there is no data characterizing the performance of the most used configurations reducing the risk of complications., Methods: 487 patients were identified from an international multicenter EOS database., Inclusion Criteria: EOS patients, primary dual MCGR, complete radiographs, and minimum of 2-year follow-up. 76 patients had incomplete X-rays, 5 had apical fusions, and 18 had inconclusive complications, leaving 388 patients for review. A digital spine template was created to document UIV; number of levels; number, type, and location of anchors; as well as implant configuration. First available postoperative and latest follow-up radiographs were reviewed by two senior surgeons and two spine fellows. UPROR due to IRC was defined as any change in proximal anchors between the postoperative and final follow-up radiographs., Results: The most common proximal construct configuration: UIV at T2 (50.0%) with 17.5% UPROR, followed by T3 (34.0%) with 12.1% UPROR; number of levels was three (57.1%) with 16.8% UPROR and two (26.0%) with 17.0% UPROR; number of proximal anchors was six (49.9%) with 14.1% UPROR and four (27.0%) with 18.3% UPROR. The most common anchors were all screws (42.0%) with 9.9% UPROR, and all hooks (26.4%) with 31.4% UPROR (P < 0.001). The construct with the lowest rate of UPROR was a UIV at T2, with six anchors (all screws) across three levels (42 cases), with 0% UPROR. Other construct combinations that yielded 0% UPROR rates were UIV of T3, six anchors (all screws) across three levels (25 cases), and a UIV of T3 with six anchors (screws and hooks) across three3 levels (9 cases)., Conclusion: Proximal anchor configuration impacts the incidence of UPROR due to IRC in MCGR. UIV at T2 and T3 compared to T4, and the use of all screws or combination of screws and hooks compared to all hooks were associated with a lower UPROR rate. The most common construct configuration was T2 UIV, three levels, six anchors, and all screws. The use of a combination of six anchors (screws or screws and hooks) across three levels with a UIV at T2 or T3 was associated with a lower UPROR rate. Additional research is needed to further evaluate the variables contributing to configuration selection and their association with IRC., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Background: Hip osteoarthritis (OA) is common in patients with adult spinal deformity (ASD). Limited data exist on the prevalence of hip OA in patients with ASD, or on its impact on baseline and postoperative alignment and patient-reported outcome measures (PROMs). Therefore, this paper will assess the prevalence and impact of hip OA on alignment and PROMs., Methods: Patients with ASD who underwent L1-pelvis or longer fusions were included. Two independent reviewers graded hip OA with the Kellgren-Lawrence (KL) classification and stratified it by severity into non-severe (KL grade 1 or 2) and severe (KL grade 3 or 4). Radiographic parameters and PROMs were compared among 3 patient groups: Hip-Spine (hip KL grade 3 or 4 bilaterally), Unilateral (UL)-Hip (hip KL grade 3 or 4 unilaterally), or Spine (hip KL grade 1 or 2 bilaterally)., Results: Of 520 patients with ASD who met inclusion criteria for an OA prevalence analysis, 34% (177 of 520) had severe bilateral hip OA and unilateral or bilateral hip arthroplasty had been performed in 8.7% (45 of 520). A subset of 165 patients had all data components and were examined: 68 Hip-Spine, 32 UL-Hip, and 65 Spine. Hip-Spine patients were older (67.9 ± 9.5 years, versus 59.6 ± 10.1 years for Spine and 65.8 ± 7.5 years for UL-Hip; p < 0.001) and had a higher frailty index (4.3 ± 2.6, versus 2.7 ± 2.0 for UL-Hip and 2.9 ± 2.0 for Spine; p < 0.001). At 1 year, the groups had similar lumbar lordosis, yet the Hip-Spine patients had a worse sagittal vertebral axis (SVA) measurement (45.9 ± 45.5 mm, versus 25.1 ± 37.1 mm for UL-Hip and 19.0 ± 39.3 mm for Spine; p = 0.001). Hip-Spine patients also had worse Veterans RAND-12 Physical Component Summary scores at baseline (25.7 ± 9.3, versus 28.7 ± 9.8 for UL-Hip and 31.3 ± 10.5 for Spine; p = 0.005) and 1 year postoperatively (34.5 ± 11.4, versus 40.3 ± 10.4 for UL-Hip and 40.1 ± 10.9 for Spine; p = 0.006)., Conclusions: This study of operatively treated ASD revealed that 1 in 3 patients had severe hip OA bilaterally. Such patients with severe bilateral hip OA had worse baseline SVA and PROMs that persisted 1 year following ASD surgery, despite correction of lordosis., Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: Funding for this study was received from DePuy Synthes Spine, NuVasive, and K2/Stryker. In addition, the International Spine Study Group reports grants to the foundation from Medtronic, Globus, Stryker, SI Bone, and Carlsmed. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/H962)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: This study was a retrospective multi-center comparative cohort study., Materials and Methods: A retrospective institutional database of operative adult spinal deformity patients was utilized. All fusions > 5 vertebral levels and including the sacrum/pelvis were eligible for inclusion. Revisions, 3 column osteotomies, and patients with < 2-year clinical follow-up were excluded. Patients were separated into 3 groups based on surgical approach: 1) posterior spinal fusion without interbody (PSF), 2) PSF with interbody (PSF-IB), and 3) anteroposterior (AP) fusion (anterior lumbar interbody fusion or lateral lumbar interbody fusion with posterior screw fixation). Intraoperative, radiographic, and clinical outcomes, as well as complications, were compared between groups with ANOVA and χ 2 tests., Results: One-hundred and thirty-eight patients were included for study (PSF, n = 37; PSF-IB, n = 44; AP, n = 57). Intraoperatively, estimated blood loss was similar between groups (p = 0.171). However, the AP group had longer operative times (547.5 min) compared to PSF (385.1) and PSF-IB (370.7) (p < 0.001). Additionally, fusion length was shorter in PSF-IB (11.4) compared to AP (13.6) and PSF (12.9) (p = 0.004). There were no differences between the groups in terms of change in alignment from preoperative to 2 years postoperative. There were no differences in clinical outcomes. While postoperative complications were largely similar between groups, operative complications were higher in the AP group (31.6%) compared to the PSF (5.4%) and PSF-IB (9.1) groups (p < 0.001)., Conclusion: While there were differences in intraoperative outcomes (operative time and fusion length), there were no differences in postoperative clinical or radiographic outcomes. AP fusion was associated with a higher rate of operative complications., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Due to recent advances in artificial intelligence (AI), language model applications can generate logical text output that is difficult to distinguish from human writing. ChatGPT (OpenAI) and Bard (subsequently rebranded as "Gemini"; Google AI) were developed using distinct approaches, but little has been studied about the difference in their capability to generate the abstract. The use of AI to write scientific abstracts in the field of spine surgery is the center of much debate and controversy., Objective: The objective of this study is to assess the reproducibility of the structured abstracts generated by ChatGPT and Bard compared to human-written abstracts in the field of spine surgery., Methods: In total, 60 abstracts dealing with spine sections were randomly selected from 7 reputable journals and used as ChatGPT and Bard input statements to generate abstracts based on supplied paper titles. A total of 174 abstracts, divided into human-written abstracts, ChatGPT-generated abstracts, and Bard-generated abstracts, were evaluated for compliance with the structured format of journal guidelines and consistency of content. The likelihood of plagiarism and AI output was assessed using the iThenticate and ZeroGPT programs, respectively. A total of 8 reviewers in the spinal field evaluated 30 randomly extracted abstracts to determine whether they were produced by AI or human authors., Results: The proportion of abstracts that met journal formatting guidelines was greater among ChatGPT abstracts (34/60, 56.6%) compared with those generated by Bard (6/54, 11.1%; P<.001). However, a higher proportion of Bard abstracts (49/54, 90.7%) had word counts that met journal guidelines compared with ChatGPT abstracts (30/60, 50%; P<.001). The similarity index was significantly lower among ChatGPT-generated abstracts (20.7%) compared with Bard-generated abstracts (32.1%; P<.001). The AI-detection program predicted that 21.7% (13/60) of the human group, 63.3% (38/60) of the ChatGPT group, and 87% (47/54) of the Bard group were possibly generated by AI, with an area under the curve value of 0.863 (P<.001). The mean detection rate by human reviewers was 53.8% (SD 11.2%), achieving a sensitivity of 56.3% and a specificity of 48.4%. A total of 56.3% (63/112) of the actual human-written abstracts and 55.9% (62/128) of AI-generated abstracts were recognized as human-written and AI-generated by human reviewers, respectively., Conclusions: Both ChatGPT and Bard can be used to help write abstracts, but most AI-generated abstracts are currently considered unethical due to high plagiarism and AI-detection rates. ChatGPT-generated abstracts appear to be superior to Bard-generated abstracts in meeting journal formatting guidelines. Because humans are unable to accurately distinguish abstracts written by humans from those produced by AI programs, it is crucial to exercise special caution and examine the ethical boundaries of using AI programs, including ChatGPT and Bard., (©Hong Jin Kim, Jae Hyuk Yang, Dong-Gune Chang, Lawrence G Lenke, Javier Pizones, René Castelein, Kota Watanabe, Per D Trobisch, Gregory M Mundis Jr, Seung Woo Suh, Se-Il Suk. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 26.06.2024.)

Study Design: Retrospective review of prospectively collected data., Objective: To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD)., Background: Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD., Patients and Methods: In total, 527 preoperative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full-body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation., Results: The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, and 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment ( P <0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt ( P =0.001) and sacrofemoral angle ( P <0.001), but increased knee flexion ( P =0.012). Regression analysis revealed that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100)., Conclusions: For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis., Competing Interests: The International Spine Study Group reports the following: grants to the foundation from Medtronic, Globus, Stryker, SI Bone, Carlsmed. The remaining authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background and Objectives: We sought to compare long-term clinical and radiographic outcomes in patients who underwent staged vs same-day circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD)., Methods: We reviewed staged and same-day cMIS ASD cases in a prospective multi-institution database to compare preoperative and 2-year clinical and radiographic parameters between cohorts., Results: A total of 85 patients with a 2-year follow-up were identified (27 staged, 58 same-day). Staged patients had more extensive surgeries and greater hospital length of stay (all P < .001). There were no significant differences in preoperative or 2-year postoperative clinical metrics between cohorts. Patients in the staged cohort also had greater preoperative coronal deformity and thus experienced greater reduction in coronal deformity at 2 years (all P < .01)., Conclusion: Patients undergoing staged or same-day cMIS correction had similar outcomes at 2 years postoperatively. Staged cMIS ASD correction may be more appropriate in patients with greater deformity, higher frailty, and who require longer, more extensive surgeries., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Background: The objective of this study was to evaluate if imbalance influences complication rates, radiological outcomes, and patient-reported outcomes (PROMs) following adult spinal deformity (ASD) surgery. Methods: ASD patients with baseline and 2-year radiographic and PROMs were included. Patients were grouped according to whether they answered yes or no to a recent history of pre-operative loss of balance. The groups were propensity-matched by age, pelvic incidence-lumbar lordosis (PI-LL), and surgical invasiveness score. Results: In total, 212 patients were examined (106 in each group). Patients with gait imbalance had worse baseline PROM measures, including Oswestry disability index (45.2 vs. 36.6), SF-36 mental component score (44 vs. 51.8), and SF-36 physical component score ( p < 0.001 for all). After 2 years, patients with gait imbalance had less pelvic tilt correction (-1.2 vs. -3.6°, p = 0.039) for a comparable PI-LL correction (-11.9 vs. -15.1°, p = 0.144). Gait imbalance patients had higher rates of radiographic proximal junctional kyphosis (PJK) (26.4% vs. 14.2%) and implant-related complications (47.2% vs. 34.0%). After controlling for age, baseline sagittal parameters, PI-LL correction, and comorbidities, patients with imbalance had 2.2-times-increased odds of PJK after 2 years. Conclusions: Patients with a self-reported loss of balance/unsteady gait have significantly worse PROMs and higher risk of PJK.

Study Design: Retrospective review of an adult deformity database., Objective: To identify pelvic incidence (PI) and age-appropriate physical function alignment targets using a component angle of T1-pelvic angle within the fusion to define correction and their relationship to proximal junctional kyphosis (PJK) and clinical outcomes., Summary of Background Data: In preoperative planning, a patient's PI is often utilized to determine the alignment target. In a trend toward more patient-specific planning, age-specific alignment has been shown to reduce the risk of mechanical failures. PI and age have not been analyzed with respect to defining a functional alignment., Methods: A database of patients with operative adult spinal deformity was analyzed. Patients fused to the pelvis and upper-instrumented vertebrae above T11 were included. Alignment within the fusion correlated with clinical outcomes and PI. Short form 36-Physical Component Score (SF36-PCS) normative data and PI were used to compute functional alignment for each patient. Overcorrected, under-corrected, and functionally corrected groups were determined using T10-pelvic angle (T10PA)., Results: In all, 1052 patients met the inclusion criteria. T10PA correlated with SF36-PCS and PI (R=0.601). At six weeks, 40.7% were functionally corrected, 39.4% were overcorrected, and 20.9% were under-corrected. The PJK incidence rate was 13.6%. Overcorrected patients had the highest PJK rate (18.1%) compared with functionally (11.3%) and under-corrected (9.5%) patients ( P <0.05). Overcorrected patients had a trend toward more PJK revisions. All groups improved in HRQL; however, under-corrected patients had the worst 1-year SF36-PCS offset relative to normative patients of equivalent age (-8.1) versus functional (-6.1) and overcorrected (-4.5), P <0.05., Conclusions: T10PA was used to determine functional alignment, an alignment based on PI and age-appropriate physical function. Correcting patients to functional alignment produced improvements in clinical outcomes, with the lowest rates of PJK. This patient-specific approach to spinal alignment provides adult spinal deformity correction targets that can be used intraoperatively., Competing Interests: T.S.P.— Altus: IP royalties Globus; Medical: Paid consultant; Medtronic: Paid consultant; Nuvasive: Paid consultant. G.M.M.—Nuvasive: IP royalties: Paid consultant; Seaspine: IP royalties; Paid consultant; Stryker: IP royalties; Viseon: Paid consultant. J.S.S.—Carlsmed: Paid consultant; Cerapedics: Paid consultant; DePuy: Research support; Nuvasive: IP royalties; Paid consultant, Research support; Zimmer: IP royalties, Paid consultant. J.G.—Acuity: IP royalties, Paid consultant; Expanding Innovations: Paid consultant; Medtronic: Board or committee member, IP royalties, Paid consultant, Paid presenter, and Research support; Nuvasive: IP royalties and Paid consultant; Stryker: Paid consultant. A.H.D.—EOS: Paid consultant; Medtronic: IP royalties and Paid consultant; Orthofix, Inc.: Paid consultant and Research support; Spineart: IP royalties and Paid consultant. E.O.K.—AO: Paid consultant; DePuy: Paid consultant; Medtronic: Paid consultant; Stryker: Paid consultant. C.A.—Biomet Spine: IP royalties; DePuy: IP royalties, Paid consultant, and Research support; K2M: IP royalties and Paid consultant; Medicrea: IP royalties and Paid consultant; Next Orthosurgical: IP royalties; Nuvasive: IP royalties; Stryker: IP royalties. R.S.B.— allosource: Research support; Alphatec Spine: Paid consultant; K2 Medical: IP royalties and Paid consultant; Nuvasive: IP royalties and Research support; Stryker: IP royalties. C.I.S.—Globus Medical: Research support; Medtronic: IP royalties, Paid presenter or speaker, and Research support; Nuvasive: IP royalties, Paid consultant, Research support, and Stock or stock Options; Proprio: Paid consultant. F.J.S.—K2M: IP royalties; Mainstay Medical: Paid consultant; Medtronic: IP royalties; Nuvasive: Research support; See Spine LLC: Stock or stock Options; Zimmer: IP royalties and Paid consultant. V.L.—Alphatec Spine: Paid consultant; Globus Medical: Paid consultant; Nuvasive: IP royalties; Stryker: Paid presenter or speaker. The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective cohort., Objective: To evaluate factors associated with the long-term durability of cost-effectiveness (CE) in ASD patients., Background: A substantial increase in costs associated with the surgical treatment for adult spinal deformity (ASD) has given precedence to scrutinize the value and utility it provides., Methods: We included 327 operative ASD patients with 5-year (5 Y) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. Utility was calculated using quality-adjusted life-years (QALY) utilizing the Oswestry Disability Index (ODI) converted to Short-Form Six-Dimension (SF-6D), with a 3% discount applied for its decline with life expectancy. The CE threshold of $150,000 was used for primary analysis., Results: Major and minor complication rates were 11% and 47% respectively, with 26% undergoing reoperation by 5 Y. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at 1Y, QALY gained at 2 Y of 0.171±0.183, and at 5 Y of 0.42±0.43. The cost per QALY at 2 Y was $414,885, which decreased to $142,058 at 5 Y.With the threshold of $150,000 for CE, 19% met CE at 2 Y and 56% at 5 Y. In those in which revision was avoided, 87% met cumulative CE till life expectancy. Controlling analysis depicted higher baseline CCI and pelvic tilt (PT) to be the strongest predictors for not maintaining durable CE to 5 Y (CCI OR: 1.821 [1.159-2.862], P=0.009) (PT OR: 1.079 [1.007-1.155], P=0.030)., Conclusions: Most patients achieved cost-effectiveness after four years postoperatively, with 56% meeting at five years postoperatively. When revision was avoided, 87% of patients met cumulative cost-effectiveness till life expectancy. Mechanical complications were predictive of failure to achieve cost-effectiveness at 2 Y, while comorbidity burden and medical complications were at 5 Y., Competing Interests: Conflicts of Interest: Peter Gust Passias, MD: Cerapedics: Other financial or material support. Cervical Scoliosis Research Society: Research support. Globus Medical: Paid presenter or speaker. Medtronic: Paid consultant. Royal Biologics: Paid consultant. Spine: Editorial or governing board. Spinevision: Other financial or material support. SpineWave: Paid consultant. JNS Spine: Editorial Board. JCM: Editorial Board. Justin S Smith, MD: Alphatec Spine: Stock or stock Options. Carlsmed: Paid consultant. Cerapedics: Paid consultant. DePuy: Research support. DePuy, A Johnson & Johnson Company: Paid consultant. Journal of Neurosurgery Spine: Editorial or governing board. Neurosurgery: Editorial or governing board. Nuvasive: IP royalties; Paid consultant; Research support. Operative Neurosurgery: Editorial or governing board. Scoliosis Research Society: Board or committee member. Spine Deformity: Editorial or governing board. Stryker: Paid consultant. Thieme: Publishing royalties, financial or material support. Zimmer: IP royalties; Paid consultant. Renaud Lafage, MS: Nemaris: Stock or stock Options. Jeffrey Gum, MD: Acuity: IP royalties; Paid consultant. Alan L. & Jacqueline B. Stuart Spine Research: Research support. Cerapedics: Research support. Cingulate Therapeutics: Stock or stock Options. DePuy, A Johnson & Johnson Company: Paid presenter or speaker. Global Spine Journal - Reviewer: Editorial or governing board. Intellirod Spine Inc.: Research support. K2M /Stryker: Board or committee member. MAZOR Surgical Technologies: Paid consultant. Medtronic: Board or committee member; Paid consultant; Research support. Norton Healthcare: Research support. Nuvasive: IP royalties; Paid consultant. Pfizer: Research support. Scoliosis Research Society: Research support. Spine Deformity - Reviewer: Editorial or governing board. Stryker: Paid consultant; Paid presenter or speaker. Texas Scottish Rite Hospital: Research support. The Spine Journal - Reviewer: Editorial or governing board. Breton G Line, BS: ISSGF: Paid consultant. Alan H Daniels, MD: EOS: Paid consultant. Medicrea: Paid consultant. Medtronic Sofamor Danek: Paid consultant. Novabone: Paid consultant. Orthofix, Inc.: Paid consultant; Research support. Southern Spine: IP royalties. Spineart: IP royalties; Paid consultant. Springer: Publishing royalties, financial or material support. Stryker: Paid consultant. D. Kojo Hamilton: European Spine Journal: Editorial or governing board. Nuvasive: Research support. Robert Kenneth Eastlack, MD: Aesculap/B.Braun: Paid consultant. Alphatec Spine: Stock or stock Options. Baxter: Paid consultant. Biedermann-Motech: Paid consultant. Carevature: Paid consultant; Stock or stock Options. Globus Medical: IP royalties. Invuity: Stock or stock Options. Medtronic: Paid consultant. Nocimed: Stock or stock Options. Nuvasive: IP royalties; Paid consultant; Research support; Stock or stock Options. Radius: Paid presenter or speaker. San Diego Spine Foundation: Board or committee member. Scoliosis Research Society: Board or committee member. Seaspine: IP royalties; Paid consultant; Stock or stock Options. SI Bone: IP royalties; Paid consultant. Society of Lateral Access Surgery: Board or committee member. Spine Innovations: Stock or stock Options. Stryker: Paid consultant. Gregory Michael Mundis Jr, MD: Carlsmed: Paid consultant. ISSGF: Research support. K2M: IP royalties. Nuvasive: IP royalties; Paid consultant; Research support. Scoliosis Research Society: Board or committee member. SeaSpine: Paid consultant. Stryker: Paid consultant. Viseon: Paid consultant. Andrew J Schoenfeld, MD: AAOS: Board or committee member. Journal of Bone and Joint Surgery - American: Editorial or governing board. North American Spine Society: Board or committee member. Spine: Editorial or governing board. Springer: Publishing royalties, financial or material support. Wolters Kluwer Health - Lippincott Williams & Wilkins: Publishing royalties, financial or material support. Eric O Klineberg, MD: AO Spine: Paid presenter or speaker; Research support. DePuy, A Johnson & Johnson Company: Paid consultant. Medicrea: Paid consultant. Medtronic: Paid consultant. Stryker: Paid consultant. Khaled M Kebaish, MD: DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Paid presenter or speaker; Research support. Orthofix, Inc.: IP royalties; Paid consultant. Orthofix, Inc., K2 medical Inc: Paid presenter or speaker. Scoliosis Research Society: Board or committee member. Stryker: IP royalties. Munish C Gupta, MD: AO Spine Faculty, travel: Board or committee member. DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Paid presenter or speaker. European Spine Journal-Advisory Board: Editorial or governing board. Global Spine Journal-Reviewer: Editorial or governing board. Globus Medical: IP royalties; Paid consultant. honorarium for faculty: Board or committee member. Innomed: IP royalties. Johnson & Johnson: Stock or stock Options. Medtronic: Paid consultant. Procter & Gamble: Stock or stock Options. Spine Deformity, Associate Editor: Editorial or governing board. SRS-IMAST & Education committee: Board or committee member. travel: Board or committee member. Wolters Kluwer Health - Lippincott Williams & Wilkins: Publishing royalties, financial or material support. Han Jo Kim, MD: AAOS: Board or committee member. Alphatec Spine: Paid consultant. AO SPINE: Board or committee member. Cervical Spine Research Society: Board or committee member. HSS Journal, Asian Spine Journal: Editorial or governing board. ISSGF: Research support. K2M: IP royalties. Scoliosis Research Society: Board or committee member. Zimmer: IP royalties. Robert A Hart, MD, FAAOS: American Orthopaedic Association: Board or committee member. Cervical Spine Research Society: Board or committee member. DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Paid presenter or speaker. Globus Medical: IP royalties; Paid consultant; Paid presenter or speaker. International Spine Study Group: Board or committee member. ISSLS Textbook of the Lumbar Spine: Editorial or governing board. Medtronic: Paid consultant; Paid presenter or speaker. North American Spine Society: Board or committee member. Orthofix, Inc.: Paid consultant; Paid presenter or speaker. Scoliosis Research Society: Board or committee member. SeaSpine: IP royalties. Spine Connect: Stock or stock Options. Western Ortho Assn: Board or committee member. Christopher Ames, MD: Biomet Spine: IP royalties. DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Research support. Global Spine Analytics - Director: Other financial or material support. International Spine Study Group (ISSG): Research support. International Spine Study Group (ISSG) - Executive Committee: Other financial or material support. K2M: IP royalties; Paid consultant. Medicrea: IP royalties; Paid consultant. Medtronic: Paid consultant. Next Orthosurgical: IP royalties. Nuvasive: IP royalties. Operative Neurosurgery - Editorial Board: Other financial or material support. Scoliosis Research Society (SRS) - Grant Funding: Other financial or material support. Stryker: IP royalties. Titan Spine: Research support. Christopher I Shaffrey, MD: AANS: Board or committee member. Cervical Spine Research Society: Board or committee member. DePuy, A Johnson & Johnson Company: Paid presenter or speaker; Research support. Globus Medical: Research support. Medtronic: Other financial or material support; Paid consultant. Medtronic Sofamor Danek: IP royalties; Paid presenter or speaker; Research support. Neurosurgery RRC: Board or committee member. Nuvasive: IP royalties; Paid consultant; Paid presenter or speaker; Research support; Stock or stock Options. Proprio: Paid consultant. Scoliosis Research Society: Board or committee member. SI Bone: IP royalties. Spinal Deformity: Editorial or governing board. Spine: Editorial or governing board. Frank J Schwab, MD: DePuy, A Johnson & Johnson Company: Research support. Globus Medical: Paid consultant; Paid presenter or speaker. K2M: IP royalties; Paid consultant; Paid presenter or speaker. Medicrea: Paid consultant. Medtronic: Paid consultant. Medtronic Sofamor Danek: IP royalties; Paid presenter or speaker. Nuvasive: Research support. Scoliosis Research Society: Board or committee member. spine deformity: Editorial or governing board. Stryker: Research support. VP of International Spine Society Group (ISSG): Board or committee member. Zimmer: IP royalties; Paid consultant; Paid presenter or speaker. Virginie Lafage, PhD: DePuy, A Johnson & Johnson Company: Paid presenter or speaker. European Spine Journal: Editorial or governing board. Globus Medical: Paid consultant. International Spine Study Group: Board or committee member. Nuvasive: IP royalties. Scoliosis Research Society: Board or committee member. The Permanente Medical Group: Paid presenter or speaker. Richard A Hostin, MD: DePuy, A Johnson & Johnson Company: Paid consultant. Robert Shay Bess, MD: allosource: Paid consultant; Research support. Biomet: Research support. DePuy, A Johnson & Johnson Company: Paid consultant; Research support. EOS: Research support. Globus Medical: Research support. k2 medical: IP royalties; Paid consultant; Paid presenter or speaker; Research support. Medtronic Sofamor Danek: Research support. North American Spine Society: Board or committee member. Nuvasive: IP royalties; Research support. Orthofix, Inc.: Research support. Scoliosis Research Society: Board or committee member. Stryker: IP royalties; Paid presenter or speaker. Douglas C Burton, MD, FAAOS: Bioventus: Research support. DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Research support. Pfizer: Research support. Progenerative Medical: Stock or stock Options. Scoliosis Research Society: Board or committee member. Spine Deformity: Editorial or governing board. Other Authors: None., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective review of prospectively collected data., Objective: To analyze the impact of operative room (OR) time in adult spinal deformity (ASD) surgery on patient outcomes., Background: It is currently unknown if OR time in ASD patients matched for deformity severity and surgical invasiveness is associated with patient outcomes., Materials and Methods: ASD patients with baseline and two-year postoperative radiographic and patient-reported outcome measures (PROM) data, undergoing a posterior-only approach for long fusion (>L1-Ilium) were included. Patients were grouped into short OR time (<40th percentile: <359 min) and long OR time (>60th percentile: >421 min). Groups were matched by age, baseline deformity severity, and surgical invasiveness. Demographics, radiographic, PROM data, fusion rate, and complications were compared between groups at baseline and two years follow-up., Results: In total, 270 patients were included for analysis: the mean OR time was 286 minutes in the short OR group versus 510 minutes in the long OR group ( P <0.001). Age, gender, percent of revision cases, surgical invasiveness, pelvic incidence minus lumbar lordosis, sagittal vertical axis, and pelvic tilt were comparable between groups ( P >0.05). Short OR had a slightly lower body mass index than the short OR group ( P <0.001) and decompression was more prevalent in the long OR time ( P =0.042). Patients in the long group had greater hospital length of stay ( P =0.02); blood loss ( P <0.001); proportion requiring intensive care unit ( P =0.003); higher minor complication rate ( P =0.001); with no significant differences for major complications or revision procedures ( P >0.5). Both groups had comparable radiographic fusion rates ( P =0.152) and achieved improvement in sagittal alignment measures, Oswestry disability index, and Short Form-36 ( P <0.001)., Conclusion: Shorter OR time for ASD correction is associated with a lower minor complication rate, a lower estimated blood loss, fewer intensive care unit admissions, and a shorter hospital length of stay without sacrificing alignment correction or PROMs. Maximizing operative efficiency by minimizing OR time in ASD surgery has the potential to benefit patients, surgeons, and hospital systems., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Depression has been implicated with worse immediate postoperative outcomes in adult spinal deformity (ASD) correction, yet the specific impact of depression on those patients undergoing minimally invasive surgery (MIS) requires further clarity. This study aimed to evaluate the role of depression in the recovery of patients with ASD after undergoing MIS., Methods: Patients who underwent MIS for ASD with a minimum postoperative follow-up of 1 year were included from a prospectively collected, multicenter registry. Two cohorts of patients were identified that consisted of either those affirming or denying depression on preoperative assessment. The patient-reported outcome measures (PROMs) compared included scores on the Oswestry Disability Index (ODI), numeric rating scale (NRS) for back and leg pain, Scoliosis Research Society Outcomes Questionnaire (SRS-22), SF-36 physical component summary, SF-36 mental component summary (MCS), EQ-5D, and EQ-5D visual analog scale., Results: Twenty-seven of 147 (18.4%) patients screened positive for preoperative depression. The nondepressed cohort had an average of 4.83 levels fused, and the depressed cohort had 5.56 levels fused per patient (p = 0.267). At 1-year follow-up, 10 patients still reported depression, representing a 63% decrease. Postoperatively, both cohorts demonstrated improvement in their PROMs; however, at 1-year follow-up, those without depression had statistically better outcomes based on the EQ-5D, MCS, and SRS-22 scores (p < 0.05). Patients with depression continued to experience higher NRS leg scores at 1-year follow-up (3.63 vs 2.22, p = 0.018). After controlling for covariates, the authors found that depression significantly impacted only 1-year follow-up MCS scores (β = 8.490, p < 0.05)., Conclusions: Depressed and nondepressed patients reported similar improvements after MIS surgery, except MCS scores were more likely to improve in nondepressed patients.

Study Design/setting: This was a retrospective cohort study., Background: Little is known of the intersection between surgical invasiveness, cervical deformity (CD) severity, and frailty., Objective: The aim of this study was to investigate the outcomes of CD surgery by invasiveness, frailty status, and baseline magnitude of deformity., Methods: This study included CD patients with 1-year follow-up. Patients stratified in high deformity if severe in the following criteria: T1 slope minus cervical lordosis, McGregor's slope, C2-C7, C2-T3, and C2 slope. Frailty scores categorized patients into not frail and frail. Patients are categorized by frailty and deformity (not frail/low deformity; not frail/high deformity; frail/low deformity; frail/high deformity). Logistic regression assessed increasing invasiveness and outcomes [distal junctional failure (DJF), reoperation]. Within frailty/deformity groups, decision tree analysis assessed thresholds for an invasiveness cutoff above which experiencing a reoperation, DJF or not achieving Good Clinical Outcome was more likely., Results: A total of 115 patients were included. Frailty/deformity groups: 27% not frail/low deformity, 27% not frail/high deformity, 23.5% frail/low deformity, and 22.5% frail/high deformity. Logistic regression analysis found increasing invasiveness and occurrence of DJF [odds ratio (OR): 1.03, 95% CI: 1.01-1.05, P =0.002], and invasiveness increased with deformity severity ( P <0.05). Not frail/low deformity patients more often met Optimal Outcome with an invasiveness index <63 (OR: 27.2, 95% CI: 2.7-272.8, P =0.005). An invasiveness index <54 for the frail/low deformity group led to a higher likelihood of meeting the Optimal Outcome (OR: 9.6, 95% CI: 1.5-62.2, P =0.018). For the frail/high deformity group, patients with a score <63 had a higher likelihood of achieving Optimal Outcome (OR: 4.8, 95% CI: 1.1-25.8, P =0.033). There was no significant cutoff of invasiveness for the not frail/high deformity group., Conclusions: Our study correlated increased invasiveness in CD surgery to the risk of DJF, reoperation, and poor clinical success. The thresholds derived for deformity severity and frailty may enable surgeons to individualize the invasiveness of their procedures during surgical planning to account for the heightened risk of adverse events and minimize unfavorable outcomes., Competing Interests: P.G.P.: Allosource: Other financial or material support; Cervical Scoliosis Research Society: Research support; Globus Medical: Paid presenter or speaker; Medtronic: Paid consultant; Royal Biologics: Paid consultant; Spine: Editorial or governing board; SpineWave: Paid consultant; Terumo: Paid consultant; Zimmer: Paid presenter or speaker. V.L.: DePuy, A Johnson & Johnson Company: Paid presenter or speaker; European Spine Journal : Editorial or governing board; Globus Medical: Paid consultant; International Spine Study Group: Board or committee member; Nuvasive: IP royalties; Scoliosis Research Society: Board or committee member; The Permanente Medical Group: Paid presenter or speaker. R.F.: Nemaris: Stock or stock options. H.J.K.: AAOS: Board or committee member; Alphatec Spine: Paid consultant; AO SPINE: Board or committee member; Cervical Spine Research Society: Board or committee member; HSS Journal , Asian Spine Journal : Editorial or governing board; ISSGF: Research support; K2M: IP royalties; Scoliosis Research Society: Board or committee member; Zimmer: IP royalties. A.H.D.: EOS: Paid consultant; Medicrea: Paid consultant; Medtronic Sofamor Danek: Paid consultant; Novabone: Paid consultant; Orthofix Inc.: Paid consultant; Research support; Southern Spine: IP royalties; Spineart: IP royalties; Paid consultant; Springer: Publishing royalties, financial or material support; Stryker: Paid consultant. J.L.G.: Acuity: IP royalties; Paid consultant; Alan L. & Jacqueline B. 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E.O.K.: AO Spine: Paid presenter or speaker; Research support; DePuy, A Johnson & Johnson Company: Paid consultant; Medicrea: Paid consultant; Medtronic: Paid consultant; Stryker: Paid consultant. B.G.L.: ISSGF: Paid consultant. R.A.H.: American Orthopaedic Association: Board or committee member; Cervical Spine Research Society: Board or committee member; DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Paid presenter or speaker; Globus Medical: IP royalties; Paid consultant; Paid presenter or speaker; International Spine Study Group: Board or committee member; ISSLS Textbook of the Lumbar Spine: Editorial or governing board; Medtronic: Paid consultant; Paid presenter or speaker; North American Spine Society: Board or committee member; Orthofix Inc.: Paid consultant; Paid presenter or speaker; Scoliosis Research Society: Board or committee member; SeaSpine: IP royalties; Spine Connect: Stock or stock Options; Western Ortho Assn: Board or committee member. 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P.V.M.: AANS/CNS Spine Section and Scoliosis Research Society: Board or committee member; American Association of Neurological Surgeons: Board or committee member; Cervical Spine Research Society: Board or committee member; Congress of Neurological Surgeons: Board or committee member; DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Global Spine Journal : Editorial or governing board; Globus Medical: Paid consultant; International Spine Study Group: Research support; Neurosurgery: Editorial or governing board; NREF: Research support; Spinal Deformity: Editorial or governing board; Spinicity/ISD: Stock or stock Options; Springer: Publishing royalties, financial or material support; Stryker: Paid consultant; Taylor and Francis: Publishing royalties, financial or material support; Thieme: Publishing royalties, financial or material support; World Neurosurgery: Editorial or governing board. 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C.P.A.: Biomet Spine: IP royalties; DePuy, A Johnson & Johnson Company: IP royalties; Paid consultant; Research support; Global Spine Analytics—Director: Other financial or material support; International Spine Study Group (ISSG): Research support; International Spine Study Group (ISSG)—Executive Committee: Other financial or material support; K2M: IP royalties; Paid consultant; Medicrea: IP royalties; Paid consultant; Medtronic: Paid consultant; Next Orthosurgical: IP royalties; Nuvasive: IP royalties; Operative Neurosurgery—Editorial Board: Other financial or material support; Scoliosis Research Society (SRS)—Grant Funding: Other financial or material support; Stryker: IP royalties; Titan Spine: Research support. J.S.S.: Alphatec Spine: Stock or stock Options; Carlsmed: Paid consultant; Cerapedics: Paid consultant; DePuy: Research support; DePuy, A Johnson & Johnson Company: Paid consultant; Journal of Neurosurgery Spine : Editorial or governing board; Neurosurgery: Editorial or governing board; Nuvasive: IP royalties; Paid consultant; Research support; Operative Neurosurgery: Editorial or governing board; Scoliosis Research Society: Board or committee member; Spine Deformity : Editorial or governing board; Stryker: Paid consultant; Thieme: Publishing royalties, financial or material support; Zimmer: IP royalties; paid consultant. The remaining authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Cadaveric study., Objectives: The purpose of this study was to compare a novel, integrated 3D navigational system (NAV) and conventional fluoroscopy in the accuracy, efficiency, and radiation exposure of thoracolumbar percutaneous pedicle screw (PPS) placement., Methods: Twelve skeletally mature cadaveric specimens were obtained for twelve individual surgeons. Each participant placed bilateral PS at 11 segments, from T8 to S1. Prior to insertion, surgeons were randomized to the sequence of techniques and the side (left or right). Following placement, a CT scan of the spine was obtained for each cadaver, and an independent reviewer assessed the accuracy of screw placement using the Gertzbein grading system. Outcome metrics of interest included a comparison of breach incidence/severity, screw placement time, total procedure time, and radiation exposure between the techniques. Bivariate statistics were employed to compare outcomes at each level., Results: A total of 262 screws (131 using each technique) were placed. The incidence of cortical breaches was significantly lower with NAV compared to FG (9% vs 18%; P = .048). Of breaches with NAV, 25% were graded as moderate or severe compared to 39% in the FG subgroup ( P = .034). Median time for screw placement was significantly lower with NAV (2.7 vs 4.1 min/screw; P = .012), exclusive of registration time. Cumulative radiation exposure to the surgeon was significantly lower for NAV-guided placement (9.4 vs 134 μGy, P = .02)., Conclusions: The use of NAV significantly decreased the incidence of cortical breaches, the severity of screw breeches, screw placement time, and radiation exposure to the surgeon when compared to traditional FG., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: RKE, JSU, PP, and GMM have consulting agreements with Nuvasive. LS is employed as a biostatistician by Nuvasive. All data were analyzed by independent, academic clinicians with no financial conflicts of interest.

Study Design: Retrospective cohort study., Objectives: Identify optimal lumbar lordosis in adult deformity correction to achieve age-adjusted targets and sustained alignment., Methods: Surgical adult spinal deformity patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regression analysis was used to identify the relationship between regional curvatures (LL and TK) that enabled achievement of a given global alignment (T1 pelvic angle, TPA) based on pelvic incidence (PI)., Results: 347 patients out of 1048 available reached their age-adjusted TPA within 5° (60-year-old, 72% women, body mass index 29 ± 6.2). They had a significant improvement in all sagittal parameters (except PI) from pre-operative baseline to 1 year following surgery ( P < .001). Multilinear regression predicting L1-S1 based on TK, TPA, and PI demonstrated excellent results (R2 = .85). Simplification of the coefficients of prediction combined with a conversion to an age-based formula led to the following: LL = PI - 0.3TK - 0.5Age + 10. Internal validation of the formula led to a mean error of -.4°, and an absolute error of 5.0°. Internal validation on patients with an age-adjusted alignment revealed similar accuracy across the entire age-adjusted TPA spectrum (ranges of LL errors: ME = .2° to 1.7°, AE = 4.0° to 5.3°)., Conclusion: This study provides a simple guideline to identify the amount of LL needed to reach a given alignment (i.e., age-adjusted target) based on PI and associated TK. Implementation of this predictive formula during pre-operative surgical planning may help to reduce unexpected sub-optimal post-operative alignment outcomes., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective review of prospective multicenter data., Objectives: This study aimed to investigate the shape of TK before and after fusion in ASD patients treated with long fusion., Methods: ASD patients undergoing posterior spinal fusions including at least T5 to L1 without prior fusion extending to the thoracic spine were included. Patients were categorized based on the preoperative T1-T12 kyphosis into: Hypo-TK (if < 30°), Normal-TK, and Hyper-TK (if > 70°). Regional kyphosis at T10-L1 (Distal), T5-T10 (Middle), and T1-T5 (Proximal) and their relative contributions to total kyphosis were compared between groups, and the pre-to postoperative changes were investigated using paired t test., Results: In total, 329 patients were included in this analysis (mean age: 57 ± 16 years, 79.6% female). Preoperative T1-T12 TK for the entire cohort was 40.9 ± 2° (32% Hypo-TK, 11% Hyper-TK, 57% Normal-TK). The Hypo-TK group had the smallest distal TK (5.9 vs 17.1 & 26.0), and middle TK (8.0 vs 25.3 & 45.4), but the percentage of contribution to total kyphosis was not significantly different (Distal: 24.1% vs 34.1% vs 32.8%; Middle: 46.6% vs 53.9% vs 56.8%, all P > .1). Postoperatively, T1-12 TK increased significantly (40.9 ± 2.0° vs 57.8 ± 17.6°). Each group had a decrease in distal kyphosis (Hypo-TK 2.6 ± 10.4°; Normal-TK 8.9 ± 11.5°; Hyper-TK 14.9 ± 12°, all P < .05). The middle kyphosis significantly decreased for Hyper-TK (11.8 ± 12.4) and increased for both Normal-TK and Hypo-TK (3.8 ± 11° and 14.2 ± 11°). Proximal TK increased significantly for all groups by 14-18°. Deterioration from Normal-TK to Hyper-TK postoperatively was associated with lower rate of patient satisfaction (59.6% vs 77.3%, P = .032)., Conclusions: Posterior spinal fusion for ASD alters the magnitude and shape of thoracic kyphosis. While 60% of patients had a normal TK at baseline, 30% of those patients developed iatrogenic hyperkyphosis postoperatively. Patients with baseline hypokyphosis were more likely to be corrected to normal TK than hyperkyphotic patients. Future research should investigate TK restoration in ASD and its impact on clinical outcomes and complications., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Multicenter cohort., Objectives: A report from the International Spine Study Group (ISSG) noted that surgeons failed to achieve alignment goals in nearly two-thirds of 266 complex adult deformity surgery (CADS) cases. We assess whether personalized interbody spacers are associated with improved rates of achieving goal alignment following adult spinal deformity (ASD) surgery., Methods: ASD patients were included if their surgery utilized 3D-printed personalized interbody spacer(s) and they met ISSG CADS inclusion criteria. Planned alignment was personalized by the surgeon during interbody planning. Planned vs achieved alignment was assessed and compared with the ISSG CADS series that used stock interbodies., Results: For 65 patients with personalized interbodies, 62% were women, mean age was 70.3 years (SD = 8.3), mean instrumented levels was 9.9 (SD = 4.1), and the mean number of personalized interbodies per patient was 2.2 (SD = .8). Segmental alignment was achieved close to plan for levels with personalized interbodies, with mean difference between goal and achieved as follows: intervertebral lordosis = .9° (SD = 5.2°), intervertebral coronal angle = .1° (SD = 4.7°), and posterior disc height = -0.1 mm (SD = 2.3 mm). Achieved pelvic incidence-to-lumbar lordosis mismatch (PI-LL) correlated significantly with goal PI-LL (r = .668, P < .001). Compared with the ISSG CADS cohort, utilization of personalized interbodies resulted in significant improvement in achieving PI-LL <5° of plan ( P = .046) and showed a significant reduction in cases with PI-LL >15° of plan ( P = .012)., Conclusions: This study supports use of personalized interbodies as a means of better achieving goal segmental sagittal and coronal alignment and significantly improving achievement of goal PI-LL compared with stock devices., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Intraoperative neuromonitoring (IONM) has become commonplace in assessing neurological integrity during lateral approaches to lumbar interbody fusion surgeries. Neuromonitoring is designed to aid surgeons in identifying the potential for intraoperative nerve injury and reducing associated postoperative complications. However, standardized protocols for neuromonitoring have not been provided, and outcomes are not well described. The purpose of this study was to provide a standardized protocol for IONM, and to describe clinical outcomes in a cohort of individuals who underwent lateral lumbar interbody fusion (LLIF) surgery., Methods: A retrospective review of 169 consecutive patients who underwent LLIF surgery at a single institution from October 2014 to October 2016 was performed. Patient characteristics, intraoperative details, clinical outcomes, and postoperative deficits (PODs) were compared between patients who did and did not trigger IONM alerts, and between patients who did and did not demonstrate a POD. A protocol for IONM decision-making was generated based on these observations., Results: Most patients (91.7%) underwent surgery for a degenerative spine condition. Twenty-three patients (13.6%) triggered neuromonitoring alerts, and 16 patients (9.5%) demonstrated a POD. Leg pain, back pain, and disability improved significantly (p < 0.045), and 2 patients had both motor and sensory deficits at the 12-week postoperative time point. Patients with a POD demonstrated greater operating room time (p = 0.034) and a greater number of interbody fusion levels (p = 0.015) but were less likely to have triggered a neuromonitoring alert (p = 0.04). There was no association between retractor time and POD (p = 0.98). When an IONM protocol was followed, individuals who experienced a POD were less likely to trigger an alert than those who did not experience a POD (p = 0.04)., Conclusions: This study provides a protocol algorithm for IONM alert responses in patients undergoing LLIF surgery. PODs are most associated with multilevel fusion, and patients with alerts had a low rate of persistent deficit. Future research is needed to validate these findings using a more rigorous comparative study design.

Study Design: Retrospective review of a prospectively enrolled adult spinal deformity (ASD) database., Objective: To investigate what patient factors elevate the risk of sub-optimal outcomes after deformity correction., Background: Currently, it is unknown what factors predict a poor outcome after adult spinal deformity surgery, which may require increased preoperative consideration and counseling., Materials and Methods: Patients >18 yrs undergoing surgery for ASD(scoliosis≥20°, SVA≥5 cm, PT≥25°, or TK≥60°). An unsatisfactory outcome was defined by the following categories met at two years: (1) clinical: deteriorating in ODI at two years follow-up (2) complications/reoperation: having a reoperation and major complication were deemed high risk for poor outcomes postoperatively (HR). Multivariate analyses assessed predictive factors of HR patients in adult spinal deformity patients., Results: In all, 633 adult spinal deformity (59.9 yrs, 79% F, 27.7 kg/m 2, CCI: 1.74) were included. Baseline severe Schwab modifier incidence (++): 39.2% pelvic incidence and lumbar lordosis, 28.8% sagittal vertical axis, 28.9% PT. Overall, 15.5% of patients deteriorated in ODI by two years, while 7.6% underwent reoperation and had a major complication. This categorized 11 (1.7%) as HR. HR were more comorbid in terms of arthritis (73%), heart disease (36%), and kidney disease (18%), P <0.001. Surgically, HR had greater EBL (4431ccs) and underwent more osteotomies (91%), specifically Ponte(36%) and Three Column Osteotomies(55%), which occurred more at L2(91%). HR underwent more PLIFs (45%) and had more blood transfusion units (2641ccs), all P <0.050. The multivariate regression determined a combination of a baseline Distress and Risk Assessment Method score in the 75th percentile, having arthritis and kidney disease, a baseline right lower extremity motor score ≤3, cSVA >65 mm, C2 slope >30.2°, CTPA >5.5° for an R2 value of 0.535 ( P <0.001)., Conclusions: When addressing adult spine deformities, poor outcomes tend to occur in severely comorbid patients with major baseline psychological distress scores, poor neurologic function, and concomitant cervical malalignment., Competing Interests: P.G.P.: Cerapedics: Other financial or material support; Cervical Scoliosis Research Society: Research support; Globus Medical: Paid presenter or speaker; Medtronic: Paid consultant; Royal Biologics: Paid consultant; Spine: Editorial or governing board; Spinevision: Other financial or material support; SpineWave: Paid consultant; Terumo: Paid consultant; The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Optimal orientation for magnetically controlled growing rods (MCGRs) is unclear. The objective of this study was to investigate associations of rod orientation with implant-related complications (IRCs) and spinal height gains. Using an international early-onset scoliosis (EOS) database, we retrospectively reviewed 57 patients treated with dual MCGRs from May 2013 to July 2015 with minimum 2-year follow-up. Outcomes of interest were IRCs and left/right rod length gains and thoracic (T1-T12) and spinal (T1-S1) heights. We compared patients with two rods lengthened in the cephalad ( standard; n  = 18) versus opposite ( offset; n  = 39) directions. Groups did not differ in age, sex, BMI, duration of follow-up, EOS cause, ambulatory status, primary curve magnitude, baseline thoracic height, or number of distractions/year. We compared patients whose constructs used ≥1 cross-link (CL group; n  = 22) versus no CLs (NCL group; n  = 35), analyzing thoracic height gains per distraction ( α  = 0.05). Offset and standard groups did not differ in left or right rod length gains overall or per year or in thoracic or spinal height gain. Per distraction, the CL and NCL groups did not differ significantly in left or right rod length or thoracic or spinal height gain. Complications did not differ significantly between rod orientation groups or between CL groups. MCGR orientation and presence of cross-links were not associated with differences in rod length gain, thoracic height, spinal height, or IRCs at 2-year follow-up. Surgeons should feel comfortable using either MCGR orientation. Level of evidence: 3, retrospective., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: The aim of this study was to determine if spinal deformity patients with L5 sacralization should have pelvic incidence (PI) and other spinopelvic parameters measured from the L5 or S1 endplate., Methods: This study was a multicenter retrospective comparative cohort study comprising a large database of adult spinal deformity (ASD) patients and a database of asymptomatic individuals. Linear regression modeling was used to determine normative T1 pelvic angle (TPA) and PI - lumbar lordosis (LL) mismatch (PI-LL) based on PI and age in a database of asymptomatic subjects. In an ASD database, patients with radiographic evidence of L5 sacralization had the PI, LL, and TPA measured from the superior endplate of S1 and then also from L5. The differences in TPA and PI-LL from normative were calculated in the sacralization cohort relative to L5 and S1 and correlated to the Oswestry Disability Index (ODI). Patients were grouped based on the Scoliosis Research Society (SRS)-Schwab PI-LL modifier (0, +, or ++) using the L5 PI-LL and S1 PI-LL. Baseline ODI and SF-36 Physical Component Summary (PCS) scores were compared across and within groups., Results: Among 1179 ASD patients, 276 (23.4%) had transitional anatomy, 176 with sacralized L5 (14.9%) and 100 (8.48%) with lumbarization of S1. The 176 patients with sacralized L5 were analyzed. When measured using the L5 superior endplate, pelvic parameters were significantly smaller than those measured relative to S1 (PI: 24.5° ± 11.0° vs 55.7° ± 12.0°, p = 0.001;TPA: 11.2° ± 12.0° vs 20.3° ± 12.5°, p = 0.001; and PI-LL: 0.67° ± 21.1° vs 11.4° ± 20.8°, p = 0.001). When measured from S1, 76 (43%), 45 (25.6%), and 55 (31.3%) patients had SRS-Schwab PI-LL modifiers of 0, +, and ++, respectively, compared with 124 (70.5%), 22 (12.5%), and 30 (17.0%), respectively, when measured from L5. There were significant differences in ODI and PCS scores as the SRS-Schwab grade increased regardless of L5 or S1 measurement. The L5 group had lower PCS functional scores for SRS-Schwab modifiers 0 and ++ relative to same grades in the S1 group. Offset from normative TPA (0.5° ± 11.1° vs 9.6° ± 10.8°, p = 0.001) and PI-LL (4.5° ± 20.4° vs 15.2° ± 19.3°, p = 0.001) were smaller when measuring from L5. Moreover, S1 measurements were more correlated with health status by ODI (TPA offset from normative: S1, R = 0.326 vs L5, R = 0.285; PI-LL offset from normative: S1, R = 0.318 vs L5, R = 0.274)., Conclusions: Measuring the PI and spinopelvic parameters at L5 in sacralized anatomy results in underestimating spinal deformity and is less correlated with health-related quality of life. Surgeons may consider measuring PI and spinopelvic parameters relative to S1 rather than at L5 in patients with a sacralized L5.

This article focuses on the treatment of sagittal spinal deformity using a minimally invasive technique, anterior column realignment. Traditional methods to address sagittal spine deformity have been associated with high morbidity, long operative times, and excessive blood loss. This technique uses a minimally invasive lateral retroperitoneal approach to release the anterior longitudinal ligament and apply a hyperlordotic implant for interbody fusion to restore lumbar lordosis and sagittal alignment., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Height gain following a surgical procedure for patients with adult spinal deformity (ASD) is incompletely understood, and it is unknown if height gain correlates with patient-reported outcome measures (PROMs)., Methods: This was a retrospective cohort study of patients undergoing ASD surgery. Patients with baseline, 6-week, and subanalysis of 1-year postoperative full-body radiographic and PROM data were examined. Correlation analysis examined relationships between vertical height differences and PROMs. Regression analysis was utilized to preoperatively estimate T1-S1 and S1-ankle height changes., Results: This study included 198 patients (mean age, 57 years; 69% female); 147 patients (74%) gained height. Patients with height loss, compared with those who gained height, experienced greater increases in thoracolumbar kyphosis (2.81° compared with -7.37°; p < 0.001) and thoracic kyphosis (12.96° compared with 4.42°; p = 0.003). For patients with height gain, sagittal and coronal alignment improved from baseline to postoperatively: 25° to 21° for pelvic tilt (PT), 14° to 3° for pelvic incidence - lumbar lordosis (PI-LL), and 60 mm to 17 mm for sagittal vertical axis (SVA) (all p < 0.001). The full-body mean height gain was 7.6 cm, distributed as follows: sella turcica-C2, 2.9 mm; C2-T1, 2.8 mm; T1-S1 (trunk gain), 3.8 cm; and S1-ankle (lower-extremity gain), 3.3 cm (p < 0.001). T1-S1 height gain correlated with the thoracic Cobb angle correction and the maximum Cobb angle correction (p = 0.002). S1-ankle height gain correlated with the corrections in PT, PI-LL, and SVA (p < 0.001). T1-ankle height gain correlated with the corrections in PT (p < 0.001) and SVA (p = 0.03). Trunk height gain correlated with improved Scoliosis Research Society (SRS-22r) Appearance scores (r = 0.20; p = 0.02). Patient-Reported Outcomes Measurement Information System (PROMIS) Depression scores correlated with S1-ankle height gain (r = -0.19; p = 0.03) and C2-T1 height gain (r = -0.18; p = 0.04). A 1° correction in a thoracic scoliosis Cobb angle corresponded to a 0.2-mm height gain, and a 1° correction in a thoracolumbar scoliosis Cobb angle resulted in a 0.25-mm height gain. A 1° improvement in PI-LL resulted in a 0.2-mm height gain., Conclusions: Most patients undergoing ASD surgery experienced height gain following deformity correction, with a mean full-body height gain of 7.6 cm. Height gain can be estimated preoperatively with predictive ratios, and height gain was correlated with improvements in reported SRS-22r appearance and PROMIS scores., Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/H620 )., (Copyright © 2023 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved.)

Background: While reimbursement is centered on 90-day outcomes, many patients may still achieve optimal, long-term outcomes following adult spinal deformity (ASD) surgery despite transient short-term complications., Objective: Compare long-term clinical success and cost-utility between patients achieving optimal realignment and suboptimally aligned peers., Study Design/setting: Retrospective cohort study of a prospectively collected multicenter database., Methods: ASD patients with two-year (2Y) data included. Groups were propensity score matched (PSM) for age, frailty, body mass index (BMI), Charlson Comorbidity Index (CCI), and baseline deformity. Optimal radiographic criteria are defined as meeting low deformity in all three (Scoliosis Research Society) SRS-Schwab parameters or being proportioned in Global Alignment and Proportionality (GAP). Cost-per-QALY was calculated for each time point. Multivariable logistic regression analysis and ANCOVA (analysis of covariance) adjusting for baseline disability and deformity (pelvic incidence (PI), pelvic incidence minus lumbar lordosis (PI-LL)) were used to determine the significance of surgical details, complications, clinical outcomes, and cost-utility., Results: A total of 930 patients were considered. Following PSM, 253 "optimal" (O) and 253 "not optimal" (NO) patients were assessed. The O group underwent more invasive procedures and had more levels fused. Analysis of complications by two years showed that the O group suffered less overall major (38% vs. 52%, p = 0.021) and major mechanical complications (12% vs. 22%, p = 0.002), and less reoperations (23% vs. 33%, p = 0.008). Adjusted analysis revealed O patients more often met MCID (minimal clinically important difference) in SF-36 PCS, SRS-22 Pain, and Appearance. Cost-utility-adjusted analysis determined that the O group generated better cost-utility by one year and maintained lower overall cost and costs per QALY (both p < 0.001) at two years., Conclusions: Fewer late complications (mechanical and reoperations) are seen in optimally aligned patients, leading to better long-term cost-utility overall. Therefore, the current focus on avoiding short-term complications may be counterproductive, as achieving optimal surgical correction is critical for long-term success.

Purpose: It is unknown whether the biomechanics of the posterior ligamentous complex (PLC) are impaired in individuals undergoing surgery for adult spinal deformity (ASD). Characterizing these properties may improve our understanding of proximal junctional kyphosis (PJK; defined as proximal junctional angle [PJA] of >10 deg from UIV-1 to UIV + 2), as well as proximal junctional failure (PJF; symptomatic PJK requiring revision). The purpose of this prospective observational study is to compare biomechanical properties of the PLC in individuals with ASD who do, and do not develop PJK or PJF within 1 year of spinal fusion surgery., Methods: Intraoperative biopsies of PLC were obtained from 32 consecutive patients undergoing spinal fusions for ASD (>4 levels). Ligament peak force, tensile stress, tensile strain, and elastic modulus (EM) were measured with a materials testing system. Biomechanical properties and tissue dimensions were correlated with age, gender, BMI, vitamin D level, osteoporosis, sagittal alignment, PJA and change in PJA preoperatively, within 3 months, and at 1 year postoperatively., Results: Longer ligaments were associated with greater PJA change at 3 months ( p  = 0.04), and thinner ligaments were associated with greater PJA change at 1 year ( r  = 0.57, p  = 0.01). Greater EM was associated with greater PJA at both 3 months and 1 year ( p  = 0.03). Five participants had a change in PJA of >10 1 year postoperatively, and three participants demonstrated PJF. EM was significantly higher in individuals who required revision surgery ( p  = 0.003), and ligament length was greater ( p  = 0.03). Preoperative sagittal alignment was not related to incidence of revision surgery ( p  > 0.10)., Conclusions: The biomechanical properties of the PLC may be associated with higher risk for proximal failure. Ligaments that are longer, thinner, and less elastic are associated with higher postoperative PJA. Furthermore stiffer EM of the ligament is associated with the need for revision surgery., Competing Interests: Author Bahar Shahidi is a consultant for San Diego Spine Foundation. Gregory M. Mundis is a consultant for Carlsmed, Nuvasive, Seaspine, SIBone, and Viseon; holds stock/stock options in Alphatec, Nuvasive, and Orthofix Inc; receives IP royalties from Nuvasive, Seaspine, and Stryker. Robert K. Eastlack is a consultant for Aesculap, Biedermann‐Motech, Johnson & Johnson, Medtronic, Neo Medical NuVasive, SeaSpine, & SIBone; holds stock in Alphatec, NuVasive, SeaSpine, SIBone, and Spine Innovations. These disclosures/relationships did not influence this research, and the authors have no conflicts., (© 2023 The Authors. JOR Spine published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Study Design: Controlled animal study., Objective: To assess the cellular contribution of autograft to spinal fusion and determine the effects of intraoperative storage conditions on fusion., Summary of Background Data: Autograft is considered the gold standard graft material in spinal fusion, purportedly due to its osteogenic properties. Autograft consists of adherent and non-adherent cellular components within a cancellous bone scaffold. However, neither the contribution of each component to bone healing is well understood nor are the effects of intraoperative storage of autograft., Materials and Methods: Posterolateral spinal fusion was performed in 48 rabbits. Autograft groups evaluated included: (1) Viable, (2) partially devitalized, (3) devitalized, (4) dried, and (5) hydrated iliac crest. Partially devitalized and devitalized grafts were rinsed with saline, removing nonadherent cells. Devitalized graft was, in addition, freeze/thawed, lysing adherent cells. For 90 minutes before implantation, air dried iliac crest was left on the back table whereas the hydrated iliac crest was immersed in saline. At 8 weeks, fusion was assessed through manual palpation, radiography, and microcomputed tomography. In addition, the cellular viability of cancellous bone was assayed over 4 hours., Results: Spinal fusion rates by manual palpation were not statistically different between viable (58%) and partially devitalized (86%) autografts ( P = 0.19). Both rates were significantly higher than devitalized and dried autograft (both 0%, P < 0.001). In vitro bone cell viability was reduced by 37% after 1 hour and by 63% after 4 hours when the bone was left dry ( P < 0.001). Bone cell viability and fusion performance (88%, P < 0.001 vs . dried autograft) were maintained when the graft was stored in saline., Conclusions: The cellular component of autograft is important for spinal fusion. Adherent graft cells seem to be the more important cellular component in the rabbit model. Autograft left dry on the back table showed a rapid decline in cell viability and fusion but was maintained with storage in saline., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: The aim of this study was to investigate whether surgery for high-risk patients is being optimized over time and if poor outcomes are being minimized., Methods: Patients who underwent surgery for cervical deformity (CD) and were ≥ 18 years with baseline and 2-year data were stratified by year of surgery from 2013 to 2018. The cohort was divided into two groups based on when the surgery was performed. Patients in the early cohort underwent surgery between 2013 and 2015 and those in the recent cohort underwent surgery between 2016 and 2018. High-risk patients met at least 2 of the following criteria: 1) baseline C2-7 Cobb angle > 15°, mismatch between T1 slope and cervical lordosis ≥ 35°, C2-7 sagittal vertical axis > 4 cm, or chin-brow vertical angle > 25°; 2) age ≥ 70 years; 3) severe baseline frailty (Miller index); 4) Charlson Comorbidity Index (CCI) ≥ 1 SD above the mean; 5) three-column osteotomy as treatment; and 6) fusion > 10 levels or > 7 levels for elderly patients. The mean comparison analysis assessed differences between groups. Stepwise multivariable linear regression described associations between increasing year of surgery and complications., Results: Eighty-two CD patients met high-risk criteria (mean age 62.11 ± 10.87 years, 63.7% female, mean BMI 29.70 ± 8.16 kg/m2, and mean CCI 1.07 ± 1.45). The proportion of high-risk patients increased with time, with 41.8% of patients in the early cohort classified as high risk compared with 47.6% of patients in the recent cohort (p > 0.05). Recent high-risk patients were more likely to be female (p = 0.008), have a lower BMI (p = 0.038), and have a higher baseline CCI (p = 0.013). Surgically, high-risk patients in the recent cohort were more likely to undergo low-grade osteotomy (p = 0.003). By postoperative complications, recent high-risk patients were less likely to experience any postoperative adverse events overall (p = 0.020) or complications such as dysphagia (p = 0.045) at 2 years. Regression analysis revealed increasing year of surgery to be correlated with decreasing minor complication rates (p = 0.030), as well as lowered rates of distal junctional kyphosis by 2 years (p = 0.048)., Conclusions: Over time, high-risk CD patients have an increase in frequency and comorbidity rates but have demonstrated improved postoperative outcomes. These findings suggest that spine surgeons have improved over time in optimizing selection and reducing potential adverse events in high-risk patients.

Background and Objectives: Mitigating post-operative complications is a key metric of success following interbody fusion. LLIF is associated with a unique complication profile when compared to other approaches, and while numerous studies have attempted to report the incidence of post-operative complications, there is currently no consensus regarding their definitions or reporting structure. The aim of this study was to standardize the classification of complications specific to lateral lumbar interbody fusion (LLIF). Materials and Methods : A search algorithm was employed to identify all the articles that described complications following LLIF. A modified Delphi technique was then used to perform three rounds of consensus among twenty-six anonymized experts across seven countries. Published complications were classified as major, minor, or non-complications using a 60% agreement threshold for consensus. Results: A total of 23 articles were extracted, describing 52 individual complications associated with LLIF. In Round 1, forty-one of the fifty-two events were identified as a complication, while seven were considered to be approach-related occurrences. In Round 2, 36 of the 41 events with complication consensus were classified as major or minor. In Round 3, forty-nine of the fifty-two events were ultimately classified into major or minor complications with consensus, while three events remained without agreement. Vascular injuries, long-term neurologic deficits, and return to the operating room for various etiologies were identified as important consensus complications following LLIF. Non-union did not reach significance and was not classified as a complication. Conclusions: These data provide the first, systematic classification scheme of complications following LLIF. These findings may improve the consistency in the future reporting and analysis of surgical outcomes following LLIF.

Background Context: Lateral mass screw fixation is the standard for posterior subaxial cervical fixation. Several freehand surgical techniques for placing lateral mass screws have been described which rely on anatomical landmarks and surgeon mastery of the technique to safely place screws. The accuracy of these freehand techniques is inherently variable and can be influenced by a surgeon's level of clinical experience. A novel technique was developed that utilizes the plane of the facet joint to create lateral mass screw pilot holes parallel with the joint line to improve the safety and accuracy of lateral mass screw placement regardless of experience., Purpose: To assess the safety and accuracy of lateral mass screw placement using a novel lateral mass drill guide instrument (LM Guide), compared to standard freehand technique., Study Design: Randomized cadaveric study utilizing multiple surgeon evaluators to compare the safety and accuracy of guided cervical lateral mass placement compared to traditional freehand techniques., Materials and Methods: Lateral mass screws were placed from C3 to C7 in 20 cadaver specimens by 8 spine surgeons of varying levels of clinical experience (4 attendings, 4 fellows). Screws were placed bilaterally using standard anatomic landmarks ("freehand") randomly allocated on one side and using the LM Guide on the other. Cadaveric specimens were imaged with high-resolution CT to assess screw placement. Zone grading for safety was conducted based on screw tip position and clinical severity of screw breach was based on proximity to surrounding neurovascular anatomy. Screws were graded as safe, at-risk, or critical, with at-risk and critical screws considered malpositioned. To assess the accuracy of screw trajectory placed using the LM Guide compared to freehand, sagittal screw angle was measured and compared to an "ideal" screw path parallel to the facet joint line. Freehand and LM Guide groups were compared using Pearson's chi-square correlation., Results: Screw placement using the LM guide yielded a significantly lower rate of screw malpositioning, with 7 of 91 (7.7%) compared with 18 of 99 (18.2%) screws placed in the At-Risk or Critical Zones, p<.05. Of the 91 screws inserted using the LM Guide, 84 (92.3%) were in the Safe Zone, 7 (7.7%) were At-Risk, and 0 were in Critical zones. There was no incidence of neural or transverse foramen breaches with the LM Guide. In comparison, for the 99 screws inserted freehand, 81 (81.8%) were Safe, 14 (14.1%) were At-Risk, and 4 (4.1%) were in Critical zones. The 4 Critical zone freehand screw breaches included 1 neural foramen breach, 2 transverse foramen breaches, and 1 facet breach. The LM Guide also resulted in higher accuracy of screw trajectory, as indicated by a significant reduction in sagittal screw angle compared with freehand, p<.01. Notably, in the less-experienced surgeon cohort, the LM Guide significantly reduced the sagittal screw angle and resulted in no critical screw breaches compared to 3 critical breaches with freehand technique suggesting there might be a benefit in decreasing the learning curve associated with lateral mass screw placement., Conclusions: Lateral mass screw placement with a novel LM Guide that uses the facet joint to control screw trajectory improved the accuracy and reproducibility of screw placement with a significant reduction in screw breach rate and sagittal screw angle compared to freehand techniques regardless of surgeon experience level., Clinical Significance: The inherent variability of freehand lateral mass screw placement can increase the risk of clinical complications associated with screw malpositioning. The technique presented in this cadaveric study may be a viable alternative to standard freehand technique that can improve the overall safety of lateral mass screw placement., Competing Interests: Declaration of Competing Interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objective: To compare the outcomes of patients with adult spinal deformity (ASD) following spinal fusion with the lowest instrumented vertebra (LIV) at L4/L5 versus S1/ilium., Methods: A multicenter ASD database was evaluated. Patients were categorized into 2 groups based on LIV levels-groups L (fusion to L4/L5) and S (fusion to S1/ilium). Both groups were propensity matched by age and preoperative radiographic alignments. Patient demographics, operative details, radiographic parameters, revision rates, and health-related quality of life (HRQOL) scores were compared., Results: Overall, 349 patients had complete data, with a mean follow-up of 46 months. Patients in group S (n = 311) were older and had larger sagittal and coronal plane deformities than those in group L (n = 38). After matching, 28 patients were allocated to each group with similar demographic, radiographic, and clinical parameters. Sagittal alignment restoration at postoperative week 6 was significantly better in group S than in group L, but it was similar in both groups at the 2-year follow-up. Fusion to S1/ilium involved a longer operating time, higher PJK rates, and greater PJK angles than that to L4/L5. There were no significant differences in the complication and revision rates between the groups. Both groups showed significant improvements in HRQOL scores., Conclusions: Fusion to S1/ilium had better sagittal alignment restoration at postoperative week 6 and involved higher PJK rates and greater PJK angles than that to L4/L5. The clinical outcomes and rates of revision surgery and complications were similar between the groups.

Purpose: To evaluate the impact of the lowest instrumented vertebra (LIV) on Distal Junctional kyphosis (DJK) incidence in adult cervical deformity (ACD) surgery., Methods: Prospectively collected data from ACD patients undergoing posterior or anterior-posterior reconstruction at 13 US sites was reviewed up to 2-years postoperatively (n = 140). Data was stratified into five groups by level of LIV: C6-C7, T1-T2, T3-Apex, Apex-T10, and T11-L2. DJK was defined as a kyphotic increase > 10° in Cobb angle from LIV to LIV-1. Analysis included DJK-free survival, covariate-controlled cox regression, and DJK incidence at 1-year follow-up., Results: 25/27 cases of DJK developed within 1-year post-op. In patients with a minimum follow-up of 1-year (n = 102), the incidence of DJK by level of LIV was: C6-7 (3/12, 25.00%), T1-T2 (3/29, 10.34%), T3-Apex (7/41, 17.07%), Apex-T10 (8/11, 72.73%), and T11-L2 (4/8, 50.00%) (p < 0.001). DJK incidence was significantly lower in the T1-T2 LIV group (adjusted residual = -2.13), and significantly higher in the Apex-T10 LIV group (adjusted residual = 3.91). In covariate-controlled regression using the T11-L2 LIV group as reference, LIV selected at the T1-T2 level (HR = 0.054, p = 0.008) or T3-Apex level (HR = 0.081, p = 0.010) was associated with significantly lower risk of DJK. However, there was no difference in DJK risk when LIV was selected at the C6-C7 level (HR = 0.239, p = 0.214)., Conclusion: DJK risk is lower when the LIV is at the upper thoracic segment than the lower cervical segment. DJK incidence is highest with LIV level in the lower thoracic or thoracolumbar junction., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: Comparative cohort study., Objective: Factors that influence the lower instrumented vertebra (LIV) selection in adult cervical deformity (ACD) are less reported, and outcomes in the cervicothoracic junction (CTJ) and proximal thoracic (PT) spine are unclear., Methods: A prospective ACD database was analyzed using the following inclusion criteria: LIV between C7 and T5, upper instrumented vertebra at C2, and at least a 1-year follow-up. Patients were divided into CTJ (LIV C7-T2) and PT groups (LIV T3-T5) based on LIV levels. Demographics, operative details, radiographic parameters, and the health-related quality of life (HRQOL) scores were compared., Results: Forty-six patients were included (mean age, 62 years), with 22 and 24 patients in the CTJ and PT groups, respectively. Demographics and surgical parameters were comparable between the groups. The PT group had a significantly higher preoperative C2-C7 sagittal vertical axis (cSVA) (46.9 mm vs 32.6 mm, P = 0.002) and T1 slope minus cervical lordosis (45.9° vs 36.0°, P = 0.042) than the CTJ group and was more likely treated with pedicle-subtraction osteotomy (33.3% vs 0%, P = 0.004). The PT group had a larger correction of cSVA (-7.7 vs 0.7 mm, P = 0.037) and reciprocal change of increased T4-T12 kyphosis (8.6° vs 0.0°, P = 0.001). Complications and reoperations were comparable. The HRQOL scores were not different preoperatively and at 1-year follow-up., Conclusions: The selection of PT LIV in cervical deformities was more common in patients with larger baseline deformities, who were more likely to undergo pedicle-subtraction osteotomy. Despite this, the complications and HRQOL outcomes were comparable at 1-year follow-up.

Background: We developed a spinal deformity complexity checklist (SDCC) to assess the difficulty in performing a circumferential minimally invasive surgery (MIS) for adult spinal deformity., Methods: A modified Delphi method of panel experts was used to construct an SDCC checklist of radiographic and patient-related characteristics that could affect the complexity of surgery via MIS approaches. Ten surgeons with expertise in MIS deformity surgery were queried to develop and refine the SDCC with 3 radiographic categories (x-ray, magnetic resonance imaging, computed tomography) and 1 patient-related category. Within each category, characteristics affecting MIS complexity were identified by initial roundtable discussion. Second-round discussion determined which characteristics substantially impacted complexity the most., Results: Thirteen characteristics within the x-ray category were determined. Spinopelvic characteristics, endpoints of instrumentation, and prior hardware/fusion were associated with increased complexity. Vertebral body rotation-as reflected by the Nash-Moe grade-added significant complexity. Psoas anatomy and spinal stenosis added the most complexity for the 5 magnetic resonance imaging characteristics. There were 3 characteristics in the CT category with pre-exisiting fusion, being the variable most highly selected. Of the 5 patient-related characteristics, osteoporosis and BMI were found to most affect complexity., Conclusions: The SDCC is a comprehensive list of pertinent radiographic and patient-related characteristics affecting complexity level for MIS deformity surgery. The value of the SDCC is that it allows rapid assessment of key factors when determining whether MIS surgery can be performed effectively and safely. Patients with scores of 4 in any characteristic should be considered challenging to treat with MIS; open surgery may be a better alternative., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Circumferential minimally invasive surgery (cMIS) may provide incremental benefits compared with open surgery for patients with increasing frailty status by decreasing peri- and postoperative complications., Methods: Operative patients with adult spinal deformity (ASD) ≥ 18 years old with baseline and 2-year postoperative data were assessed. With propensity score matching, patients who underwent cMIS (cMIS group) were matched with similar patients who underwent open surgery (open group) based on baseline BMI, C7-S1 sagittal vertical axis, pelvic incidence to lumbar lordosis mismatch, and S1 pelvic tilt. The Passias modified ASD frailty index (mASD-FI) was used to determine patient frailty stratification as not frail, frail, or severely frail. Baseline and postoperative factors were assessed using two-way analysis of covariance (ANCOVA) and multivariate ANCOVA while controlling for baseline age, Charlson Comorbidity Index (CCI) score, and number of levels fused., Results: After propensity score matching, 170 ASD patients (mean age 62.71 ± 13.64 years, 75.0% female, mean BMI 29.25 ± 6.60 kg/m2) were included, split evenly between the cMIS and open groups. Surgically, patients in the open group had higher numbers of posterior levels fused (p = 0.021) and were more likely to undergo three-column osteotomies (p > 0.05). Perioperatively, cMIS patients had lower intraoperative blood loss and decreased use of cell saver across frailty groups (with adjustment for baseline age, CCI score, and levels fused), as well as fewer perioperative complications (p < 0.001). Adjusted analysis also revealed that compared to open patients, increasingly frail patients in the cMIS group were also more likely to demonstrate greater improvement in 1- and 2-year postoperative scores for the Oswestry Disability Index, SRS-36 (total), EQ-5D and SF-36 (all p < 0.05). With regard to postoperative complications, increasingly frail patients in the cMIS group were also noted to experience significantly fewer complications overall (p = 0.036) and fewer major intraoperative complications (p = 0.039). The cMIS patients were also less likely to need a reoperation than their open group counterparts (p = 0.043)., Conclusions: Surgery performed with a cMIS technique may offer acceptable outcomes, with diminishment of perioperative complications and mitigation of catastrophic outcomes, in increasingly frail patients who may not be candidates for surgery using traditional open techniques. However, further studies should be performed to investigate the long-term impact of less optimal alignment in this population.

Objective: The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity., Methods: A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2-T3 Cobb angle ≤ -30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3-S1 ≤ -60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm)., Results: Compared with asymptomatic control patients, cervical deformity was associated with increased C0-2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10-L2 Cobb angle -7.0° vs -1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0-2 lordosis (R = -0.57, p < 0.01) and lumbar lordosis (LL) (R = -0.20, p = 0.03). Cervical reconstruction resulted in decreased C0-2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0-2 lordosis (p < 0.01) and postoperative reduction of C0-2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01)., Conclusions: Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.

Study Design: Retrospective review of a cervical deformity database., Objective: This study aimed to develop a model that can predict the postoperative distal junctional kyphosis angle (DJKA) using preoperative and postoperative radiographic measurements., Summary of Background Data: Distal junctional kyphosis (DJK) is a complication following cervical deformity correction that can reduce of patient quality of life and functional status. Although researchers have identified the risk factors for DJK, no model has been proposed to predict the magnitude of DJK., Materials and Methods: The DJKA was defined as the Cobb angle from the lower instrumented vertebra (LIV) to LIV-2 with traditional DJK having a DJKA change >10°. Models were trained using 66.6% of the randomly selected patients and validated in the remaining 33.3%. Preoperative and postoperative radiographic parameters associated with DJK were identified and ranked using a conditional variable importance table. Linear regression models were developed using the factors most strongly associated with postoperative DJKA., Results: A total of 131 patients were included with a mean follow-up duration of 14±8 months. The mean postoperative DJKA was 14.6±14° and occurred in 35% of the patients. No significant differences between the training and validation cohort were observed. The variables most associated with postoperative DJK were: preoperative DJKA (DJKApre), postoperative C2-LIV, and change in cervical lordosis (∆CL). The model identified the following equation as predictive of DJKA: DJKA=9.365+(0.123×∆CL)-(0.315×∆C2-LIV)-(0.054×DJKApre). The predicted and actual postoperative DJKA values were highly correlated ( R =0.871, R2 =0.759, P <0.001)., Conclusions: The variables that most increased the DJKA were the preoperative DJKA, postoperative alignment within the construct, and change in cervical lordosis. Future studies can build upon the model developed to be applied in a clinical setting when planning for cervical deformity correction., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Frailty is influential in determining operative outcomes, including complications, in patients with cervical deformity (CD)., Objective: To assess whether frailty status limits the highest achievable outcomes of patients with CD., Methods: Adult patients with CD with 2-year (2Y) data included. Frailty stratification: not frail (NF) <0.2, frail (F) 0.2 to 0.4, and severely frail (SF) >0.4. Analysis of covariance established estimated marginal means based on age, invasiveness, and baseline deformity, for improvement, deterioration, or maintenance in Neck Disability Index (NDI), Modified Japanese Orthopaedic Association (mJOA), and Numerical Rating Scale Neck Pain., Results: One hundred twenty-six patients with CD included 29 NF, 83 F, and 14 SF. The NF group had the highest rates of deterioration and lowest rates of improvement in cervical Sagittal Vertical Axis and horizontal gaze modifiers. Two-year improvements in NDI by frailty: NF: -11.2, F: -16.9, and SF: -14.6 ( P = .524). The top quartile of NF patients also had the lowest 1-year (1Y) NDI (7.0) compared with F (11.0) and SF (40.5). Between 1Y and 2Y, 7.9% of patients deteriorated in NDI, 71.1% maintained, and 21.1% improved. Between 1Y and 2Y, SF had the highest rate of improvement (42%), while NF had the highest rate of deterioration (18.5%)., Conclusion: Although frail patients improved more often by 1Y, SF patients achieve most of their clinical improvement between 1 and 2Y. Frailty is associated with factors such as osteoporosis, poor alignment, neurological status, sarcopenia, and other medical comorbidities. Similarly, clinical outcomes can be affected by many factors (fusion status, number of pain generators within treated levels, integrity of soft tissues and bone, and deformity correction). Although accounting for such factors will ultimately determine whether frailty alone is an independent risk factor, these preliminary findings may suggest that frailty status affects the clinical outcomes and improvement after CD surgery., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Summary of Background Data: The influence of frailty on economic burden following corrective surgery for the adult cervical deformity (CD) is understudied and may provide valuable insights for preoperative planning., Objective: To assess the influence of baseline frailty status on the economic burden of CD surgery., Study Design: Retrospective cohort., Materials and Methods: CD patients with frailty scores and baseline and two-year Neck Disability Index data were included. Frailty score was categorized patients by modified CD frailty index into not frail (NF) and frail (F). Analysis of covariance was used to estimate marginal means adjusting for age, sex, surgical approach, and baseline sacral slope, T1 slope minus cervical lordosis, C2-C7 angle, C2-C7 sagittal vertical axis. Costs were derived from PearlDiver registry data. Reimbursement consisted of a standardized estimate using regression analysis of Medicare payscales for services within a 30-day window including length of stay and death. This data is representative of the national average Medicare cost differentiated by complication/comorbidity outcome, surgical approach, and revision status. Cost per quality-adjusted life-year (QALY) at two years was calculated for NF and F patients., Results: There were 126 patients included. There were 68 NF patients and 58 classified as F. Frailty groups did not differ by overall complications, instance of distal junctional kyphosis, or reoperations (all P >0.05). These groups had similar rates of radiographic and clinical improvement by two years. NF and F had similar overall cost ($36,731.03 vs. $37,356.75, P =0.793), resulting in equivocal costs per QALYs for both patients at two years ($90,113.79 vs. $80,866.66, P =0.097)., Conclusion: F and NF patients experienced similar complication rates and upfront costs, with equivocal utility gained, leading to comparative cost-effectiveness with NF patients based on cost per QALYs at two years. Surgical correction for CD is an economical healthcare investment for F patients when accounting for anticipated utility gained and cost-effectiveness following the procedure., Level of Evidence: III., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objectives: Establish simultaneous focal and regional corrective guidelines accounting for reciprocal global and pelvic compensation., Methods: 433 ASD patients (mean age 62.9 yrs, 81.3% F) who underwent corrective realignment (minimum L1-pelvis) were included. Sagittal parameters, and segmental and regional Cobb angles were assessed pre and post-op. Virtual postoperative alignment was generated by combining post-op alignment of the fused spine with the pre-op alignment on the unfused thoracic kyphosis and the pre-op pelvic retroversion. Regression models were then generated to predict the relative impact of segmental (L4-L5) and regional (L1-L4) corrections on PT, SVA (virtual), and TPA., Results: Baseline analysis revealed distal (L4-S1) lordosis of 33 ± 15°, flat proximal (L1-L4) lordosis (1.7 ± 17°), and segmental kyphosis from L2-L3 to T10-T11. Post-op, there was no mean change in distal lordosis (L5-S1 decreased by 2°, and L4-L5 increased by 2°), while the more proximal lordosis increased by 18 ± 16°. Regression formulas revealed that Δ10° in distal lordosis resulted in Δ10° in TPA, associated with Δ100 mm in SVA or Δ3° in PT; Δ10° in proximal lordosis yielded Δ5° in TPA associated with Δ50 mm in SVA; and finally Δ10° in thoraco-lumbar junction yielded Δ2.5° in TPA associated with Δ25 mm in SVA and no impact on PT correction., Conclusions: Overall impact of lumbar lordosis restoration is critically determined by location of correction. Distal correction leads to a greater impact on global alignment and pelvic retroversion. More specifically, it can be assumed that 1° L4-S1 lordosis correction produces 1° change in TPA / 10 mm change in SVA and 0.5° in PT.

Objective: Spine surgeons have a heuristic sense of how to surgically restore alignment and address adult spinal deformity (ASD) symptoms, but consensus on the extent of treatment remains unclear. We sought to determine the variability of surgical approaches in treating ASD., Methods: Sixteen spine surgeons were surveyed on treatment approaches in 10 select ASD cases. We repeated the survey with the same surgeons 4 weeks later, with cases ordered differently. We examined the variability in length of construct, use of interbody spacers, osteotomies, and pelvic fixation frequency., Results: Treatment approaches for each case varied by surgeon, with some surgeons opting for long fusion constructs in cases for which others offered no surgery. There was no consensus among surgeons on the number of levels fused, interbody spacer use, or anterior/posterior osteotomies. Intersurgeon and intrasurgeon variability was 48% (kappa = 0.31) and 59% (kappa = 0.44) for surgeons performing minimally invasive surgery (MIS) versus 37% (kappa = 0.21) and 47% (kappa = 0.30) for those performing open surgery. In the second-round survey, 8 of 15 (53%) surgeons substantially changed the construct length, number of interbody spacers, and osteotomies in at least half the cases they previously reviewed. Surgeons performing MIS versus open surgery were less likely to extend constructs to the pelvis (42.5% vs. 67.5%; P = 0.02), but construct length was not correlated with whether a surgeon performed MIS or open surgery., Conclusions: Spinal deformity surgeons lack consensus on the optimal surgical approach for treating ASD. Classifying surgeons as performing MIS or open surgery does not mitigate this variability., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Revision surgery is often necessary for adult spinal deformity (ASD) patients. Satisfaction with management is an important component of health-related quality of life. The authors hypothesized that patients who underwent multiple revision surgeries following ASD correction would exhibit lower self-reported satisfaction scores., Methods: This was a retrospective cohort study of 668 patients who underwent ASD surgery and were eligible for a minimum 2-year follow-up. Visits were stratified by occurrence prior to the index surgery (period 0), after the index surgery only (period 1), after the first revision only (period 2), and after the second revision only (period 3). Patients were further stratified by prior spine surgery before their index surgery. Scoliosis Research Society-22 (SRS-22r) health-related quality-of-life satisfaction subscore and total satisfaction scores were evaluated at all periods using multiple linear regression and adjustment for age, sex, and Charlson Comorbidity Index., Results: In total, 46.6% of the study patients had undergone prior spine surgery before their index surgery. The overall revision rate was 21.3%. Among patients with no spine surgery prior to the index surgery, SRS-22r satisfaction scores increased from period 0 to 1 (from 2.8 to 4.3, p < 0.0001), decreased after one revision from period 1 to 2 (4.3 to 3.9, p = 0.0004), and decreased further after a second revision from period 2 to 3 (3.9 to 3.3, p = 0.0437). Among patients with spine surgery prior to the index procedure, SRS-22r satisfaction increased from period 0 to 1 (2.8 to 4.2, p < 0.0001) and decreased from period 1 to 2 (4.2 to 3.8, p = 0.0011). No differences in follow-up time from last surgery were observed (all p > 0.3). Among patients with multiple revisions, 40% experienced rod fracture, 40% proximal junctional kyphosis, and 33% pseudarthrosis., Conclusions: Among patients undergoing ASD surgery, revision surgery is associated with decreased satisfaction, and multiple revisions are associated with additive detriment to satisfaction among patients initially undergoing primary surgery. These findings have direct implications for preoperative patient counseling and establishment of postoperative expectations.