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Purpose: To assess and compare coronal alignment correction at 2 year follow-up in adult spinal deformity (ASD) patients treated with and without the kickstand rod (KSR) construct. Methods: ASD patients who underwent posterior spinal fusion at a single-center with a preoperative coronal vertical axis (CVA) ≥ 3 cm and a minimum of 2 year clinical and radiographic follow-up were identified. Patients were divided into two groups: those treated with a KSR and those who were not. Patients were propensity score-matched (PSM) controlling for preoperative CVA and instrumented levels to limit potential biases that my influence the magnitude of coronal correction. Results: One hundred sixteen patients were identified (KSR = 42, Control = 74). There were no statistically significant differences in patient characteristics (p> 0.05). At baseline, the control group presented with a greater LS curve (29.0 ± 19.6 vs. 21.5 ± 10.8, p= 0.0191) while the KSR group presented with a greater CVA (6.3 ± 3.6 vs. 4.5 ± 1.8, p= 0.0036). After 40 PSM pairs were generated, there were no statistically significant differences in baseline patient and radiographic characteristics. Within the matched cohorts, the KSR group demonstrated greater CVA correction at 1 year (4.7 ± 2.4 cm vs. 2.9 ± 2.2 cm, p= 0.0012) and 2 year follow-up (4.7 ± 2.6 cm vs. 3.1 ± 2.6 cm, p= 0.0020) resulting in less coronal malalignment one (1.5 ± 1.3 cm vs. 2.4 ± 1.6 cm, p= 0.0056) and 2 year follow-up (1.6 ± 1.0 vs. 2.5 ± 1.5 cm, p= 0.0110). No statistically significant differences in PROMs, asymptomatic mechanical complications, reoperations for non-mechanical complications were observed at 2 year follow-up. However, the KSR group experienced a lesser rate of mechanical complications requiring reoperations (7.1% vs. 24.3%. OR = 0.15 [0.03–0.72], p= 0.0174). Conclusions: Patients treated with a KSR had a greater amount of coronal realignment at the 2 year follow-up time period and reported less mechanical complications requiring reoperation. However, 2 year patient-reported outcomes were similar between the two groups.

Purpose: To determine if an improvement in cord-level intraoperative neuromonitoring (IONM) data following data loss results in a reduced risk for new postoperative motor deficit in pediatric and adult spinal deformity surgery. Methods: A consecutive series of 1106 patients underwent spine surgery from 2015 to 2023 by a single surgeon. Cord alerts were defined by Somatosensory-Evoked Potentials (SSEP; warning criteria: 10% increase in latency or > 50% loss in amplitude) and Motor-Evoked Potentials (MEP; warning criteria: 75% loss in amplitude without return to acceptable limits after stimulation up 100 V above baseline level). Timing of IONM loss and recovery, interventions, and baseline/postoperative day 1 (POD1) lower extremity motor scores were analyzed. Results: IONM Cord loss was noted in 4.8% (53/11,06) of patients and 34% (18/53) with cord alerts had a POD1 deficit compared to preoperative motor exam. MEP and SSEP loss attributed to 98.1% (52/53) and 39.6% (21/53) of cord alerts, respectively. Abnormal descending neurogenic-evoked potential (DNEP) was seen in 85.7% (12/14) and detected 91.7% (11/12) with POD1 deficit. Abnormal wake-up test (WUT) was seen in 38.5% (5/13) and detected 100% (5/5) with POD1 deficit. Most cord alerts occurred during a three-column osteotomy (N= 23/53, 43%); decompression (N= 12), compression (N= 7), exposure (N= 4), and rod placement (N= 14). Interventions were performed in all 53 patients with cord loss and included removing rods/less correction (N= 11), increasing mean arterial pressure alone (N= 10), and further decompression with three-column osteotomy (N= 9). After intervention, IONM data improved in 45(84.9%) patients (Full improvement: N= 28; Partial improvement: 17). For those with full and partial IONM improvement, the POD1 deficit was 10.7% (3/28) and 41.2% (7/17), respectively. For those without any IONM improvement (15.1%, 8/53), 100% (8/8) had a POD1 deficit, P< 0.001. Conclusion: A full or partial improvement in IONM data loss after intraoperative intervention was significantly associated with a lower risk for POD1 deficit with an absolute risk reduction of 89.3% and 58.8%, respectively. All patients without IONM improvement had a POD1 neurologic deficit.

Purpose: To evaluate previously popular technologies in the field of spine surgery, and to better understand their advantages and limitations to the current standards of care. Spine surgery is an ever-evolving field that serves to resolve various spinal pathologies in patients of all ages. While there are established treatments for various conditions, such as lumbar spinal stenosis, idiopathic scoliosis, and degenerative lumbar disease, there is always further research and development in these areas to produce innovative technologies that can lead to better outcomes. As this process progresses, we must remind ourselves of previously tried and tested inventions and their outcomes that have fallen short of becoming a standard to ensure we are able to learn lessons from the past. Methods: A thorough literature review was conducted with the aim of compiling literature of previously utilized technologies in spine surgery. Biomedical databases were utilized to gather relevant articles including PubMed, MEDLINE, and EMBASE. Emphasis was placed on gathering articles with technologies or therapeutics aimed at treating common spinal pathologies including lumbar spinal stenosis (LSS), adolescent idiopathic scoliosis (AIS), and other degenerative lumbar spine diseases. The keywords used were: “failed technologies”, “historical technologies”, “spine surgery”, “spinal stenosis”, “adolescent idiopathic scoliosis”, and “degenerative lumbar spine disease”. A total of 47 articles were gathered after initial review. Results: Different technologies pertaining to spine surgery were identified and critically evaluated. Some of these technologies included X-STOP, Vertiflex, Vertebral Body Stapling, and Dynesys. These technologies were evaluated for their strengths and limitations across their spinal pathology applications. While each type of technology had their benefits, the data tended to be mixed with various limitations across studies. Conclusion: These technologies have been trialed in the field of spine surgery across various spinal pathologies, but still prove of limited efficacy and shortcomings to the current standards of care.

Purpose: Postoperative physical therapy (PT) is a cornerstone of orthopedic and musculoskeletal rehabilitation, proven to provide various positive clinical benefits. However, there is a paucity of literature evaluating the utility of preoperative rehabilitation specific to spine surgery. Thus, this review article aims to provide an overview of previously published studies discussing the efficacy of preoperative rehabilitation programs and its role in spinal surgery. Special emphasis was given to preoperative frailty assessments, physical performance tests, interventional strategies, feasibility, and future directions. Methods: We performed a literature review using PubMed, Google Scholar, EMBASE, and PubMed Central (PMC) using directed search terms. Articles that examined preoperative rehabilitation in adult spine surgery were compiled for this review. Summary of key finding: Prehabilitation programs focused on exercise, flexibility, and behavioral modifications have been shown to significantly improve pain levels and functional strength assessments in patients undergoing elective spine surgery. In addition, studies suggest that these programs may also decrease hospital stays, return to work time, and overall direct health care expenditure costs. Screening tools such as the FRAIL scale can be used to assess frailty while physical function tests like the timed-up-and go (TUGT), 5 repetition sit-to-stand test (5R-STST), and hand grip strength (HGS) can help identify patients who would most benefit from prehabilitation. Conclusions: This review illustrates that prehabilitation programs have the potential to increase quality of life, improve physical function and activity levels, and decrease pain, hospital stays, return to work time, and overall direct costs. However, there is a paucity of literature in this field that requires further study and investigation.

Study Design Single center, retrospective cohort study.Objectives Little is known about the surgical outcomes and quality of life in patients with C2-sacrum posterior spinal fusion (PSF). Though it is thought to be a “final” construct, it remains unknown how patients fare postoperatively. We sought to evaluate the surgical outcomes and quality of life of patients after C2-sacrum PSF.Methods Consecutive patients undergoing C2-Sacrum PSF from 2015-2020 by 4 surgeons at a single institution were included. The study time period for each patient began after their index operation that led to the C2-sacrum fusion. Dates of surgery, complications, reoperations, patient reported outcomes (PROs) including EuroQol 5 Dimensions (EQ-5D), Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) questionnaires, and activities of daily living (ADL) questions were collected and analyzed. Descriptive statistics, paired t-tests, student t-tests, and linear regression were used.Results Of the 23 patients who underwent C2-sacrum PSF, 6 patients (26%) required a total of 10 reoperations after a mean of 1.5 years (range 0-4 years) after C2-sacrum PSF. Five reoperations were for mechanical failure; 3 for wound complications/infection; and 2 for instrumentation and spinous process prominence. PROs were collected on 18 patients with mean follow-up of 2.4 years (range .5-4.5) after their C2-sacrum PSF. At 6-months, both SRS-22 and ODI scores improved significantly after C2-sacrum PSF (SRS: 57.5 to 76.3, P= .0014; ODI: 47.0 to 31.7, P= .013). Similarly, at a mean 2.4 years postoperatively, mean ODI improved significantly (47.0 to 30.4, P= .0032). Six patients (33%) had minimal symptoms (ODI <20). The median postoperative EQ-5D score was .74 (range .19 to 1.0), which compares favorably to patients with hip/knee osteoarthritis (EQ-5D .63) and diabetes mellitus (DM) (EQ-5D .69) and hypertension (HTN). In terms of activities of daily living (ADL), 10 patients (56%) exercised regularly—a mean 4.5 days/week. 11 (61%) could do light aerobic activity (e.g. stationary bike). 10 (55%) were able to play with children/grandchildren as desired. Eight patients (44%) hiked, and 2 (11%) drove independently. 11 (61%) could tolerate short air-travel comfortably. Of the 17 patients who could toilet and perform basic hygiene preoperatively, 16 (94%) were able to do so postoperatively.Conclusion Though C2-sacrum PSF is thought to be a “final” construct, approximately 1 in 4 patients require subsequent operations. However, C2-sacrum PSF patients had a significant improvement in SRS and ODI scores by 6 months postop. Over 60% of patients were regularly performing light aerobic activity 2 years after their C2-sacrum PSF. EQ-5D suggests that this population fares better than those with degenerative hip/knee arthritis and similarly to those with common chronic conditions like DM and HTN.

Objective /Hypothesis:Patients undergoing C2-sacrum PSF have unique medical histories and multiple prior operations over an extended period.Design Single center, retrospective cohortMethods Consecutive C2-sacrum PSF patients operated on by 4 surgeons at a single-center from 2015-2020 were reviewed. Demographics, comorbidities, indications, surgical history, and radiographic parameters were collected.Results 23 patients underwent C2-sacrum PSF. 13 (57%) were male, and 21 (91.3%) were adults. Mean age at time of first spine surgery was 44 years (range 5-71) and 53 years (range 14-72) at the time of C2-sacrum PSF. Six patients (26%) had osteoporosis, and 6 patients (26%) had neurologic comorbidities—including Parkinson’s disease (4), cerebral palsy (1), and Brown Sequard syndrome (1). Four (17%) had connective tissue disease. Two patients underwent C2-sacrum PSF as an index procedure: (1) 67M with myelomatous fractures and 124° of cervicothoracic kyphosis; (2) 28F with severe Marfan syndrome with 140° thoracic scoliosis and 130° thoracic kyphosis. The remaining 21 (91%) underwent C2-sacrum PSF as a revision following prior spinal surgeries on average, 4 previous surgeries (range 1-13) over 10.5 years (range .3-37.4). Indications for the remaining 21 C2-sacrum PSF revision procedures included 17 (81%) for kyphosis (5 of whom also had significant coronal deformity), 1 (5%) for only coronal malalignment, 2 (10%) for instrumentation failure, and 1 (5%) for myelopathy.Conclusions 91% (21/23) of patients requiring C2-sacrum PSF were treated as revisions of prior fusions, with a mean of 4 prior surgeries over 10 years. Over 80% of these patients underwent C2-sacrum PSF to address kyphosis. 26% had neurologic conditions, and 26% had osteoporosis.

Study Design Retrospective, propensity-matched analysisObjectives Cervical disc arthroplasty (CDA) is being increasingly utilized for cervical disc generation. Surgeon specialty has been shown to influence the risk for postoperative complications in spine surgery, but this has not yet been explored for CDA. Thus, the purpose of this study is to determine whether there is any difference in 30-day complications between patients undergoing single-level CDA by neurosurgeons vs by orthopaedic surgeons.Methods A retrospective, 1:1 propensity score matched analysis was performed using the NSQIP database from 2015 to 2020. Patient demographics, operative characteristics, and postoperative complications were recorded. Independent multivariate logistic regression models were constructed using the propensity-matched dataset to assess surgical specialty influence on any complication, any site complication, any operative infection, and any medical complications.Results 3179 single-level CDAs (28.8% orthopaedic surgery patients, 71.2% neurosurgery patients) were identified that met the inclusion criteria. Well-matched cohorts of 916 patients each were generated. After controlling for all possible confounders, orthopedic surgery specialty was not associated with a higher odds for any complication (OR: .87, 95% CI: .35 – 2.20, P= .7696), any site complication (OR: .32, 95% CI: .08 – 1.32, P= .1359), any operative infection (OR: .31, 95% CI: .07 – 1.34), P= .1172), nor any medical complication (OR: 2.11, 95% CI: .62 – 7.20, P= .2311) vs neurosurgery.Conclusion This is the first propensity-matched analysis to show that spine surgeon specialty does not influence the risk for any complication, any site complication, any operative infection, nor any medical complication following single-level CDA within the first 30 days after surgery.

Study Design Retrospective Cohort Study.Objectives Few previous studies have examined the relationship between preoperative disability and patient outcomes after complex adult spinal deformity surgery. In this study, we hypothesized that patients with worse preoperative disability would be more likely achieve a clinically significant improvement in their symptoms after surgery.Methods Demographics, comorbidities, surgical data, and health related survey results were analyzed from a consecutive series of adults (≥18 years old) who underwent spinal deformity correction, instrumentation, and fusion. Patients included had 6 or more levels fused and their surgery performed at single institution between 2015 and 2018 with minimum 2 year follow up.Results A total of 108 patients met inclusion criteria. Bivariate analysis demonstrated the following as having a greater probability of reaching minimum clinically important difference (MCID) at 2 years postoperatively: >50thpercentile Oswestry Disability Index (ODI) score (ODI >36), cardiac comorbidities, and use of pelvic fixation, pedicle subtraction osteotomy, and transforaminal lumbar interbody fusion. Conversely, baseline Scoliosis research society score (SRS) >50thpercentile (SRS ≥62) and use of vertebral column resection (VCR) were significant predictors of not reaching MCID at 2 years. On logistic regression analysis, >50thpercentile ODI score (ODI >36) was identified as the only independent predictor of achieving MCID.Conclusions Patients with greater disability, independent of other preoperative or surgical factors, are more likely to have clinically significant improvement in their daily functioning after complex deformity surgery. For patients who undergo surgical intervention for severe or progressive deformity, including VCR, MCID might be an ineffective outcome measure.

Purpose: To evaluate radiographic and clinical outcomes following revision surgery after HRC fusions. Methods: Single-institution, retrospective study of patients revised following HRC with minimum 2-year follow-up post-revision. Demographics, perioperative information, radiographic parameters, complications, and Oswestry disability index (ODI) scores were collected. Radiographic parameters included global alignment, coronal and sagittal measurements pre and postoperatively, as well as final follow-up time points. Results: 26 patients were included with a mean follow-up of 3.3 ± 1.1 years. Mean age was 55.5 ± 7.8 years, BMI 25.2 ± 5.8, and 22 (85%) were females. Instrumented levels increased from 9.7 ± 2.8 to 16.0 ± 2.2. Five (19.2%) patients underwent lumbar pedicle subtraction osteotomies, and 23 (88.4%) had interbody fusions. Patients significantly improved in all radiographic parameters at immediate and final follow-up (p&lt; 0.005), except for thoracic kyphosis and pelvic incidence (p> 0.05). Correction was maintained from immediate postop to final follow-up (p> 0.05). 20 (76.9%) of patients experienced a complication at some point within the follow-up period with the most common being a lumbar nerve root deficit (n= 7). However, only one patient had a nerve root deficit at final follow-up, that being a 4/5 unilateral anterior tibialis function. 5 (19.2%) patients required further revision within a mean of 1.8 ± 1.1 years. On average, patients had an improvement in ODI score by final follow-up (35.6 ± 16.8 vs 25.4 ± 19.8, p= 0.035). Conclusion: Patients revised for HRCs significantly improve, both clinically and radiographically by final follow-up. This group did have a propensity for distal lumbar root neurological issues, which were common but all patients except for one, recovered to full strength by two-year follow-up.

Purpose: To determine whether maintaining good sagittal balance with significant knee flexion (KF) constitutes a suboptimal outcome after adult spinal deformity (ASD) correction. Methods: This single-center, single-surgeon retrospective study, assessed ASD patients who underwent posterior spinal fusion between 2014 and 2020. Inclusion criteria included meeting at least one of the following: PI–LL ≥ 25°, T1PA ≥ 20°, or CrSVA-H ≥ 2 cm. Those with lower-extremity contractures were excluded. Patients were classified into four groups based on their 6-week postoperative cranio-hip balance and KF angle, and followed for at least 2 years: Malaligned with Knee Flexion (MKF+) (CrSVA-H > 20 mm + KFA > 10), Malaligned without Knee Flexion (MKF−) (CrSVA-H > 20 mm + KFA &lt; 10), Aligned without Knee Flexion (AKF−) (CrSVA-H &lt; 20 mm + KFA &lt; 10), and Aligned with Knee Flexion (AKF+) (CrSVA-H &lt; 20 mm + KFA > 10). The primary outcomes of this study included one and two year reoperation rates. Secondy outcomes included clinical and patient reported outcomes. Results: 263 patients (mean age 60.0 ± 0.9 years, 74.5% female, and mean Edmonton Frailty Score 3.3 ± 0.2) were included. 60.8% (160/263 patients) exhibited good sagittal alignment at 6-week postop without KF. Significant differences were observed in 1-year (p= 0.0482) and 2-year reoperation rates (p= 0.0374) across sub-cohorts, with the lowest and highest rates in the AKF− cohort (5%, n= 8) and MKF + cohort (16.7%, n= 4), respectively. Multivariable Cox regression demonstrated the AKF− cohort exhibited significantly better reoperation outcomes compared to other groups: AKF + (HR: 5.24, p= 0.025), MKF + (HR: 31.7, p&lt; 0.0001), and MKF− (HR: 11.8, p&lt; 0.0001). Conclusion: Our findings demonstrate that patients relying on knee flexion compensation in the early postoperative period have inferior outcomes compared to those achieving sagittal balance without knee flexion. When compared to malaligned patients, those with CrSVA-H &lt; 20 mm and KFA > 10 degrees experience fewer early reoperations but similar delayed reoperation rates. This insight emphasizes the importance of considering knee compensation perioperatively when managing sagittal imbalance in clinical practice.

Purpose: To investigate whether patients with spinopelvic mismatch (PI–LL ≥ 10) report worse patient-reported outcomes (PROs) compared to patients who achieve PI–LL &lt; 10 at 2-year postop. Methods: In this retrospective study, propensity score matching (PSM) was used to analyze patients who underwent posterior spinal fusion due to deformity, as defined by one or more of the following criteria: PI–LL ≥ 25°, T1 pelvic angle ≥ 30°, sagittal vertical axis ≥ 15 cm, thoracic scoliosis ≥ 70°, thoracolumbar scoliosis ≥ 50°, coronal malalignment ≥ 7 cm, or those who underwent a three-column osteotomy or fusion with ≥ 12 levels. Key outcomes were total Scoliosis Research Society-22r, Oswestry Disability Index (PROs), and reoperation at 1- and 2-year postop. Patients were dichotomized based on their 2-year alignment: PI–LL ≥ 10° and PI–LL &lt; 10°. A multivariable logistic regression model identified factors associated with achieving PI–LL &lt; 10°, and independent predictors were matched using propensity score matching. Binary outcomes within matched cohorts were analyzed using the McNemar test, while continuous outcomes were analyzed using the Wilcoxon rank-sum test. Results: One hundred sixty-four patients with 2-year follow-up were included; mean age was 50.5 (standard error mean (SEM): 1.4) years, body mass index was 24.1(SEM 1.0), and number of operative levels was 13.5 (SEM 0.3). 84 (51.2%) and 80 (48.8%) patients achieved PI–LL &lt; 10 and PI–LL ≥ 10 at 2-year follow-up, respectively. Baseline pelvic incidence [odds ratio (OR): 0.96 (95% CI 0.92–0.99)] and baseline PI–LL [OR: 0.95 (95% CI 0.9–0.99)] were independent predictors of achieving PI–LL &lt; 10 at 2 years. When comparing propensity matched pairs, no significant differences were found in baseline PROs. At both 1- and 2-year follow-up, outcomes on the SRS-22r scale were nearly identical for both groups (function [4.1(0.1) vs 4.0 (0.1), P= 0.75] ,Pain [3.9 (0.2) vs 3.9 (0.2),P= 0.86], appearance [4.2 (0.2) vs 3.8 (0.2),P= 0.08], mental health [4.1 (0.2) vs 4.1 (0.1), P= 0.96], satisfaction [4.4 (0.2) vs 4.4 (0.2),P= 0.72], and total [90.2 (2.5) vs 88.1 (2.5),P= 0.57]). Additionally, ODI scores at 2 years were comparable [18.1 (2.9) vs 22.4 (2.9),P= 0.30]. The 90-day reoperation rate was 2.6% (one patient) in both matched cohorts (P> 0.99). There was no significant difference in 1-year (P> 0.9999) or 2-year (P= 0.2207) reoperation rates between the groups. Conclusion: Patients who achieve and maintain PI–LL &lt; 10 2-years postop following adult spinal deformity surgery have nearly identical SRS-22r and ODI outcomes, and comparable 2-year reoperation rates as compared to patients who have PI–LL ≥ 10.

Purpose: In Lenke type 5 and 6 curves, a major thoracolumbar or lumbar curve, the rates of PJK are reported as high as 50%. The purpose of this study was to confirm the rate of PJK, investigate possible risk factors, and evaluate surgical complications and the long-term effects of PJK on patient outcomes. Methods: A retrospective review of multicenter data identified 192 with patients with 2 year and 94 with 5-year follow-up. Included patients had a Lenke type 5 or 6 curve and underwent a selective thoracolumbar or lumbar curve fusion. All radiographs preoperatively and postoperatively (1 year, 2 years, and 5 years) were evaluated. Demographic and radiographic data was analyzed as risk factors for PJK using a multi-variate regression. Outcomes scores and complications were compared between groups. Results: 17 patients (8.9%) developed radiographic PJK; 1 at 1 year, 7 at 2 years, and another 9 at 5 years. All 17 patients had an upper instrumented vertebra (UIV) within 3 levels or less caudal of the thoracic kyphosis apex (the most horizontal vertebra on the sagittal); no patient with a UIV 4 or more levels from the thoracic apex (n = 96) developed PJK (X2= 13.03, p &lt; 0.001). In addition, PJA > 8° was found to significantly increase the risk of PJK (p = 0.039). SRS scores were significantly worse for PJK patients at 5 years in the self-image and function (p &lt; 0.01). Conclusion: In Lenke 5/6 curves, no patient with a UIV 4 or more levels caudal to the thoracic kyphosis apex had PJK up to 5 years postoperatively. PJA greater than 8° was identified as a risk factor for PJK. Patients with radiographic PJK had worse SRS scores 5 years postoperatively.

Purpose: Assess normative values of sagittal spinal and lower extremity alignment in asymptomatic volunteers of three difference races. Methods: Asymptomatic volunteers between the ages of 18–80 years were enrolled prospectively and then analyzed retrospectively from six different centers. Volunteers included reported no significant neck or back pain, nor any known spinal disorder(s). All volunteers underwent a standing full-body or full-spine low dose stereoradiograph. Volunteers were grouped into three main races; Asian (A), Arabo-Bèrbère (B), and Caucasian (C). The Asian volunteers included in this study were from Japan and Singapore. Results: There were statistical differences in the Age, ODI, and BMI of the volunteers from the three different races. Asian volunteers had the lowest age (A: 36.7, B: 45.5, C: 42.0) and BMI (A: 22.1, B: 27.1, C: 27.3). Pelvic morphology including pelvic incidence (A: 51.0, B: 52.0, C: 52.5, p= 0.37), pelvic tilt (A: 11.9, B: 12.3, C: 12.9, p= 0.44), and sacral slope (A: 39.1, B: 39.7, C: 39.6, p= 0.77) were similar amongst the 3 races. Regional spinal alignment was different between the groups. Thoracic Kyphosis (A: 32.9, B: 43.3, C: 40.0, p&lt; 0.0001) and Lumbar lordosis (A: − 54.2, B: − 60.4, C: − 59.6, p&lt; 0.0001) were lower in Asians compared to Caucasian and Arabo-Bèrbère volunteers despite having similar pelvic incidence. Conclusion: Volunteers in the Asian group had lower lumbar lordosis and thoracic kyphosis when compared to the Arabo-Bèrbère and Caucasian groups while all groups had similar pelvic morphology. Thoracic Kyphosis had no correlation with Pelvic Incidence, while Lumbar Lordosis correlated well with both Thoracic Kyphosis and Pelvic Incidence. Thoracic kyphosis may be an independent variable in establishing adequate lumbar lordosis and varies based on an individual’s race.

Study Design: Retrospective cohort.Objective: Provide a comparison of surgical approach in the treatment of degenerative cervical myelopathy in patients with OPLL.Methods: A national database was queried to identify adult (≥18 years) patients with OPLL, who underwent at least a 2-level cervical decompression and fusion for cervical myelopathy from 2012-2014. A propensity-score-matching algorithm was employed to compare outcomes by surgical approach.Results: After propensity-score matching, 627 patients remained. An anterior approach was found to be an independent predictor for higher inpatient surgical complications(OR 5.9), which included dysphagia:14%[anterior]vs.1.1%[posterior] P-value < 0.001, wound hematoma:1.7%[anterior]vs.0%[posterior] P-value = 0.02, and dural tear:9.4%[anterior]vs.3.2%[posterior] P-value = 0.001. A posterior approach was an predictor for longer hospital length of stay by nearly 3 days(OR 3.4; 6.8 days[posterior]vs.4.0 days[anterior] P-value < 0.001). The reasons for readmission/reoperation did not vary by approach for 2-3-level fusions; however, for >3-level fusions, patients with an anterior approach more often had respiratory complications requiring mechanical ventilation(P-value = 0.038) and required revision fusion surgery(P-value = 0.015).Conclusions: The national estimates for inpatient complications(25%), readmissions(9.9%), and reoperations(3.5%) are substantial after the surgical treatment of multi-level OPLL. An anterior approach resulted in significantly higher inpatient surgical complications, but this did not result in a longer hospital length of stay and the overall 90-day complication rates requiring readmission or reoperation was similar to those seen after a posterior approach. For patients requiring >3-level fusion, an anterior approach is associated with significantly higher risk for respiratory complications requiring mechanical ventilation and revision fusion surgery. Precise neurological complications and functional outcomes were not included in this database, and should be further assessed in future studies.

Purpose: The main objective of this review article is to examine the role that nutrition has on adult spinal deformity. The information presented in this review aims to provide spine surgeons with a broad overview of screening, assessment, and interventional strategies that may be used for presurgical nutritional optimization. Methods: A comprehensive literature review utilizing three biomedical databases was performed to generate articles of interest. Published articles related to nutrition, adult spinal deformity, spine surgery and orthopaedics were reviewed for the composition of this article. Summary of key findings: Nutrition may play a role in optimizing postoperative outcomes following adult spinal deformity surgeries, such as limiting delirium, length of stay, blood transfusion, and other medical complications. The use of screening tools, such as the PNI and CONUT score can assess preoperative nutritional status and may provide some utility in evaluating nutrition status in patients undergoing deformity surgery. Balancing both macronutrients and micronutrients, notably, carbohydrates, protein, albumin, and vitamin D can play a role in preoperative optimization. Conclusion: Adult spinal deformity patients are at an increased risk for malnutrition. These patients should be assessed for nutrition status to prime them for surgery, minimize complications, and maximize their outcomes. However, further studies are needed to determine how nutrition ultimately affects adult spinal deformity patients in the postoperative period and to establish specific nutritional recommendations for this unique population.

Study design: Retrospective cohort study.Objective: Respiratory compromise (RC) is a rare but catastrophic complication of anterior cervical spine surgery (ACSS) commonly due to compressive fluid collections or generalized soft tissue swelling in the cervical spine. Established risk factors include operative duration, size of surgical exposure, myelopathy, among others. The purpose of this current study is to identify the incidence and clinical course of patients who develop RC, and identify independent predictors of RC in patients undergoing ACSS for cervical spondylosis.Methods: A large, prospectively-collected registry was used to identify patients undergoing ACSS for spondylosis. Patients with posterior cervical procedures were excluded. Baseline patient characteristics were compared using bivariate analysis, and multivariate analysis was employed to compare postoperative complications and identify independent predictors of RC.Results: 298 of 52,270 patients developed RC (incidence 0.57%). Patients who developed RC had high rates of 30-day mortality (11.7%) and morbidity (75.8%), with unplanned reoperation and pneumonia the most common. The most common reason for reoperations were hematoma evacuation and tracheostomy. Independent patient-specific factors predictive of RC included increasing patient age, male gender, comorbidities such as chronic cardiac and respiratory disease, preoperative myelopathy, prolonged operative duration, and 2-level ACCFs.Conclusion: This is among the largest cohorts of patients to develop RC after ACSS identified to-date and validates a range of independent predictors, many previously only described in case reports. These results are useful for taking preventive measures, identifying high risk patients for preoperative risk stratification, and for surgical co-management discussions with the anesthesiology team.

Study Design Narrative ReviewObjectives The objective of this study was to compare publication status of clinical trials in adult spine surgery registered on ClinicalTrials.govby funding source as well as to identify other trends in clinical trials in adult spine surgery.Methods All prospective, comparative, therapeutic (intervention-based) trials of adult spinal disease that were registered on ClinicalTrials.govwith a start date of January 1, 2000 and completion date before December 17, 2018 were included. Primary outcome was publication status of published or unpublished. A bivariate analysis was used to compare publication status to funding source of industry vs non-industry.Results Our search identified 107 clinical trials. The most common source of funding was industry (62 trials, 57.9% of total), followed by University funding (26 trials, 24.3%). The results of 76 trials (71.0%) were published, with industry-funded trials less likely to be published compared to non–industry-funded trials (62.9% compared to 82.2%, P= .03). Of the 31 unpublished studies, 13 did not report any results on ClinicalTrials.gov, and of those with reported results, none was a positive trial.Conclusions Clinician researchers in adult spine surgery should be aware that industry-funded trials are less likely to go on to publication compared to non–industry-funded trials, and that negative trials are frequently not published. Future opportunities include improvement in result reporting and in publishing negative studies.

Study Design: Retrospective study.Objective: To examine the associated indications, procedures, and postoperative outcomes after revision ACDA.Methods: We utilized a national database to identify adult(≥18 years) patients who underwent either a primary ACDA or removal of ACDA over a 10-year period(2008-2017). An in-depth assessment of the reasons for revision surgery and the subsequent procedures performed after the removal of ACDA was done by using both Current Procedural Terminology(CPT) and International Statistical Classification of Diseases (ICD-9,10) coding.Results: From 2008 to 2017, a total of 3,350 elective, primary ACDA cases were performed. During this time, 69 patients had a revision surgery requiring the removal of ACDA. The most common reasons for revision surgery included cervical spondylosis(59.4%) and mechanical complications(27.5%). After removal of ACDA, common procedures performed included anterior cervical fusion with or without decompression(69.6%), combined anterior/posterior fusion/decompression (11.6%), and replacement of ACDA (7.2%). The indications for surgery did not vary significantly among the different procedures performed (p = 0.318). Patients requiring revision surgery for mechanical complications or those who underwent a combined surgical approach were at significantly higher risk for subsequent short-term complications (p<0.05).Conclusion: Over a 10-year period, the rate of revision surgery for ACDA was low (2.1%). Nearly 90% of revision cases were due to either cervical spondylosis or mechanical complications. These indications for surgery did not vary significantly among the different procedures performed. These findings will be important during the shared-decision making process for patients undergoing primary or revision ACDA.

Objectives This current systematic review sought to identify and evaluate all current research-based spine surgery applications of AI/ML in optimizing preoperative patient selection, as well as predicting and managing postoperative outcomes and complications.Methods A comprehensive search of publications was conducted through the EMBASE, Medline, and PubMed databases using relevant keywords to maximize the sensitivity of the search. No limits were placed on level of evidence or timing of the study. Findings were reported according to the PRISMA guidelinesResults After application of inclusion and exclusion criteria, 41 studies were included in this review. Bayesian networks had the highest average AUC (.80), and neural networks had the best accuracy (83.0%), sensitivity (81.5%), and specificity (71.8%). Preoperative planning/cost prediction models (.89,82.2%) and discharge/length of stay models (.80,78.0%) each reported significantly higher average AUC and accuracy compared to readmissions/reoperation prediction models (.67,70.2%) (P< .001, P= .005, respectively). Model performance also significantly varied across postoperative management applications for average AUC and accuracy values (P< .001, P< .027, respectively).Conclusions Generally, authors of the reviewed studies concluded that AI/ML offers a potentially beneficial tool for providers to optimize patient care and improve cost-efficiency. More specifically, AI/ML models performed best, on average, when optimizing preoperative patient selection and planning and predicting costs, hospital discharge, and length of stay. However, models were not as accurate in predicting postoperative complications, adverse events, and readmissions and reoperations. An understanding of AI/ML-based applications is becoming increasingly important, particularly in spine surgery, as the volume of reported literature, technology accessibility, and clinical applications continue to rapidly expand.

Study Design: Retrospective cohort.Objective: To provide a national-level assessment of the short-term outcomes after spinal deformity surgery in pediatric patients with cerebral palsy.Methods: A national, prospectively collected database was queried to identify pediatric (≤18 years) patients with cerebral palsy, who underwent spinal fusion surgery from 2012 to 2017. Separate multivariate analyses were performed for the primary outcomes of interest including extended length of stay (>75th percentile, >8 days), and readmissions within 90 days after the index admission.Results: A total of 2856 patients were reviewed. The mean age ± standard deviation was 12.8 ± 2.9 years, and 49.4% of patients were female. The majority of patients underwent a posterior spinal fusion (97.0%) involving ≥8 levels (79.9%) at a teaching hospital (96.6%). Top medical complications (24.5%) included acute respiratory failure requiring mechanical ventilation (11.4%), paralytic ileus (8.2%), and urinary tract infections (4.6%). Top surgical complications (40.7%) included blood transfusion (35.6%), wound complication (4.9%), and mechanical complication (2.7%). The hospital cost for patients with a length of hospital stay >8 days ($113 669) was nearly double than that of those with a shorter length of stay ($68 411). The 90-day readmission rate was 17.6% (mean days to readmission: 30.2). The most common reason for readmission included wound dehiscence (21.1%), surgical site infection (19.1%), other infection (18.9%), dehydration (16.9%), feeding issues (14.5%), and acute respiratory failure (13.1%). Notable independent predictors for 90-day readmissions included preexisting pulmonary disease (odds ratio [OR] 1.5), obesity (OR 3.4), cachexia (OR 27), nonteaching hospital (OR 3.5), inpatient return to operating room (OR 1.9), and length of stay >8 days (OR 1.5).Conclusions: Efforts focused on optimizing the perioperative pulmonary, hematological, and nutritional status as well as reducing wound complications appear to be the most important for improving clinical outcomes.

Study Design: Consecutively collected cases.Objective: To determine if a machine-learning (ML) program can accurately predict the postoperative thoracic kyphosis through the uninstrumented thoracic spine and pelvic compensation in patients who undergo fusion from the lower thoracic spine (T10 or T11) to the sacrum.Methods: From 2015 to 2019, a consecutive series of adult (≥18 years old) patients with adult spinal deformity underwent corrective spinal fusion from the lower thoracic spine (T10 or T11) to the sacrum. Deidentified data was processed by a ML system-based platform to predict the postoperative thoracic kyphosis (TK) and pelvic tilt (PT) for each patient. To validate the ML model, the postoperative TK (T4-T12, instrumented thoracic, and uninstrumented thoracic) and the pelvic tilt were compared against the predicted values.Results: A total of 20 adult patients with a minimum 6-month follow-up (mean: 22.4 ± 11.3 months) were included in this study. No significant differences were observed for TK (predicted 37.6° vs postoperative 38.3°, P= .847), uninstrumented TK (predicted 33.9° vs postoperative 29.8°, P= .188), and PT (predicted 23.4° vs postoperative 22.7°, P= .754). The predicted PT and the TK of the uninstrumented thoracic spine correlated well with postoperative values (uninstrumented TK: R2= 0.764, P< .001; PT: R2= 0.868, P< .001). The mean error with which kyphosis through the uninstrumented thoracic spine can be measured was 4.8° ± 4.0°. The mean error for predicting PT was 2.5° ± 1.7°.Conclusion: ML algorithms can accurately predict the spinopelvic compensation after spinal fusion from the lower thoracic spine to the sacrum. These findings suggest that surgeons may be able to leverage this technology to reduce the risk of proximal junctional kyphosis in this population.

Study Design: Retrospective review.Objective: Identify surgical complex adult spine deformity patients who are at increased risk for an unplanned postoperative 90-day readmission and/or reoperation.Methods: A total of 227 consecutive records of complex adult (≥18 years old) spine deformity surgeries from 2015 to 2018 were reviewed. Demographics, comorbidities, operative details, and postoperative complication data was collected. Chi-square/Fisher’s exact test and ttests were used for bivariate analysis. To determine independent predictors for readmissions/reoperations, stepwise multivariate logistic regressions were employed. The C-statistic and Hosmer-Lemeshow (HL) value was used to measure concordance and goodness of fit.Results: Average age was 50.5 ± 17.8 years and 67.8% were female. Ninety-day readmission and reoperation rates were 7.0% and 5.3%, respectively. Median number of days after index discharge date resulting in readmission and reoperation were 16.5 and 28, respectively. The multivariate regression for 90-day readmissions included pulmonary comorbidity, depression, history of deep vein thrombosis/pulmonary embolism (DVT/PE), and gastrointestinal comorbidity (C-statistic = 0.82; HL = 0.79). Pulmonary comorbidity, depression, and history of DVT/PE increased risk for 90-day readmission by 5-, 3.5-, and 10.2-fold, respectively. The multivariate regression for 90-day reoperations was similar to readmissions (C-statistic = 0.89; HL = 0.31). Operative time>7 hours and history of DVT/PE increased risk for early reoperation by 5.8- and 8.7-fold, respectively.Conclusions: An emphasis on medically optimizing patients with preexisting pulmonary comorbidities, depression, and history of DVT/PE may have a substantial impact on improving short-term outcomes in this population. The present study provides benchmark data and may serve as an initial model to predict unplanned reoperations and readmissions.

Purpose: Assess whether a novel deformity angular ratio (DAR) calculated using preoperative three-dimensional computed tomography (3D CT) is more accurate than total DAR (T-DAR) radiographic measurements at predicting intraoperative neuromonitoring (IONM) events during vertebral column resection (VCR). Methods: Consecutive, unique patients undergoing thoracic VCR by a single surgeon from 2015 to 2021 were identified. The T-DAR was calculated by dividing the total radiographic Cobb angle by the number of vertebral segments the angle subtends. 3D CT DAR was calculated for each patient from a preoperative CT scan by finding the maximum angle subtended by three contiguous vertebral segments. All patients were assessed for IONM events. A binary threshold of 25 was used for T-DAR and 3D CT DAR measurements for predictive analysis. p&lt; 0.05 indicated significance. Results: In total, 68 patients were identified. Mean age was 28 years. Mean levels fused was 15. Twenty-one patients (31%) had IONM events. In patients, with and without an IONM event, mean T-DAR was 26.6 ± 9.8 and 21.5 ± 8.8 (p= 0.04), respectively. 3D CT DAR mean values were 26.4 ± 10.8 and 18.4 ± 5.6, respectively (p&lt; 0.001). 3D CT DAR accurately classified 81% of patients with a positive predictive value (PPV) of 75%. In comparison, T-DAR accurately classified 60% of patients with a PPV of 39%. Conclusion: 3D CT substantially improves preoperative IONM event prediction when compared to traditional radiographic measurements. A 3D CT DAR of 25 or greater was correlated with an increased rate of IONM events. 3D CT reconstructions are a useful adjunct for planning prior to a VCR.

Purpose: Restoring coronal alignment in spine deformity patients has been shown to play an important role in improving patient reported outcomes (PRO). Recently, the “kickstand rod” (KSR) technique was developed as a novel coronal correction method in complex spine deformity cases. The goal of the present study was to assess outcomes of this technique at two years of follow-up. Methods: Consecutive, unique adult patients who underwent KSR constructs for coronal spinal malalignment between 2015 and 2019 with a minimum 2 year clinical and radiographic follow-up were identified. A KSR construct includes a more laterally placed iliac screw and additional rod that effectively depresses the ipsilateral ilium/pelvis for coronal correction, while serving as a buttress to prevent future loss of correction. Outcomes included revision for instrumentation-related complications, radiographic alignment, and PROs. Results: Twenty patients were included with a mean age of 54 years [range: 20–73 years]. Mean follow-up time was 2.5 years [range: 2.0–5.0]. Mean number of levels fused was 17.3 [range: 10–24]. There were significant improvements in coronal alignment (CVA: 5.8 cm ± 2.6 cm vs. 1.7 cm ± 1.5 cm), sagittal alignment (SVA: 5.6 cm ± 5.9 cm vs. 1.6 cm ± 2.5 cm) and major Cobb angle (55º ± 32 vs. 26º ± 21) maintained at 2 years (p&lt; 0.05). One patient experienced an asymptomatic fracture at the shank of the KSR iliac screw. There were significant improvements in Oswestry Disability Index and SRS-22 domains (p&lt; 0.05). Conclusion: The KSR technique is a safe and effective method for correcting coronal malalignment in complex spinal deformity patients with no revisions specific for the KSR or iliac screw and significantly improved PROs at a minimum two-year follow-up.

Study Design: Retrospective cohort study.Objectives: Although cervical disc arthroplasty (CDA) has become a well-established and effective treatment for symptomatic cervical degeneration, many patients with multilevel disease are not good candidates for CDA at all levels. For such patients, hybrid surgery (HS)—a combination of adjacent anterior cervical discectomy and fusion (ACDF) and CDA—may be more appropriate. Given the novelty of HS and the relative dearth of studies adequately assessing short-term perioperative complications, this current study sought to assess the short-term morbidity profile of HS, differences in operative duration, length of stay (LOS), and readmission and reoperation rates and reasons relative to a 2-level ACDF cohort.Methods: All patients who underwent HS and 2-level ACDF were identified between 2011 and 2018 using a large, prospectively collected registry. Baseline patient characteristics and postoperative complications were compared using bivariate and/or multivariate analysis.Results: A total of 390 patients undergoing HS were identified. Two-level procedures were the most common (74.9%). Patients undergoing HS were more likely to be younger, male, and have fewer comorbidities. There were no differences between HS and 2-level ACDF in rates of any postoperative complication, transfusion, readmissions, and operative duration. However, HS had a decreased LOS (0.5 days), relative to a 2-level ACDF. HS patients had low rates of reoperation (1.28%) with 1 case for hematoma evacuation and another for revision CDA.Conclusions: This study represents one of the largest cohorts of patients undergoing HS reported to date. Patients undergoing HS are not at increased risk of perioperative complications relative to a 2-level ACDF and may benefit from shorter LOS.

Study Design: Systematic review.Objectives: This current systematic review seeks to identify current applications and surgical outcomes for 3-dimensional printing (3DP) in the treatment of adult spinal deformity.Methods: A comprehensive search of publications was conducted through literature databases using relevant keywords. Inclusion criteria consisted of original studies, studies with patients with adult spinal deformities, and studies focusing on the feasibility and/or utility of 3DP technologies in the planning or treatment of scoliosis and other spinal deformities. Exclusion criteria included studies with patients without adult spinal deformity, animal subjects, pediatric patients, reviews, and editorials.Results: Studies evaluating the effect of 3DP drill guide templates found higher screw placement accuracy in the 3DP cohort (96.9%), compared with non-3DP cohorts (81.5%, P< .001). Operative duration was significant decreased in 3DP cases (378 patients, 258 minutes) relative to non-3DP cases (301 patients,272 minutes, P< .05). The average deformity correction rate was 72.5% in 3DP cases (245 patients). There was no significant difference in perioperative blood loss between 3DP (924.6 mL, 252 patients) and non-3DP cases (935.6 mL, 177 patients, P= .058).Conclusions: Three-dimensional printing is currently used for presurgical planning, patient and trainee communication and education, pre- and intraoperative guides, and screw drill guides in the treatment of scoliosis and other adult spinal deformities. In adult spinal deformity, the usage of 3DP guides is associated with increased screw accuracy and favorable deformity correction outcomes; however, average costs and production lead time are highly variable between studies.

Proximal junctional kyphosis (PJK) is a common problem that may occur following the surgical treatment of adult patients with spinal deformity. It is defined as the proximal junctional sagittal angle from the UIV and UVI + 2 of at least 10° AND at least 10° greater than the preop measurement. The reported incidence of radiographic PJK in the literature varies between 17 and 46%. A smaller subset of these patients may need revision surgery and are defined as proximal junctional failure (PJF), which can be associated with vertebral fracture, vertebral subluxation, failure of instrumentation, and neurological deficits. Several risk factors for development of PJK have been proposed. However, large-scale prospective studies are needed to better identify strategies to reduce the incidence of PJK.

Study Design Cross-sectional Cohort Study.Objective To determine the cervicothoracic inflection point in an asymptomatic, adult population.Introduction The cervicothoracic inflection point (CTIP) is an important sagittal marker to understand for patients with cervical deformities. We aimed to identify the CTIP and understand the relationship to other sagittal alignment markers.Methods 468 adult asymptomatic volunteers (18-80 years) from 5 countries (United States, France, Japan, Singapore, Tunisia). All volunteers underwent standing full body, low dose stereo radiographs. The CTIP was identified by measuring the cervical sagittal angle (CSA) and thoracic kyphosis maximum angle (TKMax), using the end vertebra concept. The CTIP was defined as the vertebra or disc between the lower end vertebra of the CSA and upper end vertebra of TKMax. A correlation matrix was utilized to identify the relationship between the CTIP and spinopelvic sagittal parameters of interest.Results The most common CTIP value was the T1 vertebra. CTIPs ranged from C5 to T4, respectively. CTIP showed a weak positive correlation to age (r = 0.10, P= 0.03) and negative correlation to BMI (r = −0.11, P= 0.04). Additionally, CTIP had a minor positive correlation with OC2-CL, C7 slope, T1 slope, T1PA, T1-T12 TK, and T4-T12 TK, all statistically significant. Linear regression demonstrated increased cervical lordosis and increased TK was associated with more caudal CTIP segments.Conclusion CTIP segments ranged from C5 to T4, with the most common segment being T1. Understanding the relationship of the CTIP to other sagittal variables is critical to patients with CD.

Study Design Prospective cohort study.Objectives To show population variance in the Inflection Point (IP) and its role in defining maximum Thoracic Kyphosis (TK) and Lumbar Lordosis (LL).Methods 468 asymptomatic adult volunteers were included in the Multi-Ethnic Normative Alignment Study (MEANS). To find parameters correlating with IP, the vertebrae and discs were numbered such that C7 was 0, T1 was 1, with T1-T2 disc being 1.5, etc. Statistical analysis was performed by a correlation matrix for IP and the 9 other selected parameters along with linear regressions.Results The overall mean IP was 12.44 approximately corresponding to T12-L1 disc with the median being 12.50, range was T8-L4. The cohort was then stratified by sex and ethnicity, but there was no significant difference in IP between groups. IP in younger subjects was 13 (L1), compared to 12.5 (T12-L1 disc) in older subjects (P< .05). IP was moderately correlated with the TK apex (r = .66). No strong correlation was found between IP and LL magnitude or apex, TK magnitude, sacral slope, or Pelvic Incidence (PI). In terms of other sagittal parameters, PI and LL demonstrated a significant positive correlation. PI and TK did not have a strong association.Conclusions The mean IP was at the T12-L1 disc, however IP ranged from T8 to L4. Older subjects tended to have a relatively more cephalad IP. No radiographic variable was found to be a strong predictor of the IP. TK apex was found to have a moderate correlation.

Study Design Cross-sectional cohort study.Objective To classify spinal morphology using the “current” and “theoretical” Roussouly systems and assess sagittal alignment in an asymptomatic cohort.Methods 467 asymptomatic volunteers were recruited from 5 countries. Radiographic parameters were measured via the EOS imaging system. “Current” and “theoretical” Roussouly classification was assigned with sagittal whole spine imaging using sacral slope (SS), pelvic incidence (PI), and the lumbar apex. One-way analysis of variance (ANOVA) was performed to compare subject characteristics across Roussouly types, followed by post hoc Bonferroni correction.Results Volunteers were categorized into 4 groups (Types 1-4) and 1 subgroup (Type 3 AP) using the “current” and “theoretical” Roussouly systems. The mean PI in “current” Roussouly groups was 40.8° (Type 1), 43.6° (Type 2), 52.4° (Type 3), 62.4° (Type 4), and 43.7° (Type 3AP). The mean PI in “theoretical” Roussouly groups was 36.5° (Type 1), 39.1°(Type 2), 52.5° (Type 3), 67.3° (Type 4), and 51.0° (Type 3AP). The difference in PI between “current” and “theoretical” Roussouly types was significant for Type 1 (P= .02), Type 2 (P< .001), Type 4 (P< .001), and Type 3AP (P< .001). 34.7% of subjects had a “current” Roussouly type different from the “theoretical” type. Type 3 theoretical shape had the most frequent mismatch, constituting 61.1% of the mismatched subjects. 51.5% of mismatched Type 3 become “current” Type 4.Conclusion The distribution of Roussouly types differs depending on whether the “current” or “theoretical” classification are employed. A sizeable proportion of volunteers exhibited current and theoretical type mismatch, highlighting the need to interpret sagittal alignment cautiously when utilizing the Roussouly system.

Single-center retrospective analysis of consecutive patients who have undergone circumferential minimally invasive surgery (cMIS) for correction of adult spinal deformity (ASD).

Study design: Single-center retrospective analysis of consecutive patients who have undergone circumferential minimally invasive surgery (cMIS) for correction of adult spinal deformity (ASD). Objectives: To study the rates of reoperations and readmissions within the first 30 days following cMIS for correction of ASD. Background: Hospital readmission and reoperation rates have been emphasized as an important measure of quality and cost-effectiveness of care. However, there is little information about the readmission rates following cMIS correction of ASD. Methods: This is a retrospective cohort study of 214 consecutive patients with ASD who underwent correction using cMIS involving at least 2 levels. Major complications encountered during surgery or within 30 days following the index procedure that needed reoperation or readmission were recorded. The primary outcomes measured were early readmission, and early reoperation. Results: An average of 4 levels were fused. Nineteen complications were noted in the 30-day period following the index surgery, giving an early complication rate of 8.9%. Twelve of those complications occurred during the initial hospitalization and 7 complications occurred after the patient had been discharged home. Forty-seven percent of the complications occurred within the first 3 years of our experience, 37% in the next 2 years, and only 16% in the following 3 years. The 30-day readmission rate was 3.3%, which showed no statistically significant difference based on the number of levels fused. Conclusions: Our study delivers significant evidence that efforts to reduce hospital readmissions for ASD patients should begin by concentrating on the postoperative complications. Although minimally invasive approaches will not eliminate all complications, they may have an effect on reducing the rate of major complications, most notably the rate of postoperative infection. This in turn can lead to a substantially lower readmission and reoperation rate as is reported in our study. Level of Evidence: Level IV, case series.

Study Design A biomechanical and radiographic study using vertebral analogues.Objectives Kyphoplasty and vertebroplasty are widely used techniques to alleviate pain in fractures secondary to osteoporosis. However, cement leakage toward vital structures like the spinal cord can be a major source of morbidity and even mortality. We define safe cement injection as the volume of the cement injected into a vertebra before the cement leakage occurs. Our objective is to compare the amount of cement that can be safely injected into an osteoporotic vertebra with simulated compression fracture using either vertebroplasty or balloon kyphoplasty techniques.Methods Forty artificial vertebral analogues made of polyurethane with osteoporotic cancellous matrix representing the L3 vertebrae were used for this study and were divided into four groups of 10 vertebrae each. The four groups tested were: low-viscosity cement injected using vertebroplasty, high-viscosity cement injected using vertebroplasty, low-viscosity cement injected using balloon kyphoplasty, and high-viscosity cement injected using balloon kyphoplasty. The procedures were performed under fluoroscopic guidance. The injection was stopped when the cement started protruding from the created vascular channel in the osteoporotic vertebral fracture model. The main outcome measured was the volume of the cement injected safely into a vertebra before leakage through the posterior vascular channel.Results The highest volume of the cement injected was in the vertebroplasty group using high-viscosity cement, which was almost twice the injected volume in the other three groups. One-way analysis of variance comparing the four groups showed a statistically significant difference (p?

A biomechanical study.

The ideal treatment for unstable thoracolumbar fractures remains controversial with posterior reduction and stabilization, anterior reduction and stabilization, combined posterior and anterior reduction and stabilization, and even nonoperative management advocated. Short segment posterior osteosynthesis of these fractures has less comorbidities compared with the other operative approaches but settles into kyphosis over time. Biomechanical comparison of the divergent bridge construct versus the parallel tension band construct was performed for anteriorly destabilized T11–L1 spine segments using three different models: (1) finite element analysis (FEA), (2) a synthetic model, and (3) a human cadaveric model. Outcomes measured were construct stiffness and ultimate failure load. Our objective was to determine if the divergent pedicle screw bridge construct would provide more resistance to kyphotic deforming forces. All three modalities showed greater stiffness with the divergent bridge construct. The FEA calculated a stiffness of 21.6 N/m for the tension band construct versus 34.1 N/m for the divergent bridge construct. The synthetic model resulted in a mean stiffness of 17.3 N/m for parallel tension band versus 20.6 N/m for the divergent bridge (p?=?0.03), whereas the cadaveric model had an average stiffness of 15.2 N/m in the parallel tension band compared with 18.4 N/m for the divergent bridge (p?=?0.02). Ultimate failure load with the cadaveric model was found to be 622?N for the divergent bridge construct versus 419?N (p?=?0.15) for the parallel tension band construct. This study confirms our clinical experience that the short posterior divergent bridge construct provides greater stiffness for the management of unstable thoracolumbar fractures.