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Background: S2 alar-iliac (S2AI) screws provide spinopelvic fixation with the advantages of minimized dissection, easier rod contouring, and decreased symptomatic screw-head prominence. However, placement of S2AI screws may be challenging because of the anatomy of the lumbosacral junction. Augmented reality is a nascent technology that may enhance placement of S2AI screws., Objective: To report the first in-human placement of augmented reality (AR)-assisted S2 alar-iliac screws and evaluate the accuracy of screw placement., Methods: A retrospective review was performed of patients who underwent AR-assisted S2AI screw placement. All surgeries were performed by 2 neurosurgeons using an AR head-mounted display (Xvision, Augmedics). Screw accuracy was analyzed in a blinded fashion by an independent neuroradiologist using the cortical breach grading scale., Results: Twelve patients underwent AR-assisted S2AI screw placement for a total of 23 screws. Indications for surgery included deformity, degenerative disease, and tumor. Twenty-two screws (95.6%) were accurate-defined as grade 0 or grade 1. Twenty-one screws (91.3%) were classified as grade 0, 1 screw (4.3%) was grade 1, and 1 screw (4.3%) was grade 3. All breaches were asymptomatic., Conclusion: AR-assisted S2AI screw placement had an overall accuracy rate of 95.6% (grade 0 and grade 1 screws) in a cohort of 12 patients and 23 screws. This compares favorably with freehand and robotic placement. 1,2 AR enables spine surgeons to both better visualize anatomy and accurately place spinal instrumentation. Future studies are warranted to research the learning curve and cost analysis of AR-assisted spine surgery., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background and Objective: Comparative effectiveness research plays a vital role in health care delivery. Specialty training is one of these variables; surgeons who are trained in different specialties may have different outcomes performing the same procedure. The objective of this study was to investigate the impact of spine surgeon specialty (neurosurgery vs orthopedic surgery) on early perioperative outcome measures of elective posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS)., Methods: This is a retrospective, 1:4 propensity score-matched cohort study. 5520 AIS patients were reviewed from ACS-NSQIP pediatric database. Propensity score matching was utilized., Results: Patients operated on by orthopedic surgeons were more likely to have shorter operation time (263 min vs 285 min), shorter total hospital stay (95 h vs 118 h), lower rate of return to operating room within the same admission (1.2% vs 3.8%), lower discharge rates after postoperative day 4 (23.8% vs 30.9%), and lower unplanned readmission rate (1.6% vs 4.1%), (p < 0.05). On the other hand, patients operated on by neurosurgeons had lower perioperative blood transfusion rate (62.1% vs 69.8%), (p < 0.05). Other outcome measures and mortality rates were not significantly different between the two cohorts., Conclusions: This retrospective study found significant differences in early perioperative outcomes of patients undergoing PSF for AIS by neurosurgeons and orthopedic surgeons. Further studies are recommended to corroborate this finding which may trigger changes in the educational curriculum for neurosurgery residents., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Comparative effectiveness research has a vital role in recent health reform and policies. Specialty training is one of these provider-side variables, and surgeons who were trained in different specialties may have different outcomes on performing the same procedure., Objective: To investigate the impact of spine surgeon specialty (neurosurgery vs orthopedic surgery) on early perioperative outcome measures of elective anterior cervical diskectomy and fusion (ACDF) for degenerative spine diseases., Methods: This was a retrospective, 1:1 propensity score-matched cohort study. In total, 21 211 patients were reviewed from the American College of Surgeons National Surgical Quality Improvement Program database. Propensity score matching and subgroup analysis were performed., Results: In both groups (single-level/multilevel ACDF), patients operated on by neurosurgeons had longer operation time (133 vs 104 min/164 vs 138 min), shorter total hospital stay (24 vs 41 h/25 vs 46 h), and lower rates of return to operating room (0.7% vs 2.1%/0.6% vs 2.4%), nonhome discharge (1.2% vs 4.6%/1.0% vs 4.9%), discharge after postoperative day 1 (6.7% vs 11.9%/10.1% vs 18.9%), perioperative blood transfusion (0.4% vs 2.1%/0.6% vs 3.1%), and sepsis (0.2% vs 0.7%/0.1% vs 0.7%; P < .05). In the single-level ACDF group, patients operated on by neurosurgeons had lower readmission (1.9% vs 4.1%) and unplanned intubation rates (0.1% vs 1.1%; P < .05). Other outcome measures and mortality rates were similar among the 2 cohorts in both groups., Conclusion: Our analysis found significant differences in early perioperative outcomes of patients undergoing ACDF by neurosurgeons and orthopedic surgeons. These differences might have significant clinical and cost implications for patients, physicians, program directors, payers, and health systems., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

Background: Comparative effectiveness research has a vital role in health reform and policies. Specialty training is one of these provider-side variables, and surgeons performing the same procedure who were trained in different specialties may have different outcomes. The objective of this study was to investigate the impact of spine surgeon specialty (neurosurgery vs. orthopedic surgery) on early perioperative outcome measures of elective anterior/lateral lumbar interbody fusion (ALIF/LLIF) for degenerative disc diseases., Methods: In a retrospective, 1:1 propensity score-matched cohort study, 9070 patients were reviewed from the American College of Surgeons National Surgical Quality Improvement Program database. Propensity score matching and subgroup analysis were used., Results: In both groups (single-level and multilevel ALIF/LLIF), patients operated on by neurosurgeons had longer operative time (188 minutes vs. 172 minutes/239 minutes vs. 221 minutes); shorter total hospital stay (71 hours vs. 90 hours/89 hours vs. 96 hours); and lower rates of return to the operating room (2.1% vs. 4.1%/2.4% vs. 4.2%), nonhome discharge (8.7% vs. 11.1%/10.1% vs. 14.9%), discharge after postoperative day 3 (22.0% vs. 30.0%/38.0% vs. 43.9%), and perioperative blood transfusion (2.1% vs. 5.1%/5.0% vs. 9.9%) (P < 0.05). In multilevel ALIF/LLIF, patients operated on by neurosurgeons had lower readmission rates (3.9% vs. 6.9%) (P < 0.05). Other outcome measures and mortality rates were similar between the single-level and multilevel ALIF/LLIF cohorts regardless of surgeon specialty., Conclusions: Our analysis found significant differences in early perioperative outcomes of patients undergoing ALIF/LLIF by neurosurgeons and orthopedic surgeons. These differences have significant clinical and cost implications for patients, physicians, program directors, payers, and health systems., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Study Design: Rat posterolateral lumbar fusion model., Objective: The aim of this study was to compare the efficacy of freshly isolated adipose tissue-derived stromal vascular fraction (A-SVF) and bone marrow cells (BMCs) cells in achieving spinal fusion in a rat model., Summary of Background Data: Adipose tissue-derived stromal cells (ASCs) offer advantages as a clinical cell source compared to bone marrow-derived stromal cells (BMSCs), including larger available tissue volumes and reduced donor site morbidity. While pre-clinical studies have shown that ex vivo expanded ASCs can be successfully used in spinal fusion, the use of A-SVF cells better allows for clinical translation., Methods: A-SVF cells were isolated from the inguinal fat pads, whereas BMCs were isolated from the long bones of syngeneic 6- to 8-week-old Lewis rats and combined with Vitoss (Stryker) bone graft substitute for subsequent transplantation. Posterolateral spinal fusion surgery at L4-L5 was performed on 36 female Lewis rats divided into three experimental groups: Vitoss bone graft substitute only (VO group); Vitoss + 2.5 × 106 A-SVF cells/side; and, Vitoss + 2.5 × 106 BMCs/side. Fusion was assessed 8 weeks post-surgery via manual palpation, micro-computed tomography (μCT) imaging, and histology., Results: μCT imaging analyses revealed that fusion volumes and μCT fusion scores in the A-SVF group were significantly higher than in the VO group; however, they were not significantly different between the A-SVF group and the BMC group. The average manual palpation score was highest in the A-SVF group compared with the BMC and VO groups. Fusion masses arising from cell-seeded implants yielded better bone quality than nonseeded bone graft substitute., Conclusion: In a rat model, A-SVF cells yielded a comparable fusion mass volume and radiographic rate of fusion to BMCs when combined with a clinical-grade bone graft substitute. These results suggest the feasibility of using freshly isolated A-SVF cells in spinal fusion procedures.Level of Evidence: N/A., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer-irrigator-aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion., Methods: Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft, syngeneic iliac crest allograft, and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation, and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources., Results: Although no differences were observed between groups in CT fusion mass volumes, iliac allografts displayed an increased number of radiographically fused fusion masses and a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow., Conclusions: This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

Background: Local, intrawound use of antibiotic powder, such as vancomycin and tobramycin, in spinal fusion surgery has become an increasingly common prophylactic measure in an attempt to reduce rates of postsurgical infection. However, the effects of localized antibiotic delivery on fusion remain unclear. The objective of this study was to examine the in vivo effects of intraoperative local delivery of 2 antibiotics commonly used in bone-grafting surgery on spinal fusion outcomes in a rat model., Methods: Single-level (L4-L5), bilateral posterolateral intertransverse process lumbar fusion surgery was performed on 60 female Lewis rats (6 to 8 weeks of age) using syngeneic iliac crest allograft mixed with clinical bone-graft substitute and varying concentrations of antibiotics (n = 12 each): (1) control without any antibiotics, (2) low-dose vancomycin (14.3 mg/kg), (3) high-dose vancomycin (71.5 mg/kg), (4) low-dose tobramycin (28.6 mg/kg), and (5) high-dose tobramycin (143 mg/kg). Eight weeks postoperatively, fusion was evaluated via micro-computed tomography (µCT), manual palpation, and histological analysis, with blinding to treatment group. In the µCT analysis, fusion-mass volumes were measured for each rat. Each spine specimen (L4-L5) was rated (manual palpation score) on a scale of 2 to 0 (2 = fused, 1 = partially fused, and 0 = non-fused)., Results: The mean fusion-mass volume on µCT (mm) was as follows: control, 29.3 ± 6.2; low-dose vancomycin, 26.3 ± 8.9; high-dose vancomycin, 18.8 ± 7.9; low-dose tobramycin, 32.7 ± 9.0; and high-dose tobramycin, 43.8 ± 11.9 (control versus high-dose vancomycin, p < 0.05; and control versus high-dose tobramycin, p < 0.05). The mean manual palpation score for each group was as follows: control, 1.46 ± 0.58; low-dose vancomycin, 0.86 ± 0.87; high-dose vancomycin, 0.68 ± 0.62; low-dose tobramycin, 1.25 ± 0.71; and high-dose tobramycin, 1.32 ± 0.72 (control versus high-dose vancomycin, p < 0.05). The histological analyses demonstrated a similar trend with regard to spinal fusion volume., Conclusions: Intraoperative local application of vancomycin, particularly at a supraphysiological dosage, may have detrimental effects on fusion-mass formation. No inhibitory effect of tobramycin on fusion-mass formation was observed., Clinical Relevance: When spine surgeons decide to use intraoperative intrawound antibiotics in spinal fusion surgery, they should weigh the reduction in surgical site infection against a possible inhibitory effect on fusion.

Background: Few studies have described rates of proximal clinical adjacent segment pathology (CASP) after posterior cervical decompression and fusion (PCDF)., Objective: To investigate rates of proximal CASP at C2 vs C3 in PCDFs for degenerative spine disease., Methods: A retrospective review of 380 cases of PCDF for degenerative disease with proximal constructs ending at C2 vs C3 was performed. Minimum follow-up was 12 mo. The primary outcome was proximal CASP requiring reoperation. Variable analysis included demographic, operative, and complication data., Results: There were 119 patients in the C2 group and 261 in the C3 group with no significant differences in age, gender, comorbidities, presenting symptoms, or complications. Vertebral artery injury rates were 0.8% in the C2 group and 0.0% in the C3 group (P = .12). No patients in the C2 group had reoperation for proximal CASP, while 5.0% of patients in the C3 group did (P = .01). Patients with arthrodesis up to C3 had an increased risk of proximal failure when the fusion construct crossed the cervicothoracic junction (P = .03). Multivariate logistic regression analysis showed no factors that were independently associated with re-instrumentation for proximal CASP., Conclusion: Instrumenting to the C2 level reduces the risk for proximal CASP compared to fusion only up to C3. The type of instrumentation used at these 2 levels, form of ASP disease at C1-C2, and natural motion of the relevant proximal adjacent joint may contribute to this difference. Furthermore, within the C3 cohort, fusion across the cervicothoracic junction increased the risk for proximal CASP., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background Context: Recently, preclinical and clinical studies suggest an association between renin-angiotensin system (RAS) blockers and bone healing, particularly in the context of osteoporotic bone fractures., Purpose: To determine the correlation between the use of RAS inhibitors and fusion outcomes and neurologic status in anterior cervical discectomy and fusion (ACDF) surgery., Study Design: Retrospective observational study., Patient Sample: Patients who underwent ACDF for degenerative disorders., Outcome Measures: Spinal fusion status and neurologic function (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales)., Methods: A retrospective chart review was performed, including 200 patients who underwent ACDF for degenerative disorders with 1-year minimum follow-up. Demographic data, comorbidities, antihypertensive medication, neurologic examination, and fusion status were collected. Spinal fusion was assessed via plain cervical x-ray, resorting to dynamic radiographs and/or computer tomography (CT) in cases of uncertainty. Preoperative mJOA and Nurick scores and recovery rates were calculated to determine neurologic status., Results: Of the 200 patients (42.5% females, 57.5% males, median age of 53.7 years), 82 hypertensive patients were identified. Seventy-seven (93.9%) were taking antihypertensive medication as follows: 36.4% angiotensin-II receptor blockers (ARBs), 35.1% angiotensin-converting enzyme inhibitors (ACEIs), and the remaining patients were taking other medication. In the analysis of fusion rates, patients treated with ARBs exhibited a higher fusion rate, while those treated with ACEIs displayed a lower fusion rate compared to untreated nonhypertensive patients (p = .04 and .02, respectively). The difference in fusion rates between ARBs and ACEIs was also significant, with the former displaying higher rates (p < .001). Smoking exhibited a negative correlation with spinal fusion (p < .001). In the multivariate analysis, ARBs remained an independent factor for successful fusion (p = .02), while smoking remained a risk factor for failed fusion (p = .002). In the neurologic examination, ACEIs, hypertension status, and older age correlated with lower modified Japanese Orthopedic Association (mJOA) recovery rates (p = .001, <.001, and <.001, respectively) in the univariate analysis., Conclusions: In ACDF patients, we observed that ARBs were associated with higher fusion rates. Conversely, ACEIs and smoking were related to failed fusion. Prospective case-control studies are needed to confirm these RAS inhibitors effects on spinal fusion., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Pedicle screws (PSs) are routinely used for stabilization to enhance fusion in a variety of spinal diseases. Although the accuracy of different PS placement methods has been previously reported, most of these studies have been limited to 1 or 2 techniques. The purpose was to determine the current accuracy of PS placement among 4 modalities of PS insertion (freehand [FH], fluoroscopy-assisted [FA], computed tomography navigation-guided [CTNav], and robot-assisted [RA]) and analyze variables associated with screw misplacement., Methods: A systematic review was performed of peer-reviewed articles reporting PS accuracy of 1 technique from January 1990 to June 2018. Accuracy of PS placement, PS insertion technique, and pedicle breach (PB) data were collected. A meta-analysis was performed to estimate the overall pooled (OP) rates of PS accuracy as a primary outcome, stratified by screw insertion techniques. Potential determinants were analyzed via meta-regression analyses., Results: Seventy-eight studies with 7858 patients, 51,161 PSs, and 3614 cortical PBs were included. CTNav showed the highest PS placement accuracy compared with other techniques: OP accuracy rates were 95.5%, 93.1%, 91.5%, and 90.5%, via CTNav, FH, FA, and RA techniques, respectively. RA and CTNav were associated with the highest PS accuracy in the thoracic spine, compared with FH., Conclusions: The OP data show that CTNav has the highest PS accuracy rates. Thoracic PSs were associated with lower accuracy rates; however, RA showed fewer breaches in the thoracic spine compared with FH and FA. Given the heterogeneity among studies, further standardized and comparative investigations are required to confirm our findings., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Purpose: Bone marrow aspirate has been successfully used alongside a variety of grafting materials to clinically augment spinal fusion. However, little is known about the fate of these transplanted cells. Herein, we develop a novel murine model for the in vivo monitoring of implanted bone marrow cells (BMCs) following spinal fusion., Methods: A clinical-grade scaffold was implanted into immune-intact mice undergoing spinal fusion with or without freshly isolated BMCs from either transgenic mice which constitutively express the firefly luciferase gene or syngeneic controls. The in vivo survival, distribution and proliferation of these luciferase-expressing cells was monitored via bioluminescence imaging over a period of 8 weeks and confirmed via immunohistochemistry. MicroCT imaging was performed 8 weeks to assess fusion., Results: Bioluminescence imaging indicated transplanted cell survival and proliferation over the first 2 weeks, followed by a decrease in cell numbers, with transplanted cell survival still evident at the end of the study. New bone formation and increased fusion mass volume were observed in mice implanted with cell-seeded scaffolds., Conclusions: By enabling the tracking of transplanted bone marrow-derived cells during spinal fusion in vivo, this mouse model will be integral to developing a deeper understanding of the biological processes underlying spinal fusion in future studies. These slides can be retrieved under Electronic Supplementary Material.

Study Design: Technical report and case illustration., Objective: To review the rationale and steps for a sublaminar decompression in the setting of adult deformity surgery and in degenerative spondylosis., Summary of Background Data: Several variations of lumbar laminotomy and posterior decompressions have been reported, although these are primarily in the setting of isolated lumbar stenosis, and often focus on treatment of central stenosis., Materials and Methods: Our operative technique is illustrated and 1 patient with a 1-year follow-up is presented to further describe this surgical approach., Results and Surgical Techniques: The patient underwent a lumbar decompression and fusion procedure. A sublaminar decompression with bilateral foraminotomies was performed at L4-L5, combined with instrumented posterior fusion., Conclusions: The presented sublaminar decompression technique allows for adequate decompression of the central canal, lateral recess, and neural foramina while providing maximum bone surface area for posterolateral as well as posterior fusion.

The rat posterolateral spinal fusion model with autogenic/allogenic bone graft (rat PFABG) has been increasingly utilized as an experimental model to assess the efficacy of novel fusion treatments. The objective of this study was to investigate the reliability of the rat PFABG model and examine the effects of different variables on spinal fusion. A web-based literature search from January, 1970 to September, 2015, yielded 26 studies, which included 40 rat PFABG control groups and 449 rats. Data regarding age, weight, sex, and strain of rats, graft volume, graft type, decorticated levels, surgical approach, institution, the number of control rats, fusion rate, methods of fusion assessment, and timing of fusion assessment were collected and analyzed. The primary outcome variable of interest was fusion rate, as evaluated by manual palpation. Fusion rates varied widely, from 0 to 96%. The calculated overall fusion rate was 46.1% with an I 2 value of 62.4, which indicated moderate heterogeneity. Weight >300 g, age >14 weeks, male rat, Sprague-Dawley strain, and autogenic coccyx grafts increased fusion rates with statistical significance. Additionally, an assessment time-point ≥8 weeks had a trend towards statistical significance (p = 0.070). Multi-regression analysis demonstrated that timing of assessment and age as continuous variables, as well as sex as a categorical variable, can predict the fusion rate with R 2  = 0.82. In an inter-institution reliability analysis, the pooled overall fusion rate was 50.0% [44.8, 55.3%], with statistically significant differences among fusion outcomes at different institutions (p < 0.001 and I 2 of 72.2). Due to the heterogeneity of fusion outcomes, the reliability of the rat PFABG model was relatively limited. However, selection of adequate variables can optimize its use as a control group in studies evaluating the efficacy of novel fusion therapies.

Background: In sacropelvic fixation, the iliac screw technique offers biomechanically strong constructs, but its disadvantages include screw prominence, wound dehiscence, and postoperative pain secondary to the high profile nature. To overcome this drawback, S2-alar-iliac (S2AI) screws were developed as an alternative technique for sacropelvic fixation. This study aimed to compare the S2AI screw technique with the iliac screw technique in terms of postoperative symptomatic screw prominence., Methods: A retrospective review of the records of sacropelvic fusion procedures performed at a single institution between October 2010 and January 2015 identified 32 patients with 72 iliac screws and 68 patients with 148 S2AI screws, and clinical and radiographic data were collected. If a patient had wound dehiscence and/or tenderness in the buttock immediately overlying a pelvic screw head postoperatively, it was defined as symptomatic screw prominence. The minimal distance from screw head to skin (MDSS) on postoperative computed tomography scans was measured for each patient to clarify the relationship between symptomatic screw prominence and MDSS., Results: Mean follow-up period was 22.0 months. There was significantly more symptomatic pelvic screw prominence in the iliac screw group (11.1% vs. 1.4%, P = 0.002). MDSS ≤23 mm was the strongest predictor of symptomatic pelvic screw prominence, which yielded sensitivity of 100%, specificity of 94.1%, positive predictive value of 47.6%, and negative predictive value of 100%., Conclusions: The use of the S2AI screw technique resulted in a reduced rate of symptomatic screw prominence. MDSS ≤23 mm was the strongest predictor of symptomatic screw prominence., (Published by Elsevier Inc.)

Traditional treatment for lumbar stenosis with instability is laminectomy and posterolateral arthrodesis, with or without interbody fusion. However, laminectomies remove the posterior elements and decrease the available surface area for fusion. Therefore, a sublaminar decompression may be a preferred approach for adequate decompression while preserving bone surface area for fusion. A retrospective review of 71 patients who underwent sublaminar decompression in conjunction with instrumented fusion for degenerative spinal disorders at a single institution was performed. Data collected included demographics, preoperative symptoms, operative data, and radiographical measurements of the central canal, lateral recesses, and neural foramina, and fusion outcomes. Paired t-tests were used to test significance of the outcomes. Thirty-one males and 40 females with a median age 60years underwent sublaminar decompression and fusion. A median of two levels were fused. The mean Visual Analog Scale pain score improved from 6.7 preoperatively to 2.9 at last follow-up. The fusion rate was 88%, and the median time to fusion was 11months. Preoperative and postoperative mean thecal sac cross-sectional area, right lateral recess height, left lateral recess height, right foraminal diameter, and left foraminal diameter were 153 and 209mm(2) (p<0.001), 5.9 and 5.9mm (p=0.43), 5.8 and 6.3mm (p=0.027), 4.6 and 5.2mm (p=0.008), and 4.2 and 5.2mm (p<0.001), respectively. Sublaminar decompression provided adequate decompression, with significant increases in thecal sac cross-sectional area and bilateral foraminal diameter. It may be an effective alternative to laminectomy in treating central and foraminal stenosis in conjunction with instrumented fusion., (Published by Elsevier Ltd.)

Study Design: A posterolateral rabbit spinal fusion model was used to evaluate the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) and teriparatide (PTH [1-34]) used individually and in combination on spinal fusion outcomes., Objective: To test the efficacy of parathyroid hormone on improving spinal fusion outcomes when used with BMP-2., Summary of Background Data: Of the more than 250,000 spinal fusion surgical procedures performed each year, 5% to 35% of these will result in pseudarthrosis. Growing controversy on the efficacy and cost of rhBMP-2 for improving spinal fusion outcomes has presented a challenge for clinicians. Research into PTH as an adjunct therapy to rhBMP-2 for spinal fusion has not yet been investigated., Methods: Forty-eight male New Zealand white rabbits underwent bilateral posterolateral intertransverse process arthrodesis surgery at the L5-L6 level. Animals were divided into 6 groups. Two groups were treated with autograft alone or autograft and PTH (1-34), whereas the other 4 groups were treated with low-dose rhBMP-2 alone, high-dose rhBMP-2 alone, or either dose combined with PTH (1-34). All animals were euthanized 6 weeks after surgery. The L4-L7 spinal segment was removed and assessed using manual palpation, computed tomography (CT), and biomechanical testing., Results: CT assessments revealed fusion in 50% of autograft controls, 75% of autograft PTH (1-34) animals, 87.5% in the 2 groups treated with low-dose rhBMP-2, and 100% in the 2 groups treated with high-dose rhBMP-2. CT volumetric analysis demonstrated that all groups treated with biologics had fusion masses that were on average significantly larger than those observed in the control group (P < 0.0001). Biomechanical data demonstrated no statistical difference between controls, PTH (1-34), and low-dose rhBMP-2 in any testing orientation. PTH (1-34) did not increase bending stiffness when used adjunctively with either low-dose or high-dose rhBMP-2., Conclusion: Although intermittent teriparatide administration results in increased fusion mass volume, it does not improve biomechnical stiffness over use of autograft alone. When delivered concurrently with high- and low-dose rhBMP-2, teriparatide provided no statistically significant improvement in biomechanical stiffness., Level of Evidence: N/A.

Study Design: Retrospective comparative study.Objective: To compare clinical and radiographic outcomes between the S2-alar-iliac (S2AI) and the iliac screw (IS) techniques in the adult population and clarify the clinical strength of S2AI screws.Summary Of Background Data: S2AI screws have been described as an alternative method for lumbosacropelvic fixation in place of ISs. The S2AI technique has several advantages with lower prominence, increased ability to directly connect to proximal instrumentation, less extensive dissection of tissue, and enhanced biomechanical strength over the IS technique. However, the clinical significance of these advantages remains unclear.Methods: A single-center retrospective review of patients who underwent lumbosacropelvic fixation yielded 25 IS group patients and 65 S2AI group patients. Baseline demographic information, postoperative complications, pain and functional outcomes, and screw-related outcomes were collected.Results: The S2AI group had lower rates of reoperation (8.8% vs. 48.0%, P < 0.001), surgical site infection (SSI) (1.5% vs. 44.0%, P < 0.001), wound dehiscence (1.5% vs. 36.0%, P < 0.001), and symptomatic screw prominence (0.0% vs. 12.0%, P = 0.02) than the IS group, whereas rates of L5-S1 pseudarthrosis, proximal junctional failure, and sacroiliac joint pain were similar in both groups. Statistically significant pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, age [odds ratio (OR) = 0.91, P = 0.004] and S2AI instrumentation (OR = 0.08, P < 0.001) were protective of reoperation, whereas diabetes mellitus (OR = 10.9, P = 0.03) and preoperative diagnosis of tumor (OR = 12.3, P = 0.04) were associated with SSI, and S2AI instrumentation (OR = 0.09, P < 0.001) was protective of SSI.Conclusion: The use of the S2AI technique over the IS technique was an independent predictor of preventing reoperation and SSI, while achieving similar clinical and functional outcomes.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Comparative effectiveness research has a vital role in health reform and policies. Specialty training is one of these provider-side variables and surgeons who were trained in different specialties may have different outcomes upon performing the same procedure. To investigate the impact of spine surgeon specialty on early perioperative outcome of anterior cervical discectomy and fusion (ACDF). Retrospective, 1:1 propensity score-matched cohort study. A total of 21,211 patients who underwent ACDF between 2016-2018 were reviewed from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Outcomes included 30-day perioperative morbidity and mortality measures that are predefined in the ACS-NSQIP database. Patients were stratified by the specialty of surgeon performing the procedure (neurosurgery vs orthopedic surgery), and the number of levels operated on (single- vs multi-level surgery) Patients operated on by neurosurgeons were more likely to be older, smokers, of Hispanic ethnicity, functionally dependent, and to have higher BMI, an ASA class 3 or more, baseline dyspnea, bleeding disorders, and myelopathy. In both groups (single/multi-level ACDF), cases in the orthopedic surgery cohort were more likely to have shorter operation time (104 vs 133 minutes/ 138 vs 164 minutes), longer total hospital stay (41 vs 24 hours/ 46 vs 25 hours), higher return to operating room rates within the same admission (2.1% vs 0.7%/ 2.4% vs 0.6%), be discharged to destination other than home (4.6% vs 1.2%/ 4.9% vs 1.0%), be discharged after postoperative day 1 (11.9% vs 6.7%/ 18.9% vs 10.1%), higher perioperative blood transfusion rate (2.1% vs 0.4%/ 3.1% vs 0.6%) and higher sepsis rates (0.7% vs 0.2%/ 0.7% vs 0.1%). In the single-level ACDF group, cases in the orthopedic surgery cohort had higher readmission (4.1% vs 1.9%) and unplanned intubation rates (1.1% vs 0.1%). Other outcome measures and mortality rates were similar among the cohorts. Significant differences in early perioperative outcomes of patients undergoing ACDF by neurosurgeons and orthopedic surgeons were noted. These differences have significant clinical and cost implications for patients, physicians, payors and health systems. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Background The pathogenesis of synovial cysts is largely unknown; however, they have been increasingly thought of as markers of spinal facet instability and typically associated with degenerative spondylosis. We specifically investigated the incidence of concomitant synovial cysts with underlying degenerative spondylolisthesis. Methods A literature search was performed using 4 online databases to assess the association between lumbar synovial cysts and degenerative spinal pathological features. Meta-analyses were performed on the prevalence rates of coexisting degenerative spinal pathological entities and treatment modalities. A random effects model was used to calculate the mean and 95% confidence intervals. Results A total of 17 studies encompassing 824 cases met the inclusion criteria. The pooled prevalence rates of concurrent spondylolisthesis, facet arthropathy, and degenerative disc disease at the same level of the synovial cysts were 42.5% (range, 39.0%–46.1%), 89.3% (range, 79.0%–94.8%), and 48.8% (range, 43.8%–53.9%), respectively. Among these, patients with coexisting spondylolisthesis were more likely to undergo spinal fusion surgery (vs. laminectomy alone) and reoperation than were patients without spondylolisthesis with a pooled odds ratio of 11.5 (95% confidence interval, 4.5–29.1; P < 0.0001) and 2.0 (95% confidence interval, 0.9–4.2; P = 0.088), respectively. Conclusions Patients with a combination of synovial cysts and degenerative spondylolisthesis are more likely to undergo spinal fusion surgery than laminectomy alone compared with patients with synovial cysts and no preoperative spondylolisthesis. Furthermore, patients with synovial cysts and spondylolisthesis are more likely to require additional fusion surgery. The results from the present review lend credence to the argument that synovial cyst herniation might be a manifestation of an unstable spinal level. [ABSTRACT FROM AUTHOR]

Existing literature demonstrates well-identified racial disparities in spine surgery outcomes. However, previous studies are of significant limitations. To investigate the association of race with 30-day perioperative complication rates of elective posterior spinal fusions (PSF) for adolescent idiopathic scoliosis (AIS). Retrospective cohort study. All pediatric patients with AIS who underwent PSF between 2012-2018 were reviewed from the (ACS-NSQIP) pediatric database. Thirty-day postoperative morbidity and mortality outcomes were analyzed. Complications included perioperative blood transfusion, venous thromboembolism, unplanned intubation, pneumonia, urinary tract infection, surgical site infection, sepsis, return to operating room, and death. Hospital course data, including operative time, the total length of hospital stay, the proportion of patients needed ICU admission, the proportion of patients discharged to other than home and discharged after the 4th postoperative day were also noted. Readmission data was included. These outcome variables are predefined in the ACS-NSQIP pediatric database, except for the discharge event after the 4th postoperative day, which was considered to be any discharge event occurring after a total hospital stay of 120 hours. Propensity score matching was used to determine whether race (ie, black vs white) had an influence on 30-day perioperative complications. A total of 4,051 PSF for AIS cases met inclusion criteria and were reviewed. Of these, 3221 (79.5%) patients were white and 830 (20.5%) were black. Patients in the black cohort were more likely to have higher BMI (23.8 vs 21.1), be of female gender (78.2% vs 74.5%), have an ASA class 3 or more (13.7% vs 11.1%), have asthma (8.3% vs 4.9%), have cardiac risk factors (5.1% vs 2.6%), use steroids (3.8% vs 1.1%). In the black cohort, 8% of the cases had up to 6 vertebral segments fused, 64.4% had 7-12 vertebral segments fused and 27.6% had 13 or more vertebral segments fused. In the white cohort, 15.9% of the cases had up 6 vertebral segments fused, 57.2% had 7-12 vertebral segments fused and 26.9% had 13 or more vertebral segments fused. After controlling for differences in baseline factors, except for the higher incidence of venous thromboembolism in the black cohort (2.8% vs 0.1%), (p <0.001), there were no significant differences in morbidity and mortality between the black and white cohorts. In contrast to prior literature, our analysis did not identify black race as an independent risk factor for higher perioperative morbidity or mortality in patients undergoing PSF for AIS, except for the higher incidence of venous thromboembolism. We believe that these results are important findings for clinicians and spine surgeons while counseling patients undergoing these types of procedures. It is important to address patient's concerns and to explain that the previously reported inferior perioperative morbidity and mortality outcomes in black patients might be due differences in baseline health status, and not due to the race difference itself. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Transplantation of adipose-derived mesenchymal stem cells (ADSCs) has become a promising approach for bone regeneration therapies, particularly in elderly patients. However, poor cell survival in vivo after implantation due to the ischemic tissue environment has been one of the major limitations of the effectiveness of this strategy. Hypoxia Inducible Factor-1α (HIF-1α) plays an important role in angiogenic-osteogenic coupling during bone regeneration, as it is a critical mediator of the adaptive cell response to hypoxia. DMOG treatment has been demonstrated to stabilize cellular expression of HIF-1α in cells, as well as enhance osteogenic and angiogenic capacity of MSCs. By therapeutically targeting both osteogenesis and vascularization via DMOG preconditioned MSCs, this tissue-engineering approach sought to yield superior bone quality and integration, thereby increasing rates of spinal fusion. We aimed to demonstrate that preconditioning adipose (ADSC)-derived (AD) MSCs with DMOG prior to implantation will prolong survival in vivo and improve spinal fusion outcomes in a rat model. In vivo study via a rat posterolateral spinal fusion model. Syngeneic 6-8 week old Lewis rats. Manual palpation scoring was performed by blinded researchers as follows: 0 = non-fused; 1 = partial fusion, some motion across operative joint; and, 2 = fused, no motion across the operated joint. MicroCT images were used to assess fusion mass volume (mm^3) via ImageJ software and determine CT fusion score (0 = non-fused; 1 = unilateral fusion; 2 = bilateral fusion). ADSCs were isolated from the inguinal fat pads of syngeneic 6-8 week old Lewis rats and cultured in vitro. When passage 1 (P1) ADSCs reached approximately 80% confluency they were pre-conditioned for 24 hours with 1 ng of DMOG (Fisher Scientific). After pre-conditioning, 2 × 10^6 ADSCs were seeded onto Vitoss (Stryker) bone graft substitute scaffolds for subsequent transplantation. Posterolateral spinal fusion surgery at L4-L5 was performed on 18 female Lewis rats divided into 2 experimental groups: [1] Vitoss+ADSCs pre-conditioned with DMOG; and, [2] Vitoss+non pre-conditioned ADSCs. Fusion was evaluated eight weeks post-surgery. Manual palpation scoring evaluated the motion across the operated joint, and MicroCT images were assessed for fusion mass volume and CT fusion. Preliminary microCT imaging data suggest that DMOG pre-conditioned ADSCs (n=12) yielded significantly higher fusion mass volumes than non-preconditioned ADSCs (n=6) (23.49 mm^3 vs. 15.39 mm^3, respectively, p=.001). DMOG pre-conditioned ADSCs showed a trend towards higher rates of fusion and manual palpation scores compared to non-conditioned ADSCs (1.16 vs. 0.50, respectively, p=.06; and 1.25 vs. 0.66, respectively, p>.05). In our rat posterolateral fusion model, DMOG pre-conditioned ADSCs displayed an increased fusion mass volume, CT fusion rates, and manual palpation score compared to non-conditioned ADSCs. Ongoing histological studies will evaluate whether there are any differences in the quality of bone formed within the fusion masses. Future studies will also compare whether these results are also similar in bone marrow-derived MSCs. Dimethyloxaloylglycine (Investigational/Not approved) [ABSTRACT FROM AUTHOR]

Approximately 132,000 patients per year undergo anterior cervical discectomy and fusion (ACDF) in the United States. Although the utilization of instrumentation and bone graft alternatives has enhanced fusion rates, pseudarthrosis remains a problem, with incidence rates up to 56%. Renin-angiotensin system (RAS) modulators are typically used to treat arterial hypertension, which affects 50-80% of spinal fusion patients. Recent evidence suggests an association between RAS blockers and bone metabolism, particularly in the context of bone healing. In addition, preclinical and clinical studies have suggested a potential correlation between the use of RAS blockers and reduced osteoporotic fracture risk. We aimed to determine whether there was a correlation between the use of antihypertensive medication, particularly angiotensin-II type-1 receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs), and outcomes in anterior cervical discectomy and fusion (ACDF) surgery. Retrospective observational study. Degenerative disc disease patients who underwent ACDF. Spinal fusion status and neurological function (modified Japanese Orthopaedic Association [mJOA] and Nurick grading scales. A cohort of adult patients with symptomatic cervical degenerative disc disease who were operated upon using an allograft implant, and with a 1-year minimum follow-up was considered eligible. Information on demographic data, comorbidities (especially hypertension status), antihypertensive medication, neurological examination and fusion status were collected. Fusion criteria in static radiographs were increased opacification and bridging trabecular bone at the margins of the graft. In dynamic radiographs, fusion criteria were interspinous motion of < 1 mm and superjacent interspinous motion of < 4 mm. For CT scans, fusion was defined as solid bridging of bone across the disc space of the intended fusion. A total of 178 patients with cervical degenerative disc disease who underwent ACDF, with a median age of 53.7 (range 24-90) years, were included in the analysis. Median follow-up was 21.7 months. Out of the 82 hypertensive patients who were identified, 77 (93.9%) were taking antihypertensive drugs (28 [36.4%] received ARBs and 27 [35.1%] received ACEIs). The overall pooled fusion rate was 69.5%. Patients treated with ARBs exhibited a higher fusion rate compared to those who were untreated (88.9% vs 69.7%, respectively, p=.04). By contrast, patients treated with ACEIs displayed a lower fusion rate than untreated patients (45.8% vs 69.7%, respectively, p=.02). Comparisons between successful fusion and failed fusion groups identified treatment with ACEIs as risk factors for the development of pseudarthrosis. Treatment with ARBs displayed a trend towards being a favorable factor for fusion (RR=1.2, 95% CI 1.0, 1.5). In the multivariate nominal logistic analysis, ARB (p=.02) treatment remained an independent risk and beneficial factor, respectively, for fusion. In our retrospective study of a cohort of ACDF patients, treatment with ARBs was associated with an increased fusion rate, while treatment with ACEIs identified as risk factor for failed fusion. Further preclinical and clinical studies are needed to verify the beneficial effects of ARBs and deleterious influence of ACEIs on spinal fusion. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT Occipitocervical fusion is the gold standard stabilization method for several pathologies involving craniovertebral junctions, including basilar invagination, atlantoaxial trauma and neoplasm. However, its postoperative clinical course is oftentimes complicated by dysphagia and dyspnea, presumably due to loss of mobility across occiput-C1-C2 joints, which could lead to aspiration pneumonia and acute airway obstruction, respectively, and are life-threatening complications in this procedure. The exact mechanism and its predictors still remain widely unstudied, but a previous article involving healthy volunteers elaborated on the importance of the occipital and external acoustic meatus to axis angle (O-EAa, "the angle formed by the McGregor line and the line connecting the external acoustic meatus and the midpoint of the inferior end plate of C2"), when predicting the narrowest oropharyngeal airway space (nPAS, "the narrowest anterior–posterior distance from the posterior pharyngeal wall to the back of the tongue between the levels of the uvula tip and the epiglottis tip") on X-rays, which theoretically should directly correlate with postoperative dysphagia. Here, we aimed to evaluate whether pre- and postoperative radiographical measurements such as O-EAa and nPAS could predict postoperative dysphagia in adult patients who underwent occipitocervical fusion procedures. PURPOSE To identify predictors of postoperative dysphagia in patients with adult occiptocervical fusion surgery. STUDY DESIGN/SETTING Retrospective, single-center. PATIENT SAMPLE Patients who underwent occipitocervical fusion at a single institution. OUTCOME MEASURES Prolonged postoperative dysphagia (more than 30 days). METHODS Single-center, retrospective data review from 2010 to 2016 identified 57 patients who underwent spine surgery involving occipitocervical fusion procedures. Among those, 51 patients had more than one-year follow-up as well as an adequate postoperative assessment of swallowing functions. Clinical records of those 51 patients (average age: 53.3, female: 54%) were collected and statistically analyzed. A total of 16 patients (31.4%, group (A)) were diagnosed with postoperative dysphagia associated with occipitocervical fusion, who were compared with 35 patients without this complication (group (B)) in terms of baseline characteristics, operative data and radiographical findings including perioperative O-EAa and nPAS at patients' neutral positions. Intergroup comparison of binary variables was performed via Fisher's exact test. Intergroup comparison of continuous variables was achieved using unpaired t -tests. ROC curves were drawn to evaluate the diagnostic value of O-EAa and nPAS for postoperative dysphagia. Furthermore, the Pearson's correlation was assessed between O-EAa and nPAS. Finally, a multilinear regression model was created to identify factors influencing nPAS. All reported p values are two-sided and p values <.05 were regarded as statistically significant. RESULTS There were no statistically significant difference in terms of baseline characteristics including age, sex, BMI, smoking and comorbidities or operative data such as estimated blood loss, operative time and operated levels. While preoperative O-EAa and nPAS were similar between the two groups (P=.39 and.55, respectively), postoperative O-EAa ((A) 89.3° versus (B) 104.5°, p<.01) and nPAS ((A) 9.9 mm versus (B) 13.6 mm, P=.01) as well as perioperative changes in O-EAa ((dO-EAa), (A) −4.1° vs. (B) 0.6°, P=.01) and nPAS (dnPAS, (A) −2.0 mm vs. (B) 0.2 mm, P=.01) were significantly different. The cut-off value of dOEA-a <−2.4° to predict postoperative dysphasia yielded sensitivity of 81.8% and specificity of 100% (AUC=0.939), which was comparable to dnPAS >−1.1 (sensitivity 81.8%, specificity 100%). The Pearson's correlation coefficient between these two parameters were 0.747 (p<.001). In a linear regression analysis, nPAS (mm) was found to be affected by O-EAa (estimate=0.2, P=.04) and sex (estimate=−4.8 (female=1), P=.03), but not by BMI in this model (R square=0.42). CONCLUSIONS Perioperative changes in O-EAa and nPAS were associated with postoperative dysphagia. Intraoperatively, O-EAa measurement on fluoroscopic images could be utilized as a surrogate marker for nPAS, thereby potentially allowing us to decrease the risk of this crucial complication. These data may prompt multicenter, prospective studies to further validate them and translate them into better patient care in the future. [ABSTRACT FROM AUTHOR]