Faculty Bibliography

OBJECTIVE:The purpose of this study was to compare rod fracture (RF) rates among three types of rod constructs (RCs) following lumbar pedicle subtraction osteotomy (PSO) for adult spinal deformity (ASD). METHODS:A retrospective review of consecutive patients with adult spinal deformity who were treated with lumbar PSO between 2007 and 2017 was performed. The minimum follow-up was 2 years. Three RCs were compared: standard (2 main rods), satellite (2 main rods with satellite rod), and nested (2 main rods and 2 short rods spanning osteotomy). Outcomes examined included RF rate, time to RF, pseudarthrosis, and reoperation. Multivariate analysis was used. RESULTS:A total of 141 patients were included 55 with standard, 23 with satellite, and 63 with nested RCs. The mean age was 65.2 years and 34.8% of patients were male. Radiographic preoperative and postoperative results were as follows: sagittal vertical axis (11.0 vs 3.9 cm), lumbar lordosis (28.5° vs 57.1°), pelvic tilt (30.6° vs 21.0°), pelvic incidence (61.5° vs 60.0°), distance between central sacral vertical line and C7 plumb line (2.2 vs 1.5 cm), and scoliosis (18.9° vs 11.3°). The average time to RF was 12.4 months. Overall RF, bilateral RF, pseudarthrosis, and reoperation rates were 22.7%, 5.0%, 20.6%, and 17.7%, respectively. Standard RCs had a significantly higher RF (36.4% vs 13.0% vs 14.3%, p = 0.008), bilateral RF (35.0% vs 0.0% vs 0.0%, p = 0.021), pseudarthrosis (34.5% vs 8.7% vs 12.7%, p = 0.004), and reoperation (30.9% vs 4.3% vs 11.1%, p = 0.004) rates. Satellite RCs (OR 0.21, p = 0.015), nested RCs (OR 0.24, p = 0.003), and bone morphogenetic protein-2 (OR 0.28, p = 0.005) were independently associated with lower odds of RF. CONCLUSIONS:Use of multiple rods in the satellite RC and nested RC groups was associated with lower rates of RF, pseudarthrosis, and reoperations following lumbar PSO. Bone morphogenetic protein-2 was associated with a reduction in RF rate as well.

OBJECTIVE:For severe and rigid adult cervical deformity, posterior-based three-column osteotomies (3COs) are warranted, but neurological complications are relatively high with such procedures. The performance measures of intraoperative neuromonitoring (IONM) during cervicothoracic 3CO have yet to be studied, and there remains a paucity of literature regarding the topic. Therefore, the authors of this study examined the performance of IONM in predicting new neurological weakness following lower cervical and upper thoracic 3CO. In addition, they report the 6-month, 1-year, and 2-year outcomes of patients who experienced new postoperative weakness. METHODS:The authors performed a retrospective review of a single surgeon's experience from 2011 to 2018 with all patients who had undergone posterior-based 3CO in the lower cervical (C7) or upper thoracic (T1-4) spine. Medical and neuromonitoring records were independently reviewed. RESULTS:A total of 56 patients were included in the analysis, 38 of whom had undergone pedicle subtraction osteotomy and 18 of whom had undergone vertebral column resection. The mean age was 61.6 years, and 41.1% of the patients were male. Among the study cohort, 66.1% were myelopathic and 33.9% had preoperative weakness. Mean blood loss was 1565.0 ml, and length of surgery was 315.9 minutes. Preoperative and postoperative measures assessed were cervical sagittal vertical axis (6.5 and 3.8 cm, respectively; p < 0.001), cervical lordosis (2.3° and -6.7°, p = 0.042), and T1 slope (48.6° and 35.8°, p < 0.001). The complication rate was 49.0%, and the new neurological deficit rate was 17.9%. When stratifying by osteotomy level, there were significantly higher rates of neurological deficits at C7 and T1: C7 (37.5%), T1 (44.4%), T2 (16.7%), T3 (14.3%), and T4 (0.0%; p = 0.042). Most new neurological weakness was the nerve root pattern rather than the spinal cord pattern. Overall, there were 16 IONM changes at any threshold: 14 at 50%, 8 at 75%, and 13 if only counting patients who did not return to baseline (RTB). Performance measures for the various thresholds were accuracy (73.2% to 77.8%), positive predictive value (25.0% to 46.2%), negative predictive value (81.3% to 88.1%), sensitivity (18.2% to 54.5%), and specificity (77.8% to 86.7%). Sensitivity to detect a spinal cord pattern of weakness was 100% and 28.6% for a nerve root pattern of weakness. In patients with a new postoperative deficit, 22.2% were unchanged, 44.4% improved, and 33.3% had a RTB at the 2-year follow-up. CONCLUSIONS:Complication rates are high following posterior 3CO for cervical deformity. 3CO at C7 and T1 has the highest rates of neurological deficit. Current IONM modalities have modest performance in predicting postoperative deficits, especially for nerve root neuropraxia. A large prospective multicenter study is warranted.

OBJECTIVE:Neurofibromatosis type 1 (NF1) dystrophic scoliosis is an early-onset, rapidly progressive multiplanar deformity. There are few studies on the surgical management of this patient population. Specifically, perioperative morbidity, instrument-related complications, and quality-of-life outcomes associated with surgical management have not been systematically evaluated. In this study, the authors aimed to perform a systematic review on the natural history, management options, and surgical outcomes in patients who underwent NF1 dystrophic scoliosis surgery. METHODS:A PubMed search for articles with "neurofibromatosis" and either "dystrophic" or "scoliosis" in the title or abstract was performed. Articles with 10 or more patients undergoing surgery for NF1 dystrophic scoliosis were included. Data regarding indications, treatment details, morbidity, and outcomes were summarized and analyzed with descriptive statistics. RESULTS:A total of 310 articles were identified, 48 of which were selected for full-text review; 30 studies describing 761 patients met the inclusion criteria. The mean age ranged from 7 to 22 years, and 99.7% of patients were younger than 18 years. The mean preoperative coronal Cobb angle was 75.2°, and the average correction achieved was 40.3°. The mean clinical follow-up in each study was at least 2 years (range 2.2-19 years). All patients underwent surgery with the intent of deformity correction. The scoliosis regions addressed were thoracic curves (69.6%) and thoracolumbar (11.1%) and lumbar (14.3%) regions. The authors reported on a variety of approaches: posterior-only, combined anterior-posterior, and growth-friendly surgery. For fixation techniques, 42.5% of patients were treated with hybrid constructs, 51.5% with pedicle screw-only constructs, and 6.0% with hook-based constructs. Only 0.9% of patients underwent a vertebral column resection. The nonneurological complication rate was 14.0%, primarily dural tears and wound infections. The immediate postoperative neurological deficit rate was 2.1%, and the permanent neurological deficit rate was 1.2%. Ultimately, 21.5% required revision surgery, most commonly for implant-related complications. Loss of correction in both the sagittal and coronal planes commonly occurred at follow-up. Five papers supplied validated patient-reported outcome measures, showing improvement in the mental health, self-image, and activity domains. CONCLUSIONS:Data on the surgical outcomes of dystrophic scoliosis correction are heterogeneous and sparse. The perioperative complication rate appears to be high, although reported rates of neurological deficits appear to be lower than clinically observed and may be underreported. The incidence of implant-related failures requiring revision surgery is high. There is a great need for multicenter prospective studies of this complex type of deformity.

BACKGROUND:Dumbbell schwannomas of the thoracic spine are challenging to cure surgically. Surgeons are familiar with posterolateral approaches to the spine, however, these may provide inadequate exposure for large tumors extending to ventral extraspinal compartments. Ventrolateral transpleural approaches offer direct access to the ventral thoracic spine and intrathoracic cavity, though are associated with increased morbidity and pulmonary complications, and may necessitate a staged procedure in order to address concomitant dorsal pathology. Herein we describe our experience with single-stage, posterior approach to dumbbell schwannomas with large ventral extraspinal components, and review the literature regarding surgical approaches for these tumors. METHODS:Retrospective review of patients who underwent a single-stage, posterior spinal surgery for thoracic dumbbell schwannomas from 2008 to 2018. Inclusion criteria were age > 18 years and ventral thoracic tumor component. RESULTS:Three patients underwent a simultaneous retropleural thoracotomy and posterior spinal approach, through a single incision, for the resection of dumbbell (intradural and extradural) schwannomas. Mean age was 49.7 years and 2 patients were female. All patients were neurologically intact at baseline. Lesions were 4-8.2 cm in the largest dimension (mean 6.1 cm). GTR was achieved in all patients. One pleural rent occurred intraoperatively; there were no other intraoperative or perioperative complications. At a mean follow-up of 14.1 months all patients remained motor and sensory intact and there was no evidence of recurrence. CONCLUSIONS:The combined retropleural thoracotomy-posterior spinal approach provides safe and sufficient access for resection of large dumbbell schwannomas of the thoracic spine.

STUDY DESIGN/METHODS:Literature review. OBJECTIVE:The aim of this review is to summarize recent literature on adult spinal deformity (ASD) treatment failure as well as prevention strategies for these failure modes. SUMMARY OF BACKGROUND DATA/BACKGROUND:There is substantial evidence that ASD surgery can provide significant clinical benefits to patients. The volume of ASD surgery is increasing, and significantly more complex procedures are being performed, especially in the aging population with multiple comorbidities. Although there is potential for significant improvements in pain and disability with ASD surgery, these procedures continue to be associated with major complications and even outright failure. METHODS:A systematic search of the PubMed database was performed for articles relevant to failure after ASD surgery. Institutional review board approval was not needed. RESULTS:Failure and the potential need for revision surgery generally fall into 1 of 4 well-defined phenotypes: clinical failure, radiographic failure, the need for reoperation, and lack of cost-effectiveness. Revision surgery rates remain relatively high, challenging the overall cost-effectiveness of these procedures. CONCLUSION/CONCLUSIONS:By consolidating the key evidence regarding failure, further research and innovation may be stimulated with the goal of significantly improving the safety and cost-effectiveness of ASD surgery.

Introduction: The objective of this analysis was to compare sociodemographic characteristics and outcomes between cohorts of patients receiving separation surgery for spinal metastases at two neighboring institutions, one private and one public, affiliated with a major academic medical center in a large metropolitan area.
Method(s): Patients who received separation surgery for spinal metastases between 2013 and 2021 were included in this analysis. Sociodemographic factors, treatment characteristics, and outcomes were compared between those treated at a private hospital and those treated at a neighboring public hospital using Rao-Scott chi square tests.
Result(s): Compared to those treated at our private hospital, patients treated at our public hospital were more often younger (p=0.005), of Black or Hispanic race (70% vs. 14.9%, p<0.001), and insured via Medicaid or Emergency Medicaid (48.6% vs. 3.2%, p<0.001). They more frequently presented with ESCC grade 3 compression (81.6% vs. 49.2%), potentially unstable or unstable lesions as denoted by SINS >7 (64.1% vs. 37.7%), and increased neurologic impairment as denoted by ASIA Impairment Scale scores of A, B, or C (35% vs. 7.9%). Local progression was less frequently observed in patients treated at our public hospital (28.2% vs. 54.7%, p=0.001), although this is likely due to poorer clinical and radiographic follow-up amongst this cohort. Median survival was significantly lower in patients treated at our public hospital (Median [Range]: 81 [11-1,873] days vs. 264 [0-3,092] days, p<0.001), although this is also likely confounded by lower rates of follow-up.
Conclusion(s): This study highlights substantial disparities amongst patients treated for spinal metastases at neighboring institutions affiliated with a major academic medical center. Further work is needed to identify reasons for these disparities and create avenues by which to mitigate them

OBJECTIVE:Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are well-recognized complications of long-segment spinal fusion. Previous studies have suggested that ligament augmentation can decrease rates of PJF by reducing junctional stress and strengthening upper instrumented vertebrae (UIVs) and adjacent segments. However, there is a paucity of long-term data on the efficacy of ligament augmentation in preventing PJF. In this study, the authors sought to determine the effect of ligament augmentation on rates of PJF in a cohort of adult spinal deformity patients with at least 1 year of follow-up. METHODS:They conducted a retrospective analysis of ligament augmentation in a consecutive series of surgical patients with adult spinal deformity. Data on patient demographics, surgical characteristics, and surgery for PJF were collected. The minimum follow-up was 12 months. Univariate and multivariate analyses were performed to identify factors associated with reoperation for PJF. RESULTS:The authors identified a total of 242 patients (166 women [68.6%]) with ligament augmentation whose mean age was 66 years. The mean number of fused levels was 10, with a UIV distribution as follows: 90 upper thoracic UIVs (37.2%) and 152 lower thoracic UIVs (62.8%). Compared to a historical cohort of 77 patients treated before implementation of ligament augmentation, reoperation for PJF was significantly lower with ligament augmentation (15.6% vs 3.3%, p < 0.001). In a multivariate model, only ligament augmentation (OR 0.184, 95% CI 0.071-0.478, p = 0.001) and number of fused levels (OR 0.762, 95% CI 0.620-0.937, p = 0.010) were associated with reductions in reoperation for PJF. CONCLUSIONS:Ligament augmentation was associated with significant reductions in the rate of reoperation for PJF at 12 months in a cohort of adult spinal deformity patients. The most dramatic reduction was seen among patients with lower thoracic UIV. These data suggest that in appropriately selected patients, ligament augmentation may be a valuable adjunct for PJF reduction; however, long-term follow-up is needed.

STUDY DESIGN/METHODS:International, multicenter, prospective, longitudinal observational cohort. OBJECTIVE:To assess how new motor deficits affect patient reported quality of life scores after adult deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Adult spinal deformity surgery is associated with high morbidity, including risk of new postoperative motor deficit. It is unclear what effect new motor deficit has on Health-related Quality of Life scores (HRQOL) scores. METHODS:Adult spinal deformity patients were enrolled prospectively at 15 sites worldwide. Other inclusion criteria included major Cobb more than 80°, C7-L2 curve apex, and any patient undergoing three column osteotomy. American Spinal Injury Association (ASIA) scores and standard HRQOL scores were recorded pre-op, 6 weeks, 6 months, and 2 years. RESULTS:Two hundred seventy two complex adult spinal deformity (ASD) patients enrolled. HRQOL scores were worse for patients with lower extremity motor score (LEMS). Mean HRQOL changes at 6 weeks and 2 years compared with pre-op for patients with motor worsening were: ODI (+12.4 at 6 weeks and -4.7 at 2 years), SF-36v2 physical (-4.5 at 6 weeks and +2.3 at 2 years), SRS-22r (0.0 at 6 weeks and +0.4 at 2 years). Mean HRQOL changes for motor-neutral patients were: ODI (+0.6 at 6 weeks and -12.1 at 2 years), SF-36v2 physical (-1.6 at 6 weeks and +5.9 at 2 years), and SRS-22r (+0.4 at 6 weeks and +0.7 at 2 years). For patients with LEMS improvement, mean HRQOL changes were: ODI (-0.6 at 6 weeks and -16.3 at 2 years), SF-36v2 physical (+1.0 at 6 weeks and +7.0 at 2 years), and SRS-22r (+0.5 at 6 weeks and +0.9 at 2 years). CONCLUSION/CONCLUSIONS:In the subgroup of deformity patients who developed a new motor deficit, total HRQOLs and HRQOL changes were negatively impacted. Patients with more than 2 points of LEMS worsening had the worst changes, but still showed overall HRQOL improvement at 6 months and 2 years compared with pre-op baseline.Level of Evidence: 3.

Metastases cause 90% of human cancer deaths. The metastatic cascade involves local invasion, intravasation, extravasation, metastatic site colonization, and proliferation. Although individual mediators of these processes have been investigated, interactions between these mediators remain less well defined. We previously identified a complex between receptor tyrosine kinase c-Met and β1 integrin in metastases. Using cell culture and in vivo assays, we found that c-Met/β1 complex induction promoted intravasation and vessel wall adhesion in triple-negative breast cancer cells, but did not increase extravasation. These effects may have been driven by the ability of the c-Met/β1 complex to increase mesenchymal and stem cell characteristics. Multiplex transcriptomic analysis revealed upregulated Wnt and hedgehog pathways after c-Met/β1 complex induction. A β1 integrin point mutation that prevented binding to c-Met reduced intravasation. OS2966, a therapeutic antibody disrupting c-Met/β1 binding, decreased breast cancer cell invasion and mesenchymal gene expression. Bone-seeking breast cancer cells exhibited higher levels of c-Met/β1 complex than parental controls and preferentially adhered to tissue-specific matrix. Patient bone metastases demonstrated higher c-Met/β1 complex than brain metastases. Thus, the c-Met/β1 complex drove intravasation of triple-negative breast cancer cells and preferential affinity for bone-specific matrix. Pharmacological targeting of the complex may have prevented metastases, particularly osseous metastases.

OBJECTIVE:Correction of rigid cervical deformities can be associated with high complication rates and result in prolonged intensive care unit (ICU) and hospital stays. In this study, the authors aimed to examine the risk factors contributing to length of stay (LOS) in both the hospital and ICU following adult cervical deformity (ACD) surgery and to identify severe adverse events that occurred in this setting. METHODS:A retrospective review of ACD patients who underwent posterior-based osteotomies for deformity correction from 2010 to 2019 was performed. Inclusion criteria were cervical kyphosis > 20° and/or cervical sagittal vertical axis (cSVA) > 4 cm. Multivariate analysis was used to identify risk factors independently associated with ICU and hospital LOS. RESULTS:A total of 107 patients were included. The mean age was 63.5 years, and 61.7% were female. Over half (52.3%) underwent 3-column osteotomies, while 47.7% underwent posterior column osteotomies. There was significant correction of all cervical parameters: cSVA (6.0 vs 3.6 cm, p < 0.001), cervical lordosis (8.2° vs -5.3°, p < 0.001), cervical scoliosis (6.5° vs 2.2°, p < 0.001), and T1-slope (40.2° vs 34.5°, p < 0.001). There were also reciprocal changes to the distal spine: thoracic kyphosis (54.4° vs 46.4°, p < 0.001), lumbar lordosis (49.9° vs 45.8°, p = 0.003), and thoracolumbar scoliosis (13.9° vs 11.1°, p = 0.009). Overall, 4 patients (3.7%) suffered aspiration-related complications, 3 patients (2.8%) experienced dysphagia requiring a feeding tube, and 4 patients (3.7%) had compromised airways, with 1 resulting in death. The mean ICU and hospital LOS were 2.8 days and 7.9 days, respectively. Multivariate analysis identified three factors independently associated with longer ICU LOS: female sex (3.0 vs 2.4 days, p = 0.004), ≥ 12 segments fused (3.5 vs 1.9 days, p = 0.002), and postoperative complication (4.0 vs 1.9 days, p = 0.017). These same factors were independently associated with longer hospital LOS as well: female sex (8.3 vs 7.3 days, p = 0.013), ≥ 12 segments fused (9.4 vs 6.2 days, p = 0.001), and complication (9.7 vs 6.7 days, p = 0.026). CONCLUSIONS:Posterior-based osteotomies are very effective for the correction of ACD, but postoperative hospital stays are relatively longer than those following surgery for degenerative disease. Risk factors for prolonged ICU and hospital LOS consist of both nonmodifiable (female sex) and modifiable (≥ 12 segments fused and presence of complication) risk factors. Additional multicenter prospective studies will be needed to validate these findings.