Faculty Bibliography

STUDY DESIGN/METHODS:Cross-Sectional Study. OBJECTIVE:The goal of this study is to investigate how surgeons differ in collar and narcotic use, as well as return to driving recommendations following cervical spine surgeries and the associated medico-legal ramifications of these conditions. SUMMARY OF BACKGROUND DATA/BACKGROUND:Restoration of quality of life is one of the main goals of cervical spine surgery. Patients frequently inquire when they may safely resume driving after cervical spine surgery. There is no consensus regarding post-operative driving restrictions. This study addresses how surgeons differ in their recommendations concerning cervical immobilization, narcotic analgesia, and suggested timeline of return to driving following cervical spine surgery. METHODS:Surgeons at the Cervical Spine Research Society annual meeting completed anonymous surveys assessing postoperative patient management following fusion and non-fusion cervical spine surgeries. RESULTS:70% of surgeons returned completed surveys (n = 71). 80.3% were orthopaedic surgeons and 94.2% completed a spine fellowship. Experienced surgeons (>15y in practice) were more likely to let patients return to driving within 2 weeks than less experienced surgeons (47.1% vs 24.3%, p = .013) for multi-level ACDF and laminectomy with fusion procedures. There were no differences between surgeons practicing inside and outside the USA for prescribing collars or return to driving time. Cervical collars were used more for fusions than non-fusions (57.7% vs 31.0%, p = .001). Surgeons reported 75.3% of patients ask when they may resume driving. For cervical fusions, 31.4% of surgeons allowed their patients to resume driving while restricting them with collars for longer durations. Furthermore, 27.5% of surgeons allowed their patients to resume driving while taking narcotics post-operatively. CONCLUSIONS:This survey-based study highlights the lack of consensus regarding patient 'fitness to drive' following cervical spine surgery. The importance of establishing evidence-based guidelines is critical as recommendations for driving in the post-operative period may have significant medical, legal, and financial implications. LEVEL OF EVIDENCE/METHODS:5.

OBJECTIVE Preoperative planning of thoracolumbar deformity (TLD) surgery has been shown to improve radiographic and clinical outcomes. One of the confounders in attaining optimal postoperative alignment is the reciprocal hyperkyphosis of unfused thoracic segments. Traditional planning utilizes standing radiographs, but the value of sitting radiographs to predict thoracic flexibility has not been investigated. Authors of the present study propose that alignment changes from a sitting to a standing position will predict changes in unfused thoracic segments after TLD correction. METHODS Patients with degenerative spine pathology underwent preoperative sitting and standing full-spine stereotactic radiography. A subset of TLD patients who had undergone corrections with minimum T10-pelvis fusions was analyzed in terms of pre- to postoperative alignment. Radiographic parameters were analyzed, including the T1 pelvic angle (TPA), T1-L1 pelvic angle (TLPA), lumbar pelvic angle (LPA), pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL mismatch), and T2-12 kyphosis (TK). Thoracic compensation was calculated as the expected TK minus actual TK (i.e., [2/3 × PI] - actual TK). Statistical analysis consisted of paired and unpaired t-tests and linear regression analysis. RESULTS The authors retrospectively identified 137 patients with full-body standing and sitting radiographs. The mean age of the patients was 60.9 years old, 60.0% were female, and the mean BMI was 27.8 kg/m². The patients demonstrated significantly different radiographic alignments in baseline spinopelvic and global parameters from the preoperative sitting versus the standing positions: LL (-34.20° vs -47.87°, p < 0.001), PT (28.31° vs 17.50°, p < 0.001), TPA (27.85° vs 16.89°, p < 0.001), TLPA (10.63° vs 5.17°, p < 0.001), and LPA (15.86° vs 9.67°, p < 0.001). Twenty patients (65.0% female) with a mean age of 65.3 years and mean BMI of 30.2 kg/m² had TLD and underwent surgical correction (pre- to postoperative standing change in TPA: 33.90° to 24.50°, p = 0.001). Preoperative sitting radiographs demonstrated significant differences in alignment compared to postoperative standing radiographs: larger TPA (39.10° vs 24.50°, p < 0.001), PT (35.40° vs 28.10°, p < 0.001), LL (-11.20° vs -44.80°, p < 0.001), LPA (22.80° vs 14.20°, p < 0.001), and unfused Cobb (T2 to upper instrumented vertebra [UIV] Cobb angle: 19.95° vs 27.50°, p = 0.039). Also in the TLD group, mean thoracic compensation was 6.75°. In the linear regression analysis, the change from sitting to standing predicted pre- to postoperative changes for TK and the unfused thoracic component of TPA (5° change in preoperative sitting to preoperative standing corresponded to a pre- to postoperative change in standing TK of 6.35° and in standing TPA of 7.23°, R² = 0.30 and 0.38, respectively). CONCLUSIONS Sitting radiographs were useful in demonstrating spine flexibility. Among the TLD surgery group, relaxation of the unfused thoracic spine in the sitting position predicted the postoperative increase in kyphosis of the unfused thoracic segments. Sitting radiographs are a useful tool to anticipate reciprocal changes in thoracic alignment that diminish global corrections.

PURPOSE/OBJECTIVE:Sagittal spinal deformity (SSD) patients utilize pelvic tilt (PT) and their lower extremities in order to compensate for malalignment. This study examines the effect of hip osteoarthritis (OA) on compensatory mechanisms in SSD patients. METHODS:Patients ≥ 18 years with SSD were included for analysis. Spinopelvic, lower extremity, and cervical alignment were assessed on standing full-body stereoradiographs. Hip OA severity was graded by Kellgren-Lawrence scale (0-4). Patients were categorized as limited osteoarthritis (LOA: grade 0-2) and severe osteoarthritis (SOA: grade 3-4). Patients were matched for age and T1-pelvic angle (TPA). Spinopelvic [sagittal vertical axis (SVA), T1-pelvic angle, thoracic kyphosis (TK), pelvic tilt (PT), lumbar lordosis (LL), pelvic incidence minus lumbar lordosis (PI-LL), T1-spinopelvic inclination (T1SPi)] and lower extremity parameters [sacrofemoral angle, knee angle, ankle angle, posterior pelvic shift (P. Shift), global sagittal axis (GSA)] were compared between groups using independent sample t test. RESULTS:136 patients (LOA = 68, SOA = 68) were included in the study. SOA had less pelvic tilt (p = 0.011), thoracic kyphosis (p = 0.007), and higher SVA and T1Spi (p < 0.001) than LOA. SOA had lower sacrofemoral angle (p < 0.001) and ankle angle (p = 0.043), increased P. Shift (p < 0.001) and increased GSA (p < 0.001) compared to LOA. There were no differences in PI-LL, LL, knee angle, or cervical alignment (p > 0.05). CONCLUSIONS:Patients with coexisting spinal malalignment and SOA compensate by pelvic shift and thoracic hypokyphosis rather than PT, likely as a result of limited hip extension secondary to SOA. As a result, SOA had worse global sagittal alignment than their LOA counterparts. These slides can be retrieved under Electronic Supplementary Material.

Introduction/objectives: Routine use of DM may not be a cost-effective measure, but an increasing number of THA candidates have coexisting spinal disorders, substantially increasing their risk for instability. This study seeks to expand our understanding of the cost-effectiveness of dual mobility components as an alternative to standard articulations in this high-risk dislocation population. Methods: A state-transition Markov model with expectedvalue decision analysis was used to evaluate the costeffectiveness of DM cups for high-risk patients who would be at high risk for dislocation within one year of their index THA. Direct and indirect costs of dislocation, incremental DM cost ($1000), quality-adjusted life years (QALY) values and dislocation probabilities were derived from published data. Results: Spine fusion patients were modelled to have a 15% probability of dislocation following primary THA based on published clinical ranges. A hypothetical reduction of 5% in probability of dislocation was deemed clinically plausible with the addition of a DM implant. Under these model parameters, sensitivity analysis was used to identify scenarios for which DM would be cost effective. For example, if the probability of dislocation is 15% with traditional bearings, then the use of DM is cost-effective if it reduces the dislocation risk to 10% and costs less than $640 (Figure 1). However, at its current average selling price ($1000), it would only be cost-effective if it reduces the probability of dislocation from 15% to 7% in this population. Conclusion: Dislocation is a significant complication and spine fusion patients have been shown to be at high risk. Our results indicate that under specific conditions DM cups are cost-effective for this high risk spine fusion population

Introduction/objectives: Diagnosis and treatment of patients with coexisting hip and spine pathologies can be challenging. Patients with sagittal spinopelvic deformity utilize pelvic tilt (PT) and their lower extremities in order to compensate for malalignment. In patients with lower extremity osteoarthritis (OA), these compensatory mechanisms can be compromised, leading to further disability. Methods: Patients > 18 years with SSD [SVA > 50mm, PT > 25degree, or TK > 60degree] were included for analysis. Spinopelvic, lower extremity, and cervical alignment were assessed on standing full-body stereoradiographs. Hip OA severity was graded by Kellgren-Lawrence scale (0-4). Propensity score matching was used to control for age and T1 pelvic angle (TPA). Patients were categorized as limited OA (LOA: grade 0-2) and severe OA (SOA: grade 3-4). Results: A total of 997 patients (LOA=929, SOA=68) were identified meeting inclusion criteria. After PSM, 136 patients (SOA: n=68, LOA n=68) were included in the study. SOA had less PT (17.8degree+/-12.6degree vs 22.6degree+/-8.4degree, p=0.011), TK (42.5degree+/-21.2degree vs 52.3degree+/-20.2degree, p=0.007), higher SVA (71.6 mm+/-47.1 vs 40.7 mm+/-43.9, p<0.001) and T1Spi (+2.3degree+/-6.4degree vs -2.6degree+/-5.5degree, p<0.001) than LOA. SOA also had a lower SFA (194.3degree+/-12.4degree vs 202.4degree+/-9.5degree, p<0.001) and AA (5.9degree+/-3.5degree vs 7.2degree+/-3.6degree, p=0.043), increased P.Shift (49.7mm+/-39.5 vs 19.7mm+/-28.4; p<0.001) and increased GSA (7.7degree+/-4.5degree vs 5.0degree+/-4.0degree, p< 0.001) compared to LOA. There was no difference in PI, PI-LL mismatch, LL, KA or cervical alignment (p >0.05). Conclusion: Patients with coexisting spinal malalignment and severe hip OA compensate by pelvic shift and thoracic hypokyphosis rather than pelvic tilt, likely as a result of limited hip extension

Introduction/objectives: The aim of this study was to investigate how gender, age and lumbar degenerative disease affect the number of patients at risk of excessive sagittal pelvic rotation. Methods: Pre-operatively, 3428 patients had their pelvic tilt (PT) and lumbar lordotic angle (LLA) measured in three positions; supine, standing and flexed-seated, as part of routine planning for THR. The pelvic rotation from supine-to- standing and from supine-to-seated was determined from the difference in pelvic tilt measurements between positions. Lumbar flexion was determined as the difference between LLA standing and LLA when flexed-seated. Patients were stratified into groups based upon age, gender and lumbar flexion. The percentage of patients in each group with excessive pelvic rotation, defined by rotation >13degree in a detrimental direction, was determined. Results: Posterior pelvic rotation from supine-to-stand increased with age and decreasing lumbar flexion. This was more pronounced in females. Similarly, anterior pelvic rotation from supine-to-flex seated increased with age and decreasing lumbar flexion. This was more pronounced in males. Notably, 30% of elderly females had excessive pelvic rotation. Furthermore, 38% of patients with lumbar flexion <20degree had excessive pelvic rotation. Conclusion: Excessive pelvic rotation was more common in older patients and in patients with limited lumbar flexion. This might be a reason for the increased dislocation rate in the elderly population. A more constrained bearing might be a more viable option in patients with limited lumbar flexion (<20degree), which constitutes 5% of the THR population. The large range of pelvic rotation in each group supports individual analysis on all patients undergoing THR

OBJECTIVE Verifying the adequacy of surgical correction of adult spinal sagittal deformity (SSD) leads to improved postoperative alignment and clinical outcomes. Traditionally, surgeons relied on intraoperative measurements of lumbar lordosis (LL) correction. However, T-1 pelvic angle (TPA) and its component angles more reliably predict postoperative alignment. While TPA is readily measured on standing radiographs, intraoperative radiographs offer poor resolution of the bicoxofemoral axis. A method to recreate this radiographic landmark by extrapolating preoperative measurements has been described. The authors aimed to assess the reliability of measurements of global spinal alignment obtained via geometrical reconstitution of the bicoxofemoral axis on prone intraoperative radiographs. METHODS A retrospective review was performed. Twenty sets of preoperative standing full-length and intraoperative prone 36-inch lateral radiographs were analyzed. Pelvic incidence (PI) and sacral to bicoxofemoral axis distance (SBFD) were recorded on preoperative films. A perpendicular line was drawn on the intraoperative radiograph from the midpoint of the sacral endplate. This was used as one limb of the PI, and the second limb was digitally drawn at an angle that reproduced the preoperatively obtained PI, extending for a distance that matched the preoperative SBFD. This final point marked the obscured bicoxofemoral axis. These landmarks were used to measure the L-1, T-9, T-4, and T-1 pelvic angles (LPA, T9PA, T4PA, and TPA, respectively) and LL. Two spine fellows and 2 attending spine surgeons made independent measurements and repeated the process in 1 month. Mixed-model 2-way intraclass correlation coefficient (ICC) and Cronbach's α values were calculated to assess interobserver, intraobserver, and scale reliability. RESULTS Interobserver reliability was excellent for preoperative PI and intraoperative LPA, T9PA, and T4PA (ICC = 0.88, 0.84, 0.84, and 0.93, respectively), good for intraoperative TPA (ICC = 0.68), and fair for preoperative SBFD (ICC = 0.60) and intraoperative LL (ICC = 0.50). Cronbach's α was ≥ 0.80 for all measurements. Measuring PI on preoperative standing images had excellent intraobserver reliability for all raters (ICC = 0.89, range 0.80-0.93). All raters but one showed excellent reliability for measuring the SBFD. Reliability for measuring prone LL was good for all raters (ICC = 0.71, range 0.64-0.76). The LPA demonstrated good to excellent reliability for each rater (ICC = 0.76, range 0.65-0.81). The thoracic pelvic angles tended to be more reliable at more distal vertebrae (T9PA ICC = 0.71, range 0.49-0.81; T4PA ICC = 0.62, range 0.43-0.83; TPA ICC = 0.56, range 0.31-0.86). CONCLUSIONS Intraoperative assessment of global spinal alignment with TPA and component angles is more reliable than intraoperative measurements of LL. Reconstruction of preoperatively measured PI and SBFD on intraoperative radiographs effectively overcomes poor visualization of the bicoxofemoral axis. This method is easily adopted and produces accurate and reliable prone intraoperative measures of global spinal alignment.

STUDY DESIGN/METHODS:Retrospective radiographic review. OBJECTIVES/OBJECTIVE:To understand the effect of variability in sacral endplate selection in transitional lumbosacral vertebrae (TLSV) and its impact on pelvic, regional, and global spinal alignment parameters. BACKGROUND:TLSV can have the characteristics of both lumbar and sacral vertebrae. Difficulties in identification of the S1 endplate may come from nomenclature, number of lumbar vertebrae, sacra, and morphology and may influence the interpretation and consistency of spinal alignment parameters. METHODS:Patients with TLSV were identified and radiographic measurements including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), sagittal vertical axis (SVA), T1-pelvic angle (TPA), pelvic incidence-lumbar lordosis (PI-LL) mismatch, thoracic kyphosis (TK), and spinal inclination (T1SPi) were obtained. Radiographic measurements were performed twice with the sacral endplate at the cephalad and caudal options. Paired t tests assessed the difference between different selection groups. RESULTS:Of 1,869 patients, 70 (3.7%) were found to have TLSV on radiographic imaging. Fifty-eight (82.9%) had lumbarized sacral segments whereas 12 (17.1%) had sacralized lumbar segments. T1-SPi (mean: -1.77°) and TK (mean: 34.86°) did not vary from altering sacral endplate selection. Selection of the caudal TLSV as the sacral endplate resulted in an increase in all pelvic parameters (PI: 66.8° vs. 44.3°, PT: 25.1° vs. 12.7°, and SS: 41.6° vs. 31.6°), regional lumbar parameters (LL: -54.1° vs. 44.0°, PI-LL: 12.7° vs. 0.3°), and global parameters (SVA: 46.1 mm vs. 28.3 mm, TPA: 23.3° vs. 10.8°) as compared to selecting the cephalad TLSV. All mean differences between radiographic parameters were found to be statistically significant (p < .001). CONCLUSIONS:Variation in sacral endplate selection in TLSV significantly affects spinal alignment parameter measurements. A standardized method for measuring TLSV is needed to reduce measurement error and ultimately allow more accurate understanding of alignment targets in patients with TLSV. LEVEL OF EVIDENCE/METHODS:Level III.

BACKGROUND CONTEXT/BACKGROUND:Obesity as a comorbidity in spine pathology may increase the risk of complications following surgical treatment. The body mass index (BMI) threshold at which obesity becomes clinically relevant, and the exact nature of that effect, remains poorly understood. PURPOSE/OBJECTIVE:Identify the BMI that independently predicts risk of postoperative complications following lumbar spine surgery. STUDY DESIGN/SETTING/METHODS:Retrospective review of the National Surgery Quality Improvement Program (NSQIP) years 2011-2013. PATIENT SAMPLE/METHODS:A total of 31,763 patients were undergoing arthrodesis, discectomy, laminectomy, laminoplasty, corpectomy, or osteotomy of the lumbar spine. OUTCOME MEASURES/METHODS:Complication rates. METHODS:The patient sample was categorized preoperatively by BMI according to the World Health Organization stratification: underweight (BMI <18.5), normal overweight (BMI 20.0-29.9), obesity class 1 (BMI 30.0-34.9), 2 (BMI 35.0-39.9), and 3 (BMI≥40). Patients were dichotomized based on their position above or below the 75th surgical invasiveness index (SII) percentile cutoff into low-SII and high-SII. Differences in complication rates in BMI groups were analyzed by Bonferroni analysis of variance (ANOVA) method. Multivariate binary logistic regression evaluated relationship between BMI and complication categories in all patients and in high-SII and low-SII surgeries. RESULTS:. The odds ratios for any complication (odds ratio [OR] [95% confidence interval {CI}]; obesity 2: 1.218 [1.020-1.455]; obesity 3: 1.742 [1.439-2.110]), infection (obesity 2: 1.335 [1.110-1.605]; obesity 3: 1.685 [1.372-2.069]), and surgical complication (obesity 2: 1.622 [1.250-2.104]; obesity 3: 2.798 [2.154-3.634]) were significantly higher in obesity classes 2 and 3 relative to the normal-overweight cohort (all p<.05). CONCLUSION/CONCLUSIONS:There is a significant increase in complications, specifically infection and surgical complications, in patients with BMI≥35 following lumbar spine surgery, with that rate further increasing with BMI≥40.

BACKGROUND:Previous studies have built a foundation for understanding compensation in patients with adult spinal deformity (ASD) by using full-body stereographic assessments. These mechanisms, in relation to age-adjusted alignment targets, have yet to be studied fully. The aim of this study was to assess lower-limb compensatory mechanisms of patients failing to meet age-adjusted alignment goals. METHODS:Patients with ASD ≥40 years with full body baseline and follow-up radiographs were included. Patients were stratified by age (40-65 years, >65 years) and spinopelvic correction. Lower-limb compensation parameters (pelvic shift, hip extension, knee flexion [KA], ankle flexion [AA], and global sagittal angle [GSA]) for patients who matched and failed to match age-adjusted alignment targets were compared with analysis of variance and t-test analysis. RESULTS:In total, 108 patients were included. At 1 year, AA increased with age in the "match" pelvic tilt (PT) and spinopelvic mismatch (PI-LL) cohorts (PT: AA, 5.6-7.8, P = 0.041; PI-LL: 4.9-8.8, P = 0.026). KA, AA, and GSA increased with age in the "match" sagittal vertical axis (SVA) cohort (KA: 3.8-13.1, P = 0.002; AA: 5.8-10.2, P = 0.008; GSA: 3.9-7.8, P < 0.001), as did KA and GSA in the "match" T1 pelvic angle group (KA: 1.8-8.7, P = 0.020; GSA: 2.6-5.7, P = 0.004). CONCLUSIONS:Greater compensation captured by KA and GSA was associated with age progression in the "match" SVA and T1 pelvic angle cohorts. In addition, older SVA, PT, and PI-LL "match" cohorts used increased AA, suggesting that ideal postoperative alignment of aged individuals with ASD involves increased compensation.