Faculty Bibliography

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.

Retrospective review of National Inpatient Sample (2000-2012) revealed that 31.28% of musculoskeletal (MSK) patients were found to have in-hospital psychological burdens (PBs). Adult spinal deformity (ASD), degenerative disc disease (DDD) and lung cancer patients had highest PB-prevalence. MSK patients with PB were more often young, white females with increased Deyo index compared to no-PB patients. Patients who underwent spinal revision procedures had higher PB rates than with primary procedures; a converse trend was observed for total hip/knee arthroplasty. Psychological disorders were identified as significant predictors of increased total-hospital charges. Augmenting counseling with psychological screening/support is recommended to complement MSK management.

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.

Study Design/UNASSIGNED:Retrospective radiological review. Purpose/UNASSIGNED:To quantify the effect of sitting vs supine lumbar spine magnetic resonance imaging (MRI) and change in anterior displacement of the psoas muscle from L1-L2 to L4-L5 discs. Overview of Literature/UNASSIGNED:Controversy exists in determining patient suitability for lateral lumbar interbody fusion (LLIF) based on psoas morphology. The effect of posture on psoas morphology has not previously been studied; however, lumbar MRI may be performed in sitting or supine positions. Methods/UNASSIGNED:A retrospective review of a single-spine practice over 6 months was performed, identifying patients aged between 18-90 years with degenerative spinal pathologies and lumbar MRIs were evaluated. Previous lumbar fusion, scoliosis, neuromuscular disease, skeletal immaturity, or intrinsic abnormalities of the psoas muscle were excluded. The anteroposterior (AP) dimension of the psoas muscle and intervertebral disc were measured at each intervertebral disc from L1-L2 to L4-L5, and the AP psoas:disc ratio calculated. The morphology was compared between patients undergoing sitting and/or supine MRI. Results/UNASSIGNED:Two hundred and nine patients were identified with supine-, and 60 patients with sitting-MRIs, of which 13 patients had undergone both sitting and supine MRIs (BOTH group). A propensity score match (PSM) was performed for patients undergoing either supine or sitting MRI to match for age, BMI, and gender to produce two groups of 43 patients. In the BOTH and PSM group, sitting MRI displayed significantly higher AP psoas:disc ratio compared with supine MRI at all intervertebral levels except L1-L2. The largest difference observed was a mean 32%-37% increase in sitting AP psoas:disc ratio at the L4-L5 disc in sitting compared to supine in the BOTH group (range, 0%-137%). Conclusions/UNASSIGNED:The psoas muscle and the lumbar plexus become anteriorly displaced in sitting MRIs, with a greater effect noted at caudal intervertebral discs. This may have implications in selecting suitability for LLIF, and intra-operative patient positioning.

STUDY DESIGN/METHODS:Consensus-building using the Delphi and nominal group technique. OBJECTIVE:To establish best practice guidelines using formal techniques of consensus building among a group of experienced spinal deformity surgeons to avert wrong-level spinal deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Numerous previous studies have demonstrated that wrong-level spinal deformity occurs at a substantial rate, with more than half of all spine surgeons reporting direct or indirect experience operating on the wrong levels. Nevertheless, currently, guidelines to avert wrong-level spinal deformity surgery have not been developed. METHODS:The Delphi process and nominal group technique were used to formally derive consensus among 16 fellowship-trained spine surgeons. Surgeons were surveyed for current practices, presented with the results of a systematic review, and asked to vote anonymously for or against item inclusion during three iterative rounds. Agreement of 80% or higher was considered consensus. Items near consensus (70% to 80% agreement) were probed in detail using the nominal group technique in a facilitated group meeting. RESULTS:Participants had a mean of 13.4 years of practice (range: 2-32 years) and 103.1 (range: 50-250) annual spinal deformity surgeries, with a combined total of 24,200 procedures. Consensus was reached for the creation of best practice guidelines (BPGs) consisting of 17 interventions to avert wrong-level surgery. A final checklist consisting of preoperative and intraoperative methods, including standardized vertebral-level counting and optimal imaging criteria, was supported by 100% of participants. CONCLUSION/CONCLUSIONS:We developed consensus-based best practice guidelines for the prevention of wrong-vertebral-level surgery. This can serve as a tool to reduce the variability in preoperative and intraoperative practices and guide research regarding the effectiveness of such interventions on the incidence of wrong-level surgery. LEVEL OF EVIDENCE/METHODS:Level V.

BACKGROUND: Hospital length of stay (LOS), 30-day readmission rate, and other metrics are increasingly being used to evaluate quality of surgical care. The factors most relevant to cervical spondylotic myelopathy (CSM) are not yet established. OBJECTIVE: To identify peri-operative factors associated with extended LOS and/or 30-day readmission following elective surgery for CSM. METHODS: Surgical CSM patients at institutions represented by the American-College-of-Surgeons-National-Surgical-Quality-Improvement-Program (ACS-NSQIP) from 2010-2012 were included. Patients with fracture, >/=9 levels fused, or cancer were excluded. Extended LOS was defined as 75th percentile of the cohort. Univariate analysis and multivariate logistic regression identified predictors for extended LOS, 30-day readmission, and reoperation. Linear regression modeling was used to evaluate variables. RESULTS: 3057 surgical CSM cases were isolated. Age (OR-1.496), diabetes (OR-1.691), American Society of Anesthesiologists (ASA) class (OR-2.081), posterior surgical approach (OR-2.695), and operative time (OR-1.008) were all positive predictors (P<0.05) for extended LOS (>/=4 days). 32% of the cohort (976 patients) had 30-day readmission data. Among these, 915 patients were not readmitted (93.8%), while 61 (6.2%) were. Diabetes (OR-1.460) and ASA-class (OR-2.539) were significant positive predictors for hospital readmission. Age (OR-0.918) was a negative predictor of re-operation in readmitted patients, and pulmonary comorbidities (OR-4.584) were a positive predictor (P<0.05). CONCLUSIONS: Patients with diabetes and higher ASA-Class were at increased risk for extended LOS and readmission within 30-days. Patients with increased operative time have greater risk for extended LOS. Pre-operative pulmonary comorbidities increased reoperation risk, while increased age reduced the risk. Attention to these factors may benefit CSM patients.

PURPOSE: While there is a consensus that pelvic incidence (PI) remains constant after skeletal maturity, recent reports argue that PI increases after 60 years. This study aims to investigate whether PI increases with age and to determine potential associated factors. METHODS: 1510 patients with various spinal degenerative and deformity pathologies were enrolled, along with an additional 115 asymptomatic volunteers. Subjects were divided into six age subgroups with 10-year intervals. RESULTS: PI averaged 54.1 degrees in all patients. PI was significantly higher in the 45-54-year age group than 35-44-year age group (55.8 degrees vs. 49.7 degrees ). There were significant PI differences between genders after age 45. Linear regression revealed age, gender and malalignment as associated factors for increased PI with R 2 of 0.22 (p < 0.001). CONCLUSIONS: PI is higher in female patients and in older patients, especially those over 45 years old. Spinal malalignment also may have a role in increased PI due to increased L5-S1 bending moment.

PURPOSE: A comprehensive understanding of normative sagittal profile is necessary for adult spinal deformity. Roussouly described four sagittal alignment types based on sacral slope, lumbar lordosis, and location of lumbar apex. However, the lower limb, a newly described component of spinal malalignment compensation, is missing from this classification. This study aims to propose a full-body sagittal profile classification in an asymptomatic population based on full-body imaging. METHODS: This is a retrospective analysis of a prospective single-center study of 116 asymptomatic volunteers. Cluster analysis including all sagittal parameters was first performed, and then ANOVA was performed between sub-clusters to eliminate the non-significantly different parameters. This loop was repeated until all parameters were significantly different between each sub-cluster. RESULTS: Three types of full-body sagittal profiles were finalized according to cluster analysis with ten radiographic parameters: hyperlordosis type (77 subjects), neutral type (28 subjects), and compensated type (11 subjects). Radiographic parameters included knee angle, pelvic shift, pelvic angle, PT, PI-LL, C7-S1 SVA, TPA, T1 slope, C2-C7 angle, and C2-C7 SVA. Age was significantly different across compensation types, while BMI and gender were comparable. Age-matched subjects were randomly selected with 11 subjects in each type. ANOVA analysis revealed that all parameters but PT and C2-C7 angle remained significantly different. CONCLUSIONS: The current three compensation types of full-body sagittal profiles in asymptomatic adults included significant changes from cervical region to knee, indicating that subjects should be evaluated with full-length imaging. All three types exist regardless of age, but the distribution may vary.

STUDY DESIGN: Retrospective cohort study of spine fusion surgery utilizing the New York State Inpatient Database. OBJECTIVE: The objective was to determine whether there were differences in reoperation rates among pediatric scoliosis associated with various etiologies compared with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The incidence of postoperative complications and reoperations is known to vary among patients with diverse scoliosis pathologies. As these are heterogeneous conditions and often with rare occurrence, it is difficult to compare them in a single study. We aimed to assess reoperation events after fusion for several etiologies of pediatric scoliosis. METHODS: The 2008 to 2011 New York State Inpatient Database was queried using International Classification of Diseases (ICD-9-CM) codes for patients with in-hospital stays including a spine arthrodesis for scoliosis. All approaches, all fusion lengths, and ages 10 to 21 were included. Patient identifiers and linkage variables were used to identify revisits. The relative risk of reoperation was calculated for several rare conditions associated with scoliosis. RESULTS: Two thousand three hundred fifty-six pediatric scoliosis fusion surgeries were identified in 2008 in the state of New York. The 1- and 4-year reoperation rate for idiopathic scoliosis was 0.9% and 1.6%, respectively. For nonidiopathic scoliosis, the 1- and 4-year rates were 4.2% and 20.4%, respectively. Of the nonidiopathic scoliosis subtypes, congenital scoliosis (4.7% risk at 1 y, 41.6% at 4 y), the neuromuscular disease arthrogryposis (7.3% risk at 1 y, 28.6% at 4 y), and syndrome neurofibromatosis (9.1% at 1 y, 32.3% at 4 y) showed the highest risk for reoperation. Length of stay and hospital charges were higher for reoperations. CONCLUSIONS: Using a large administrative database, we identified neuromuscular, syndromic, and congenital forms of scoliosis that have the highest relative risk for a reoperation within 1 year. At-risk populations should be identified and resources allocated and preventative measures instituted accordingly to prevent these costly events. LEVEL OF EVIDENCE: Level III.

STUDY DESIGN:Retrospective review of a prospective database. OBJECTIVES:To investigate adult spinal deformity (ASD) surgery outcome trends on a nationwide scale using the Nationwide Inpatient Sample (NIS) from 2003 to 2010. METHODS:ASD patients ≥25 years from 2003 to 2010 in the NIS undergoing anterior, posterior, or combined surgical approaches were included. Fractures, 9+ levels fused, or any cancer were excluded. Patient demographics, hospital data, and procedure-related complications were evaluated. Yearly trends were analyzed using univariate analysis and linear regression modeling. RESULTS:Of 10,966 discharges, 1,952 were anterior, 6,524 were posterior, and 1,106 were combined. The total surgical ASD volume increased by 112.5% (p = .029), and both the average patient age (p < .001) and number of patients >65 years old significantly increased from 2003 to 2010 (p = .009). Anterior approach case volume decreased by 13.7% (p = .019), whereas that of combined increased by 22.7% (p = .047). Posterior case volume increased by 38.9% from 2003 to 2010, though insignificantly (p = .084). Total hospital charges for all approaches increased over the interval (p < .001). Total length of stay for all approaches decreased over the time interval (p < .005). Although the overall morbidity for all approaches increased by 22.7% (p < .001), mortality did not change (p = .817). The most common morbidities in 2003 were hemorrhagic anemia, accidental cut, puncture, perforation, or laceration during a procedure, and device-related complications, which persisted in 2010 with the exception of increased acute respiratory distress syndrome and pulmonary-related complications. CONCLUSIONS:For ASD surgery from 2003 to 2010, the volume of anterior approaches decreased, whereas posterior procedures did not change, and combined approaches increased. Total hospital charges increased for all considered procedures, length of hospital stay decreased, whereas operative patients were increasingly elderly, and more procedures were observed for patients >65 years old. For all approaches, morbidity increased whereas mortality did not change. Future study is required to develop methods to reduce morbidity and costs, thereby optimizing patient outcomes.