Faculty Bibliography

STUDY DESIGN/METHODS:Retrospective analysis of 2 prospectively collected multicenter databases, one for cervical deformity (CD) and the other for general adult spinal deformity. OBJECTIVE:To investigate the relative quality-of-life and disability burden in patients with uncompensated cervical, thoracolumbar, or cervical and thoracolumbar deformities. SUMMARY OF BACKGROUND DATA/BACKGROUND:The relative quality-of-life burden of cervical and thoracolumbar deformities have never been compared with each other. This may have significant implications when deciding on the appropriate treatment intervention for patients with combined thoracolumbar and cervical deformities. METHODS:When defining CD C2-C7 sagittal vertical axis (SVA)>4 cm was used while a C7-S1 SVA>5 cm was used to defined thoracolumbar deformity. Patients with both SVA criteria were defined as "combined." Primary analysis compared patients in the different groups by demographic, comorbidity data, and quality-of-life scores [EuroQOL 5 dimensions questionnaire (EQ-5D)] using t tests. Secondary analysis matched deformity groups with propensity scores matching based on baseline EQ-5D scores. Differences in disease-specific metrics [the Oswestry Disability Index, Neck Disability Index, modified Japanese Orthopaedic Association questionnaire (mJOA)] were analyzed using analysis of variance tests and post hoc analysis. RESULTS:In total, 212 patients were included in our analysis. Patients with CD only had less neurological deficits (mJOA: 14.6) and better EQ-5D (0.746) scores compared with patients with combined deformities (11.9, 0.716), all P<0.05. Regarding propensity score-matched deformity cohorts, 99 patients were matched with similar quality-of-life burden, 33 per deformity cohort. CD only patients had fewer comorbidities (1.03 vs. 2.12 vs. 2.70; P<0.001), whereas patients with combined deformity had more baseline neurological impairment compared with CD only patients (mJOA: 12.00 vs. 14.25; P=0.050). CONCLUSIONS:Combined deformity patients were associated with the lowest quality-of-life and highest disability. Furthermore, regarding deformity cohorts matched by similar baseline quality-of-life status (EQ-5D), patients with combined deformities were associated with significantly worse neurological impairments. This finding implies that quality of life may not be a direct reflection of a patient's disability status, especially in patients with combined cervical and thoracolumbar deformities. LEVEL OF EVIDENCE/METHODS:Level III.

Background/UNASSIGNED:The study is a retrospective review of a multi-institutional database, aiming to determine predictors of non-depressed, satisfied adult spinal deformity (ASD) patients with good self-image at 2-year follow-up (2Y). ASD significantly impacts a patients' psychological status. Following treatment, little is known about predictors of satisfied patients with high self-image and mental status. Methods/UNASSIGNED:Inclusion: primary ASD pts >18 y/o with complete 2Y follow-up. Non-depressed [Short Form 36-mental component score (SF36-MCS) >42], satisfied patients (SRS22-satisfaction >3) with good self-image (SR22-self-image >3) at 2Y were isolated (happy). Happy and control patients were propensity-matched by baseline and 2Y leg pain, Charlson, frailty, and radiographic measures for the operative (OP) and non-operative cohorts (NOP). Health related quality of life (HRQL), surgical and radiographic metrics were compared. Regression models identified predictors of happy patients. Thresholds were calculated using area under the curve (AUC) and 95%CI. Results/UNASSIGNED:22.09), SRS22 component, total, and SF36 scores (P<0.05). Baseline SRS-mental (OR: 2.199, AUC: 0.617, cutoff: 2.5) and ODI improvement (OR: 1.055, AUC: 0.717, cutoff: >12) predicted happy OP patients, while baseline SRS-self-image (OR: 5.195, AUC: 0.740, cutoff: 3.5) and ODI improvement (OR: 1.087, AUC: 0.683, cutoff: >9) predicted happy NOP patients. Conclusions/UNASSIGNED:Baseline mental-status, self-image and ODI improvement significantly impact long-term happiness in ASD patients. Despite equivalent management and alignment outcomes, operative and non-operative happy patients had better 2Y disability scores. Management strategies aimed at improving baseline mental-status, perception-of-deformity, and maximizing ODI may optimize treatment outcomes.

BACKGROUND CONTEXT/BACKGROUND:Distal Junctional Kyphosis (DJK) is a primary concern of surgeons correcting cervical deformity. Identifying patients and procedures at higher risk for developing this condition is paramount in improving patient selection and care. PURPOSE/OBJECTIVE:Develop a risk index for DJK development in the first year after surgery. STUDY DESIGN/SETTING/METHODS:Retrospective review of a prospective multicenter cervical deformity database. PATIENT SAMPLE/METHODS:). OUTCOME MEASURES/METHODS:Development of DJK at any time before 1 year. METHODS:distal vertebra, as well as a change in this angle by <-10 from baseline. Conditional Inference Decision Trees were used to identify factors predictive of DJK incidence and the cut-off points at which they have an effect. A conditional Variable-Importance table was constructed based on a non-replacement sampling set of 2000 Conditional Inference Trees. 12 influencing factors were found, binary logistic regression for each variable at significant cut-offs indicated their effect size. RESULTS:(OR:5.4 CI:2.20-13.23), and [6] C4_Tilt >56.7 (OR:5.0 CI:1.90-13.1).Clinically, combined approaches (OR:2.67 CI:1.21-5.89) and usage of Smith Petersen osteotomy (OR:2.55 CI:1.02-6.34) were the most important predictors for DJK. CONCLUSIONS:In a surgical cohort of cervical deformity patients, we found a 23.8% incidence of DJK. Different procedures and patient malalignment predicted incidence of DJK up to 1-year. Preoperative TS-CL, Cervical Kyphosis, SVA, and Cervical Lordosis all strongly predicted DJK at specific cut-off points. Knowledge of these factors will potentially help direct future study and strategy aimed at minimizing this potentially dramatic occurrence.

BACKGROUND:The impact of obesity on global spinopelvic alignment is poorly understood. This study investigated the effect of body mass index on achieving alignment targets and compensation mechanisms after corrective surgery for adult spinal deformity (ASD). METHODS:Retrospective review of a single-center database. Inclusion: patients ≥18 years with full-body stereographic images (baseline and 1 year) and who met ASD criteria (sagittal vertical axis [SVA] >5 cm, pelvic incidence minus lumbar lordosis [PI-LL] >10°, coronal curvature >20° or pelvic tilt >20°). Patients were stratified by age (<40, 40-65, and ≥65 years) and body mass index (<25, 25-30, and >30). Postoperative alignment was compared with age-adjusted ideal values. Prevalence of patients who matched ideals and unmatched (undercorrected/overcorrected) was assessed. Health-related quality of life (HRQL) scores, alignment, and compensatory mechanisms were compared across cohorts using analysis of variance and temporally with paired t tests. RESULTS:A total of 116 patients were included (average age, 62 years; 66% female). After corrective surgery, obese and overweight patients had more residual malalignment (worse PI-LL, T1 pelvic angle, pelvic tilt, and SVA) compared with normal patients (P < 0.05). In addition, obese and overweight patients recruited more pelvic shift (obese, 62.36; overweight, 49.80; normal, 31.50) and had a higher global sagittal angle (obese, 6.51; overweight, 6.35; normal, 3.40) (P < 0.05). Obese and overweight patients showed lower overcorrection rates and higher undercorrection rates (P < 0.05). Obese patients showed worse postoperative HRQL scores (Scoliosis Research Society 22 Questionnaire, Oswestry Disability Index, visual analog scale-leg) than did overweight and normal patients (P < 0.05). Obese and overweight patients who matched age-adjusted alignment targets for SVA or PI-LL showed no HRQL improvements (P > 0.05). CONCLUSIONS:After surgery, obese patients were undercorrected, showed more residual malalignment, recruited more pelvic shift, and had a greater global sagittal angle and worse HRQL scores. The benefits from age-adjusted alignment targets seem to be less substantial for obese and overweight patients.

STUDY DESIGN/METHODS:This is a retrospective review of a single surgeon cervical deformity (CD) database. OBJECTIVE:Quantitatively describe the cervical extensor musculature in a CD population, and delineate associations between posterior musculature atrophy and progressive sagittal deformity. SUMMARY OF BACKGROUND DATA/BACKGROUND:While fatty infiltration (FI; ie, posterior musculature atrophy) of lumbar extensor musculature has been associated with pain and deformity, little is known of the relationship between FI, CD, cervical sagittal alignment, and functionality. METHODS:CD patients [TS-CL>20 degrees, C2-C7 Cobb>10 degrees, CL>10 degrees, cervical sagittal vertical axis (cSVA)>4 cm, or chin-brow vertical angle>25 degrees] 18 years old and above, undergoing spinal fusion, with baseline T2-weighted magnetic resonance images were included. FI was assessed using dedicated imaging software at each intervertebral level from C2-C7. FI was gauged as a ratio of fat-free muscle cross-sectional area over total muscle cross-sectional area, with lower values indicating increasing FI. Influence of BL C2-C7 FI on patient-reported outcome measures (PROMs) and alignment was investigated. Multiple linear regression analysis (covariates: age, sex, body mass index, C2-C7 FI ratio) determined predictors of postoperative sagittal alignment and PROMs. RESULTS:Thirty-eight patients were included (age: 56.6, sex: 73.7% female, body mass index: 30.1, Charlson Comorbidity Index 0.61). BL deformity presentation: TS-CL 27.4 degrees, CL 2.1 degrees, cSVA: 27.2 mm. Mean baseline C2-C7 FI ratio was 0.65±0.11. Worsening FI was associated with malaligned baseline cSVA (rs=0.389, P=0.019), T1SS (rs=0.340, P=0.062), and impaired gait (rs=0.358, P=0.078). FI was not associated with BL PROMs (P>0.05). Following surgical intervention, regression models determined BL C2-C7 FI ratio as the strongest predictor of 1-year postoperative cSVA (β=-0.482, P=0.007, R=0.317). No associations between BL FI and postoperative PROMS or alignment parameters were observed (P>0.05). CONCLUSIONS:Patients with significant CD demonstrate alterations in the posterior extensor musculature of the cervical spine. Atrophic changes with FI of these muscle groups is associated with worsening CD and is an important predictor of postoperative sagittal alignment. LEVEL OF EVIDENCE/METHODS:Level III.

Background/UNASSIGNED:Cervical deformity (CD) surgery has become increasingly more common and complex, which has also led to reoperations for complications such as distal junctional kyphosis (DJK). Cost-utility analysis has yet to be used to analyze CD revision surgery in relation to the cost-utility of primary CD surgeries. The aim of this study was to determine the cost-utility of revision surgery for CD correction. Methods/UNASSIGNED:Retrospective review of a multicenter prospective CD database. CD was defined as at least one of the following: C2-C7 Cobb >10°, cervical lordosis (CL) >10°, cervical sagittal vertical axis (cSVA) >4 cm, chin-brow vertical angle (CBVA) >25°. Quality-adjusted life year (QALY) were calculated by EuroQol Five-Dimensions questionnaire (EQ-5D) and Neck Disability Index (NDI) mapped to SF-6D index and utilized a 3% discount rate to account for residual decline to life expectancy (men: 76.9 years, women: 81.6 years). Medicare reimbursement at 30 days assigned costs for index procedures (9+ level posterior fusion, 4-8 level posterior fusion with anterior fusion, 2-3 level posterior fusion with anterior fusion, 4-8 level anterior fusion) and revision fusions (2-3 level, 4-8 level, or 9+ level posterior refusion). Cost per QALY gained was calculated. Results/UNASSIGNED:Eighty-nine CD patients were included (61.6 years, 65.2% female). CD correction for these patients involved a mean 7.7±3.7 levels fused, with 34% combined approach surgeries, 49% posterior-only and 17% anterior-only, 19.1% three-column osteotomy. Costs for index surgeries ranged from $20,001-55,205, with the average cost for this cohort of $44,318 and cost per QALY of $27,267. Eleven revision surgeries (mean levels fused 10.3) occurred up to 1-year, with an average cost of $41,510. Indications for revisions were DJK (5/11), neurologic impairment [4], infection [1], prominent/painful instrumentation [1]. Average QALYs gained was 1.62 per revision patient. Cost was $28,138 per QALY for reoperations. Conclusions/UNASSIGNED:CD revisions had a cost of $28,138 per QALY, in addition to the $27,267 per QALY for primary CD surgeries. For primary CD patients, CD surgery has the potential to be cost effective, with the caveats that a patient livelihood extends long enough to have the benefits and durability of the surgery is maintained. Efforts in research and surgical technique development should emphasize minimization of reoperation causes just as DJK that significantly affect cost utility of these surgeries to bring cost-utility to an acceptable range.

Chiari malformations are structural defects in the posterior fossa where the cerebellum displaces caudally into the foramen magnum and upper spinal canal. These malformations are classified by severity as Types 1-4, each presenting with different associated and/or concurrent conditions and anomalies. The aim of this study was to utilize a nationwide database to study patients with Chiari malformations including their concurrent diagnoses and associated anomalies. Using a retrospective review of the Nationwide Inpatient Sample (NIS) database from 2003 to 2012, Chiari malformations were assessed by Chiari type and rates of concurrence for various additional anomalies were evaluated using cross-tabulations. There were 305,726 national cases of Chiari Type 1, 119,632 cases of Chiari Type 2, 15,540 cases of Type 3, and 79,663 cases of Type 4. Overall 44.3% of Chiari patients have at least one concurrent anomaly. Stratified by Chiari Type, 7.1% of Type 1 patients, 12.3% of Type 2, and 100% of Type 3 and 4 have at least one concurrent anomaly. The most common isolated neurologic associations were tethered cord, syringomyelia, and hydrocephalus, while the most common anomaly clusters were syringomyelia and scoliosis in Type 1 (0.63), tethered cord syndrome and scoliosis (0.72%) in Type 2, encephalocele and acquired hydrocephalus (11.45%) in Type 3, and reduction deformity of the brain with acquired hydrocephalus (15.95%) in Type 4. Chiari malformations have strong associations with other abnormalities outside of known relationships in the current classification. While neurologic abnormalities are most common, additional body systems are frequently involved especially with worsening hindbrain defects.

Background/UNASSIGNED:The recommended timing of surgical intervention for vertebral osteomyelitis (VO) is controversial; however, most studies are not sufficiently powered. Our goal was to investigate the associated effects of delaying surgery in VO patients on in-hospital complications, neurologic deficits, and mortality. Methods/UNASSIGNED:Retrospective review of the National Inpatient Sample. Patients who underwent surgery for VO from 1998 to 2013 were identified using codes from the International Classification of Disease, Ninth Revision, Clinical Modification. Patients were stratified into groups based on incremental delay of surgery: 0-day delay (same-day surgery), 1-day delay, 2-day delay, 3- to 6-day delay, 7- to 14-day delay, and 14- to 30-day delay. Univariate analysis compared demographics and outcomes between groups. Multivariate logistic regression models calculated independent predictors of any complication, mortality, and neurologic deficits. A 0-day delay was the reference group. Results/UNASSIGNED: < .001. Conclusion/UNASSIGNED:VO patients who operate within 24 hours of admission are more likely to have desirable outcomes. Patients with delayed surgery had a significantly increased risk of developing any complication, mortality, and discharging with neurologic deficits. Level of Evidence/UNASSIGNED:III. Clinical Relevance/UNASSIGNED:Medically fit patients may benefit from earlier surgical management in order to reduce risk of postoperative complications, improve outcomes, and reduce overall hospital costs.

BACKGROUND:Bariatric surgery (BS) is an increasingly common treatment for morbid obesity that has the potential to effect bone and mineral metabolism. The effect of prior BS on spine surgery outcomes has not been well established. The aim of this study was to assess differences in complication rates following spinal surgery for patients with and without a history of BS. METHODS:Retrospective analysis of the prospectively collected New York State Inpatient Database (NYSID) years 2004-2013. BS patients and morbidly obese patients (non-BS) were divided into cervical and thoracolumbar surgical groups and propensity score matched for age, gender, and invasiveness and complications compared. RESULTS:One thousand nine hundred thirty-nine spine surgery patients with a history of BS were compared to 1625 non-BS spine surgery patients. The average time from bariatric surgery to spine surgery is 2.95 years. After propensity score matching, 740 BS patients were compared to 740 non-BS patients undergoing thoracolumbar surgery, with similar comorbidity rates. The overall complication rate for BS thoracolumbar patients was lower than non-BS (45.8% vs 58.1%, P < 0.001), with lower rates of device-related (6.1% vs 23.2%, P < 0.001), DVT (1.2% vs 2.7%, P = 0.039), and hematomas (1.5% vs 4.5%, P < 0.001). Neurologic complications were similar between BS patients and non-BS patients (2.3% vs 2.7%, P = 0.62). For patients undergoing cervical spine surgery, BS patients experienced lower rates of bowel issues, device-related, and overall complication than non-BS patients (P < 0.05). CONCLUSIONS:Bariatric surgery patients undergoing spine surgery experience lower overall complication rates than morbidly obese patients. This study warrants further investigation into these populations to mitigate risks associated with spine surgery for bariatric patients.

INTRODUCTION/BACKGROUND:Spondylolysis is an increasingly common diagnoses for young individuals and presents with a wide range of pathological and clinical findings. Most patients are treated conservatively, and surgery is reserved for severe cases. This is a populations study defining the incidence of spondylolysis in the Kids' Inpatient Database (KID) and assess trends in diagnoses, causes, and treatments. METHODS:Retrospective analysis of the prospectively collected information in KID was performed for the years 2003 through 2012. Patients with a diagnosis of spondylolysis (ICD-9-CM 756.11) between the ages of 0 and 20 years in the KID were identified. Incidence of spondylolysis was established using KID-supplied hospital- and year-adjusted trend weights. Demographics including age, race, gender, and Charlson Comorbidity Index were assessed for all spondylolysis patients. Primary outcome measures were yearadjusted and hospital-adjusted incidence of spondylolysis. Secondary outcome measures were concurrent diagnoses and surgical details. RESULTS:Six hundred and sixteen patients with a diagnosis of spondylolysis (329 with primary diagnosis) were identified (female: 53.8%; age: 15.27 ± 3.32 years). The incidence of spondylolysis is 7 per 100,000 patients nationally. Spondylolysis incidence has increased over time (p < 0.001) though the operative rate for spondylolysis has remained the same in the last decade (70% average, p = 0.52). The average CCI is 0.234, the average length of stay is 3.76 days and 92.4% of patients were discharged home. The etiology of the spondylolysis was trauma in 8.6% of patients (3.2% car crash, 1.9% pedestrian, 1.3% fall, 1.3% assault, 1.1% other transport, 1.0% sports, 0.3% motorcycle, 0.2% firearm, 0.2% bicycle; 1.9% reported multiple trauma etiologies). The most common concurrent diagnoses for all spondylolysis patients were spondylolisthesis (28%), idiopathic scoliosis (4.4%), cerebral palsy (1.9%), and spina bifida (1.8%). Four hundred and thirty patients with spondylolysis underwent surgical treatment and 40% of the surgically treated patients had spondylolisthesis. The rate of fusions was 54.9% fusions and 21% decompression, though the rate of fusions or decompressions being performed for spondylolysis has remained the same in the last decade (average fusion rate: 55%; average decompression rate: 18%; both p > 0.05). Levels fused and complications did not differ depending on whether or not decompression was performed (p > 0.05). The posterior-only approach was used in 62.2% of surgeries and were mostly 2 to 3 level procedures (63.5%). Perioperative complications occurred in 8.1% of patients, with the most common complications being device-related (2.3%), respiratory (1.5%), and digestive (1.5%). CONCLUSIONS:The national incidence of spondylolysis has increased over time, and the surgical rate and treatment techniques have remained constant. The most common concurrent diagnoses were idiopathic scoliosis, cerebral palsy, and spina bifida. Further work is required to determine the significance of these trends and associations.