Faculty Bibliography

STUDY DESIGN: Retrospective review of prospective multicenter database. OBJECTIVE: Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20 degrees , C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10 degrees . While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery. METHODS: Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0 degrees 0 degrees . Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve. RESULTS: Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005). CONCLUSION: This study created a statistical model that predicts poor 2-year postoperative cervical malalignment in ASD patients. T3 (patients not meeting all three alignment criteria) was the most effective threshold for modeling nonCA, and included increased baseline C2-T3 angle and increased Smith-Peterson osteotomies during index. LEVEL OF EVIDENCE: 3.

BACKGROUND: Few reports have focused on treatment of adult cervical deformity (ACD). OBJECTIVE: To present early complication rates associated with ACD surgery. METHODS: A prospective multicenter database of consecutive operative ACD patients was reviewed for early (10 degrees, cervical scoliosis >10 degrees, C2-7 sagittal vertical axis >4 cm, or chin-brow vertical angle >25 degrees. RESULTS: Seventy-eight patients underwent surgical treatment for ACD (mean age, 60.8 years). Surgical approaches included anterior-only (14%), posterior-only (49%), anterior-posterior (35%), and posterior-anterior-posterior (3%). Mean numbers of fused anterior and posterior vertebral levels were 4.7 and 9.4, respectively. A total of 52 early complications were reported, including 26 minor and 26 major. Twenty-two (28.2%) patients had at least 1 minor complication, and 19 (24.4%) had at least 1 major complication. Overall, 34 (43.6%) patients had at least 1 complication. The most common complications included dysphagia (11.5%), deep wound infection (6.4%), new C5 motor deficit (6.4%), and respiratory failure (5.1%). One (1.3%) mortality occurred. Early complication rates differed significantly by surgical approach: anterior-only (27.3%), posterior-only (68.4%), and anterior-posterior/posterior-anterior-posterior (79.3%) (P = .007). CONCLUSION: This report provides benchmark rates for overall and specific ACD surgery complications. Although the surgical approach(es) used were likely driven by the type and complexity of deformity, there were significantly higher complication rates associated with combined and posterior-only approaches compared with anterior-only approaches. These findings may prove useful in treatment planning, patient counseling, and ongoing efforts to improve safety of care. ABBREVIATIONS: 3CO, 3-column osteotomiesACD, adult cervical deformityEBL, estimated blood lossISSG, International Spine Study groupSVA, sagittal vertical axis.

Anterior cervical discectomy and fusion (ACDF) performed as an outpatient has become increasingly common for treating cervical spine pathology, largely due to its cost savings compared with inpatient ACDF. Nearly all outpatient ACDF patient reports have originated from single-center studies, with the procedure yet to be addressed via a meta-analysis of the peer-reviewed literature. The Entrez gateway of the PubMed database was used to conduct a comprehensive literature search for articles published in English up to 3/9/16. Data from studies meeting inclusion criteria (minimum of 25 patients, control group of inpatient ACDF patients, non-duplicative data source) was then categorized and assimilated for analysis. Seven studies met inclusion criteria, encompassing a 21-year timespan. Each provided Oxford Center for Evidence-Based Medicine Level 3 evidence. The studies yielded a total of 2448 outpatient ACDF patients; only 125 (5.1%) originated from studies published prior to 2011. Single-level surgery occurred in 63.8% of patients, with 0.5% extending beyond two-level fusions. The overall complication rate was 1.8% (mean follow-up of 141.2days); only 2% of patients required readmission. In conclusion, outpatient ACDF has become increasingly popular, with more than 95% of patients represented by studies published since 2011. Nearly two-thirds of outpatient ACDFs underwent single-level fusion, with virtually none undergoing 3+ level ACDF. Outpatient ACDF is safe, with a low readmission rate and complication rates comparable to those (2-5%) associated with inpatient ACDF. These findings support an argument for increasing ACDFs performed on an outpatient basis in appropriately selected patients.

INTRODUCTION: Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spinal deformity (ASD). The premise is that MIS techniques will lead to equivalent outcomes and a reduction in perioperative complications when compared with open techniques. Potential issues with MIS techniques are a limited capacity to correct lumbar lordosis, unknown long-term efficacy, and the potential need for revision surgery. This study compares reoperation rates and reasons for reoperation following MIS, hybrid, and open surgery for ASD through multicenter database analysis. METHODS: We retrospectively analyzed a prospective multicenter ASD database comparing open and MIS correction techniques. Inclusion criteria were: age > 18 years with minimum 20 degrees coronal lumbar Cobb angle, a minimum of three levels fused, and minimum 2-year follow-up. Patients were propensity matched for preoperative sagittal vertebral axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and number of levels fused. We included 189 patients from three propensity-matched subgroups of 63 patients each: (1) MIS: lateral or transforaminal lumbar interbody fusion (LIF) and percutaneous pedicle instrumentation, (2) Hybrid: MIS LIF with open posterior segmental fixation (PSF), and (3) OPEN: open posterior fixation +/- osteotomies. RESULTS: With propensity matching, there were significant differences between groups in pre-op SVA or PI-LL (p > 0.05). The MIS group had significantly fewer levels fused (5.4) (0-14) than the OPEN group (7.4) (p = 0.002) (0-17). The rate of revision surgery was significantly different between the groups with a higher rate of revision (27 %) amongst the HYB group versus MIS = 11.1 %, and OPEN = 12.0 %. The most common reason for reoperation in the OPEN and HYB groups was a postoperative neurological deficit (7.9 and 11.1 %), respectively. The most common reason for reoperation in the MIS group was pseudoarthrosis (7.9 %). CONCLUSIONS: Reoperation rates were not statistically different among the MIS, and OPEN surgical groups, but differed significantly on multivariate analysis with HYB group. The incidence of reoperations was twice as high in the Hybrid group compared to OPEN and MIS.