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Effect of body mass index on surgical outcomes after posterior spinal fusion for adolescent idiopathic scoliosis

Rafael De la Garza Ramos, Jonathan Nakhla, Rani Nasser, Jacob F. Schulz, Taylor E. Purvis, Daniel M. Sciubba, Merritt D. Kinon, and Reza Yassari

OBJECTIVE

Obesity is an increasing public health concern in the pediatric population. The purpose of this investigation was to examine the impact of body mass index (BMI) on 30-day outcomes after posterior spinal fusion for adolescent idiopathic scoliosis (AIS).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program Pediatric database (2013 and 2014) was reviewed. Patients 10–18 years of age who had undergone fusion of 7 or more spinal levels for AIS were included. Thirty-day outcomes (complications, readmissions, and reoperations) were compared based on patient BMI per age- and sex-adjusted growth charts as follows: normal weight (NW; BMI < 85th percentile), overweight (OW; BMI 85th–95th percentile), and obese (OB; BMI > 95th percentile).

RESULTS

Patients eligible for study numbered 2712 (80.1% female and 19.9% male) and had a mean age of 14.4 ± 1.8 years. Average BMI for the entire cohort was 21.9 ± 5.0 kg/m2; 2010 patients (74.1%) were classified as NW, 345 (12.7%) as OW, and 357 (13.2%) as OB. The overall complication rate was 1.3% (36/2712). For NW and OW patients, the complication rate was 0.9% in each group; for OB patients, the rate was 4.2% (p < 0.001). The 30-day readmission rate was 2.0% (55/2712) for all patients, 1.6% for NW patients, 1.2% for OW patients, and 5.0% for OB patients (p < 0.001). The 30-day reoperation rate was 1.4% (39/2712). Based on BMI, this reoperation rate corresponded to 0.9%, 1.2%, and 4.8% for NW, OW, and OB patients, respectively (p < 0.001). After controlling for patient age, number of spinal levels fused, and operative/anesthesia time on multiple logistic regression analysis, obesity remained a significant risk factor for complications (OR 4.61), readmissions (OR 3.16), and reoperations (OR 5.33; all p < 0.001).

CONCLUSIONS

Body mass index may be significantly associated with short-term outcomes after long-segment fusion procedures for AIS. Although NW and OW patients may have similar 30-day outcomes, OB patients had significantly higher wound complication, readmission, and reoperation rates and longer hospital stays than the NW patients. The findings of this study may help spine surgeons and patients in terms of preoperative risk stratification and perioperative expectations.

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Development of cerebral vasospasm following traumatic intracranial hemorrhage: incidence, risk factors, and clinical outcomes

Alis J. Dicpinigaitis, Eric Feldstein, Nitesh Damodara, Jared B. Cooper, Steven D. Shapiro, Haris Kamal, Merritt D. Kinon, Jared Pisapia, Jon Rosenberg, Chirag D. Gandhi, and Fawaz Al-Mufti

OBJECTIVE

Limited evidence exists characterizing the incidence, risk factors, and clinical associations of cerebral vasospasm following traumatic intracranial hemorrhage (tICH) on a large scale. Therefore, the authors sought to use data from a national inpatient registry to investigate these aspects of posttraumatic vasospasm (PTV) to further elucidate potential causes of neurological morbidity and mortality subsequent to the initial insult.

METHODS

Weighted discharge data from the National (Nationwide) Inpatient Sample from 2015 to 2018 were queried to identify patients with tICH who underwent diagnostic angiography in the same admission and, subsequently, those who developed angiographically confirmed cerebral vasospasm. Multivariable logistic regression analysis was performed to identify significant associations between clinical covariates and the development of vasospasm, and a tICH vasospasm predictive model (tICH-VPM) was generated based on the effect sizes of these parameters.

RESULTS

Among 5880 identified patients with tICH, 375 developed PTV corresponding to an incidence of 6.4%. Multivariable adjusted modeling determined that the following clinical covariates were independently associated with the development of PTV, among others: age (adjusted odds ratio [aOR] 0.98, 95% CI 0.97–0.99; p < 0.001), admission Glasgow Coma Scale score < 9 (aOR 1.80, 95% CI 1.12–2.90; p = 0.015), intraventricular hemorrhage (aOR 6.27, 95% CI 3.49–11.26; p < 0.001), tobacco smoking (aOR 1.36, 95% CI 1.02–1.80; p = 0.035), cocaine use (aOR 3.62, 95% CI 1.97–6.63; p < 0.001), fever (aOR 2.09, 95% CI 1.34–3.27; p = 0.001), and hypokalemia (aOR 1.62, 95% CI 1.26–2.08; p < 0.001). The tICH-VPM achieved moderately high discrimination, with an area under the curve of 0.75 (sensitivity = 0.61 and specificity = 0.81). Development of vasospasm was independently associated with a lower likelihood of routine discharge (aOR 0.60, 95% CI 0.45–0.78; p < 0.001) and an extended hospital length of stay (aOR 3.53, 95% CI 2.78–4.48; p < 0.001), but not with mortality.

CONCLUSIONS

This population-based analysis of vasospasm in tICH has identified common clinical risk factors for its development, and has established an independent association between the development of vasospasm and poorer neurological outcomes.

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Thirty-day readmission and reoperation rates after single-level anterior cervical discectomy and fusion versus those after cervical disc replacement

Niketh Bhashyam, Rafael De la Garza Ramos, Jonathan Nakhla, Rani Nasser, Ajit Jada, Taylor E. Purvis, Daniel M. Sciubba, Merritt D. Kinon, and Reza Yassari

OBJECTIVE

The goal of this study was to compare 30-day readmission and reoperation rates after single-level anterior cervical discectomy and fusion (ACDF) versus those after cervical disc replacement (CDR).

METHODS

The authors used the 2013–2014 American College of Surgeons National Surgical Quality Improvement Program database. Included were adult patients who underwent first-time single-level ACDF or CDR for cervical spondylosis or disc herniation. Primary outcome measures were readmission and/or reoperation within 30 days of the original surgery. Logistic regression analysis was used to assess the independent effect of the procedure (ACDF or CDR) on outcome, and results are presented as odds ratios with 95% confidence intervals.

RESULTS

A total of 6077 patients met the inclusion criteria; 5590 (92.0%) patients underwent single-level ACDF, and 487 (8.0%) patients underwent CDR. The readmission rates were 2.6% for ACDF and 0.4% for CDR (p = 0.003). When stratified according to age groups, only patients between the ages of 41 and 60 years who underwent ACDF had a significantly higher readmission rate than those who underwent CDR (2.5% vs 0.7%, respectively; p = 0.028). After controlling for patient age, sex, body mass index, smoking status, history of chronic obstructive pulmonary disease (COPD), diabetes, hypertension, steroid use, and American Society of Anesthesiologists (ASA) class, patients who underwent CDR were significantly less likely to undergo readmission within 30 days than patients who underwent ACDF (OR 0.23 [95% CI 0.06–0.95]; p = 0.041). Patients with a history of COPD (OR 1.97 [95% CI 1.08–3.57]; p = 0.026) or hypertension (OR 1.62 [95% CI 1.10–2.38]; p = 0.013) and those at ASA Class IV (OR 14.6 [95% CI 1.69–125.75]; p = 0.015) were significantly more likely to require readmission within 30 days. The reoperation rates were 1.2% for ACDF and 0.4% for CDR (p = 0.086), and multivariate analysis revealed that CDR was not associated with lower odds of reoperation (OR 0.60 [95% CI 0.14–2.55]; p = 0.492). However, increasing age was associated with a higher risk (OR 1.02 [95% CI 1.00–1.05]; p = 0.031) of reoperation; a 2% increase in risk per year of age was found.

CONCLUSIONS

Patients who underwent single-level ACDF had a higher readmission rate than those who underwent single-level CDR in this study. When stratified according to age, this effect was seen only in the 41- to 60-year age group. No significant difference in the 30-day single-level ACDF and single-level CDR reoperation rates was found. Although patients in the ACDF group were older and sicker, other unmeasured covariates might have accounted for the increased rate of readmission in this group, and further investigation is encouraged.

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Selecting the lowest instrumented vertebra in a multilevel posterior cervical fusion across the cervicothoracic junction: a biomechanical investigation

Yaroslav Gelfand, Daniel Franco, Merritt D. Kinon, Rafael De la Garza Ramos, Reza Yassari, Jonathan A. Harris, Samantha Flamand, Joshua P. McGuckin, Jorge L. Gonzalez, Jonathan M. Mahoney, and Brandon S. Bucklen

OBJECTIVE

Posterior cervical fusion is a common surgical treatment for patients with myeloradiculopathy or regional deformity. Several studies have found increased stresses at the cervicothoracic junction (CTJ) and significantly higher revision surgery rates in multilevel cervical constructs that terminate at C7. The purpose of this study was to investigate the biomechanical effects of selecting C7 versus T1 versus T2 as the lowest instrumented vertebra (LIV) in multisegmental posterior cervicothoracic fusion procedures.

METHODS

Seven fresh-frozen cadaveric cervicothoracic spines (C2–L1) with ribs intact were tested. After analysis of the intact specimens, posterior rods and lateral mass screws were sequentially added to create the following constructs: C3–7 fixation, C3–T1 fixation, and C3–T2 fixation. In vitro flexibility tests were performed to determine the range of motion (ROM) of each group in flexion-extension (FE), lateral bending (LB), and axial rotation (AR), and to measure intradiscal pressure of the distal adjacent level (DAL).

RESULTS

In FE, selecting C7 as the LIV instead of crossing the CTJ resulted in the greatest increase in ROM (2.54°) and pressure (29.57 pound-force per square inch [psi]) at the DAL in the construct relative to the intact specimen. In LB, selecting T1 as the LIV resulted in the greatest increase in motion (0.78°) and the lowest increase in pressure (3.51 psi) at the DAL relative to intact spines. In AR, selecting T2 as the LIV resulted in the greatest increase in motion (0.20°) at the DAL, while selecting T1 as the LIV resulted in the greatest increase in pressure (8.28 psi) in constructs relative to intact specimens. Although these trends did not reach statistical significance, the observed differences were most apparent in FE, where crossing the CTJ resulted in less motion and lower intradiscal pressures at the DAL.

CONCLUSIONS

The present biomechanical cadaveric study demonstrated that a cervical posterior fixation construct with its LIV crossing the CTJ produces less stress in its distal adjacent discs compared with constructs with C7 as the LIV. Future clinical testing is necessary to determine the impact of this finding on patient outcomes.