265. Sarcopenia as a risk factor for complications following pedicle subtraction osteotomy

Abstract

<h3>BACKGROUND CONTEXT</h3> Sarcopenia, the loss of muscle mass and function, has been linked to morbidity and mortality in several orthopedic procedures. At present, there is a paucity of data concerning sarcopenia in adult spinal deformity (ASD) surgery and particularly with respect to the most complex techniques performed on this population such as pedicle subtraction osteotomy (PSO). Due to the high surgical burden placed on patients undergoing PSOs, appropriate patient selection is critical for minimizing complications. <h3>PURPOSE</h3> The aim of this study was to 1) determine if sarcopenia was an independent risk factor for complications in ASD patients undergoing PSO, and 2) define discrete categories of complication risk based on sarcopenia severity. <h3>STUDY DESIGN/SETTING</h3> Single-center retrospective review. <h3>PATIENT SAMPLE</h3> Seventy-three ASD patients who underwent PSO. <h3>OUTCOME MEASURES</h3> The primary outcome measure was the presence of any 2-year complication: cardiac, pulmonary, neurologic, dural tear, epidural hematoma, wound infection, proximal junctional kyphosis (PJK), nonunion and revision surgery. Secondary outcome measures included intraoperative blood loss (EBL) and length of stay (LOS). <h3>METHODS</h3> We identified 73 ASD patients with available lumbar CT/MRI scans who underwent PSO with spinal fusion ≥5 levels at a tertiary care center from 2005-2014. Sarcopenia was assessed based on the psoas-lumbar vertebral index (PLVI), a validated marker for central sarcopenia. The PLVI was calculated by dividing a patient's average iliopsoas cross-sectional area (CSA) by the CSA of the L4 vertebrae. Using stratum-specific likelihood ratio (SSLR) analysis, patients were separated into three distinct sarcopenia groups based on complication risk. Cutoffs generated through SSLR were confirmed using multivariable regression controlling for demographic and surgical factors. <h3>RESULTS</h3> The mean age of the cohort was 61±8 years, 75% female. The mean PLVI was 0.84±0.28, with 47% of patients having any complication. Patients with a complication had a 27% lower PLVI on average than those without complications (0.76 vs. 0.91, p=0.021). SSLR analysis produced 3 complication categories: 32% complication rate for PLVI ≥ 0.81; 61% for PLVI 0.60-0.80; and 69% for PLVI < 0.60. Relative to patients with PLVI ≥ 0.81, those with PLVI 0.60-0.80 and PLVI < 0.60 had 3.2x and 4.3x greater odds of developing a complication, respectively (p<0.05 for both). With respect to individual complications, patients with PLVI < 1.0 had significantly higher risk of PJK (34% vs. 0%, p=0.022), while patients with PLVI < 0.8 had significantly higher risk of wound infection (12% vs. 0%, p=0.028) and dural tear (14% vs. 0%, p=0.019). There were no significant associations between sarcopenia, EBL and LOS (p>0.05 for all). <h3>CONCLUSIONS</h3> Increasing severity of sarcopenia is associated with significantly and incrementally increased risk of complications following PSO for ASD surgery. We define PLVI cutoffs (0.60 and 0.81) below which complication risk is significantly increased. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.