P74. Preoperative muscle health impacts the time taken to reach minimally clinically important differences in health-related quality of life scores for one-level lumbar fusions

Abstract

BACKGROUND CONTEXT There is evidence that degenerative changes in paralumbar musculature impact conditions like low back pain, and lumbar spinal stenosis. For patients undergoing spinal surgery we hypothesized that paralumbar muscle health would alter the time it took for patients to reach minimal clinically important differences (MCIDs) in health-related quality of life scores (HRQOLs). PURPOSE Determine how preoperative muscle health impacts the time to MCID for one level MIS TLIF and/or decompression. STUDY DESIGN/SETTING Retrospective review of a prospectively collected database PATIENT SAMPLE Eighty-five adult patients with lumbar spine pathology requiring MIS lumbar decompression/fusion. OUTCOME MEASURES Health-related-quality of life (HRQL) scores, lumbar indentation value (LIV). METHODS We performed a retrospective review of patients that eventually went on to undergo either a lumbar decompressive surgery or a 1-level lumbar spinal fusion. We analyzed magnetic resonance imaging (MRI) to quantify muscle health using the lumbar indentation value (LIV) which is a validated method of measuring the relative cross-sectional area of lumbar musculature. T2 axial slices from the disc space at the operative level were analyzed. We separated our cohort of patients into whether they had a lumbar decompression alone or 1-level TLIF. Health related quality of life (HRQOL) scores were collected on these patients in the pre-operative period and the post-operative period up to 1 year out from surgery. These scores included the Visual analog back and leg scores (VAS leg and VAS back), the oswestry disability index (ODI), short form 12 (SF-12) mental health scores (MHS) and physical health scores (PHS). We defined MCID as has been previously reported in the literature. We then correlated the LIV calculated off preoperative MRI and correlated this finding with time to MCID using a linear regression analysis. RESULTS A total of 85 patients were included within our analysis. The average age was 58.4+/-15.7 years old and there were 45 men and 40 women. There were 93 disc spaces operated on within this cohort. The majority of patients undergoing a lumbar decompression (LD) had a diagnosis of disc herniation (49.2%) and the majority of patients that had a lumbar fusion (LF) were diagnosed with lumbar spinal stenosis (93.1%). We found that the average LIV for LD patients was 16.2+/-6.5mm and for LF patients was 17.1+/-6.6mm. There was no statistically significant correlation between time to MCID for ODI, SF-12 MHS. SF-12 PHS, VAS leg, or VAS back scores and LIV for patients undergoing a lumbar decompression. There was a statistically significant inverse relationship between time to MCID for ODI (p =0.02) and LIV and time to MCID for SF-12 MHS (p = 0.04) and LIV (ie, higher LIV correlated with lower time to MCID for ODI and SF-12 MHS). CONCLUSIONS These results emphasize the need for evaluation of paralumbar muscle health for patients undergoing lumbar surgery. Specifically, lumbar muscle health correlates with time to MCID for ODI and SF-12 MHS for patients undergoing lumbar fusion surgery. Further investigations are needed to determine how improvement of cross-sectional area of paralumbar muscle impacts MCID for patients undergoing lumbar surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.