LAUSR

STUDY DESIGN Prospective, observational. OBJECTIVES The aim of our study was to assess the amount of reduction in lean muscle mass (LMM) of multifidus muscle (MFM) between conventional open Transforaminal lumbar interbody fusion (CO-TLIF) as compared to Minimally invasive spine Transforaminal lumbar interbody fusion (MIS-TLIF). METHODS This study was conducted between 2017 and 2020. It included 100 patients divided into two groups, 50 patients treated with CO-TLIF, 50 treated with MIS-TLIF. Only patients undergoing single level, primary lumbar fusion at L4-5 or L5-S1 level for degenerative pathologies were included. All patients were assessed by magnetic resonance imaging (MRI) scans 1-year post surgery. Measurements were performed using ImageJ image processing program. RESULTS Mean percentage reduction in LMM in CO-TLIF group was 45.52 ± 12.36% and MIS-TLIF group was 25.83 ± 9.64% [statistically significant (t = 8.78, P < .001)]. Mean percentage reduction in LMM on side of cage insertion was 39.63 ± 15.96% and opposite side was 31.40 ± 15.01% [statistically significant (t = 9.06, P < .001)]. Mean reduction of LMM among males was 29.38 ± 15.23% and females was 40.42 ± 12.67% [statistically significant (t = -3.95, P < .001)].We observed significant but weak degree of correlation between age and percentage reduction of LMM (r = .22, P = .028). CONCLUSION Mean reduction in LMM was greater in CO-TLIF group as compared to MIS-TLIF. There was greater reduction in LMM in females and on side of cage insertion. We also found greater reduction in LMM with increasing age in both groups.