Preoperative multifidus and psoas major muscle quality and patient-reported outcomes after anterolateral lumbar interbody fusion: predictors for preoperative disability and back pain improvement

Abstract

To investigate associations between preoperative lumbar multifidus muscle (LMM) and psoas major muscle (PMM) qualities and pre- and postoperative patient-reported outcomes (PROs) after anterolateral lumbar interbody fusion (A-LLIF). A retrospective review was conducted of patients with A-LLIF between L1 and S1 during 2017-2022 at a single institution who had at least approximately1 year of follow-up and preoperative MRI available. Preoperative MRI was analyzed using 2 image analysis platforms (AMBRA and ImageJ). Parameters studied included cross-sectional area (CSA) and fat infiltration (FI) indices. Pearson correlation and multiple linear regression analyses were used to study relationships between muscle quality and pre- and postoperative PROs. Subanalyses were performed for LMM CSA percentiles and stratification of previous surgery. One hundred patients met the inclusion criteria (mean [SD] age, 65.3 [11.0] years; 57% women, 43% men) during a mean (SD) follow-up period of 1.29 (0.20) years. In total, 207 surgical levels were analyzed. Smaller LMM CSA was significantly associated with greater preoperative disability and preoperative back pain (p<0.04 [ImageJ]). There were no statistically significant confounding factors. Patients with greater LMM CSA and previous lumbar procedures (n=42) had more improvement in visual analog scale for lower back pain delta scores (p=0.02 [ImageJ]; p=0.04 [AMBRA]). Neither LMM FI indices nor PMM morphology influenced PROs. Significant associations were found between LMM CSA and preoperative disability and back pain. Compared to A-LLIF patients with larger LMM (CSA > 12 cm2), those with LMM CSA <5 cm2 had significantly greater preoperative disability and back pain.