Objectives:

To investigate whether the preoperative morphology of multifidus influences the surgical outcomes of stand-alone lateral lumbar interbody fusion (LLIF) for lumbar spondylolisthesis.

Patients and methods:

Fifty-eight patients with lumbar spondylolisthesis who underwent single-level, stand-alone LLIF at the L4-5 level were included and followed up for at least 12 months. Preoperative axial cross-sectional area (CSA) and fat infiltration rate (FIR) of multifidus on MRI scans were measured using the ImageJ software. The CSA ratio and FIR were calculated and classified into three grades. Preoperative and final visual analogue scale (VAS) scores for back pain and leg pain, Oswestry Disability Index (ODI) scores were recorded. Cage subsidence and fusion were also evaluated at the final follow-up. Correlations between VAS scores, ODI scores, obvious cage subsidence and fusion rate with the CSA ratio and FIR were analyzed.

Results:

There were significant correlations between preoperative and final VAS scores for back pain and ODI scores with the CSA ratio and FIR. There was an overall trend towards improvements in back pain and lumbar function in patients with superior morphology of multifidus. In addition, obvious cage subsidence was found to be associated with lower preoperative CSA ratios and higher FIR, whereas fusion rate was only correlated with FIR.

Conclusions:

The preoperative morphology of multifidus influenced the surgical outcomes of stand-alone LLIF for lumbar spondylolisthesis. Patients with superior morphology of multifidus showed better outcomes following stand-alone LLIF.