Paraspinal muscular fat infiltration was associated with the development of adjacent segmental disease after microsurgical decompression without fusion for single-level lumbar spinal stenosis.

PURPOSE: This study investigated the association between preoperative radiological parameters, including paraspinal muscle sarcopenia, and the development of adjacent segmental disease (ASD) after microsurgical decompression (MSD) without fusion for lumbar spinal stenosis (LSS).

METHODS

Patients who underwent MSD for single-level LSS and were followed-up for ≥ 5 years at our institution were retrospectively reviewed. Paraspinal muscle volumes were calculated as the total cross-sectional area of each muscle divided by the L3 vertebral body area. The paraspinal muscle quality (percentage of psoas fat infiltration [PMFI%] and percentage of multifidus muscle fat infiltration [MFMFI%]) was calculated as the hyperintensity area divided by the cross-sectional area of each muscle in the preoperative L3 vertebral body level on axial T2-weighted magnetic resonance image. The preoperative radiological factors including the abovementioned parameters, which can affect the development of ASD requiring surgery after MSD for LSS, were statistically analyzed.

RESULTS

In total, 97 patients with a mean age of 69.1 ± 7.99 years and a median follow-up period of 7.00 (5.00-9.00) years were included in the analysis. The preoperative radiographical factors, including paraspinal muscle volumes, did not influence the development of postoperative ASD. However, the preoperative PMFI% and MFMFI% were significantly related to postoperative ASD. Based on a multivariate analysis, MFMFI% was independently associated with the development of postoperative ASD.

CONCLUSION

A higher paraspinal muscular fat infiltration is an important predictive factor of ASD after single-level MSD for LSS and after fusion surgery. Therefore, spine-specific sarcopenia can have a significant effect on surgical prognosis.