Age-Related Association Between Unilateral Single-Channel and Double-Channel Surgery and Postoperative Multifidus Muscle Atrophy and Fat Infiltration.

Background: Unilateral biportal endoscopic laminotomy (UBE) and percutaneous endoscopic laminotomy (PEL) are minimally invasive spinal surgery (MISS) techniques used for unilateral and dual-channel endoscopic laminectomy. However, limited research has been conducted on lumbosacral multifidus muscle injuries in elderly individuals undergoing MISS for lumbar spinal canal stenosis. The objective of this study was to investigate the impact of single-channel and double-channel MISS on the multifidus muscle in elderly patients.

Materials and methods: A total of 107 patients who underwent MISS were stratified into two cohorts: group A (<65 years) and group B (≥65 years). Preoperative imaging data, including magnetic resonance imaging, were gathered to classify the degree of stenosis based on the nerve root compression. The extent of multifidus muscle atrophy and fat infiltration was assessed by calculating the fat-free cross-sectional area (FCSA)/cross-sectional area (CSA) ratio before and after surgery through measurements of CSA and FCSA. Total cross-sectional area/FCSA were calculated using MRI cross-sectional T2WI.

Results: The degree of atrophy and fat infiltration did not change between procedures in group A (P>.05), but changed significantly in group B (P<.05).

Conclusion: Unilateral single-channel and double-channel surgery had no significant effect on the degree of multifidus muscle atrophy and fat infiltration in patients younger than 65 years. However, in patients 65 years and older, the degree of multifidus muscle atrophy and fat infiltration significantly increased with the increasing incidence of lateral recess stenosis, which was positively correlated with the duration of surgery. [Orthopedics. 202x;4x(x):xx-xx.].