Relationship between changes in physical function parameters and Roland-Morris disability questionnaire score after decompression surgery for lumbar spinal canal stenosis

Although decompression surgery for lumbar spinal canal stenosis (LSS) improves leg symptoms, low back pain (LBP), and disability, the factors related to the improvement of subjective disability have not been studied sufficiently. The purpose of the study was to clarify the relationship between subjective disability and objective physical function parameters. A total of 51 patients who underwent decompression were included and evaluated preoperatively and 6 and 12 months postoperatively. Patient-reported outcomes related to activity limitation due to LBP were evaluated using Roland–Morris disability questionnaire (RDQ) and VAS (Visual Analog Scale). Physical function was assessed using 6-min walk distance (6MWD) and trunk muscle strength. Univariate analysis and multivariable linear regression analysis were performed to identify significant factors for RDQ score change. The 6- and 12-month postoperative RDQ scores, VAS scores, and trunk extensor strength significantly improved relative to the preoperative values. In the univariate analysis, age, changes in VAS (LBP, leg pain, and numbness) scores, and change in 6MWD were associated with the RDQ score change (p < 0.05). Multivariable linear regression showed that 6MWD changes were significantly associated with RDQ score changes, explaining 41% of the variance in the RDQ score change. This study showed the change in 6MWD was significantly associated with the RDQ score change. Our results suggest that improving 6MWD may reduce disability in activities of daily living.