Recovery Patterns of Lower Limb Motor Function Following Lumbar Spinal Stenosis Surgery: A 5-Year Retrospective Cohort Study Utilizing the Foot Tapping Test.

Abstract

Retrospective cohort study. To investigate 5-year motor recovery patterns after lumbar spinal stenosis (LSS) surgery using the foot-tapping test (FTT) and identify prognostic factors. Long-term recovery from mild paresis after LSS is unclear. The FTT offers an objective method of quantifying subtle motor deficits missed by conventional Manual Muscle Testing. We retrospectively analyzed patients who underwent primary LSS for L5 nerve root involvement over a 5-year period. The FTT was performed by counting the number of ankle dorsiflexions over 10 seconds with the heel placed on the floor. A linear mixed-effects model was used to analyze longitudinal FTT changes, adjusting for covariates comprising age, sex, and neurological intermittent claudication type. Changes from baseline (ΔFTT) were compared among and within NIC types across 0-1, 1-3, and 3-5 year windows. Of 541 eligible patients, 145 were analyzed. FTT scores significantly improved over time (P=0.004), whereas older age was a negative predictor (P< 0.001). Recovery rates were similar among NIC types. However, at 3-5 years, ΔFTT was significantly lower in the Cauda Equina versus the Radicular type (P=0.043). Notably, the improvement in the Cauda Equina type from baseline was no longer significant at this late stage (P=0.289), unlike the other types. The FTT is a useful tool for long-term motor assessment after LSS surgery. Poor long-term recovery in the Cauda Equina type may reflect severe, irreversible neural damage. This finding highlights the importance of considering early surgical intervention to potentially improve long-term motor outcomes, especially in patients presenting with Cauda Equina type impairment.