Lower limb strength asymmetry and its association with functional changes in persons with multiple sclerosis.
Academic Article
Overview
abstract
BACKGROUND: Lower limb (LL) asymmetry is associated with fatigue, instability, and fear of falling in persons with MS (PwMS). However, research is limited on how LL strength asymmetry contributes to functional status changes in PwMS. OBJECTIVES: To determine if there is a difference in LL strength asymmetry between functional status groups in PwMS and identify which asymmetry score indicates a change in functional status in PwMS. METHODS: This secondary analysis of a cross-sectional study collected the 12-item MS Walking Scale (MSWS-12) to classify PwMS (n = 183) into functional groups (minimal: 0-24.99, mild: 25-49.99, moderate: 50-74.99, or severe: 75-100). Peak isometric torque and asymmetry of hip abduction (HA), extension (HE), and flexion (HF), knee extension (KE) and flexion (KF), and ankle plantarflexion (APF) and dorsiflexion (ADF) were captured. Differences between functional groups were examined. Receiver operating characteristic analyses were performed on significant differences. Optimal cutoff scores were identified. Exploratory regressions examined asymmetry cut-off scores and function. RESULTS: Overall differences between functional groups occurred in KF (P < 0.001), ADF (P = 0.012), and KE (P = 0.013) asymmetry. KF (cut-off: ≥19.74%, sensitivity: 67.19%, specificity: 92.86%) and ADF (cut-off: ≥14.29%, sensitivity: 67.39%, specificity: 82.14%) had useful asymmetry cut-off scores (sensitivity and specificity totaled ≥1.5). KF asymmetry (aOR: 264.75, 95%CI: 4.33, 16,199.33, P = 0.008) was a significant predictor of function. CONCLUSIONS: Only KE, KF and ADF asymmetry differed between the functional levels. The asymmetry differentiating between the minimal and severe functional groups was above the typically used 10% criterion, and KF asymmetry was predictive of functional change in PwMS.
