Lower limb strength asymmetry and its association with functional changes in persons with multiple sclerosis

Area of Science:

• Neurology
• Rehabilitation Science
• Biomedical Engineering

Background:

• Lower limb (LL) asymmetry is linked to fatigue, instability, and fear of falling in persons with MS (PwMS).
• Limited research exists on the specific contribution of LL strength asymmetry to functional status changes in PwMS.

Purpose of the Study:

• To investigate differences in LL strength asymmetry across various functional status groups in PwMS.
• To identify specific asymmetry scores indicative of functional status changes in PwMS.

Main Methods:

• A cross-sectional study analyzed data from 183 PwMS classified into functional groups using the MS Walking Scale (MSWS-12).
• Peak isometric torque and asymmetry of hip abduction/extension/flexion, knee extension/flexion, and ankle plantarflexion/dorsiflexion were measured.
• Statistical analyses included examining differences between functional groups and performing receiver operating characteristic (ROC) analyses to identify optimal cutoff scores for asymmetry.

Main Results:

• Significant differences in knee flexion (KF), ankle dorsiflexion (ADF), and knee extension (KE) asymmetry were observed between functional groups.
• KF asymmetry (cutoff ≥19.74%) and ADF asymmetry (cutoff ≥14.29%) demonstrated clinically relevant sensitivity and specificity.
• KF asymmetry emerged as a significant predictor of functional status in PwMS (aOR: 264.75).

Conclusions:

• Only KE, KF, and ADF asymmetry showed significant differences across functional levels in PwMS.
• The asymmetry thresholds differentiating minimal from severe functional groups exceeded the conventional 10% criterion.
• KF asymmetry is a key predictor of functional changes, highlighting its importance in managing PwMS.