Development of a Position-Specific Index of Muscle Strength to be Used in Stroke Evaluation

Abstract

Moriello C, Mayo NE. Development of a position-specific index of muscle strength to be used in stroke evaluation. Objective To develop a position-specific index of muscle strength for individuals with stroke. Design Cross-sectional design. Setting A major teaching hospital in a Canadian urban city. Participants Sixty-three patients with poststroke onset between 3 and 12 months. Interventions Not applicable. Main Outcome Measure The muscle strength of the lower-extremity muscles was tested bilaterally in multiple positions using hand-held dynamometry. Results A principal components analysis resulted in grouping the muscles of the affected and unaffected sides of the gravity related and gravity eliminated positions into 5 indices. The 5 indices were moderately to highly correlated ( r 2 range, .59−.81) with each other and so were combined into 1 global index. The gravity related muscle strength on the affected side was, on average, 85% of the unaffected side (range, 37%–157%); the gravity eliminated muscle strength of the affected side was, on average, 92% of the unaffected side (range, 53%–121%). Conclusions This study resolves the methodologic issue of how to summarize multiple data points that relate to one construct, namely, strength of different muscle groups assessed in several positions.