Correlation of knee strength to functional outcomes in becker muscular dystrophy

Introduction: The correlation of strength with performance on functional outcomes has not been evaluated in Becker muscular dystrophy (BMD), yet the determination of proper outcome measures is critical to the success of upcoming trials designed to improve strength. Methods: Lower extremity strength and performance on functional outcome measures were tested in 25 ambulatory subjects with BMD. Results: All subjects demonstrated marked knee extensor and flexor muscle weakness. Knee extensor strength was correlated with performance on the Berg Balance Scale and stair climbing. Knee flexor strength was highly correlated with performance on all functional outcomes, including timed walking distances. Conclusions: This profile differs from that previously reported in other neuromuscular diseases and demonstrates the importance of designing outcome measures for clinical trials in muscle disorders with considerations for the disease process, the mode, and the target of intervention. The findings emphasize that 1 set of outcomes is not appropriate for all neuromuscular diseases. Muscle Nerve, 2013