Manual muscle strength testing: intraobserver and interobserver reliabilities for the intrinsic muscles of the hand

The reliability of manual muscle strength testing of the intrinsic muscles of the hand is reported. The muscle strengths of 28 patients who had neuropathies of the ulnar nerve or the ulnar and median nerves were graded by two physiotherapists to determine intraobserver and interobserver reliabilities. Muscle strength was graded using the numeric scale developed by the Medical Research Council (grades 0 to 5). Reliabilities were established for nine muscles or muscle groups. Intraobserver reliabilities ranged from 0.71 to 0.96 and interobserver reliabilities from 0.72 to 0.93. It is difficult to isolate, and hence grade, most of the intrinsic muscles of the hand. Therefore, it is suggested that specific movements be tested and graded when assessing and evaluating muscle or nerve function.