Measurement of wrist, metacarpophalangeal joint, and thumb extension strength in a normal population.

An objective method of measuring isometric wrist, finger (metacarpophalangeal joints) and thumb extension strength was developed, and values for a normal population were defined. Disability due to extensor dysfunction was not assessed in this study. The testing technique involved the use of a load cell myometer held in a specially constructed jig. A total of 2232 measurements in 372 persons were made. Mean values for the strength of extension were as follows: men--wrist, 13 kg; metacarpophalangeal joint, 6 kg; thumb, 3 kg; women--wrist, 7 kg; metacarpophalangeal joint, 4 kg; thumb, 2 kg. Strength was greatest in the third decade and decreased in each subsequent age group. Wrist extension strength was 10% greater in the dominant hand. Interrater and test-retest reliability were assessed and found to be satisfactory. The method is proposed primarily as a clinical research tool, providing the clinician with an objective means of assessing wrist, metacarpophalangeal joint, and thumb extensor function. Potential applications include measurements of recovery after radial nerve injury or grafting and after other reconstructive procedures to restore extensor function.