Measurement of health outcomes following tendon and nerve repair.

The World Health Organization's model of health suggests that tendon and nerve injury outcomes can be assessed in terms of impairment, activity limitations, and participation restrictions. A tendon injury results in impairment of motion and strength of affected digits. Literature on outcome of tendon surgery has focused on active motion. Recently developed devices can be used to measure strength impairments associated with individual digits after tendon injury, although the importance of either grip or digital strength measures as indicators of post-tendon recovery has not been fully delineated. Published impairment rating scales have expressed outcome based on regained total active motion of relevant joints. These scales also tend to classify outcomes on a subjective four-point scale ranging from poor to excellent. Subjective ratings have not been validated, vary across scales, and inhibit meaningful comparisons by diluting information. Nerve injuries result in an impairment of motion, strength, sensibility, and sympathetic nerve function. Development of quantitative measures of sensibility continues to evolve, although all current methods have some limitations. Two-point discrimination was once a mainstay of assessment, but current evidence suggests it is less valid and responsive than other quantitative sensory testing. Cold sensitivity is common and can be measured through rewarming responses or by self-report. A comprehensive impairment rating scale for nerve injury with subscales addressing sensory, motor, and pain/discomfort domains has been developed. Use of this validated instrument will facilitate more meaningful comparisons across centers and studies. Recent literature on treatment outcomes has focused on impairment measures with minimal attention to activity limitations and participation restrictions. Validation of appropriate scales and inclusion of both impairment and disability measures in future clinical studies is required to fully understand health outcomes after tendon and nerve injury.