An electromyography study of wrist extension orthoses and upper-extremity function.

OBJECTIVE This study examined the effect of commonly used long and short styles of commercially produced wrist extension orthoses on the activity of the proximal muscles of the shoulder and elbow and on wrist flexor and extensor muscle activity. METHOD While 17 women between 22 and 40 years of age (M = 26.6) performed a specified movement wearing each of the two styles of orthosis and without an orthosis, their motor unit recruitment of five proximal joint muscle groups, wrist extensors, and wrist flexors was measured by surface electromyography. RESULTS Motor unit recruitment was significantly greater in both orthosis conditions for four of five proximal muscles and for wrist flexors. There were no significant differences between the short and long orthosis conditions for proximal muscle groups. CONCLUSION Wearing a wrist extension orthosis appears to place additional stress on the proximal joint musculature beyond that found without splint use. The study has implications for the prescription of wrist extension orthoses, especially for patients whose proximal joints are already compromised.