INFLUENCE OF WRIST JOINT POSITION AND METACARPOPHALANGEAL JOINT RANGE OF MOTION ON EXTENSOR DIGITORUM COMMUNIS (EDC) ACTIVITY: AN ELECTROMYOGRAPHIC STUDY

Early controlled stress on the healing tendon has proved to have many positive effects such as reduction of oedema and improved excursion. The purpose of this study was to investigate the effect of the position of the wrist and metacarpophalangeal (MCP) joints on the EDC muscle activity during MCP movement and thus: i) provide an electromyographic basis for dynamic extensor splinting, and ii) examine the safest position for early active motion in extensor tendon injuries. Electromyography was used to monitor EDC activity during MCP extension from various wrist positions. The least muscle activity was observed when the wrist was in flexion and the greatest when the wrist was at 45 degrees extension. A statistically significant difference (p< 0.05) was established among the various MCP ranges of motion, with the greatest activity per time unit occurring when the MCP joints moved up to 20 degrees hyperextension. The results suggest that slight MCP flexion may effectively reduce EDC activity. Further research is needed to provide evidence on the influence of slight MCP flexion on the quality of repair and functional outcomes after extensor tendon repair.