Static wrist position associated with least median nerve compression - Sonographic evaluation

Objective: To determine the wrist angle that produces the least compression to the median nerve and to evaluate the usefulness of sonography in determ ining the optimal position. Design: Seventeen wrists of 17 healthy volunteers received dynamic, high-fr equency (8 MHz), high-resolution sonography with the wrist splinted at vari ous positions: 15 degrees of flexion, neutral position, and 15 degrees and 30 degrees of extension. The morphologic changes of the median nerve were e valuated with the wrist positioned at various angles. Results: The neutral position caused significantly lower compression of the median nerve than it did in the other positions. However, in some cases, t he lowest pressure was found when the wrist was fixed in 15 degrees of flex ion or 15 degrees of extension. Because median nerve compression may decrea se the anteroposterior diameter, increase the transverse diameter, and decr ease the cross-sectional area, greater anteroposterior diameter, lower flat tening ratio (transverse diameter/anteroposterior diameter), and greater cr oss-sectional area were considered to indicate lower median nerve compressi on. Conclusions: Neutral position of the wrist is the best position with the le ast median nerve compression in most individuals. However, the optimal posi tion may vary from person to person. Sonographic examination can help to de termine the splint position that results in the lowest median nerve compres sion.