Position of the wrist associated with the lowest carpal-tunnel pressure: implications for splint design.
Weiss-ND; Gordon-L; Bloom-T; So-Y; Rempel-DM
J Bone Jt Surg 1995 Nov; 77(11):1695-1699
In order to determine the position of least carpal tunnel pressure, a new method, which continually measures pressure throughout the wrist, was tested. The study consisted of twenty control subjects and four patients diagnosed with carpal tunnel syndrome. A catheter filled with saline solution was inserted into the wrist of each subject. An electrogoniometer, which continuously measured the angles and deviations of wrist movement, was secured to the dorsal surface of the hand and forearm. The elbow was flexed at a 90 degree angle while the subject moved the wrist, guided by a computer image. The position resulting in the lowest carpal tunnel pressure was thus identified. Carpal tunnel pressure had a parabolic relationship with wrist positioning in control subjects. The average lowest carpal tunnel pressure in control subjects was 8+/- 4mmHg, with the position of the wrist being 2+/-9 degrees of extension and 2+/-6 degrees of ulnar deviation. For patients with carpal tunnel syndrome, the average lowest pressure was more than double that of controls, 19+/-2mmHg, with the position of the wrist similar to that found in control subjects. Carpal tunnel pressure in patients was elevated most, relative to controls, at extreme ranges of flexion and extension, but also at smaller angles. Pressures and positions of the wrists did not alter over the four hour testing period. The authors conclude that wrist positioning of lowest carpal tunnel pressure is close to neutral, unlike current wrist splints, which place the wrist in 20 to 30 degrees of extension. This dynamic method for measuring carpal tunnel pressure would be useful for both the prevention and treatment of carpal tunnel syndrome.
Musculoskeletal-system-disorders; Humans; Carpal-tunnel-syndrome; Cumulative-trauma-disorders; Ergonomics; Arm-injuries; Chronic-inflammation; Chronic-trauma
Ergonomics Program, University of California at San Francisco, 1301 South 46th Street, building 12, Richmond, California, 94804
Journal of Bone and Joint Surgery
University of California San Francisco, San Francisco, California