Pressure Distribution in the Distal Radio-ulnar Joint. With F. Werner, M. Fortino, S. Ishii
The distal radio-ulnar joint(DRUJ) helps to stabilize the forearm. The purpose of this study is to measure the distribution of pressure within the DRUJ in different positions of pronation and supination. An electromagnetic tracking device was attached to seven fresh cadaver upper extremities. This allowed monitoring of the position of the wrist to within 0.10. An incision was made in the capsule of the distal radio-ulnar joint and a pressure sensor was inserted. Weights were suspended from the wrist flexors and extensor. Minimal forces to obtain maximum pronation or supination were applied and data were recorded. Data were also recorded by manually locating the wrist in 10 positions of forearm rotation.
The results show that increasing the compressive force across the wrist joint caused the centroid of pressure to move distally on the radius an average of 0.8 mm. In neutral rotation with 89 N of force applied 13% of the sigmoid notch was in contact with the ulna. Analysis of the pressure plots reveals that in pronation the pressure is concentrated in the dorsal portion of the sigmoid notch while in supination the pressure is distributed in the palmar portion of the sigmoid notch. The data support the hypothesis that both the amount of load on the wrist tendons as well as the position of forearm rotation help determine the pressure distribution in this joint. This study also concurs with the theoretical concepts advocated by Bowers about changes in pressure distribution in the DRUJ.
Biomechanical Study of the Ligaments of the Wrist Joint. With F. Werner, M. Fortino, K. Mann
The contribution of specific intrinsic wrist ligaments in preventing carpal instability was studied. Carpal bone motion and radioulnar carpal joint pressures was simultaneously monitored in cadaver specimens while the wrist is moved physiologically. Measurements were made in the intact wrist, and after sectioning in various combinations, the scapholunate interosseous ligament, the radioscaphocapitate ligament, and the long radiolunate ligament and the scaphotrapezial ligament. The effect of repetitive cycling of up to 2500 Hz following ligament sectioning was also analyzed. Statistical comparison of carpal motion and pressures determined the role of specific ligaments in preventing wrist instability.
Kihara H, W.H. Short, F.W. Werner, M.D. Fortino and A.K. Palmer: The stabilizing mechanism of the distal radio-ulnar joint during pronation and supination. Journal of Hand Surgery 21A:40- 47, 1996.
Sagerman, S.D. and W.H. Short: Arthroscopic repair of radial sided triangular fibrocartilage complex tears. Arthroscopy 12:339-342, 1996.