Contributions of the Radiocarpal and Midcarpal Jointin Flexion-extension Motion of Wrist / 대한정형외과학회잡지

PURPOSE: Flexion and extension of the wrist occurs at the radiocarpal and midcarpal joints. This study examined the angular contribution of the radiocarpal and midcarpal joints to the total arc of motion. MATERIALS AND METHODS: Five healthy adults were selected and ten wrists were tested. Lateral X-rays were taken with the wrist in the neutral position, 30 degrees flexion, 60 degrees flexion, 90 degrees flexion, 30 degrees extension, 60 degrees extension, and 90 degrees extension. The radiocarpal and midcarpal angle were measured. The angular contribution of the radiocarpal and midcarpal angle was calculated at each phase of motion; neutral to 30 degrees, 30 degrees to 60 degrees, 60 degrees to 90 degrees. RESULTS: During wrist flexion, the angular contribution of the midcarpal joint was 65%, 72%, 71% at each phase of motion, respectively. During wrist extension, the angular contribution of midcarpal joint was 37%, 53%, 78% at each phase of motion, respectively. Therefore, during wrist extension, the main contributor of motion is changed from the radiocarpal joint in the early phase to the midcarpal joint in the late phase. CONCLUSION: It is suggested that the proximal carpal low is not moved passively by just the link system but the motion is guided by the peculiar shape of midcarpal articulation and ligaments complex at each phase. The link system is believed to act in the early phase of flexion and in late phase of extension.

Instability Patterns of Normal Midcarpal and Radiocarpal Joint in the Sagittal Plane / 대한정형외과학회잡지

The midcarpal joint has inherent instability in the sagittal plane. Several instability patterns of midcarpal joint due to ligament insufficiency have been presented. We ohserved the normal midcarpal and radiocarpal behaviors of ligament laxity in the sagittal plane to investigate the significance of dorsal and palmar stress test which has been used for evaluation of the non-dissociative carpal instahilities. We performed the dorsal and palmar displacement stress test on fifty pairs of normal wrist joints under the flouroscopic views. The midcarpal joints were subluxed, more on dorsal stress, with variable degrees. Dorsal subluxations in females and third decades were more prominent than males and fourth decades. Three types of radiocarpal instability on dorsal stress test could be observed. We think that displacement stress test in the sagittal plane should be interpreted in consideration of normal instability patterns in the evaluation of ahnormal midcarpal and radiocarpal instabilities since there are variable patterns and degrees of ligament laxity in normal wrist joints.