ABSTRACT
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.