[Roentgenographical and anatomical study of the midcarpal joint--morphology and degenerative change of ulnar side].

The present investigator has studied the following anatomic variations and degenerative changes of the articular cartilage of the ulnar side of the midcarpal joint: the perforation of the triangular fibrocartilage (TFC), and the ruptures of the scapholunate and lunotriquetral interosseous ligaments (S-L lig., L-T lig.). The materials were 127 wrist joints obtained from 66 cadavers (age 32-95, average age 74) and were studied radiographically and anatomically. Two types of the ulnar side of the midcarpal joint were classified radiographically and anatomically. In the first type, there was no articulation present between the hamate and the lunate in 42.5% of the dissected specimens. In the second type, there was an articulation present between the hamate and the lunate in 57.5% of the dissected specimens. Wrists of the second type correlated significantly with the ulnar shift ratio of lunate on the radiographical measurement (p < 0.01). Significant cartilage erosion and exposed subchondral bone were found at the joints of the second type. There was no correlation between the TFC perforation, the carpal interosseous ligament ruptures and degenerative changes of the articular cartilage of the ulnar side of the midcarpal joint.