Effects of intra-articular distal radius depression on wrist joint contact characteristics.

Twelve cadaver extremities were used to study the effect of scaphoid and lunate facet depressions on the contact characteristics of the radiocarpal joint. Pressure-sensitive film was inserted into radiocarpal joints with varying degrees of depression, and the specimens were loaded statically in neutral position, radial deviation, and ulnar deviation. The film was removed and analyzed for contact area and pressure. The only statistically significant effect of a lunate fossa depression was an increase in scaphoid fossa pressure with a 3-mm step-off and the hand in neutral position. Scaphoid fossa depression had more significant effects. With a 1-mm scaphoid fossa depression, lunate fossa pressures increased in neutral position and in radial deviation. Lunate fossa contact area increased, compared to intact joints, in ulnar and radial deviation with 1-mm scaphoid fossa depressions and in all loading positions with 3-mm scaphoid fossa depression. Therefore, it appears that the most significant effect on radiocarpal joint contact characteristics occurs with a depression of the scaphoid side of the joint. Even with depressions as small as 1 mm, significant changes on the lunate side of the joint were observed.