Contact area inside the distal radioulnar joint: effect of axial loading and position of the forearm.

BACKGROUND

A biomechanical study was performed to define the normal profiles of contact area inside the distal radioulnar joint and how these profiles change as a result of damage to the distal radioulnar ligaments.

METHODS

Twelve cadaver arms were used and a custom-made jig was designed to allow axial loading of the hand. Tekscan sensor film was used to measure the contact area inside the joint. Measurements were taken with different loads and in different positions of the forearm. The same measurements were taken after dividing either the volar or dorsal distal radioulnar ligament. Finally the measurements were repeated after reconstruction of the divided ligament.

FINDINGS

The contact area increases with axial loading of the hand and is greater in supination than pronation. Division of a single distal radioulnar ligament increases the contact area inside the distal radioulnar joint (123% of normal) and reconstruction of the divided distal radioulnar ligament restores the contact patterns towards the normal values (113% of normal).

INTERPRETATION

The results show that axial loading of the hand and position of the forearm has a significant effect on the contact area inside the distal radioulnar joint. The study also shows that injury of the distal radioulnar ligament disturbs the normal profiles of contact.