Three-dimensional dynamic AO external fixation of distal radial fractures--a preliminary report

External fixation of unstable and intra-articular distal radial fractures has become increasingly popular. Dynamic external fixation, allowing movement of the wrist during the fixation period, is a relatively new approach which may further improve functional end results. To permit early functional treatment, the small AO external fixator was supplemented by a joint allowing all three degrees of rotational freedom. The centre of rotation is located at a point outside the device and lies approximately in the head of the capitate. With the natural centre of wrist rotation coincident with that of the fixator, admissable movements of the wrist include both flexion-extension and radio-ulnar deviation, without threatening fracture reduction. In vitro testing and initial clinical experience with a prototype are encouraging. Several improvements of the original design have been made and a multicentric clinical study is scheduled for further evaluation of the new dynamic external fixator.