Biomechanical analysis of dynamic external fixation devices for the treatment of distal radial fractures

Several dynamic external fixation devices have been introduced to permit early functional treatment of unstable distal radial fractures. An intact cadaver wrist was spanned by a dynamic external fixator. Forces between the fixator and the radius were recorded during passive motion using a single, strain-gauged pin. A device with a double ball joint was compared with a new, experimental fixator with 3 degrees of freedom and its center of rotation coincident with that of the wrist. During flexion and extension, the pin load was approximately the same for both fixators. Radioulnar deviation resulted in high pin loads for the fixator with ball joints; the new device showed no considerable pin load. The new device has a high degree of kinematic compatibility with the natural wrist joint. When used for the treatment of distal radial fractures, it should provide favorable conditions for the maintenance of fracture reduction compared with a device with an offset ball joint