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

Background: Several dynamic external fixation devices have been introduced to permit early functional treatment of unstable distal radial fractures. Methods: An intact cadaver wrist was spanned by a dynamic external fixator, Forces between the fixator and the radius were recorded during passive mot ion using a single, strain-gauged pin. A device with a double ball joint wa s compared with a new, experimental fixator with 3 degrees of freedom and i ts center of rotation coincident with that of the wrist. Results: During flexion and extension, the pin load,vas approximately the s ame for both fixators, Radioulnar deviation resulted in high pin loads for the fixator with ball joints; the new device showed no considerable pin loa d. Conclusion: The new device has a high degree of kinematic compatibility wit h the natural wrist joint. When used for the treatment of distal radial fra ctures, it should provide favorable conditions for the maintenance of fract ure reduction compared with a device with an offset hall joint.