Biomechanical efficacy of an internal fixator for treatment of distal radius fractures

Despite the effectiveness of external fixation in the treatment of complex wrist fractures, the complication rate for this modality ranges from 20% to 62%. Common complications are related to the use of percutaneous metal pins and result in an average reoperation rate of 16%. In addition, external fixation is unable to prevent dorsal collapse of the radius or maintain the normal palmar tilt of the radiocarpal joint surface. This complication may predispose to post-traumatic wrist instability and arthritis. The problems with external fixation have prompted a search for a better treatment option. An internal fixator placed through limited incisions on the dorsal aspect of the radius and spanning the fracture site can, in theory, provide the benefits of external fixation without the associated morbidity. This study determined the biomechanical efficacy of internal fixators compared with external fixators using a standardized model for an unstable wrist fracture. Two commercially available metal plates were used as internal fixators. Biomechanical testing of the devices was done, and stiffness was determined. Results showed that the internal fixators were significantly stiffer than were the external fixators in axial loading. Failure in axial loading, specifically compression, is a consistent reason for loss of reduction in intraarticular distal radius fractures. The clinical implications of these results suggest that an internal fixator theoretically can prevent loss of reduction in the axial plane and maintain palmar tilt by acting as a rigid dorsal buttress. In addition, the use of an internal fixator potentially decreases the high morbidity associated with external fixation. Additional investigation intothe clinical application of internal fixators for distal radius fractures is needed.