Arthrodesis of the ankle with cancellous-bone screws and fibular strut graft. Biomechanical analysis.

The stability of an arthrodesis with two cancellous-bone screws across the ankle joint was evaluated in eighteen ankles from fresh-frozen cadavera. Tibiotalar motion was recorded in response to the following loading modes: medial-lateral moment, plantar flexion-dorsiflexion moment, and internal-external tibial torque. The series of loading tests was performed with two cancellous-bone screws through the tibia into the talus and a lateral fibular strut graft fixed with a proximal and a distal screw. The tests were repeated after the strut graft was removed, and again after it had been reapplied. The amount of motion at the site of the arthrodesis was greatest with tibial torque and was least with medial-lateral bending; this was true for specimens with or without a fibular strut graft. Removal of the strut graft allowed increased tibiotalar motion for all modes of loading; increases in motion were far greater for specimens of poor bone quality.