Ankle arthrodesis: a comparative clinical and biomechanical evaluation.

Arthrodesis of the ankle joint is difficult to achieve when there are associated problems with bony deformity or abnormalities of the surrounding soft tissues. In a series of 50 ankle arthrodeses, in which 68% had either damaged soft tissues or fixed ankle deformity, the pseudarthrosis rate was 30%. This high failure rate led us to devise biomechanical studies to evaluate the inherent stability of the Charnley-type compression arthrodesis, the R.A.F. fusion, and a new dynamic compression T-plate. The stability of the Charnley apparatus was directly related to the tension upon the wingnuts. However, in spite of the massive compression generated by the Charnley apparatus, it was relatively unable to resist rotatory forces. The T-plate had excellent rotatory and flexion-extension stability and developed approximately 25 pounds/inch compression across the ankle fusion. The T-plates's clinical application is demonstrated in eight successful arthrodeses. The importance of an intraoperative roentgenogram to confirm satisfactory ankle alignment cannot be overemphasized.