The reason why late degenerative arthritis developed in some patients
who had sustained displaced bimalleolar fractures of the ankle was
investigated. The roentgenograms indicated that incomplete reduction of the
lateral malleolus and a residual talar tilt were present. When bimalleolar
fractures were created in cadavera the talus could be anatomically
repositioned only when the lateral malleolus was accurately reduced.
Fifty-three patients with bimalleolar fractures were treated by
anatomically fixing the lateral malleolus with a four-hole plate. There was
an anatomical reduction of the talus and medial malleolus in each instance
and there were no late cases of degenerative arthritis when these patients
were followed for from six months to nine years. We concluded that the
lateral malleolus is the key to the anatomical reduction of bimalleolar
fractures, because the displacement of the talus faithfully followed that
of the lateral malleolus.