The causes of subsequent arthrodesis of the ankle joint.

Between 1917 and 1984, we performed 217 arthrodesis of the ankle joint. Posttraumatic states were the cause of the osteoarthritis in 153 cases, whereas 118 of these cases were malleolar fractures. The accident X-rays were analyzed, and the fractures were classified in accordance with the classification of Weber (11). Our own system was used for the radiological classification of the degree of arthritis. The extent of malunion after the initial care was assessed. We found type-C malleolar fractures most frequently, the most striking malunion being the shortening of the fibula. In all fractures requiring subsequent arthrodesis, osteoarthritis of degree III-IV was present. In most cases the malleolar fractures treated surgically showed a shortening of the fibula and must be considered failures of initial care. The classification into types according to Weber also seems to provide prognostic information about the subsequent need for arthrodesis. Here it can be observed that C-fractures and compression fractures more often require arthrodeses.