Compression arthrodesis of the knee and ankle with the Hoffmann external fixator

We performed 12 arthrodeses of the knee and eight of the ankle, using the Hoffmann device as a compressor-fixator. For the knees, the double rectangular frame was used with the added fixation of a cylinder cast in six cases. In four cases a separate half frame was used in the anterior plane. Posttraumatic arthritis was the indication in seven cases, and failed arthroplasties in five cases (three of them infected). For the ankles, a double triangular compression frame was used, with transfixing pins across the talus (after trauma) or the calcaneus (after ankle replacement). The ankle arthrodeses were done for posttraumatic arthritis in five cases (ankle fracture in one case, pylon fracture in three cases, fracture of the talus in one case), and failed ankle arthroplasty in three cases. Solid union occurred in all but one of the knee arthrodeses and in all but two of the ankle arthrodeses. Two infected total ankle replacements eventually terminated in amputation.