Hemicallotasis for medial gonarthrosis: a short-term follow-up of 21 patients.

We have prospectively evaluated 21 patients (22 knees; 15 men and 6 women) who underwent hemicallotasis osteotomy (HO), using an external fixator, of the proximal tibia due to medial gonarthrosis. Their median age at the time of operation was 52 (range 39-62) years. The follow- up period was 12-28 months. The Hospital for Special Surgery score (HSS) increased from median 71 preoperatively to 83 points at the follow-up ( p < 0.001). The median hip-knee-ankle angle (HKA) was 187 degrees preoperatively, 177 degrees after distraction, and 180 degrees at the time of follow-up ( p < 0.001). In 5 knees, valgus angulation was not achieved during the distraction phase, and in two-thirds of the knees, there was no valgus at follow-up. The total time in external fixation was median 13 (range 8-16) weeks. Pin tract problems occurred in 12 cases. There was one deep vein thrombosis, and 2 patients had to undergo re-operations due to technical errors. One patient acquired a bacterial arthritis 6 months after the operation. The clinical short-term results with HO seem to be comparable to those reported earlier for closing-wedge osteotomy. However, HO is a trying procedure for the patient as well as for the surgeon, due to frequent minor complications requiring frequent follow-ups.