Early clinical results were evaluated for 22 adult patients who had undergo
ne an open wedge tibial osteotomy by hemicallotasis (HCO) due to medial com
partment osteoarthritis. The mean age at the time of the index operation wa
s 56 (range 33-66) years. The mean duration of follow up was 16 (range 9-23
) months. The median hip-knee-ankle angle (HKA) was 169 (range 162-186) deg
preoperatively and 182 (range 175-191) deg at follow up. We did not observ
e any early collapse of the new bone wedge. The median time to fixation was
79 (range 63-125) days. Complications included two pintract infections, an
d two hematomas were revised. Two patients felt pain during the phase of di
straction, but the procedure could be continued after a short break. We eva
luated the clinical results on the HSS, Lysholm, and Tegner activity scores
. At the latest follow up examination, all of the scores had improved. Our
findings demonstrate that HCO requires an exact correction, is a simple tec
hnique, and appears to reduce the chance of nerve and vascular damage.