ANATOMIC CHANCES AROUND THE KNEE AFTER HIGH TIBIAL OSTEOTOMY

Abstract

Introduction: High tibial osteotomy is an established procedure for the mid-term treatment of unicompartmental osteoarthritis of the knee. Nevertheless, it produces anatomic alterations of the proximal part of tibia, which might affect the later performance of TKR. These anatomic changes are basically patella infera and medialization of the tibial medullary canal with respect to the tibial plateau (tibial condilar offset).

Material and Method: The purpose of the present retrospective study is the evaluation of the above mentioned anatomic changes, caused by high tibial valgus osteotomy (Mittelmeier’s technique). For this purpose we studied the X-rays of 44 kness (pre-op, p-op and 1 year p-op) that had under gone the above procedure.

Results: We didn’t find any statistically significant difference of the postoperative position of the patella with respect to the preoperative one, whereas there was definite medialization of the tibial anatomic axis with respect to the preoperative situation. The latter change was directly correlated with the degree of valgus correction. The mean change of the tibial anatomic axis (as estimated by the value of the tibial condylar offset ratio) was 15%.

Conclusions: Although Mittelmeier’s high tibial valgus osteotomy does not cause any significant alteration of the position of the patella, it does alter the relationship of the tibial medullary canal with respect to the tibial plateau in direct correlation with the degree of valgus correction. Thus, the performance of TKR after proximal tibial osteotomy necessitates a thorough preoperative plan and the selection of the appropriate implant.