Introduction: The results of high tibial osteotomy tend to deteriorate over time. Consequently, a certain percentage of these patients will ultimately undergo TKR for the symptomatic treatment of the osteoarthritis of their knees. High tibial osteotomy, on the other hand, produces anatomic alterations around ipsilateral knee joint, that might bring about technical difficulties during the performance of TKR procedure. One of these difficulties has to do with the alteration of relationship between tibial anatomic axis and ipsilateral plateau.
Aim: The radiographic evaluation of the alteration of the relative position of the tibial medullary canal with respect to the ipsilateral plateau, after high tibial, closed-wedge osteotomy, with stable fixation.
Material – Method: For this aim, we studied 49 knees (in 45 patients), that had undergone high tibial valgus osteotomy, between 1990 and 1997, in our Department. The relative change of tibial anatomic axis was determined by calculating the index of “tibial condylar offset” in the AP view of each knee during three follow up examinations done at the direct post operative period, three months post operatively and at least one year post operatively.
Results: There was a definite tendency of medialization of the tibial anatomic axis post operatively (and, consequently, of the tibial medullary canal) with respect to the centre of the ipsilateral plateau. This was in direct proportion to the degree of valgus correction. The mean percentage of post operative alteration of “tibial condylar offset”, in comparison to its preoperative value, was 19%.
Conclusions: The insertion of a stemmed tibial implant, in a knee that has previously undergone high tibial osteotomy, through the centre of the tibial plateau runs a certain risk of abutment on the lateral cortex, due to the medialization of the tibial medullary canal with respect to the centre of tibial plateau. The above observations show the importance of a thorough pre-op plan of every TKR procedure that has been preceded by high tibial osteotomy
