The Position of Proximal Reference Point of Tibia Plateau for Correct Tibial Osteotomy in Total Knee Replacement: Prospective Randomized and 6 Years Follow-up Study

PURPOSE: When there is a varus deformity in proximal tibia, the extension of a tibial shaft axis tends to pass through the lateral intercondylar eminence. A prospective randomized study was conducted to find out whether the lateral eminence of tibia could serve as a reference point for proximal tibial osteotomy during total knee arthroplasty and results from 6-years follow up period were reported. MATERIALS AND METHODS: Forty-six patients (50 knees) who received total knee replacement arthroplasty from April to December 2004, were randomly divided into two groups. For a proximal tibial osteotomy, the proximal tibial reference point was located at the center of intercondylar eminence for group I and at the lateral eminence for group II and subsequently, the results were evaluated. Radiologic indices were the angles between the axis of the prosthesis and the mechanical/shaft axes of tibia and angle of the prosthesis in sagittal plane. Clinical indices were pain and function score of American knee society, functional score of Hospital for Special Surgery and range of knee joint motion. RESULTS: The angles between the axis of the prostheses and the mechanical/shaft axes of tibia were varus 1.64°/2.12° in group I and valgus 0.57°/0.38° in group II (p=0.589/p=0.558). There were 6 cases of outliers (27.2%) in group 1 and 3 cases (15.0%) in group 2. There was a significant difference in the pain score between group I (82.9) and II (91.4) (p=0.032), respectively. CONCLUSIONS: By moving the reference point of proximal tibial osteotomy laterally, lower incidence of outlier and residual varus deformity could be achieved.