The offset of the tibia plateau of osteoarthritis patients: a single-center study.

Component position and good fixation are important factors determining the success of a primary or revision total knee arthroplasty (TKA). The aim of this study was to measure the anatomic features of the tibial plateau and to assess variations in the offset of the tibial shaft from the tibial plateau in osteoarthritis (OA) patients. Computed tomography (CT) scan results were obtained from 126 knees of 121 OA patients (72 female, 49 male) with an average age of 65 ± 7 years. The anatomic features of the tibial plateau were measured and analyzed using three-dimensional reconstruction information derived from a 64-slice spiral CT. The results showed significant variations in proximal tibial anatomy among the subjects. The mean offset was 7.61 ± 3.04 mm at the resection just distal to the subchondral bone. The mean anteroposterior and mediolateral dimensions of the tibial plateau were 53.05 ± 4.82 mm and 70.42 ± 8.33 mm, respectively, at the resection just distal to the subchondral bone. The tibial shaft axis was located anterolateral to the center of the tibial plateau in 62% of knees, while in 36% of these knees, it was located anterior medial to the center of the tibial plateau at the resection just distal to the subchondral bone. Our study shows that anatomic variations should be fully evaluated before performing TKA. A wide range of implant sizes is thus necessary for optimum replacement.