The Offset of the Tibial Shaft from the Tibial Plateau in Chinese People

Background: Long-stem tibial components are available for complex primary and revision total knee arthroplasties. Most of the stems' designs are based on anatomic data from Western populations. We conducted a morphologic study to determine the relationship of the tibial shaft to the tibial plateau in Chinese people. Methods: We included knees from fifty Chinese individuals (twenty-five females and twenty-five males) in this study. On magnetic resonance imaging scans of the tibial plateau and the proximal part of the tibial shaft of each lower limb, the distance between the axis of the tibial shaft and the center of the tibial plateau was measured and was defined as the offset of the tibial shaft from the tibial plateau at three resection levels: the first just distal to the subchondral bone of the medial tibial plateau, the second 5 mm distal to it, and the third 10 mm distal to it. The dimensions of the tibial plateau were measured as well. Results: At the first, second, and third resection levels, the mean tibial shaft offsets (and standard deviations) from the center of the tibial plateau were, respectively, 7.23 +/- 2.44 mm (3.40 +/- 1.94 mm of mediolateral offset and 6.22 +/- 2.05 mm of anteroposterior offset), 6.33 +/- 2.26 mm (3.14 +/- 2.04 mm of mediolateral offset and 5.24 +/- 1.96 mm of anteroposterior offset), and 4.75 +/- 2.07 mm (2.68 +/- 1.91 mm of mediolateral offset and 3.46 +/- 2.03 mm of anteroposterior offset). At each resection level, the mean offset in the male group was significantly larger than that in the female group. Conclusions: There is a large variation in the offset of the tibial shaft from the tibial plateau in Chinese people. The axis of the tibial shaft is located anterolateral to the center of the tibial plateau in this population.