BACKGROUND:Assessment of three-dimensional (3D) femorotibial alignment is essential for successful knee osteoarthritis treatment in the elderly. The complex morphology of the posterior tibial slope (PTS) might have an influence on sagittal and rotational alignment and the positional relationship between the femur and tibia in the anterior–posterior (AP) direction under weight-bearing conditions. OBJECTIVE:This study aimed to clarify the association between the PTS and 3D femorotibial alignment under weight-bearing conditions in healthy Japanese elderly individuals. METHODS:We investigated the 3D femorotibial alignment of 110 lower extremities of 55 healthy individuals (26 women, 29 men, mean age: 70 ± 6 years). Using our previously reported 3D-to-2D image registration technique, we evaluated the 3D hip-knee-ankle angle (3DHKA) in the sagittal plane, rotational alignment, and the distance between the femoral and tibial origins in the AP direction (tibial AP position) as femorotibial alignment parameters under weight-bearing conditions. We assessed the medial and lateral PTS and their angular difference (PTS difference) as PTS parameters. Stepwise multiple linear regression analysis was performed using PTS parameters and other possible confounders (age, sex, height, and weight) as the independent variables and femorotibial alignment parameters as the dependent variable. RESULTS:Weight (𝛽 = 0.393, p < 0.001) and lateral PTS (𝛽 = 0.298, p < 0.001) were the predictors associated with 3DHKA in the sagittal plane. Lateral PTS (𝛽 = 0.304, p = 0.001) was the only predictor associated with the tibial AP position. Sex (𝛽 = −0.282, p = 0.002) and PTS difference (𝛽 = −0.231, p = 0.012) were associated with rotational alignment. CONCLUSIONS:We found that a steeper lateral PTS resulted in a more flexed knee and anterior tibia. The PTS difference was positively correlated with tibial external rotation. Our data could be used as the standard reference for realignment surgery to ensure PTS is appropriately maintained.

中文翻译：

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日本健康老年人负重条件下胫骨后斜率对三维股胫排列的影响

背景：评估 3D (3D) 股胫对齐对于老年人膝关节骨关节炎的成功治疗至关重要。胫骨后斜率 (PTS) 的复杂形态可能对负重条件下的矢状位和旋转对齐以及股骨和胫骨在前后 (AP) 方向上的位置关系产生影响。目的：本研究旨在阐明健康日本老年人在负重条件下 PTS 与 3D 股胫对齐之间的关联。方法：我们调查了 55 名健康人（26 名女性，29 名男性，平均年龄：70 ± 6 岁）的 110 条下肢的 3D 股胫对齐情况。使用我们之前报道的 3D 到 2D 图像配准技术，我们评估了矢状面中的 3D 髋-膝-踝角 (3DHKA)、旋转对齐以及 AP 方向上股骨和胫骨起点之间的距离（胫骨 AP 位置）作为负重条件下的股胫对齐参数。我们评估了内侧和外侧 PTS 及其角度差异（PTS 差异）作为 PTS 参数。使用 PTS 参数和其他可能的混杂因素（年龄、性别、身高和体重）作为自变量和股胫对齐参数作为因变量进行逐步多元线性回归分析。结果：体重（𝛽 = 0.393，p < 0.001）和横向 PTS（𝛽 = 0.298，p < 0.001）是与矢状面 3DHKA 相关的预测因子。外侧 PTS（𝛽 = 0.304，p = 0.001）是与胫骨 AP 位置相关的唯一预测因子​​。性别（𝛽 = -0.282，p = 0.002）和 PTS 差异（𝛽 = -0.231，p = 0.012）与旋转对齐相关。结论：我们发现更陡峭的外侧 PTS 会导致膝关节和胫骨前侧更加弯曲。PTS 差异与胫骨外旋呈正相关。我们的数据可用作重新调整手术的标准参考，以确保 PTS 得到适当维持。