Department of Orthopaedic Surgery, Sarawak General Hospital, Kuching, Malaysia.
National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
J Orthop Surg (Hong Kong). 2021 Jan-Apr;29(1):2309499021992618. doi: 10.1177/2309499021992618.
There is a common perception among surgeons that Asian tibiae are significantly more varus compared to non-Asians, contributed both by an acute medial tibial proximal angle (MPTA) and diaphyseal bowing. Insight into the normative morphology of the tibia allows generation of knowledge towards disease processes and subsequently planning for corrective surgeries.
Computed tomography (CT) scans of 100 normal adult knees, aged 18 years and above, were analysed using a 3-dimensional (3D) analysis software. All tibiae were first aligned to a standard frame of reference and then rotationally aligned to the tibial centroid axis (TCAx) and the transmalleolar axis (tmAx). MPTA was measured from best-fit planes on the surface of the proximal tibia for each rotational alignment. Diaphyseal bowing was assessed by dividing the shaft to three equal portions and establishing the angle between the proximal and distal segments.
The mean MPTA was 87.0° ± 2.2° (mean ± SD) when rotationally aligned to TCAx and 91.6° ± 2.7° when aligned to tmAx. The mean diaphyseal bowing was 0.1° ± 1.9° varus when rotationally aligned to TCAx and 0.3° ± 1.6° valgus when aligned to tmAx. The mean difference when the MPTA was measured with two different rotational alignments (TCAx and tmAx) was 4.6° ± 2.3°. No statistically significant differences were observed between males and females. Post hoc tests revealed statistically significant difference in MPTA between different ethnic sub-groups.
The morphology of the proximal tibiae in the disease-free Asian knee is inherently varus but not more so than other reported populations. The varus profile is contributed by the MPTA, with negligible diaphyseal bowing. These implications are relevant to surgical planning and prosthesis design.
外科医生普遍认为亚洲人的胫骨比非亚洲人明显更内翻，这归因于胫骨近端内侧角（MPTA）的锐角和骨干弯曲。对胫骨正常形态的了解有助于认识疾病过程，并随后为矫正手术进行规划。
使用三维（3D）分析软件对 100 例 18 岁及以上正常成人膝关节的 CT 扫描进行分析。所有胫骨首先与标准参考框架对齐，然后与胫骨中心轴（TCAx）和踝间轴（tmAx）进行旋转对齐。对于每种旋转对齐方式，MPTA 均从胫骨近端表面的最佳拟合平面进行测量。骨干弯曲通过将骨干分为三个相等部分并确定近端和远端部分之间的角度来评估。
当旋转对齐到 TCAx 时，平均 MPTA 为 87.0°±2.2°（平均值±标准差），当旋转对齐到 tmAx 时为 91.6°±2.7°。当旋转对齐到 TCAx 时，骨干弯曲的平均角度为 0.1°±1.9°内翻，当旋转对齐到 tmAx 时为 0.3°±1.6°外翻。当使用两种不同的旋转对齐方式（TCAx 和 tmAx）测量 MPTA 时，平均差异为 4.6°±2.3°。男性和女性之间未观察到统计学上的显著差异。事后检验显示，不同种族亚组之间的 MPTA 存在统计学上的显著差异。
无疾病亚洲膝关节的胫骨近端形态固有内翻，但并不比其他报道的人群更严重。内翻形态是由 MPTA 引起的，骨干弯曲可忽略不计。这些影响与手术规划和假体设计相关。
