Hutt Jonathan, Massé Vincent, Lavigne Martin, Vendittoli Pascal-André
Department of Surgery, Hôpital Maisonneuve-Rosemont, Université de Montréal, 5415 Boulevard de l'Assomption, Montréal, QC, H1T 2M, Canada.
Int Orthop. 2016 Jan;40(1):29-34. doi: 10.1007/s00264-015-2733-7. Epub 2015 Mar 21.
Kinematic total knee arthroplasty (TKA) is an emerging technique, but concerns remain around the effect of implanting the prosthesis in more anatomic orientations. Native knees show variation in joint line orientation relative to the tibial mechanical axis but the joint line remains parallel to the floor when standing. This study was undertaken to evaluate joint line obliquity relative to the floor when weight-bearing after kinematic TKA to see if a similar effect occurs.
Preoperative and postoperative measurements were taken for 55 consecutive kinematically aligned TKAs, including the joint line orientation angle (JLOA), formed between the joint line and a line parallel to the floor.
The mean medial proximal tibial angle (MPTA) was 3.4° varus pre-operatively (1.7° valgus to 7.9° varus, SD 2.0), and 3.0° varus postoperatively (5.5° valgus to 6.5° varus, SD 2.1). The mean postoperative JLOA was 1.0° varus with a smaller range than the MPTA (2.6° valgus to 6° varus, SD 1.9). The difference between these two measurements was significant (mean 2°, SD 2.5, p < 0.001).
Relative to the mechanical axis, 33 tibial components would be considered at risk outliers, being orientated at more than 3° in varus or valgus. However, only six components were outside this range relative to the vertical, all in varus (mean 4.2°). This latter measurement may better represent how the prosthesis is functionally loaded and is similar to mechanically aligned TKAs with good survivorship. This may help explain why kinematic alignment does not lead to higher earlier failure rates that may result if similar orientations were seen with mechanically aligned TKA.
运动学全膝关节置换术（TKA）是一种新兴技术，但对于将假体植入更符合解剖学方向的效果仍存在担忧。正常膝关节相对于胫骨机械轴的关节线方向存在变化，但站立时关节线仍与地面平行。本研究旨在评估运动学TKA术后负重时关节线相对于地面的倾斜度，以观察是否会出现类似效果。
对55例连续的运动学对齐TKA进行术前和术后测量，包括关节线方向角（JLOA），即关节线与平行于地面的线之间形成的角度。
术前胫骨近端内侧平均角（MPTA）为3.4°内翻（外翻1.7°至内翻7.9°，标准差2.0），术后为3.0°内翻（外翻5.5°至内翻6.5°，标准差2.1）。术后平均JLOA为1.0°内翻，范围小于MPTA（外翻2.6°至内翻6°，标准差1.9）。这两个测量值之间的差异具有统计学意义（平均2°，标准差2.5，p < 0.001）。
相对于机械轴，33个胫骨组件将被视为有风险的异常值，其在内外翻方向上的定位超过3°。然而，相对于垂直方向，只有6个组件超出此范围，均为内翻（平均4.2°）。后一种测量可能更好地反映假体的功能加载方式，并且与具有良好生存率的机械对齐TKA相似。这可能有助于解释为什么运动学对齐不会导致更高的早期失败率，而如果机械对齐TKA出现类似方向则可能导致更高的早期失败率。
