譯者：張軼超
目的：檢測術中脛股關節間隙和韌帶平衡及影響它們的因素對于全膝置換術（TKA）后膝關節屈曲活動的影響。通過影像學方法對采用后交叉韌帶保留型假體TKA（CR-TKA）術后的這些因素進行評估。股骨后髁的偏心距和脛骨后傾角都曾被作為影響CR-TKA術后功能的術中重要因素而被報道過。而在評估股骨后髁偏心距和脛骨后傾角時對于關節間隙和軟組織平衡還不曾研究。
方法：使用一個偏離式張力測量器來測量脛股間隙和內外側韌帶平衡。對98個因內翻膝行CR-TKA的膝關節進行測量，測量屈曲0°、45°、90°和135°時的脛股關節間隙，測量從0-90°和0-135°過程中膝關節間隙的變化。
結果：在0-90°屈曲過程中，對脛股關節間隙變化影響最大的是股骨后髁偏心距差值（術前股骨后髁偏心距減去術后偏心距的值）。0-135°時的脛股關節間隙的變化明顯與脛骨后傾角和135°時內外側韌帶平衡有關。術后膝關節屈曲度與術前膝關節屈曲度、γ角和術后脛骨后傾角有關。多元回歸分析表明對于術后的膝關節屈曲度，術前膝關節屈曲度、γ角、術后脛骨后傾角和90°時內外側軟組織平衡情況是顯著影響因素。屈曲角度的變化與術前屈曲角度、術后脛骨后傾角和90°時內外側軟組織平衡情況存在明顯的相關性。
結論：術后膝關節屈曲度受多種因素的影響，尤其是對于CR-TKA。術中我們不光要重視脛骨后傾角還要關注屈曲位時內外側軟組織平衡。通過CR-TKA手術應該達到術后關節穩定，具有良好的關節活動度及改善患者的日常生活能力。
圖1：圖示為用于測量CR-TKA手術的張力器。由三部分組成：上部的蹺蹺板樣平板（A），下面的帶龍骨的平臺基板（B)和位于關節外的主件（C）。上下板通過穿過髕內側切口進入關節腔的一個偏心的臂（D）連接到主件上，從而不受髕股關節的影響。注意股骨組件在測量時一定要頂住股骨髁。
圖2：圖示為股骨假體和脛股假體成角：α：正側位x片上顯示的股骨假體和股骨干遠端軸線間的夾角；β：正側位x片上顯示的脛骨假體和脛骨干近端軸線間的夾角；在一張準確的側位片上測量的股骨假體前緣線與股骨遠端軸線間的夾角減4°（由于NRG假體股骨前緣線與假體軸間存在4°夾角，所以減去4°所得角度才是假體軸線和股骨軸線間的真正夾角）；PTS：在一張準確的側位片上測量的脛骨假體與腓骨干間的夾角加上3°（由于脛骨干和非骨干間存在3°夾角，所以加上3°后就是脛骨假體軸線和脛骨干間的真正夾角）。
Significant effect of the posterior tibial slope and medial/lateral ligament balance on knee flexion in total knee arthroplasty
Purpose: The intra-operative femorotibial joint gap and ligament balance, the predictors affecting these gaps and their balances, as well as the postoperative knee flexion, were examined. These factors were assessed radiographically after a posterior cruciate-retaining total knee arthroplasty (TKA). The posterior condylar offset and posterior tibial slope have been reported as the most important intra-operative factors affecting cruciate-retaining-type TKAs. The joint gap and balance have not been investigated in assessments of the posterior condylar offset and the posterior tibial slope.
Methods: The femorotibial gap and medial/lateral ligament balance were measured with an offset-type tensor. The femorotibial gaps were measured at 0°, 45°, 90° and 135° of knee flexion, and various gap changes were calculated at 0°-90° and 0°-135°. Cruciate-retaining-type arthroplasties were performed in 98 knees with varus osteoarthritis.
Results: The 0°-90° femorotibial gapchange was strongly affected by the posterior condylar offset value (postoperative posterior condylar offset subtracted by the preoperative posterior condylar offset). The 0°-135° femorotibial gap change was significantly correlated with the posterior tibial slope and the 135° medial/lateral ligament balance. The postoperative flexion angle was positively correlated with the preoperative flexion angle, γ angle and the posterior tibial slope. Multiple-regression analysis demonstrated that the preoperative flexion angle, γ angle, posterior tibial slope and 90° medial/lateral ligament balance were significant independent factors for the postoperative knee flexion angle. The flexion angle change (postoperative flexion angle subtracted by the preoperative flexion angle) was also strongly correlated with the preoperative flexion angle, posterior tibial slope and 90° medial/lateral ligament balance.
Conclusion: The postoperative flexion angle is affected by multiple factors, especially in cruciate-retaining-type TKAs. However, it is important to pay attention not only to the posterior tibial slope, but also to the flexion medial/lateral ligament balance during surgery. A cruciate-retaining-type TKA has the potential to achieve both stability and a wide range of motion and to improve the patients' activities of daily living.
文獻出處：Fujimoto E, Sasashige Y, Masuda Y, Hisatome T, Eguchi A, Masuda T, Sawa M, Nagata Y. Significant effect of the posterior tibial slope and medial/lateral ligament balance on knee flexion in total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2013 Dec;21(12):2704-12. doi: 10.1007/s00167-012-2059-6. Epub 2012 May 30. PMID: 22644073.
