Faschingbauer Martin, Hacker S, Seitz A, Dürselen L, Boettner F, Reichel H
Department of Orthopedic Surgery, RKU, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany.
Institute of Orthopaedic Research and Biomechanics, University of Ulm, Helmholtzstraße 14, 89081, Ulm, Germany.
Knee Surg Sports Traumatol Arthrosc. 2021 Feb;29(2):641-651. doi: 10.1007/s00167-020-05996-5. Epub 2020 Apr 18.
Different alignment types for a better outcome after TKA were described. However, it is not clear how kinematic alignment influences knee joint kinematic. The purpose of this study was to analyze whether adapted tibial cuts in constitutional varus knees affect knee joint kinematics regarding femoral roll-back, varus/valgus angle, and femorotibial rotation.
Seven cadaveric knees with constitutional varus alignment were examined in the native state and after implantation of a cruciate retaining (CR)-TKA with 0°, 3° and 6° tibia cuts using an established knee joint simulator. The effects of varus alignment on femorotibial rollback and rotation was determined. In addition, the native knee joint and different tibial cuts in CR-TKA were compared with Student's t test.
Total knee replacement with a 3° and 6° varus tibia cut had the greatest varus deviation to the native knee (mean 1.6° ± 0.09°, respectively); while, knees with a 0° (mean 0.2° ± 0.01°) tibia cut were most similar to the constitutional varus knee joint. The femoral roll-back in the medial compartment was increased in the native knee (5.7-12.5 mm). A 6° varus cut had a restricted translation in the medial compartment (2-3.2 mm). In the lateral compartment, the extensive translation was observed with a 0° varus cut, followed by 3° and 6° and the native knee. All cuts showed significantly different mean values. Only the cuts at 3° and at 6° in the medial compartment and the cuts at 0° and at 3° in the lateral compartment did not differ significantly. In respect to tibiofemoral rotation, 0° and 3° varus cuts across all loads had the least difference to the native knee (3.4°), with a 0° varus cut showing a higher absolute internal rotation of the tibia than the native knee. Changes in knee kinematics of the tibiofemoral rotation showed significantly different mean values.
The potentially improved outcome parameters in TKA with adapted tibia cuts in constitutional varus knees cannot be completely explained by the changes to knee kinematics. Mechanical alignment seems to result in more balanced load distribution and kinematics more closely resembling the native knee. From a kinematic point of view, it is not recommended to place the tibia in more than 3° of varus.
Biomechanical study.
描述了全膝关节置换术（TKA）后不同的对线类型以获得更好的结果。然而，尚不清楚运动学对线如何影响膝关节运动学。本研究的目的是分析在先天性内翻膝关节中，适配的胫骨截骨是否会影响膝关节在股骨后滚、内翻/外翻角度和股胫旋转方面的运动学。
使用成熟的膝关节模拟器，对7个具有先天性内翻对线的尸体膝关节在自然状态下以及植入保留交叉韧带（CR）-TKA且胫骨截骨角度为0°、3°和6°后进行检查。确定内翻对线对股胫后滚和旋转的影响。此外，使用学生t检验比较自然膝关节和CR-TKA中不同的胫骨截骨情况。
胫骨截骨角度为3°和6°的全膝关节置换术与自然膝关节相比，内翻偏差最大（分别平均为1.6°±0.09°）；而胫骨截骨角度为0°（平均0.2°±0.01°）的膝关节与先天性内翻膝关节最为相似。自然膝关节内侧间室的股骨后滚增加（5.7 - 12.5毫米）。6°内翻截骨使内侧间室的平移受限（2 - 3.2毫米）。在外侧间室，0°内翻截骨观察到广泛的平移，其次是3°和6°截骨以及自然膝关节。所有截骨的平均值均有显著差异。仅内侧间室3°和6°截骨以及外侧间室0°和3°截骨之间差异不显著。关于股胫旋转，所有负荷下0°和3°内翻截骨与自然膝关节的差异最小（3.4°），0°内翻截骨时胫骨的绝对内旋高于自然膝关节。股胫旋转的膝关节运动学变化显示平均值有显著差异。
在先天性内翻膝关节中，适配胫骨截骨的TKA中潜在改善的结果参数不能完全通过膝关节运动学的变化来解释。机械对线似乎导致更平衡的负荷分布，并且运动学更接近自然膝关节。从运动学角度来看，不建议将胫骨置于超过3°的内翻位。
生物力学研究。
