van Houten Albert H, Heesterbeek Petra J C, Hannink Gerjon, Labey Luc, Wymenga Ate B
Department of Orthopaedic Surgery, Sint Maartenskliniek, Nijmegen, Hengstdal 3, 6522 JV, Nijmegen, The Netherlands.
OCON Centre for Orthopaedic Surgery, Hengelo, The Netherlands.
Knee Surg Sports Traumatol Arthrosc. 2022 Apr;30(4):1273-1281. doi: 10.1007/s00167-021-06564-1. Epub 2021 Apr 15.
The present study assessed the effect of insert articular surface geometry (anatomical versus conventional insert design) on anteroposterior (AP) translation and varus-valgus (VV) laxity in balanced posterior cruciate ligament (PCL) retaining total knee arthroplasty (TKA). Secondly, we evaluated if the AP translation and VV laxity in the reconstructed knee resembled the stability of the native knee.
Nine fresh-frozen full-leg cadaver specimens were used in this study. After testing the native knee, anatomical components of a PCL-retaining implant were implanted. The knee joints were subjected to anteriorly and posteriorly directed forces (at 20° and 90° flexion) and varus-valgus stresses (at 20°, 45° and 90° flexion) in both non-weightbearing and weightbearing situations in a knee kinematics simulator. Measurements were performed in the native knee, TKA with anatomical insert geometry (3° built-in varus, medial concave, lateral convex), and TKA with symmetrical insert geometry.
In weightbearing conditions, anterior translations ranged between 2.6 and 3.9 mm at 20° flexion and were < 1 mm at 90° flexion. Posterior translation at 20° flexion was 2.7 mm for the native knee versus 4.0 mm (p = 0.047) and 7.0 mm (p = 0.02) for the symmetrical insert and the anatomical insert, respectively. Posterior translation at 90° flexion was < 1.1 mm and not significantly different between the native knee and insert types. In non-weightbearing conditions, the anterior translation at 20° flexion was 5.9 mm for the symmetrical and 4.6 mm for the anatomical insert (n.s.), compared with 3.0 mm for the native knee (p = 0.02). The anterior translation at 90° flexion was significantly higher for the reconstructed knees (anatomical insert 7.0 mm; symmetrical insert 9.2 mm), compared with 1.6 mm for the native knee (both p = 0.02). Varus-valgus laxity at different flexion angles was independent of insert geometry. A valgus force in weightbearing conditions led to significantly more medial laxity (1°-3° opening) in the native knee at 45° and 90° flexion compared with the reconstructed knee for all flexion angles.
Insert geometry seems to have a limited effect with respect to AP translation and VV laxity, in the well-balanced PCL-retaining TKA with an anatomical femoral component. Secondly, AP translation and VV laxity in the reconstructed knee approximated the laxity of the native knee.
本研究评估了在保留后交叉韧带（PCL）的全膝关节置换术（TKA）中，植入物关节面几何形状（解剖型与传统植入物设计）对前后（AP）平移和内外翻（VV）松弛度的影响。其次，我们评估了重建膝关节的AP平移和VV松弛度是否类似于正常膝关节的稳定性。
本研究使用了9个新鲜冷冻的全腿尸体标本。在测试正常膝关节后，植入保留PCL的植入物的解剖组件。在膝关节运动模拟器中，对膝关节在非负重和负重情况下施加向前和向后的力（在20°和90°屈曲时）以及内外翻应力（在20°、45°和90°屈曲时）。在正常膝关节、具有解剖型植入物几何形状（3°内置内翻、内侧凹陷、外侧凸起）的TKA以及具有对称植入物几何形状的TKA中进行测量。
在负重条件下，20°屈曲时的前向平移范围为2.6至3.9毫米，90°屈曲时小于1毫米。正常膝关节在20°屈曲时的后向平移为2.7毫米，而对称植入物和解剖型植入物分别为4.0毫米（p = 0.047）和7.0毫米（p = 0.02）。90°屈曲时的后向平移小于1.1毫米，正常膝关节与植入物类型之间无显著差异。在非负重条件下，对称植入物在20°屈曲时的前向平移为5.9毫米，解剖型植入物为4.6毫米（无统计学差异），而正常膝关节为3.0毫米（p = 0.02）。与正常膝关节的1.6毫米相比，重建膝关节（解剖型植入物7.0毫米；对称植入物9.2毫米）在90°屈曲时的前向平移显著更高（p均 = 0.02）。不同屈曲角度下的内外翻松弛度与植入物几何形状无关。在负重条件下，与重建膝关节在所有屈曲角度相比，正常膝关节在45°和90°屈曲时，外翻力导致内侧松弛度显著更大（开口1° - 3°）。
在具有解剖型股骨组件且平衡良好的保留PCL的TKA中似乎对AP平移和VV松弛度影响有限。其次，重建膝关节的AP平移和VV松弛度接近正常膝关节的松弛度。
