Department of Orthopedic Surgery (Y.O., A.T., Y.S., H.S., and T.Y.) and Second Department of Anatomy (M.F.), Sapporo Medical University School of Medicine, Sapporo, Japan.
Biomechanics Laboratory, Faculty of System Design, Tokyo Metropolitan University, Tokyo, Japan.
J Bone Joint Surg Am. 2018 Sep 5;100(17):e114. doi: 10.2106/JBJS.18.00099.
Bicruciate-retaining total knee arthroplasty (BCR-TKA) is attracting attention because of the functional and satisfaction outcomes associated with keeping the anterior cruciate ligament (ACL) intact. However, knowledge of the functional importance of the ACL after BCR-TKA is limited. We performed a biomechanical investigation of ACL function following BCR-TKA compared with that in the intact knee.
We investigated 8 fresh-frozen human cadaveric knees using a 6-degrees-of-freedom robotic system that allowed natural joint motion. Three knee states-intact knee, BCR-TKA, and BCR-TKA with ACL transection (BCR-TKA + ACLT)-were evaluated. For each knee state, the kinematics during passive flexion-extension motion (from 0° to 120°) and anteroposterior laxity at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 100-N load were investigated. The recorded knee motions of the intact and BCR-TKA knees during each test were repeated after ACLT to calculate the ACL in situ force.
The femur in the BCR-TKA group translated posteriorly and rotated externally during passive knee flexion and was in an anterior position compared with the femur in the intact-knee state. After ACLT, the femur translated posteriorly, compared with the BCR-TKA group, at 0° and 10° (p < 0.05). The anteroposterior laxities of the BCR-TKA and intact knees were comparable at all flexion angles and increased 2-fold or more after ACLT (p < 0.01). The ACL in situ force in the BCR-TKA knees was 2-fold to 6-fold higher than that in the intact knees at 0°, 15°, 90°, and 120° during a passive path (p < 0.05) and equivalent to that in the intact knees under anterior loading.
The preserved ACL in the BCR-TKA knees was functional, like the ACL in the intact knees, under anterior tibial loading and contributed to good anteroposterior stability. However, the kinematics and ACL in situ force differed between the intact and BCR-TKA knees during passive flexion-extension movements.
Surgeons may not be able to prevent overtensioning of the ACL during a standardized BCR-TKA procedure, which could potentially limit range of motion.
由于保留前交叉韧带（ACL）完整的功能和满意度结果，双髁保留全膝关节置换术（BCR-TKA）受到关注。然而，对于 BCR-TKA 后 ACL 的功能重要性知之甚少。我们使用允许自然关节运动的六自由度机器人系统对 BCR-TKA 后 ACL 的功能进行了生物力学研究，并与完整膝关节进行了比较。
我们使用六自由度机器人系统对 8 个新鲜冷冻的人体尸体膝关节进行了研究，该系统允许进行自然关节运动。评估了三种膝关节状态：完整膝关节、BCR-TKA 和 BCR-TKA 合并 ACL 切断（BCR-TKA+ACLT）。对于每个膝关节状态，在 0°至 120°的被动屈伸运动过程中以及在 0°、15°、30°、60°和 90°的屈曲时对 100-N 负载的前后松弛度进行了研究。在每次测试中，记录完整和 BCR-TKA 膝关节的运动，然后在 ACLT 后重复这些运动，以计算 ACL 的原位力。
与完整膝关节状态相比，BCR-TKA 组的股骨在被动膝关节屈伸过程中向后平移并向外旋转，处于前位。ACLT 后，股骨在 0°和 10°时比 BCR-TKA 组向后平移（p<0.05）。BCR-TKA 和完整膝关节的前后松弛度在所有屈曲角度均相当，在 ACLT 后增加 2 倍或更多（p<0.01）。在被动路径下，BCR-TKA 膝关节的 ACL 原位力在 0°、15°、90°和 120°时是完整膝关节的 2 倍至 6 倍（p<0.05），在胫骨前负荷下与完整膝关节相当。
在胫骨前负荷下，BCR-TKA 膝关节的保留 ACL 像完整膝关节的 ACL 一样具有功能性，并有助于良好的前后稳定性。然而，在被动屈伸运动中，完整膝关节和 BCR-TKA 膝关节的运动学和 ACL 原位力存在差异。
外科医生可能无法在标准化的 BCR-TKA 手术中防止 ACL 过度紧张，这可能会限制运动范围。
