Department of Orthopaedic Surgery, Nippon Medical School, Bunkyo-ku, Tokyo, Japan.
J Knee Surg. 2022 Feb;35(3):323-330. doi: 10.1055/s-0040-1713810. Epub 2020 Jul 13.
Posterior cruciate ligament (PCL) resection during posterior-stabilized total knee arthroplasty (PS-TKA) has been reported to preferentially increase the tibiofemoral joint gap in flexion compared with extension. However, previous assessments of the joint gaps have been performed after bone resection and medial soft tissue release. Thus, these procedural steps may have the potential to influence soft tissue balance. In native knees, soft tissue laxity is generally greater in the lateral compartment than in the medial compartment both with the knee in extension and in flexion. Some surgeons may retain this natural soft tissue balance with less aggressive medial release during TKA. We performed this study to evaluate the impact of the PCL resection on the extension and flexion gaps in the absence of bone resection or medial soft tissue release. Tibiofemoral joint gaps for 41 patients (10 males and 31 females) in full extension and at 90 degrees of flexion both before and after the resections of both the anterior cruciate ligament (ACL) and PCL were assessed using a ligament tensioner device. The statistical analyze was performed using the Mann-Whitney U test. The results showed that medial gap in extension and flexion were 6.7 ± 1.0 and 7.3 ± 0.9 mm, and lateral gap in extension and flexion were 7.6 ± 1.1 and 8.4 ± 1.6 mm, respectively. Thus, physiological tibiofemoral gaps just after knee arthrotomy were trapezoidal and asymmetric shape with the significantly wider gaps in lateral and flexion, compared with the medial and extension, respectively ( < 0.05). However, the increases of the gaps with the ACL and PCL resections were less than 1 mm under the existence of medial soft tissues. As the medial collateral ligament is the primary restraint for the valgus instability, it was also considered to prevent the increase of the flexion gap although the PCL-which is the secondary restraint for the valgus instability-was resected. This finding is critically important for orthopedic surgeons applying PS-TKA implants, particularly for preserving soft tissues to achieve natural knee kinematics postoperatively.
后交叉韧带（PCL）切除术后，在膝关节后稳定型全膝关节置换术（PS-TKA）中，与伸直相比，屈膝时胫骨股骨关节间隙会优先增加。然而，以前对关节间隙的评估是在骨切除和内侧软组织松解后进行的。因此，这些手术步骤可能会影响软组织平衡。在正常膝关节中，与伸直位相比，无论是在伸展位还是在屈曲位，膝关节外侧间隙的软组织松弛度通常大于内侧间隙。一些外科医生在 TKA 期间可能会通过减少内侧更激进的释放来保留这种自然的软组织平衡。我们进行这项研究是为了评估在不进行骨切除或内侧软组织松解的情况下，PCL 切除对伸展和屈曲间隙的影响。使用韧带张力器装置评估了 41 例患者（10 例男性和 31 例女性）在 ACL 和 PCL 切除前后完全伸直和 90 度屈曲时的胫骨股骨关节间隙。统计分析采用 Mann-Whitney U 检验。结果显示，伸展位和屈曲位的内侧间隙分别为 6.7±1.0mm 和 7.3±0.9mm，伸展位和屈曲位的外侧间隙分别为 7.6±1.1mm 和 8.4±1.6mm。因此，膝关节切开术后，生理胫骨股骨间隙呈梯形且不对称，与内侧和伸展相比，外侧和屈曲的间隙明显更宽（ < 0.05）。然而，在存在内侧软组织的情况下，ACL 和 PCL 切除引起的间隙增加小于 1mm。由于外侧副韧带是外翻不稳定的主要限制因素，因此尽管切除了对外翻不稳定起次要限制作用的 PCL，但它也被认为可以防止屈曲间隙的增加。对于应用 PS-TKA 植入物的矫形外科医生来说，这一发现非常重要，特别是为了保留软组织，以实现术后膝关节的自然运动学。
