The Influence of Posterior Cruciate Ligament Resection on Tibiofemoral Joint Gap in Varus Osteoarthritic Knees

Abstract

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 (p < 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.

The Disproportionate Increase of the Intraoperative Flexion and Extension Gap Space after Posterior Cruciate Ligament Resection in Total Knee Arthroplasty

“…Other studies have indicated that PCL resection does not affect the flexion gap in PS TKA or cause a flexion–extension gap mismatch [ 17 , 18 , 19 ]; Burkhart et al and Oshima et al reported that MCL release causes flexion gap changes but not PCL resection under a similar distraction force to that used in the current study [ 20 , 21 ]. Unfortunately, the study by Burkhart et al was a cadaveric study that was different from the soft tissue in vivo, which may explain the difference between the results [ 20 ].…”

“…In their in vivo study, Oshima et al proposed results inconsistent with our findings. Differing from this study, they performed a pretest before bone resection and measured the gaps while the patella was laterally displaced, rather than in a neutral position, which may also have affected their results [ 21 ]. In addition, the femoral insertion of the PCL had two bundles [ 29 ].…”

“…Many studies have stated that PCL resection has no effect on the extension gap but increases the flexion gap by 1.1-1.9 mm [15,16]. Other studies have indicated that PCL resection does not affect the flexion gap in PS TKA or cause a flexion-extension gap mismatch [17][18][19], and that the flexion gap is affected only when PCL resection is combined with medial collateral ligament (MCL) release [20,21]. This discrepancy in the literature on the effect of PCL resection on the extension-flexion gaps may be related to the measurement methods, the recruited research participants (cadaveric or clinical study), or whether PCL resection was combined with MCL release.…”

Effects of the posterior cruciate ligament and tibia insert thickness on tibiofemoral joint pressure in total knee arthroplasty: a cadaveric study

“…The posterior cruciate ligament (PCL) plays a very important role in knee kinematics, functional recovery, and prosthesis survival after PCL-retaining total knee arthroplasty (CR-TKA). An intact or well-preserved PCL in TKA can effectively reproduce physiological kinematics such as femur rollback (1), lateral pivot at early flexion, and medial pivot at mild flexion (2). Furthermore, a wellpreserved PCL can help restore daily movement, such as walking and climbing stairs, after TKA (3).…”

“…Furthermore, a wellpreserved PCL can help restore daily movement, such as walking and climbing stairs, after TKA (3). However, there is no consensus regarding the effects of the PCL on softtissue balance in the knee (2,(4)(5)(6)(7)(8)(9)(10)(11). While some studies have reported that PCL release selectively increases the flexion gap more than the extension gap and accordingly causes a mismatch of the extension and flexion gaps, other studies have not confirmed these results (2,10).…”