More passive internal tibial rotation with posterior cruciate ligament retention than with excision in a medial pivot TKA implanted with unrestricted caliper verified kinematic alignment

Abstract

Purpose Excision of the posterior cruciate ligament (PCL) is recommended when implanting a medial pivot (MP) total knee arthroplasty (TKA) to reduce the risk of limiting flexion by over-tensioning the flexion space. The present study determined whether PCL retention (1) limits internal tibial rotation and (2) causes anterior lift-off of the insert in 90° flexion after implantation of an MP design with unrestricted caliper verified kinematic alignment (KA). Methods Four surgeons implanted an MP TKA design with medial ball-in-socket and lateral flat tibial insert in ten fresh-frozen cadaveric knees. Before and after PCL excision, trial inserts with medial goniometric markings measured the angular I–E tibial orientation relative to the trial femoral component's medial condyle in extension and at 90° flexion, and the surgeon recorded the occurrence of anterior lift-off of the insert at 90° flexion. Results PCL retention resulted in greater internal tibial rotation than PCL excision, with mean values of 15° vs 7° degrees from maximum extension to 90° flexion, respectively (p < 0.0007). At 90° flexion, no TKAs with PCL retention and one TKA with PCL excision had anterior lift-off of the insert (N.S.). Conclusions This preliminary study of ten cadaveric knees showed that PCL retention restored more passive internal tibial rotation than PCL excision with a negligible risk of anterior lift-off. However, in vivo analysis from multiple authors with a larger sample size is required to recommend PCL retention with an MP TKA design implanted with unrestricted caliper verified KA.

No Significant Differences in Clinical and Radiographic Outcomes between PCL Retained or Sacrificed Kinematic Aligned Medial Pivot Total Knee Arthroplasty in Varus Knee

“…To check the extension gap appropriateness, place the spacer block in full extension. A minimal varus/valgus laxity should be observed, and in the case of lateral or medial openings greater than 2 mm, a tibial recut is mandatory [ 35 , 36 ]. Then, position the trial component and repeat the varus/valgus stress evaluation in full extension and at 30° of knee flexion.…”

“…Until August 2019, the PCL was always sacrificed in all treated patients. Starting in September 2019, considering the theoretical advantages of PCL preservation based on recent scientific evidence [ 34 , 35 , 36 , 37 ], such as increased anteroposterior stability and improved proprioception, we decided to retain the PCL in every case. In patients with tight flexion, space was evident after bone resections and gap balancing based on tibial recut was performed ( Figure 1 ).…”

A TKA Insert with A Lateral Flat Articular Surface Maximizes External and Internal Tibial Orientations without Anterior Lift-Off Relative to Low- and Ultracongruent Surfaces

“…Randomized trials and kinematic studies report clinical and biomechanical improvements using the medial-pivot design relative to low-congruent posterior cruciate ligament (PCL) retaining (CR), posterior-substituting (PS), and ultracongruent (UC) designs [ 5 , 6 , 7 , 8 ]. However, the consequences of adding different levels of congruency to the lateral insert are less clear, especially when there is excessive tension in the PCL that can overconstrain the flexion space which is detected by anterior lift-off of the trial insert from the tibial baseplate at 90° flexion [ 9 , 10 ].…”

“…In the native knee, tibial rotation occurs about a medial pivot because of the medial compartment’s ball-in-socket-like congruency supplemented by the coronary ligament’s stabilizing effect of the medial meniscus and the lateral convex tibia with the mobile lateral meniscus that functions as a flat articular surface [ 3 , 11 ]. In addition, in the native knee and TKA, the PCL tension drives internal tibial rotation [ 9 , 11 ]. Therefore, a TKA with native knee congruency and an intact PCL could restore the external tibial orientation (i.e., screw-home) in extension and internal tibial orientation in 90° flexion, thereby promoting patellofemoral tracking.…”

Application of CT‐MRI Fusion‐Based Three‐Dimensional Reconstruction Technique in the Anatomic Study of Posterior Cruciate Ligament

“…The posterior cruciate ligament (PCL) originates from the lateral wall of the femoral medial condyle and inserts itself into the posterior half of the tibial PCL slope and the posterior angle of the lateral meniscus, which, in unison, maintains the posterior and rotational stability of the knee joint 1 , 2 , 3 , 4 . Clinically, the primary complaint after acute PCL injury is pain, and it usually involves the patellofemoral, anteromedial, or posterior part of the knee, particularly during ascending and descending from stairs.…”