Significant Effect of the Posterior Tibial Slope on the Weight-Bearing, Midflexion In Vivo Kinematics After Cruciate-Retaining Total Knee Arthroplasty

Aims This study aims to investigate the effects of posterior tibial slope (PTS) on knee kinematics involved in the post-cam mechanism in bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) using computer simulation. Methods In total, 11 different PTS (0° to 10°) values were simulated to evaluate the effect of PTS on anterior post-cam contact conditions and knee kinematics in BCS TKA during weight-bearing stair climbing (from 86° to 6° of knee flexion). Knee kinematics were expressed as the lowest points of the medial and lateral femoral condyles on the surface of the tibial insert, and the anteroposterior translation of the femoral component relative to the tibial insert. Results Anterior post-cam contact in BCS TKA was observed with the knee near full extension if PTS was 6° or more. BCS TKA showed a bicondylar roll forward movement from 86° to mid-flexion, and two different patterns from mid-flexion to knee extension: screw home movement without anterior post-cam contact and bicondylar roll forward movement after anterior post-cam contact. Knee kinematics in the simulation showed similar trends to the clinical in vivo data and were almost within the range of inter-specimen variability. Conclusion Postoperative knee kinematics in BCS TKA differed according to PTS and anterior post-cam contact; in particular, anterior post-cam contact changed knee kinematics, which may affect the patient’s perception of the knee during activities. Cite this article: Bone Joint Res 2020;9(11):761–767.

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High Varus Angle and Lower Posterior Tibial Slope Associated with PCL Injury in Cruciate Retaining Total Knee Arthroplasty: An MRI Study

The Journal of Knee Surgery ◽

10.1055/s-0037-1603334 ◽

2017 ◽

Vol 31 (03) ◽

pp. 277-283 ◽

Cited By ~ 2

Author(s):

Yunus İmren ◽

Ali Tekin ◽

Süleyman Dedeoğlu ◽

Hakan Gürbüz ◽

Haluk Çabuk

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Tibial Slope ◽

Magnetic Resonance Images ◽

Posterior Tibial Slope ◽

Varus Alignment ◽

Cruciate Retaining ◽

Posterior Tibial ◽

Tibial Cut ◽

Total Knee

AbstractThe posterior tibial slope (PTS) is important for performing a tibial cut that does not injure the posterior cruciate ligament (PCL). In this study, the amount of PCL fibers sacrificed under simulated tibial cuts with varying posterior inclinations was evaluated using magnetic resonance images (MRIs) of osteoarthritic varus knees. Knee X-rays, orthoroentgenograms, and MRIs of 113 Kellgren and Lawrence grades 3 to 4 osteoarthritic knees were included. Four different simulated tibial cuts were performed at 0, 3, 5 degrees and parallel to the tibia plateau 3 mm below of the most defective part of the cartilage in the medial plateau. Correlations between the PCL avulsion amount and the PTS and varus alignment of the lower extremity were analyzed for all four simulated tibial cut levels. The maximum amount of PCL was preserved with a 0-degree tibial cut in patients with a PTS of more than 8 degrees. With increased tibial cut angles, the posterior slope resulted in an increased amount of avulsed PCL. Although the amount of avulsed PCL was proportional with the varus alignment, it was inversely proportional with the sagittal slope. The number of injured PCLs also increased as the slope of the tibial cuts increased. Patients with mild varus alignments and high PTSs are more suitable for cruciate retaining total knee arthroplasty.

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