Significant effect of the posterior tibial slope and medial/lateral ligament balance on knee flexion in total knee arthroplasty

Abstract

Purpose The intra‐operative femorotibial joint gap and ligament balance, the predictors affecting these gaps and their balances, as well as the postoperative knee flexion, were examined. These factors were assessed radiographically after a posterior cruciate‐retaining total knee arthroplasty (TKA). The posterior condylar offset and posterior tibial slope have been reported as the most important intra‐operative factors affecting cruciate‐retaining‐type TKAs. The joint gap and balance have not been investigated in assessments of the posterior condylar offset and the posterior tibial slope. Methods The femorotibial gap and medial/lateral ligament balance were measured with an offset‐type tensor. The femorotibial gaps were measured at 0°, 45°, 90° and 135° of knee flexion, and various gap changes were calculated at 0°–90° and 0°–135°. Cruciate‐retaining‐type arthroplasties were performed in 98 knees with varus osteoarthritis. Results The 0°–90° femorotibial gap change was strongly affected by the posterior condylar offset value (postoperative posterior condylar offset subtracted by the preoperative posterior condylar offset). The 0°–135° femorotibial gap change was significantly correlated with the posterior tibial slope and the 135° medial/lateral ligament balance. The postoperative flexion angle was positively correlated with the preoperative flexion angle, γ angle and the posterior tibial slope. Multiple‐regression analysis demonstrated that the preoperative flexion angle, γ angle, posterior tibial slope and 90° medial/lateral ligament balance were significant independent factors for the postoperative knee flexion angle. The flexion angle change (postoperative flexion angle subtracted by the preoperative flexion angle) was also strongly correlated with the preoperative flexion angle, posterior tibial slope and 90° medial/lateral ligament balance. Conclusion The postoperative flexion angle is affected by multiple factors, especially in cruciate‐retaining‐type TKAs. However, it is important to pay attention not only to the posterior tibial slope, but also to the flexion medial/lateral ligament balance during surgery. A cruciate‐retaining‐type TKA has the potential to achieve both stability and a wide range of motion and to improve the patients’ activities of daily living.

Soft-tissue balancing in total knee arthroplasty: cruciate-retaining versus posterior-stabilised, and measured-resection versus gap technique

“…Measurements of soft-tissue balance were performed only with 40 lb of distraction force throughout ROM. Asano et al evaluated stiffness of the softtissue complex in osteoarthritic knees in PS and showed that stiffness in extension was significantly greater than that in flexion [36]. Different distraction forces may lead to different soft-tissue balance, which may result in different operative procedures and postoperative outcomes.…”

Changes in Femoral Posterior Condylar Offset, Tibial Posterior Slope Angle, and Joint Line Height after Cruciate-Retaining Total Knee Arthroplasty

“…In addition, the postoperative flexion angle and the amount of increase therein with regard to changes in the PCO, PSA, and JLH were analyzed (Pearson's correlation analysis) 2) . Knees showing postoperative PCO reduction within 3 mm of the preoperative value were assigned to the inlier group (PCO-inlier, n=111).…”

“…The range of flexion after TKA is probably influenced by many factors, including patient factors, prosthesis design, surgical technique, and rehabilitation. In terms of patient factors, the preoperative flexion angle is known to greatly influence the postoperative flexion angle 1 2) . In terms of surgical factors, changes in the femoral posterior condylar offset (PCO), tibial posterior slope angle (PSA), joint line height (JLH), femoral roll back, posterior cruciate ligament (PCL) tension, gap balancing, and patellar tracking have been analyzed 3 4 5 6 7 8) .…”

Increase of tibial slope reduces backside wear in medial mobile bearing unicompartmental knee arthroplasty

“…So the positioning of the tibial component has more influence on knee kinematics after UKA implantation. The role of the tibial slope in knee surgery has gained a lot of attention in total knee arthroplasty and in high tibial osteotomy (Bellemans et al, 2005;Fujimoto et al, 2012;Jojima et al, 2004).…”