Comparative study of tibial posterior slope angle following cruciate-retaining total knee arthroplasty using one of three implants

Abstract

Purpose Pre-and postoperative tibial posterior slope angles (PSAs) were assessed in patients who underwent cruciateretaining total knee arthroplasty (TKA). Material and methods A total of 386 cruciate retaining TKA were performed in 308 patients and retrospectively reviewed. Based on the prostheses, 202 cases using NexGen® were classified as group I, 120 cases using PFC sigma® as group II, and 64 cases using Vanguard® as group III. Postoperative PSA of groups I, II, and III were compared. Results In groups I, II, and III, postoperative PSA was 6.0˚, 6.0˚, and 4.5˚, respectively (p<0.001). Between preoperative measurement and final follow-up examination, mean knee score (59.7 to 97.3), function score (54.2 to 90.5), and range of motion (ROM; 126.7°to 132.2°) improved. These three values did not differ significantly among groups. Conclusions The 3°slope of the Vanguard® polyethylene insert caused the difference in PSAs. This design characteristic should be considered when using this implant in TKA.

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

“…The MA for coronal plane alignment was defined as the angle between the femoral and tibial MAs. Serial preoperative and postoperative AP and lateral views of the knee were obtained and reviewed to assess limb alignment, component positioning, PCO, PSA, and JLH 1 6) . A detailed analysis of the radiographs was performed to determine the femoral angle (α), tibial angle (β), femoral flexion angle (γ), and tibial PSA (δ) using the Knee Society roentgenographic evaluation method 14) .…”

“…The reference line of the PSA was defined as the line connecting the center of the medullary canal 10 and 20 cm distal to the tibial plateau ( Fig. 2 ) 1) . The preoperative PSA was defined as the angle between the perpendicular line of reference and a line connecting the anterior and posterior borders of the medial tibial plateau.…”

“…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) .…”

“…Other previous studies 4 12) argued that it did not correlate with the flexion angle because there were lots of variables affecting the flexion angle and a systematic analysis might be difficult to detect the complex effects of confounding variables with conventional radiographic measurements. It is difficult to perform restoration of the PCO and PSA in every knee because of mismatching between the component and bone geometry, flexion gap tightness, and wide variation in the preoperative PSA 1 13) . We thought that it would be necessary to evaluate the change of PSA, PCO, and JLH and to analyze their influences on the postoperative flexion angle concomitantly.…”

Reduced Operating Time but Not Blood Loss With Cruciate Retaining Total Knee Arthroplasty

“…The tibial cut used extramedullary guides. For the cruciate retaining implants, a posterior slope resembling local anatomy, allowed a proper gap balancing determined by using a preoperative lateral X-ray and an intraoperative inclination of the lateral plateau [ 9 ]. For the posterior stabilized implant, we aimed for a neutral slope to the tibial axis.…”