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

Pre- and postoperative tibial posterior slope angles (PSAs) were assessed in patients who underwent cruciate-retaining total knee arthroplasty (TKA). A total of 386 cruciate retaining TKA were performed in 308 patients and retrospectively reviewed. Based on the prostheses, 202 cases using NexGenA (R) were classified as group I, 120 cases using PFC sigmaA (R) as group II, and 64 cases using VanguardA (R) as group III. Postoperative PSA of groups I, II, and III were compared. In groups I, II, and III, postoperative PSA was 6.0Ee, 6.0Ee, and 4.5Ee, 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; 126.7A degrees to 132.2A degrees) improved. These three values did not differ significantly among groups. The 3A degrees slope of the VanguardA (R) polyethylene insert caused the difference in PSAs. This design characteristic should be considered when using this implant in TKA.