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

Purpose: Pre- and postoperative tibial posterior slope angles (PSAs) were assessed in patients who underwent cruciate-retaining 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.