Comparison of postoperative clinical outcome in medial‐pivotal and gradually reducing radius design cruciate‐retaining total knee arthroplasty—A multicenter analysis of propensity‐matched cohorts

Abstract

PurposeTo clarify differences in surgery duration, postoperative knee range of motion (ROM), anterior and posterior (AP) laxity, and Forgotten Joint Score (FJS) in patients undergoing medial‐pivot (MP) and GRADIUS cruciate‐retaining (CR) total knee arthroplasty (TKA) surgeries.MethodsWe examined patients who underwent either MP or CR TKA at six different Japanese centres. Patients were propensity score matched for age, sex, and preoperative hip‐knee angle (HKA). We compared the groups' average surgery duration, postoperative knee ROM, AP laxity, and FJS 1 year after surgery.ResultsThere were 86 study patients: 43 MP and 43 CR TKA matched for age, sex, and preoperative HKA. The MP group enjoyed a significantly shorter surgery duration (89.1 ± 10.9 mins vs. 95.7 ± 12.0 mins, p = 0.0091) and significantly better postoperative knee flexion than the CR group (123.7 ± 9.1° vs. 115.3 ± 12.4°, p < 0.001). The MP had significantly smaller postoperative AP laxity with 30° of knee flexion than the CR group (3.4 ± 1.3 vs. 5.6 ± 2.2 mm, p < 0.001). Conversely, postoperative AP laxity with 90° of knee flexion was significantly larger for the MP group (3.6 ± 1.3 vs. 2.7 ± 1.9 mm, p = 0.0098). There were no between‐group differences in postoperative FJS.ConclusionsThe MP group showed better postoperative knee flexion, midrange AP knee stability, and shorter surgery duration.Level of EvidenceLevel III, retrospective comparative study.