Safe and reliable clinical outcomes at 2 years of a fixed-bearing partial knee arthroplasty with a morphometric tibial tray in a large worldwide population.

PURPOSE: The purpose of this study was to evaluate: (1) improvement of functional and quality of life scores, (2) adverse events, (3) short-term implants survivorship of a newly designed fixed-bearing partial knee replacement (PKR) with a morphometric tibial tray in a large and multicentric population at a minimum follow-up of 2 years. METHODS: From 2017 to 2019, 479 medial PKR were implanted by 16 non-developing surgeons from United States, Europe, and Japan. Eight patients were lost to follow-up (1.8%). Standardized follow-up procedures included patient-reported outcomes (Oxford Knee Society score, Forgotten Joint Score, EQ VAS, EQ 5D), patient satisfaction, radiographic assessments, adverse event at 2 years. Comparisons between the preoperative and postoperative values were performed using Student t test. Kaplan-Meier survivorship analysis was performed with knee revision as the endpoint. RESULTS: The mean age was 65.6 ± 9.6 years. Mean body mass index was 29.5 ± 5.1 kg/m2. Oxford Knee Society score and Forgotten Joint Score, respectively, improved from 23.7 ± 8 and 16 ± 15.8 preoperatively to 42.4 ± 6.5 and 74 ± 24.9 at 2 years (p < 0.0001). Satisfaction Score was 92.3 ± 13.4 at 2 years. Ten re-operations (2.1%) were reported including seven implant removals (1.5%). No other adverse event was reported. The causes of conversion to total knee arthroplasty were: nickel allergy (n = 2), patellofemoral osteoarthritis (n = 1), pain (n = 1), deep infection (n = 3). Two re-operations were performed due to infection, and one for internal fixation for a tibial plateau fracture. The 2-year Kaplan-Meier survival estimate was 98.4%, with implant removals as the endpoint. CONCLUSION: This prospective multicentric study reported safe and reliable clinical outcomes of a morphometric PKR, which optimized tibial coverage and femoral fit, in a large population of patients worldwide at 2 years. LEVEL OF EVIDENCE: Prospective cohort study-therapeutic study, Level II.