Do the increment of femoral condyle curvature and the change of tibia shape improve clinical outcome in total knee arthroplasty? A propensity score matching analysis

Purpose: Recently, the Persona total knee arthroplasty (TKA) system with more anatomical features and a similarly high flexion to the previous version, LPS-Flex, was introduced and is widely used. This study aimed to compare the early outcomes obtained using Persona versus an LPS-Flex fixed PS implant. Methods: A total of 784 knees that underwent primary TKAs (162: Persona group and 622: LPS-Flex group) were included. After 1:2 propensity score matching, there were 143 and 286 knees in Persona and LPS-Flex groups, respectively. Range of motion at the 2-year follow-up was the primary variable. Secondary variables were functional score, ability to perform activities requiring deep knee flexion, patient satisfaction, and radiographic measurements, including radiolucent line (RLL). Results: The average postoperative maximal flexion measured by goniometer at 2 years after TKA was 126.1° ± 10.8° (range 95°–140°) for the Persona group and 132.7° ± 11.7° (range 103°–145°) for the LPS-Flex group (P < 0.05). This significant difference was observed from 1 year postoperatively (P < 0.05). The two groups did not show a significant difference in functional score, postoperative ability in high flexion activities, and satisfaction at the 2-year follow-up. The rate of RLL was significantly lower in the Persona group (P < 0.05). Conclusion: At the 2-year follow-up, the Persona group had less maximal flexion; however, the difference in flexion did not seem to affect clinical outcomes. According to the radiological results, the Persona system shows less RLL than does the LPS-Flex system. Level of evidence: III.