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.

purposeRecently, 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.

methodsA 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).

resultsThe 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).

conclusionAt 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.