Early recovery patterns differ between medially congruent and posterior-stabilized total knee arthroplasty, with comparable 2-year outcomes: A triple-blinded randomized clinical trial.

Abstract

Whether medially congruent (MC) total knee arthroplasty (TKA) provides clinically meaningful advantages over posterior-stabilized (PS) designs remains controversial. In this randomized trial, early recovery profiles and 2-year outcomes were compared between Persona® MC and PS TKA. In this triple-blinded randomized controlled trial, 82 patients undergoing primary TKA for Kellgren-Lawrence Grade IV osteoarthritis were allocated to receive a Persona® MC or PS system. The primary endpoint was Knee injury and Osteoarthritis Outcome Score-Activities of Daily Living (KOOS-ADL). Secondary outcomes included range of motion, visual analogue scale (VAS) pain, Forgotten Joint Score-12 (FJS-12), satisfaction and complications. Follow-up was 2 years. Group, time and group × time interaction were assessed using repeated-measures models. Both groups improved over time. Significant group × time interactions were observed for ROM, VAS pain, KOOS-ADL and FJS-12, indicating different recovery profiles. MC knees had greater flexion at 2 weeks (95.3° vs. 83.9°, <i>p</i> < 0.001), and flexion contracture at 2 weeks was observed only in the PS group (0/41 vs. 4/41). Conversely, PS patients reported lower pain scores at 2 weeks (4.75 vs. 6.17, <i>p</i> < 0.001) and 6 weeks (1.92 vs. 2.97, <i>p</i> < 0.001). Later flexion favoured PS, including at 2 years (118.8° vs. 113.9°, <i>p</i> < 0.001). MC patients reported statistically higher KOOS-ADL and FJS-12 scores at 1 and 2 years; however, between-group differences did not exceed established minimum clinically important difference thresholds. Satisfaction was high in both groups and complications were infrequent. Persona® MC and PS TKA showed different recovery profiles rather than clear superiority of either design. MC-TKA was associated with better early flexion and fewer observed early flexion contractures, whereas PS TKA was associated with lower early postoperative pain and greater flexion at later follow-up. MC showed statistically higher KOOS-ADL and FJS-12 scores, but these differences remained below minimum clinically important difference thresholds. Both designs provided substantial 2-year improvement without clinically meaningful between-group differences in patient-reported outcomes. Level I.