Propensity score-matched comparison of unicompartmental and total knee arthroplasty in older patients: Lower invasiveness and faster early recovery after UKA.

BACKGROUND

Unicompartmental knee arthroplasty (UKA) may offer lower surgical invasiveness and faster recovery than total knee arthroplasty (TKA), but comparative studies in older patients remain limited by selection bias. We therefore asked whether, in propensity score-matched older patients, UKA would (1) reduce perioperative invasiveness, (2) improve early postoperative recovery, (3) maintain comparable short-term patient-reported outcomes, and (4) show stable radiographic outcomes compared with TKA.

HYPOTHESIS: UKA would be associated with lower surgical invasiveness and faster early postoperative recovery than TKA while maintaining comparable short-term patient-reported and radiographic outcomes.

MATERIALS AND

METHODS

This retrospective cohort study included consecutive patients who underwent UKA or TKA for primary varus knee osteoarthritis or osteonecrosis between 2013 and 2021. Propensity score matching was performed using age, sex, body mass index, Kellgren-Lawrence grade, hip-knee-ankle angle, preoperative range of motion, and follow-up period. Eighty-eight knees were included in each group. Estimated blood loss, postoperative C-reactive protein levels, range of motion, time to ambulation with a single cane, length of hospital stay, Knee Society Score 2011, and radiographic outcomes were evaluated.

RESULTS

Estimated blood loss was significantly lower in the UKA group than in the TKA group (104.6 ± 68.7 mL versus 195.7 ± 85.2 mL, P < 0.001). C-reactive protein levels at 1 and 2 weeks were also significantly lower after UKA. Knee flexion at 1 and 2 weeks and at final follow-up was significantly better in the UKA group, and ambulation with a single cane was achieved earlier. Hospital stay among patients discharged home was shorter after UKA. Patient-reported outcomes at final follow-up were comparable between groups. Radiographic component positioning remained stable in both groups.

DISCUSSION: In this selected propensity score-matched cohort of older patients, UKA was associated with lower surgical invasiveness and faster early postoperative recovery than TKA, while short-term patient-reported outcomes were comparable. These findings suggest faster early recovery after UKA in a selected patient population and should not be interpreted as demonstrating the general superiority of UKA over TKA.

LEVEL OF EVIDENCE: III; retrospective comparative study.