Closing the Satisfaction Gap

Background: Medial unicompartmental knee arthroplasty (mUKA) has historically yielded higher patient satisfaction than total knee arthroplasty (TKA) for isolated medial compartment osteoarthritis, but recent advances in robotic mUKA and contemporary TKA alignment strategies have narrowed this gap in outcomes. Pragmatic comparisons of mUKA and modern cruciate-retaining (CR) TKA focusing on 1-year patient-reported outcome measures (PROMs) and healthcare utilization are limited. Methods: We analyzed 2771 CR-TKA and 696 mUKA patients between 2016 and 2023 using a prospective registry (median age: 68 years; 55% women; 89% White). Baseline and 1-year PROMs including Knee Injury and Osteoarthritis Outcome Score (KOOS) for Pain, Physical Function Shortform (PS), Joint Replacement (JR), and Veterans RAND 12-Item Mental Component Summary (VR-12 MCS) were collected. Clinically meaningful improvement was assessed using minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) thresholds. Healthcare utilization included length of stay (LOS), discharge disposition, 90-day readmissions, 1-year reoperations, and 1-year mortality. Multivariable regression models compared outcomes between mUKA and CR-TKA. Results: At 1 year, 82% to 93% of mUKA and 84%-94% of CR-TKA patients achieved MCID thresholds for KOOS subscales. PASS thresholds achievement ranged from 69% to 71% for mUKA and 68% to 73% for CR-TKA. Satisfaction was reported by 83% of mUKA and 87% of CR-TKA patients. In multivariable models, CR-TKA compared with mUKA showed no significant associations with 1-year KOOS-Pain, PS, JR, failure to achieve MCID and PASS thresholds, and risk of dissatisfaction. CR-TKA was significantly associated with LOS ≥3 days and nonhome discharge. Conclusions: At 1 year, CR-TKA and mUKA demonstrated comparable PROMs and satisfaction. CR-TKA was associated with a longer LOS and nonhome discharge. Longer-term comparative data on revision, survivorship, and cost are needed to refine patient selection and indications. Level of Evidence: Level III. See Instructions for Authors for a complete description of levels of evidence.