Preoperative Patient-Reported Outcome Measures Phenotypes as Predictors of 1-Year Outcomes in Medial Unicompartmental Knee Arthroplasty: Insights from 940 UKA Procedures.

Background: We aimed to explore the relationship between preoperative patient-reported outcome measure (PROMs) phenotypes based on pain, function, and mental health with postoperative achievement of minimal clinically important difference (MCID), patient acceptable symptom state (PASS) thresholds, and satisfaction at one year in patients undergoing medial unicompartmental knee arthroplasty (mUKA).

Methods: A prospective institutional cohort of 941 patients undergoing mUKA from 2016 to 2022 was included. Of these, 143 underwent robotic-assisted (RA)-mUKA and 798 underwent manual mUKA. Preoperative scores on Knee disability and Osteoarthritis Outcome Score for Pain (KOOS Pain), KOOS Physical Function Shortform (KOOS PS), and the Veterans RAND 12-Item Health Survey Mental Component Score (MCS) were used to develop eight distinct PROM phenotypes representing above (+) or below (-) the median score for the cohort.

Results: Select preoperative PROM phenotypes were associated with a lower likelihood of failure to achieve MCID for KOOS PS and JR, while they were more likely to fail to achieve PASS thresholds for all KOOS domains.

Conclusion: Patients undergoing mUKA who have certain baseline PROM phenotypes may not reach an acceptable symptomatic state, despite experiencing meaningful improvements at one year. These phenotypes could help determine surgical timing and identify high-risk patients who may benefit from targeted preoperative interventions and expectation management.