Abstract
BACKGROUND: Patient-reported outcome measures (PROMs) are increasingly utilized in medial unicompartmental knee arthroplasty (UKA). Total knee arthroplasty studies have shown preoperative PROMs across multiple domains (knee physical function, general physical health, mental health, etc.) influence achievement of minimal clinically important difference (MCID) or patient acceptable symptom state (PASS). However, the utility of preoperative PROMs in medial UKA is underexplored. We investigated the impact of preoperative PROMs across multiple domains on MCID and PASS achievement in medial UKA.
METHODS: We retrospectively sourced 911 medial UKAs from a prospectively maintained multi-institutional arthroplasty registry. The following preoperative PROMs were recorded: 1) Knee Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS); 2) Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function-10a (PF-10a); 3) PROMIS Global Physical; and 4) PROMIS Global Mental. These PROMs measure the following domains, respectively: 1) knee-specific physical function; 2) general physical function; 3) general physical health; and 4) general mental health. Multivariable forward binary logistic regression models identified factors independently associated with the achievement of literature-derived, anchor-based KOOS-PS thresholds for MCID and PASS.
RESULTS: Achievement of MCID was associated with a lower preoperative KOOS-PS score (P = 0.001) and a higher preoperative PROMIS Global Physical score (P = 0.013). Achievement of PASS was associated with a higher preoperative KOOS-PS score (P < 0.001), higher preoperative PROMIS Global Physical score (P = 0.038), higher preoperative PROMIS Global Mental score (P = 0.018), and higher preoperative PROMIS PF-10a score (P = 0.029).
CONCLUSION: Medial UKA patients who have severe knee symptoms have a high rate of MCID, but a low rate of PASS. Conversely, patients who have mild knee symptoms have a low rate of MCID, but a high rate of PASS. Higher baseline physical functioning, general physical health, and general mental health increase the likelihood of PASS achievement. Evaluating medial UKA patients who have several preoperative PROMs across multiple domains (knee physical function, general physical health, mental health, etc.) may aid counseling. Although PROMs are subjective and are not perfect measures, they are nevertheless validated and widely utilized, offering insights that can guide clinical decision-making. Preoperative PROMs should not restrict access to care.