Revision Total Knee Arthroplasty Achieves Minimal Clinically Important Difference Faster than Primary Total Knee Arthroplasty.

Abstract

Revision total knee arthroplasty (rTKA) remains underexplored regarding patient-reported outcome measures (PROMs), particularly in terms of time to reach Minimal Clinically Important Difference (MCID). This study addresses this gap by comparing the time to achieve MCID between primary TKA (pTKA) and rTKA patients, providing valuable insights into their recovery trajectories. A total of 8,266 TKAs (7,618 pTKA and 648 rTKA) were retrospectively studied in a multi-institutional arthroplasty registry. Patients who completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Global Physical, PROMIS Physical Function Short Form 10a (PF-10a), and Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS) questionnaires were identified by Current Procedural Terminology (CPT) codes. Survival curves with and without interval-censoring were utilized to evaluate the time to achieve MCID. Comparing the time to achieve MCID, rTKAs were significantly faster than pTKA for PROMIS Global Physical (3.5 versus 3.7 months, P = 0.004) and KOOS-PS (3.3 versus 4.2 months, P < 0.001), but similar for PROMIS PF-10a (4.4 versus 4.8 months, P = 0.057). Interval-censoring also showed similar trends with earlier times to achieve MCID for rTKAs for PROMIS Global Physical (0.6 to 0.61 versus 0.97 to 0.97 months, P = 0.009) and KOOS-PS (0.97 to 0.97 versus 1.47 to 1.47 months, P < 0.001), but not for PROMIS PF-10a (2.43 to 2.54 versus 1.90 to 1.91 months, P = 0.92). The present study revealed that the time to achieve MCID was faster in patients undergoing rTKA compared to those undergoing pTKA. These findings allow surgeons to reassure preoperative revision TKA patients that their recovery to a minimal clinically important difference postoperatively may be quicker than expected, especially when compared to their initial recovery after primary TKA.