If the Patient-Reported Outcome Measures After Total Knee Arthroplasty Are Good, Do Any Other Measurements Really Matter?

Commentary In their analysis of patient-reported outcome measures (PROMs) and radiostereometric analysis (RSA) after total knee arthroplasty (TKA), van der Lelij et al. show no association between PROMs and RSA at a 10-year follow-up. This is likely to interest both surgeons and implant manufacturers, as it is reasonable to expect that a migrating TKA implant would lead to negative clinical outcomes. Interestingly enough, van der Lelij et al. support the converse. PROMs have been used by clinicians and institutions as an important method to measure surgical outcomes and, thus, improve quality of care. Notably, van der Lelij et al. also considered RSA when evaluating patient outcomes. RSA has been used historically to detect small changes in the migration of an implant after TKA, which can lead to revision surgical procedures1. Furthermore, RSA plays an important role in evaluating new TKA implant designs. RSA-tested TKA implants have a lower revision rate when compared with those not tested by RSA2. Although it is not the standard of practice for surgeons to order RSA, surgeons should be aware that it is an important and objective way to measure TKA performance. However, objective measures to assess TKA performance did not appear to impact patient satisfaction. van der Lelij et al. report that, at 10 years postoperatively, there was no significant relationship between migration when assessed with RSA and changes in PROMs. This is supported by a study completed by the Australian Orthopaedic Association National Joint Replacement Registry, which found that PROMs had no clinical association with a surgeon’s 2-year cumulative percent revision rate3. Thus, arthroplasty outcomes cannot be evaluated solely through PROMs. Patient satisfaction is multifactorial and involves factors such as age, gender, weight, socioeconomic status, mental health, social support, education, and race. In their study, van der Lelij et al. show patients, clinicians, and institutions that a successful TKA is not measured just by electronically surveying patients with postoperative PROM questionnaires. Perhaps we should consider a variety of factors such as postoperative surveillance radiographs and examinations when evaluating TKA outcomes. Ongoing RSA studies may be another tool to consider when evaluating a TKA. Even so, there is more work to be done to help to understand and measure the performance of a TKA. Further studies are needed to evaluate any relationship of RSA-identified migration with TKA revision, PROMs, and other outcome metrics.