This “Author 360” post was written by David C. Ayers, MD and Hua Zheng, PhD, two of the authors of a new study now in JBJS: Satisfied but Failed: Patient Satisfaction Compared with Total Knee Arthroplasty Success Defined by the U.S. Centers for Medicare & Medicaid Services.
Patient-reported outcomes (PROs) are a critical measure of success following total knee arthroplasty (TKA). They represent the patient’s voice on the improvement in their condition from before to after surgery. Recently, the U.S. Centers for Medicare & Medicaid Services (CMS) mandated that PROs be collected both before surgery and again one year postoperatively. CMS defines successful TKA as an improvement of at least 20 points in the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR), which reflects substantial clinical benefit (SCB) following surgery.
Our involvement in this work was motivated by a common clinical observation: success after TKA isn’t always as clear-cut as it might seem. We often encounter patients who report high satisfaction with their surgery, but whose results fall short of the CMS standardized definition of “success.” This gap raises an important question: Does the current CMS definition of success truly align with what matters most to patients?
In this study, we aimed to explore the relationship between the CMS definition of surgical success and patient-reported satisfaction. Using a large, prospective, multicenter cohort of more than 8,000 patients, we uncovered a striking discrepancy. While 84% of patients reported being highly satisfied or satisfied after their TKA, only 64% of the procedures met the CMS criterion for success. Perhaps most surprising, nearly 30% of patients who were satisfied with their surgical outcome were classified as having a “failed” surgery according to the CMS standard. Read the study.
One key insight from our findings is that baseline patient status plays a substantial role in this discordance. Patients with better preoperative function had less room for measurable improvement, making them more likely to be labeled as having had an unsuccessful procedure by the CMS definition, despite their being satisfied with their outcomes. Conversely, those with worse baseline status were more likely to meet the success threshold, even if they didn’t report the same level of satisfaction as those with better preoperative function.
Our study suggests that the current binary definition of surgical success may oversimplify a much more complex, patient-centered reality. A more nuanced approach—one that adjusts for baseline status and takes into account what patients truly value—could offer a more accurate reflection of real-world outcomes.
This work is especially relevant as health care continues to shift toward value-based care and outcome-driven reimbursement models. Metrics like those used by CMS increasingly influence clinical practice, hospital rankings, and policy decisions. A more refined definition of success after TKA could lead to a deeper, more comprehensive understanding of patient outcomes.
Ultimately, our study highlights the need to rethink how we define success in TKA. Success should not be measured solely by measurable improvement, but by the meaningful benefit it provides to patients.
Read the study and download the related visual abstract at JBJS.org: Satisfied but Failed: Patient Satisfaction Compared with Total Knee Arthroplasty Success Defined by the U.S. Centers for Medicare & Medicaid Services
Additional perspectives on this study:
Commentary by Benjamin F. Ricciardi, MD: When Value Metrics Miss the Mark
Letter to the Editor by Daniel L. Riddle, PhD, PT, FAPTA and Levent Dumenci, PhD and Author Response by David C. Ayers, MD: Evaluating Concordance Between Complex Outcome Measures