“Neutral Satisfied” Patients Should Not Be Dichotomized to “Satisfied” or “Dissatisfied” in Patient-Reported Outcomes After Total Knee Arthroplasty

Background: The purpose of this study was to clinically characterize neutrally satisfied patients and compare outcomes between satisfied, dissatisfied, and neutral patients. Methods: This was a secondary analysis from data collected in a multicenter longitudinal cohort study comprising total knee arthroplasty (TKA) patients using a digital care management platform. The Knee Society Score (KSS) satisfaction survey was administered at post-operative 90 days, and dissatisfaction was defined as a composite score of less than 20, satisfied as a score equal to or greater than 30, and neutral as a score of 20 up to 29. Patient-reported outcome measures (PROMs) were assessed pre-operatively and at post-operative one, three, six, and twelve months. Results: Approximately 58% of patients were satisfied (n = 1486), 29.4% neutral (n = 747), and 12.2% dissatisfied (n = 311). Neutral and dissatisfied patients were younger and more likely to be female and had lower pre-operative KSS scores compared to satisfied patients, though statistical differences were found between all groups. Pre-operative pain was significantly less in satisfied compared to neutral or dissatisfied patients. Changes in the pre-operative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) displayed significant differences between all groups at all time points, with greater improvements in satisfied versus neutral patients and neutral versus dissatisfied patients. Similarly, satisfied patients experienced significantly greater improvements in pain and KSS scores at post-operative three months, and neutral patients improved more than dissatisfied patients. Conclusions: Neutral patients present with distinctively different clinical outcomes compared to satisfied or dissatisfied patients and should be classified separately as neutral.