Satisfaction after total knee replacement for osteoarthritis is usually high, but what are we measuring? A systematic review

Patient satisfaction is considered an important outcome measure after total knee replacement, but the construct is complex. There is large variation both in how satisfaction is measured and estimates of the proportion of people who are satisfied after surgery. The aim of this systematic review was to i) evaluate the proportion of people reported to be satisfied after total knee replacement for osteoarthritis; and ii) assess the content validity of the utilised satisfaction measures. We searched four literature databases with search phrases ‘Total Knee Arthroplasty’ OR ‘Total Knee Replacement’ AND ‘Patient satisfaction’ for studies that measured satisfaction at least 6 month post-unilateral primary total knee replacement for knee osteoarthritis. Identified studies were assessed for risk of bias, and studies at high risk of bias were excluded (PROSPERO: CRD42017058936). Meta-analysis was not appropriate due to the heterogeneity in satisfaction instruments, thus satisfaction scores were described. The content validity of satisfaction questionnaires was assessed using the COnsensus-based Standards for the selection of health status Measurement Instruments criteria. The present review found heterogeneity in the satisfaction questions used, as well as the satisfaction estimates from the various studies. Only two satisfaction instruments were relevant for a Total Knee Replacement population and both failed assessment for content validity due to lack of patient involvement during development and testing in accordance with the COnsensus-based Standards for the selection of health status Measurement Instruments criteria. Future research should focus on qualitative methods to elicit patients' perspectives of satisfaction to build theoretical understanding.