The influence of patient factors on patient's perceptions of satisfaction and success following total knee replacement

Purpose To determine how patient characteristics; health status and pre-operative knee function effect patient reported satisfaction and operative success following total knee replacement (TKR). We hypothesised that a number of patient factors would influence the reported levels of symptomatic improvement (success) and satisfaction and that these two outcomes would represent different aspects of the patient's perception of outcome. Design Retrospective cohort analysis of patient reported outcome measures (PROMs) and National Joint Registry (NJR) data. Complete patient data was available for 9,874 TKRs performed for osteoarthritis between 1/8/08 and 31/12/10. The relationship of the background factors to patient perceived satisfaction and success was investigated using ordinal logistic regression and structural equation modelling (SEM). Results Gender, pre-operative general health, depression, ASA grade and Euroqol index scores individually influenced satisfaction and/or success. When the interactions between variables were considered the size of the improvement in the Euroqol score and female gender were the most important predictors of lower levels of satisfaction/success. The effects of female gender were largely through its association with higher BMI, higher levels of depression and lower levels of general health. In total 8,286 (84%) of patients were satisfied and 8,789 (89%) rated their operation as a success. 712 (8%) of the patients who rated their operation as successful were dissatisfied. This is consistent with the premise that success relates to the patients perception of whether they have symptomatically improved whereas satisfaction relates to the extent to which they are happy with this improvement. Conclusions Patient perceived satisfaction and success are influenced by a number of patient factors, the most important of which are the improvement in the Euroqol score and gender. This information can be used to counsel patients about the expected outcomes and guide patient selection in cases of borderline clinical need.