Psychosocial predictors of outcomes up to one year following total knee arthroplasty

Background: Total knee arthroplasty (TKA) aims to relieve pain and improve physical functioning of the knee, however, some patients continue to experience pain and impaired function following TKA which cannot be explained by surgical and implant factors. Psychological factors may influence the outcomes of TKA. The aim of this prospective study was to examine the psychosocial factors that predicted pain, stiffness and physical functioning up to one year following TKA. Methods: One hundred and two patients completed pre-operative and one-year questionnaires which assessed a wide range of psychosocial and sociodemographic factors prior to surgery. The Oxford Knee Score (OKS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, Stiffness and Physical Functioning subscales were used as outcome measures. Pearson correlation analysis and multiple linear regression were conducted to examine relationships between predictor and outcome variables. Results: Regression analysis showed that regarding variance in WOMAC outcome measures post TKA, our model predicted 31% for physical functioning, 25% for pain and 29% for stiffness at one year. Regarding variance in OKS post TKA, the model predicted 36% at one year. Greater levels of depressive symptoms and neuroticism and worse pre-operative scores significantly predicted poorer outcomes. Conclusions: The findings indicate that pre-operative psychosocial factors are important in understanding outcomes of TKA. Psychosocial factors could be considered during pre-operative assessment. Further research conducted on psychological interventions is needed within this population to determine whether early and one-year outcomes can be improved.