Variability in long-term pain and function trajectories after total knee replacement: A cohort study

Introduction Previous research suggests that patient-reported outcomes plateau by one year after total knee replacement (TKR). Analysis of trajectories to date has predominately been based on changes in median/mean scores over the first post-operative year, rather than variability in trajectory patterns over the longer-term. The aim was to evaluate variability in long-term pain and function trajectories after TKR. Hypothesis There will be variability in long-term pain and function trajectories after TKR. Patients and methods In all, 266 patients undergoing a Triathlon® TKR because of osteoarthritis were recruited from one orthopaedic centre. Participants completed the WOMAC Pain and Function scales preoperatively and then at 3 months, 1 year, 2 years, 3 years, 5 years and 7 years post-operative. Longitudinal analyses evaluated patterns of clinically meaningful change. Results Most patients had an improvement in pain and function during the first year post-operative; improvement was greatest in the first 3 months. By 1-year post-operative, 8% of patients had no change or a worsening of pain and 21% for function. Thereafter, approximately 15% of patients improved and 15% worsened between each assessment time. For those patients who had no change in symptoms from pre-operative to 1-year post-operative, one third had further improvement between 1 and 2 years post-operative. Discussion This study identified clinically meaningful variability in long-term outcomes after TKR, which could be discussed with patients to ensure they have realistic expectations of their outcome. Further research is needed to evaluate determinants of this variability and whether patients who will do poorly can be identified early in their recovery pathway. Level of evidence IV, prospective cohort study.