Variations in pain and function before and after total knee arthroplasty : A comparison between Swedish and Australian cohorts

Objective: Preoperative pain and function is viewed as an important predictor of total knee arthroplasty (TKA) outcomes. We examined whether variations in pain and function outcomes existed at 12 months between two centres in Sweden and Australia, and whether this was explained by variations in patient presentation for TKA. Methods: This was a retrospective analysis of prospectively collected data. Patients from one centre in Australia (St. Vincent's Hospital (SVH), N = 516) and in Sweden (Trelleborg (TBG), N = 899) who underwent primary TKA between 2012 and 2013. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) was analysed pre- and 12 months' post TKA from which non-response to surgery was determined using the OMERACT-OARSI criteria. Multiple linear regression analysis was used to examine the relationship between change in pain and function and surgery centre, adjusting for preoperative patient characteristics and surgical technique. Results: Despite worse preoperative outcomes in all subscales of the WOMAC for the SVH cohort, there were no clinically meaningful differences in 12-month WOMAC subscales nor change in WOMAC subscales between SVH and TBG. Almost identical proportions of patients were considered OMERACT-OARSI responders, 85.7% (SVH) and 85.9% (TBG), however for the SVH cohort 25 (4.9%) were moderate and 417 (80.8%) were high responders, compared to the TBG cohort of which 225 (25%) were moderate and 547 (60.9%) were high responders. Conclusion: Despite differences in preoperative presentation between 2 countries, improvements in pain and function and the proportion of individual who responded to TKA surgery at 1 year were similar. Factors related to poor response to TKA surgery require further elucidation