Determinants of pain, functional limitations and health-related quality of life six months after total knee arthroplasty: results from a prospective cohort study

BACKGROUND Total knee arthroplasty (TKA) is an effective procedure. However, for some patients, the outcomes are not satisfactory. Identification of TKA determinants could help manage these patients more efficiently. The purpose of this study was to identify pre- and perioperative determinants of pain, functional limitations and health-related quality of life (HRQoL) 6 months after TKA. METHODS 138 participants were recruited from 3 hospitals in Quebec City, Canada and followed up until 6 months after surgery. Data were collected through review of the subjects' medical files and structured telephone interviews before and 6 months after TKA. Pain and functional limitations were measured with the Western Ontario and McMaster Osteoarthritis Index (WOMAC) and HRQoL was measured with the SF-36 Health Survey. Independent variables included demographic, socioeconomic, psychosocial, clinical and surgical characteristics of participants as well as data on health services utilization. Stepwise multiple regression analysis was used to assess the strength of the associations between the independent variables and the WOMAC and SF-36 scores. RESULTS Higher preoperative pain, cruciate retaining implants and the number of complications were significantly associated with worse pain 6 months after TKA (p < 0.05) and explained 11% of the variance of the WOMAC pain score. Higher preoperative functional limitations, being single, separated, divorced or widowed, being unemployed or retired and the number of complications were significantly associated (p < 0.05) with worse functional limitations 6 months after TKA and explained 16% of the variance of the WOMAC function score. Lower preoperative HRQoL, contralateral knee pain, higher psychological distress and comorbidities were significantly associated (p < 0.05) with worse HRQoL 6 months after TKA and explained 23% of the variance of the SF-36 physical functioning score. CONCLUSIONS Several variables were found to be significantly associated with worse outcomes 6 months after TKA and may help identify patients at risk of poorer outcome. The identification of these determinants could help manage patients more efficiently and may help target patients who may benefit from extensive rehabilitation.