Psychosocial predictors for outcome after total joint arthroplasty: a prospective comparison of hip and knee arthroplasty

Background: As findings regarding predictors for good outcome after total joint arthroplasty are highly inconsistent, aim of this study was to investigate the influence of the psychosocial variables sense of coherence and social support as well as mental distress on physical outcome after surgery. It should be investigated if different predictors are important in patients after total hip arthroplasty (THA) compared to patients after total knee arthroplasty (TKA). Methods: In a prospective design, 44 patients undergoing THA and 61 patients undergoing TKA were examined presurgery and 6 and 12 weeks after surgery using WOMAC (disease-specific outcome), SF-36 (health-related quality of life), BSI (psychological distress), SOC-13 (sense of coherence), and F-SozU (social support). Changes over time were calculated by analyses of variance with repeated measures. Stepwise multiple linear regression analyses were computed for each group to predict scores of WOMAC total and all WOMAC subscales 12 weeks postoperatively. Results: THA as well as TKA patients experienced improvements in all parameters (effect sizes for WOMAC scores between eta(2) = .387 and eta(2) = .631) with THA patients showing even better results than TKA patients. WOMAC scores 12 weeks after surgery were predicted predominantly by WOMAC baseline scores in TKA with an amount of explained variance between 9.6 and 19.5%. In THA, 12-weeks WOMAC scores were predicted by baseline measures of psychosocial aspects (anxiety, sense of coherence, social support). In this group, predictors accounted for 17.1 to 31.6% of the variance. Conclusions: Different predictors for outcome after total joint arthroplasty were obtained for THA and TKA patients. Although psychosocial aspects seemed to be less important in TKA patients, preoperatively, distressed patients of both groups should be offered interventions to reduce psychological distress to obtain better outcomes after surgery.