Comparative outcomes of total hip and knee arthroplasty: a prospective cohort study

Purpose The comparative outcome of primary hip and knee arthroplasty is not well understood. This study aimed to investigate the outcome and satisfaction of these procedures and determine predictive models for 1 year patient outcome with a view to informing surgical management and patient expectations. Study design Prospective cohort study of all primary hip and knee arthroplasty procedures performed at the Royal Infirmary of Edinburgh between January 2006 and November 2008. General health (SF-12) and joint specific function (Oxford Score) was assessed preoperatively and at 6 and 12 months post-operatively. Patient satisfaction was assessed at 12 months. Results 1410 total hip arthroplasty (THA) and 1244 total knee arthroplasty (TKA) procedures were assessed. Oxford Score improved by 4.9 points more in THA patients than in TKA patients. SF-12 physical scores were on average 2.7 points greater in the THA patients at one year. Satisfaction was also greater (91%) following THA compared with TKA (81%). Regression modelling was not able to predict individual patient outcome; however, mean pre-operative Oxford Scores were found to be strong predictors of mean postoperative Oxford Scores for each procedure. Age, gender and pre-operative general health scores did not influence these models. Conclusions Both THA and TKA confer substantial improvement in patient outcome; however, greater joint specific, general health and satisfaction scores are reported following THA. This difference is physical in nature. Regression models are presented that can be applied to predict mean hip/knee arthroplasty outcome based on preoperative values.