Is postoperative function after hip or knee arthroplasty influenced by preoperative functional levels?

Our objective was to evaluate functional outcomes after surgery in a subgroup of patients presenting for hip and knee surgery who had low functional scores before surgery. One hundred twenty-seven unilateral total hip and knee arthroplasty patients were assessed preoperatively and 3 consecutive years after arthroplasty using: Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Short Form 36 (SF-36), and the Quality of Well-Being index scales. Patients were placed into 2 groups based on preoperative WOMAC function scores; 51 points or more, worse functioning group, and less than 51 points, higher functioning group. Regardless of time, the worse functioning group in both procedures performed worse on the Quality of Well-Being index, SF-36 (function score), SF-36 (social score), and WOMAC total and pain scores (P < or = .0001). The greatest change (range, 2%-638%) for all variables in both groups for both procedures occurred during the first year. Patients that had severe/extreme functional impairment had worse 3-year outcomes compared with patients getting surgery when their functional levels were better.