The energy cost of walking with arthritis of the hip and knee.

The physiologic energy expenditure of walking was measured in patients with severe arthritis. Nine patients were tested following Girdlestone hip resection arthroplasty, six patients prior to total knee arthroplasty (TKA) for unilateral osteoarthritis of the knee, and 49 rheumatoid arthritis patients prior to unilateral TKA; 27 were retested after operation. The results were compared with previously published pre- and postoperative data for total hip arthroplasty (THA) following primary osteoarthritis. There were severe energetic penalties caused by rheumatoid or osteoarthritis involving the hip or knee or following Girdlestone arthroplasty. Walking speed was severely reduced in all groups (range, 33-46 m/minute). The rate of oxygen consumption was not significantly greater than the mean rate of oxygen uptake for normal subjects; however, the oxygen cost per meter travelled was elevated because of the slow walking speed. The heart rate was significantly elevated in all patient groups. The elevated cardiac response can be accounted for on the basis of deconditioning resulting from the patients' pain, limited ambulatory activities, and the systemic effects of rheumatoid disease. In addition, the elevated cardiac response may be caused by added physical exertion by the arms in patients on crutches or walkers. The improvements in speed and energy cost were the same for the group of rheumatoid patients tested after unilateral TKA as in the group of patients tested before and after THA. The clinician can anticipate the same magnitude of improvement from surgery in a rheumatoid patient as in an osteoarthritis patient if the primary joint disease is restricted to a single joint.