Changes in walking ability after knee replacement.

Walking ability has been assessed in 20 patients before and after knee replacement. In 8, who had severe osteoarthritis, a bicompartmental ICLH (Imperial College-London Hospital) prosthesis was used; in 12, with moderate arthritis, the medial side of the joint was replaced by a unicompartmental Brigham prosthesis. Knee function was assessed with the British Orthopaedic Association assessment chart, and walking capacity by the oxygen cost of level walking. Before operation, the function was the same in both groups, but patients with moderate osteoarthritis could walk faster with a lower energy cost than those with severe osteoarthritis. One year after operation, all the patients had improved clinically, alignment had been corrected, and the knees were stable with a satisfactory range of movement. Walking speed was improved; pain and perceived exertion were reduced. The oxygen cost of walking was decreased in patients with a unicompartmental arthroplasty, but not in patients with a total replacement. An uneconomic walking pattern, acquired before operation in those with severe osteoarthritis, was considered to be the reason why walking efficiency was not improved. The walking ability in patients with moderate osteoarthritis recovered to almost normal after unicompartmental replacement.