IMPROVEMENT IN GAIT ONE YEAR AFTER SURGERY FOR KNEE OSTEOARTHROSIS - A COMPARISON BETWEEN HIGH TIBIAL OSTEOTOMY AND PROSTHETIC REPLACEMENT IN A PROSPECTIVE RANDOMIZED STUDY

The aim of this study was to analyse gait improvement one year after high tibial osteotomy and unicompartmental knee arthroplasty in patients with strictly unilateral osteoarthrosis of the medial compartment of the knee. Thirty-six patients, 18 men and 18 women, received a unicompartmental Brigham knee prosthesis and 23 patients, 10 men and 13 women, were operated on with a high tibial osteotomy. Clinical and radiographical assessments were supplemented by a functional test, measurements of thigh muscle torque with a Cybex II dynamometer and analysis on a force plate walkway with electrogoniometers. All patients were assessed prior to, and one year after surgery. Both groups showed overall clinical improvement, as assessed by the British Orthopaedic Association (BOA) score. Pain during walking decreased. The range of knee flexion remained unchanged. The ability to ascend and descend steps improved. The isokinetic thigh muscle torque remained unchanged. In the prosthetic group free walking speed increased from 1.03 to 1.09 m/s (p < 0.001). Step frequency and step length increased (p < 0.001). Single stance phase ratio increased from 0.96 to 0.99 (p < 0.01), indicating a more symmetrical gait. Double stance phase (% gait cycle) of both legs decreased (p<0.001), indicating a faster transfer of weight during walking. In the osteotomy group, free walking speed did not increase. Step length of the uninvolved leg increased (p < 0.01). Double stance phase of the involved leg decreased (p < 0.001) and double stance phase of the uninvolved leg decreased (p < 0.01). Both groups improved after surgery and there was no difference between the groups. The different walking tests of this study indicated greater improvement after unicompartmental prosthetic replacement one year after surgery. Gait analysis was found to be useful by supplying important data on the functional outcome after knee surgery.