It is difficult to identify objective parameters for assessing the joint function when dealing with the evaluation of orthopaedic procedures, especially endoprosthetic hip replacement. Clinical gait analysis enables parameters of force and movement to be quantified. However, the influence of gait speed on these parameters has hardly been taken into consideration so far. The objective of the present study was therefore to investigate the effect of gait speed on gait parameters and to simplify the clinical conditions in patients with osteoarthritis of the hip by determining a standardised gait speed.
A total of 28 patients with severe unilateral osteoarthritis of the hip were investigated at different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable treadmill with force plates and an infrared video system. A special control mechanism permitted adjustment of the treadmill speed to a patient's self-determined pace.
The mean gait speed of all patients with osteoarthritis of the hip was set at 2.20 km/h (0.61 m/s). Eight of the 10 gait parameters assessed increased significantly with changing gait speed. Pathological changes in gait patterns were found at the three gait speeds investigated, with the changes more accentuated at higher speeds.
Dependence of gait parameters on gait speed could be concluded for a group of patients and for control subjects. Use of a force-instrumented treadmill is necessary for the setting of a standard gait speed, which should be set as high as achievable by patients without inducing pain and problems of coordination or balance. With the usage of standardised speeds, clinical gait analysis becomes easier to perform. Furthermore, one can assess the expected biomechanical advantages of newer prostheses, thus providing the surgeon with a basis for further decisions.