GAIT FUNCTION OF TOTAL HIP ARTHROPLASTY PATIENTS: ANALYSIS OF PREFERRED SPEED WALKING ALONE IS NOT ENOUGH.

Introduction: Gait before and after total hip arthroplasty (THA) is often determined by walking at preferred speed. However gait function comprises more than just walking at preferred speed. The objective is to describe recovery of gait after THA based on the assessment of spatio-temporal gait parameters determined with an ambulatory system whereby an extended test protocol is used. Materials and Methods: Sixty-three patients participating in a short-stay program for primary unilateral THA were assessed preoperatively and at 6 weeks and 6 months postoperatively. The spatiotemporal gait parameters walking speed, step length, step duration and variability coefficient (VC) were determined with an ambulatory system using accelerometers. The test protocol contained walking at different speeds, walking while performing an additional cognitive task, and an endurance test. Results: Patients improved significantly over time; however, the extent and speed of recovery of gait parameters was different for each test part. The relation between walking speed and step length showed systematic improvement when analyzed over a range of speeds. At 6 months, the VC of the additional cognitive task part was comparable with the preferred walking VC. The endurance test results could be predicted from the results of preferred walking. Conclusion: The assessment of the recovery of gait function requires more than only the assessment of ‘normal’ walking. Particularly, an analysis of walking at different speeds and walking while performing an additional cognitive task demonstrate different aspects of gait recovery after THA.