Abstract
Background
High functional aspirations and an active ageing population equate to a growing number of patients awaiting hip arthroplasty demanding superior biomechanical function. The purpose of this study was to compare the biomechanics of top walking speed between two commonly used hip arthroplasty procedures to determine if a performance advantage existed.
Methods
A retrospective comparative study was performed using sixty-seven subjects, twenty-two subjects in both hip resurfacing and total hip arthroplasty groups along with twenty-three healthy controls. All arthroplasty subjects were recruited based on high psychometric scoring and had been performed through a posterior approach, and had been discharged from follow-up. On an instrumented treadmill each subject was measured by a researcher blinded to which procedure that patient had undergone. After a six minute acclimatization period, the speed was increased incrementally until top walking performance had been attained. At all increments, ground reaction forces and temporospatial measurements were collected.
Results
The two arthroplasty groups were well matched demographically, with no significant differences with regards to age, sex, height, BMI and pre-operative radiological severity. Treadmill temporospatial analysis demonstrated significant differences between the two groups. The hip resurfacing group were able to walk statistically faster (p=0.023) with an increased step length(p=0.041). The top walking speed mean of 2.06m/sec by the resurfacing almost matched the healthy controls. Assessing ground reaction forces and symmetry also demonstrated hip resurfacing was superior (Graph 1).
[Graph 1: Mean Gait Biomechanics at Top Speed]
Conclusion
This study is the first to focus on high end performance following hip arthroplasty, encouraging patients to achieve as high a speed as they comfortably could. The total hip arthroplasty group walked nine percent faster than the previously published top speed of 1.73m/sec, however the resurfacings still walked ten percent faster, matching the normal controls for speed and step length.
