Lateral pelvic displacement during walking: retest reliability of a new method of measurement

This study examined the retest reliability of a new method of measuring the amplitude and symmetry of lateral pelvic displacement (LPD) during walking. Previous methods of quantifying LPD did not consider variations in walking direction or enable quantification of side-to-side symmetry of LPD. Therefore, the new method was developed to measure the amplitude and symmetry of LPD relative to the base of support provided by the feet. Three-dimensional motion analysis was used to collect the coordinates of markers placed on the sacrum and heels of 20 unimpaired adults. Subjects performed three 10 m walking trials at their preferred speed. Between trial 1 and 2 the markers were removed and then reattached. Between trial 2 and 3 the markers remained attached. Retest reliability was high for consecutive measurements of amplitude of LPD (ICC (2,1)=0.91), and marker reattachment did not affect the degree of reliability (ICC (2,1)=0.94). The reliability was also high for consecutive measurements of symmetry of LPD (ICC (2,1)=0.80). Marker reattachment did however reduce the reliability of symmetry measures (ICC (2,1)=0.54). This study provides data on the retest reliability of a new method of measuring LPD in unimpaired subjects against which the performance of patients can be compared.