Symmetries of the vertical ground reaction force, contact time and area, and center of pressure during gait in female patients 3 weeks post-total hip arthroplasty

Background: Few studies have assessed vertical ground reaction force, contact time, contact area, and center of pressure during gait in the early phase post-total hip arthroplasty. This study aimed to investigate whether these parameters are more pronounced in participants post-total hip arthroplasty compared to healthy controls.

Methods: We included 22 female participants who underwent total hip arthroplasty (age, 68.9 ± 7.2 years; body mass index, 22.9 ± 2.6 kg/m²) and 11 healthy female controls (age, 50.3 ± 7.8 years; body mass index, 19.4 ± 1.7 kg/m²) as controls. Vertical ground reaction force, contact time, contact area, and center of pressure during gait were measured using a force plate. Comparisons between the affected, unaffected, and control legs were conducted using one-way analysis of variance or the Kruskal-Wallis test, with additional comparisons using independent t-tests or the Mann-Whitney U test.

Findings: The first peak force was lower, the time to the first peak force and heel contact time were longer, and the contact area at the second peak force was significantly larger in the affected leg than in the unaffected leg or the right leg of the controls. These parameters were significantly more asymmetrical in the total hip arthroplasty cohort compared to the controls, with significant differences in the starting position and center of pressure length.

Interpretation: The loading timing, magnitude, and form of plantar contact during gait were more asymmetrical in the total hip arthroplasty cohort than in healthy females. Early-phase rehabilitation post-total hip arthroplasty should address these asymmetries.