Postural balance during quiet standing in patients with total hip arthroplasty with large diameter femoral head and surface replacement arthroplasty.

Abstract

To compare postural balance between patients who have had either a large diameter head total hip arthroplasty or surface replacement arthroplasty. Observational study. Outpatient biomechanical laboratory. Two groups of 14 patients with surface replacement or large diameter head total hip arthroplasties recruited from a larger randomized study and 14 control subjects. Not applicable. Postural balance during quiet standing in dual and one-leg stance (operated leg), hip abductor muscle strength, clinical outcomes, and radiographic analyses were compared between groups. Compared to the control group, patients in both groups showed smaller center of pressure displacement amplitude in the medial-lateral direction in dual stance. Patients with large diameter head total hip arthroplasty showed lower hip abductor muscle strength compared to control subjects. There was statistical difference between the 2 patient groups in biomechanical reconstruction of the hip. Despite these differences, there was no significant difference in the ability to complete the one-leg stance task between the 3 groups. The muscular strength in the operated limb could be mainly responsible for the lower center of pressure displacement amplitude compared to control subjects. However, the ability to complete the one-leg stance demonstrates that patients do not fear to load the hip prosthesis when needed. The large diameter femoral head may be a major mechanical factor contributing to these results.