The static balance following total hip arthroplasty

The purpose of this study was to investigate the standing balance recovery process of patients underwent unilateral total hip arthroplasty (THA) surgery. Twenty three subjects with unilateral THA participated in this study and center of pressure (CoP) and bilateral weight bearing symmetry was measured under 8 stance conditions which was a combination of 4 foot placements and 2 visual conditions. The CoP sway magnitude was greater at 2 and 6 weeks after surgery than that before surgery and reached peak at 3 months after surgery. The CoP sway magnitude began to decline at 6 months after surgery and that at 1 year after surgery was less than before surgery significantly. The load under the affected limb was greater than that under the non-affected only at 6 month after surgery except when the patients adopted tandem stance with the affected limb in the back. Clinicians and the patients should be advised of the unstable and asymmetry stance during one year after surgery even though the stance stability seemed improving gradually at 6 months after surgery. Before 6 month after surgery, patients still avoid to bear weight onto the affected limb while standing and this habit seemed to last at least for one year, especially when the challenges on balance increased by change of foot configurations.