Leg loading during quiet standing and sit-to-stand movement for one year after total hip arthroplasty.

BACKGROUND: The objective of the present study was to investigate loading of the operated leg during quiet standing and sit-to-stand (STS) movement for 1 year after total hip arthroplasty (THA).

METHODS: One hundred and fifty-eight patients with end-stage hip osteoarthritis (OA) who had undergone unilateral primary THA participated in this study. The load distribution on the operated and non-operated legs was computed by measuring the vertical reaction force of the operated and non-operated legs during quiet standing and STS movement. We investigated the load distribution using Pressure Distribution Measurement Platform preoperatively and 1, 2, 3, 6, and 12 months postoperatively.

FINDINGS: Loading of the operated leg during quiet standing was restored 1 month postoperatively. Loading of the operated leg during STS movement was higher within 2 months postoperatively than the preoperative levels and continued to increase 1 year postoperatively. Loading of the operated leg was lower during STS movement than that during quiet standing, even 1 year postoperatively.

INTERPRETATION: A longitudinal and dynamic assessment of loading of the operated leg after THA is clinically important, and the loading during STS movement might continue to increase for a year after THA.