Several studies reported better clinical results with total hip resurfacing than with conventional total hip replacement, including in young patients, but without comparative stabilometry assessment.

Resurfacing arthroplasty provides better functional performance than conventional total hip replacement.

To test the above hypothesis in a stabilometry study comparing balance and functional performance in patients with total hip resurfacing or conventional total hip replacement and healthy controls.

Results were analyzed on three cohorts of 20 patients: healthy control subjects, with unilateral total hip replacement or unilateral total hip resurfacing. The 40 operated patients were comparable in gender, age, weight (body-mass index), date of operation and clinical results. The 20 control subjects were younger and served as reference. Balance analysis employed a force platform commonly used in stabilometry, standardizing both leg or single leg stance balance analysis. The software interpreted individual balance by measuring plantar pressure center variation during the analysis so as to contour an individual both leg or single leg area of balance (statokinesigram, in mm²).

Balance analysis on both leg found comparable results in the control and resurfacing groups. The weight-bearing statokinesigraphic both leg balance area was greater in the hip replacement than in either of the other two groups (p<0.05), and five times greater than in the resurfacing group (p<0.05). The single leg weight-bearing balance results were significantly better in the resurfacing group, with a statokinesigraphic balance area half that of the hip replacement group, whether on the operated or the non-operated side (p<0.001).

The present functional performance results confirm the advantage of resurfacing over conventional hip replacement, and help explain the excellent radioclinical results reported for total hip resurfacing.

III, comparative case-control study.