Effect of the degree of hip osteoarthritis on equilibrium ability after sudden changes in direction.

This research addressed the effect of hip osteoarthritis severity on equilibrium ability after sudden changes in direction among 20 healthy elderly people, 20 with moderate hip osteoarthritis (mOA), and 20 with severe hip osteoarthritis (sOA). The Lehr's damping ratio calculated from testing while standing on both limbs (D(elderly)(both)=0.466±0.033; D(mOA)(both)=0.436±0.055; (D(sOA)(both)=0.346±0.055) did not differ significantly from results of testing while standing on the dominant limb in healthy subjects (D(elderly)(dom)=0.413±0.036) and on the unaffected limb in patients with varying degrees of osteoarthritis (D(mOA)(dom)=0.408±0.064,D(sOA)(dom)=0.309±0.060). Results from testing during standing on the non-dominant limb in healthy subjects (D(elderly)(non-dom)=0.302±0.039) and on the affected limb in patients with osteoarthritis (D(mOA)(affected)=0.219±0.068, D(sOA)(affected)=0.135±0.071) differed significantly from the results of the other two scenarios, indicating that the healthy side is dominant. In cases of sOA, equilibrium ability decreased with standing on both limbs or on the healthy limb compared to the control group and to the patients with mOA. Furthermore, an increased degree of hip osteoarthritis significantly decreased equilibrium ability on the affected side after sudden changes in direction, based on a comparison of the affected side in patients with sOA to the affected side in patients with mOA. Deterioration of equilibrium ability may indicate an increased risk of falling.