To highlight the congruence of clinical and posturographic tests in patients undergoing hip arthroplasty.

Ten patients (six males and four females) were included in this study and tested at admission and at discharge from the rehabilitation department (12 and 27 days after surgery, respectively). The patients were asked to stand undisturbed in the upright position, eyes closed, on a system composed of two force platforms. Five successive 32-s trials (sampled at 64 Hz) were conducted with rest intervals of similar duration between trials. The plantar center of pressure (CP), displacements, and resultant CP (CP_Res) were then computed and analyzed in various ways. In parallel, various clinical tests, including muscular force, hip range of motion, walking speed, functional independence, pain, sensitivity, lateral reach, and get up and go aimed at evaluating global coordination. Correlations, using the nonparametric Spearman coefficient, were computed from the differences between clinical and posturographic parameters obtained at admission and discharge from the rehabilitation department.

Certain statistically significant differences in postural behavior were observed both for clinical and posturographic tests between admission and discharge. Body weight distribution over both legs was largely asymmetric at onset and, though it declined, persisted at discharge. There was no difference for the mean positions of both the plantar CP and the resultant of the CP movements. On the other hand, it was noteworthy that the variances of CP displacements (data dispersion) were initially larger on the sound leg along the anteroposterior axis and that this compensatory feature disappeared at the end of the stay. At discharge, the variances computed from the sound and the prosthetic limbs became equivalent. All the clinical tests demonstrated statistically significant improvements in results at discharge compared with admission. Several significant correlations involving clinical tests and mean positions along the anteroposterior axis, the degree of body weight asymmetry, and variances along both the mediolateral and anteroposterior axes were found.

These results provide a better understanding of the strategies used by hip arthroplasty patients to keep balance. Even though their sensitivity was quite different, both clinical and posturographic measurements demonstrated their ability to assess recovery from surgery. These two evaluation techniques are complementary.