Introduction: A key to the analysis of function after joint replacement is the ability to identify gait adaptations specific to design features. In a prospective controlled design, we evaluated mechanics of gait in the hip joint after total hip replacement (THR) with use of two different types of implants. We also investigated whether adaptations to gait normalized postoperatively.

Material and Methods: Thirty patients were randomized to receive a hip resurfacing system (HRS group) or conventional hybrid prosthesis (MHE group). Twenty-22 patients underwent three-dimensional gait analysis 6 and 12 weeks postoperatively. To evaluate normalization of gait parameter variables in the hip joint after THR, we used data from 22 age- and sex-matched healthy controls.

Results: We found similar postoperative improvements in mechanics of gait in the hip joint between the groups, except for peak abductor moments, which improved more in the MHE group. HRS and MHE groups were similar with respect to level of peak values. Three months after surgery, most peak values were significantly different between operated and non-operated hip in all THR patients. Mean curves of kinetic and kinematic variables of THR patients and healthy controls showed that gait adaptations in the hip joint were not normalized after 3 months.

Conclusion: We found no evidence for the hypothesis that one implant was superior to the other in normalizing gait adaptation. Although THR patients improved considerably and significantly in almost all gait parameter variables of the hip, gait impairments persisted. Our results may indicate the need of gait retraining in conjunction with intensive muscle strengthening to improve function and longevity of implants, especially among young patients.