Hip arthrodesis: kineatic and kinetic effects in locomotion

The effects of hip arthrodesis on the gait of two subjects with particular attention to the temporal and sagittal plane kinematic and kinetic characteristics are reported. Each subject had a painless arthrodesis and no other gait limitation. To compensate for their disability they showed reduced step lengths and speed of progression, altered angular displacement patterns at the ipsilateral knee and ankle, at the contralateral hip joint, and exaggerated anteroposterior pelvic tipping. Resultant joint moments at the ipsilateral ankle joint were reduced while the effective moment between the thigh and trunk was of approximately normal magnitude. The effects of this repetitive and strong muscle activity on the lower back may be detrimental to these structures over time. Overall these subjects compensate effectively for the loss of hip joint motion. This work provides quantitative information about the effects of unilateral hip arthrodesis on walking. Temporal, kinematic, and kinetic compensations are described, which may provide insights into the treatment, rehabilitation, and functional evaluation of these patients.