To assess the effects of a hydraulic ankle unit on the symmetry of its user’s gait pattern, a research team evaluated the duration of stance phase and the difference in dominant and nondominant sides among a group of participants. Results of the study, published in the January 2016 issue of the Journal of Prosthetics and Orthotics (JPO), found a statistically significant reduction in the asymmetry of stance phase duration when participants used a prosthesis that included a foot with a hydraulic ankle unit. The improvement was irrespective of the patient’s activity level.
The 22 participants had a K2 or K3 activity level and were due to have their prosthetic feet upgraded to feet with hydraulic ankle units. Each person’s gait was assessed on a pressure plate to establish the difference in stance phase duration between their dominant and nondominant foot, then reassessed on the pressure plate after a four-week trial of the feet with hydraulic ankle units. The difference in stance phase durations was again measured and compared with the initial readings.
Of the 22 patients originally assessed, six were removed from the case series because of rejection of the device or incompatibility with the pressure measurement equipment. Of the remaining 16 patients, the difference in stance phase timing increased in two patients, remained unchanged in two patients, and decreased for 12 patients.