Providing appropriate prosthetic feet to those with limb loss is a complex and subjective process influenced by professional judgment and payer guidelines. A team of researchers has conducted what they say is the first randomized double blind study in which prosthetic users have expressed a preference for a specific biomechanical characteristic of prosthetic feet: participants preferred the “compliant” category of prosthetic feet over the “stiff” and “intermediate” feet. The results were published in the January 2015 issue of the Journal of Biomechanics.
The study used three complementary domains to evaluate prosthetic feet: the biomechanical domain, the activity domain, and the perceptual domain. The Orthocare Innovations Europa™ load cell was used at the base of the socket to measure the sagittal moments during walking with three categories of prosthetic feet in 11 individuals with transtibial limb loss and functional levels of K2, K3, or K4. Functional level was determined subjectively by the clinical prosthetist and objectively using the Orthocare Innovations Galileo. Forefoot stiffness and hysteresis characteristics defined the three objective foot categories: stiff, intermediate, and compliant. Prosthetic feet were randomly assigned and blinded from participants and investigators. After laboratory testing, participants completed one week of community wear tests followed by a modified prosthetics evaluation questionnaire to determine if a specific category of prosthetic feet was preferred.
The study provides some evidence that amputees can detect specific biomechanical characteristics of prosthetic feet. It concludes that this small cohort of prosthetic users with transtibial limb loss preferred compliant feet with lower peak sagittal moments during gait, but did not increase their activity level when using these feet, nor reduce activity when using nonpreferred prosthetic feet. The authors note that a larger, multisite, randomized double blind trial is warranted to determine if this preliminary result can be replicated over a broader range of participants and with more rigorous categorization of prosthetic feet.