Article

Reduced-stiffness components are often prescribed in lower-limb
prostheses, but their efficacy in augmenting shock absorption has been
inconclusive. OBJECTIVES: To perform a systematic variation of longitudinal
prosthetic stiffness over a wide range of values and to evaluate its effect on
shock absorption during gait. STUDY DESIGN: Repeated-measures crossover
experiment. METHODS: Twelve subjects with a unilateral transtibial amputation
walked at normal and fast self-selected speeds. Longitudinal prosthetic stiffness
was modified by springs within a shock-absorbing pylon: normal (manufacturer
recommended), 75% of normal (medium), 50% of normal (soft), and rigid
(displacement blocked).
The variables of interest were kinematic (stance-phase
knee flexion and pelvic obliquity) and kinetic (prosthetic-side ground reaction
force loading peak magnitude and timing). RESULTS: No changes were observed in
kinematic measures during gait. A significant difference in peak ground reaction
force magnitudes between medium and normal ( p = 0.001) during freely selected
walking was attributed to modified walking speed ( p = 0.008). Ground reaction
force peaks were found to be statistically different during fast walking, but
only between isolated stiffness conditions. Thus, altering longitudinal
prosthesis stiffness produced no appreciable change in gait biomechanics.
CONCLUSION: Prosthesis stiffness does not appear to substantially influence shock
absorption in transtibial prosthesis users. Clinical relevance Varying the level
of longitudinal prosthesis stiffness did not meaningfully influence gait
biomechanics at self-selected walking speeds. Thus, as currently prescribed
within a transtibial prosthesis, adding longitudinal stiffness in isolation may
not provide the anticipated shock absorption benefits. Further research into
residual limb properties and compensatory mechanisms is needed.

Langue : ANGLAIS