Effects of carbon fiber custom dynamic orthosis proximal cuff design on foot loading during gait: A pilot study

Limb trauma can result in decreased mobility, compensatory gait patterns, and pain. Carbon fiber custom dynamic orthoses (CDOs) include a cuff below the knee, posterior strut, and semi-rigid footplate. Custom dynamic orthoses alter foot loading within the footplate, but the effects of cuff design are not well understood. The purpose of this study was to determine the effect of cuff design on foot loading. Five individuals without, and 1 individual with, lower limb injury completed testing without a CDO and with a CDO with 3 different cuff designs. Loadsol insoles (Novel Electronics, St Paul, MN) were placed under the foot in the shoe or in the CDO footplate to measure peak forces and force impulse of the total foot, hindfoot, midfoot, and forefoot. No significant differences were observed with post-hoc paired sample t tests ( p > 0.05). Compared to walking without an orthosis, peak forces decreased in the CDO (11%-16% hindfoot, 20%-36% midfoot, 21%-29% forefoot). Effect sizes were medium to large when comparing with and without a CDO ( d = 0.56-1.97) and small to large when comparing between cuffs ( d = 0.24-2.99). Hindfoot force impulse increased with all cuffs (14%-29%), with medium effect sizes ( d = 0.51-0.78). The patellar tendon bearing cuff with ratcheting closure mechanism generally resulted in the greatest changes in peak forces and force impulse. Study data demonstrate the potential importance of cuff design on foot loading. The largest effects were generally observed with use of a patellar tendon bearing design with ratcheting closure mechanism.