Changes in Plantar Forces and Pressures During Functional Movement with an Intrepid Dynamic Exoskeletal Orthosis Brace

Abstract

Category: Ankle; Ankle Arthritis; Midfoot/Forefoot; Trauma Introduction/Purpose: Non-surgical interventions such as bracing using ankle foot orthoses (AFO) aim to assist, restore and redirect weightbearing forces with immobility in mind. We identified a custom carbon fiber specific energy storing AFO that was created to improve functional performance in veterans after limb salvage procedures. While being evaluated exclusively in a veteran population, the Intrepid Dynamic Exoskeletal Orthosis (IDEO) has also been indicated to be a conservative treatment option for veterans with posttraumatic osteoarthritis of the tibiotalar and subtalar joints. To evaluate the off-loading properties of the IDEO brace in a civilian population with osteoarthritis of the ankle. Methods: Eight civilian patients 18-years or older who were prescribed an IDEO brace by a single surgeon participated in the study. Foot pressure data were recorded using Tekscan F-Scan system, an ultra-thin, in-shoe sensor that provides force and pressure information. Participants were instructed to walk at a self-selected pace along a 20 meter walkway under three conditions. Using F-Scan Research software, the stances were identified and averaged. Then, the forefoot and heel areas were identified. Next, the maximal force, force*time integral (FTI), maximal contact area, maximal contact pressure, pressure*time integral (PTI), and center of force (COF) excursion were calculated. One-way ANOVA with repeated measures was performed to detect effects of the condition (three levels: Without, Under and Over). Pairwise comparison with least significant difference (equivalent to no adjustments) was performed to detect difference among the conditions. Results: Compared to the Without condition, the Under condition showed higher pressure in both the heel and the forefoot areas (especially in the forefoot) in most subjects; COF excursion was increased in some subjects. Compare to the Without condition, the Over condition showed reduced pressure in both the heel and the forefoot areas (especially in the forefoot) in most subjects. The statistical results below only included the involved side of the six subjects who were tested in all three conditions. Table 1 showed the results of one-way ANOVA with repeated measures of the six subjects. Conclusion: The results of this study showed that the IDEO is effective in improving gait function and relieving forefoot pressure in the civilian population. IDEO generated force (and thus power), especially in the forefoot area in late stance, to provide more push-off power and propel the body moving forward. While acting as a functional foot, the IDEO reduced force by 66% and reduced pressure by 49% in the forefoot area, which helped to relieve pain. IDEO creates functional foot by storing power in the early stance and release power in late stance.