The effect of existing and novel walker boot designs on offloading and gait mechanics.

BACKGROUND: Orthopedic walker boots are often used to treat foot ulcers and other wounds with the goal of offloading plantar pressure. However, poor ulcer healing outcomes and high recurrence rates show a need for additional solutions in the growing diabetes epidemic. We compared a novel spring-loaded walker boot to a traditional rigid ankle boot and a hinged ankle boot as well as a control shoe. Our aim was to better understand how boot design affects offloading mechanisms. We hypothesized that all boots would offload force from the foot to the shank, but that the hinged boot would have fewer gait alterations and the spring boot would further reduce pressure in early and late stance.

METHODS: Ten healthy participants tested each of the four conditions in static stance and walking gait. Offloading was quantified by the difference between pressure insole and platform forces, while joint mechanics changes were calculated from instrumented gait analysis and inverse dynamics.

RESULTS: Minimal offloading was found in the rigid and hinged boots compared to athletic shoes. In contrast, the spring boot offloaded nearly 50% of total load in static stance, with similarly large reductions in peak pressures during gait, particularly under the hindfoot during early stance. All boots resulted in some ankle joint mechanics compensations, with the rigid and spring boots showing similar restrictions in ankle motion and propulsive work. While the hinged boot resulted in ankle mechanics more like the shoe condition, it increased dorsiflexion and negative work, suggesting energetic inefficiency.

CONCLUSIONS: The novel spring boot shows promise for more effective offloading that could lead to improved healing outcomes.