Ambulatory protective device
An ambulatory protective device is configured to be worn on a person's foot who has a foot condition, such as a diabetic foot condition. The ambulatory protective device includes an insole which has viscoelastic inserts located and otherwise disposed relative to non-viscous polymeric foam strata to create zones or areas on the insole characterized by reduced force or contact pressure when subjected to forces from the foot during ambulation when the ambulatory protective device is worn. Such contact-pressure reducing areas are located in the heel area and the forefoot area of the device. The ambulatory protective device, equipped with such insole, may be in the form of a shoe, boot, brace, cast, or walker, such as a CAM walker.
1 . An ambulatory protective device for wearing on a person's foot with a diabetic condition, the device comprising:
an insole located in the device and extending in length and width sufficient to form a footbed having forefoot and heel areas sized to receive thereon a forefoot and a heel, respectively, of a user, when the device is worn on the foot, whereby the insole has an unloaded state when not bearing weight associated with the wearer, and a maximum loaded state when bearing a preselected maximum weight to be associated with the wearer;
wherein the insole includes at least first, second, and third overlying layers, the first and third layers consisting essentially of non-viscous, resiliently compressible foam;
wherein the second layer is disposed between the first and third layers, the second layer having a stratum of non-viscous, resiliently compressible foam, the second layer having two chambers defined in the stratum by respective, inwardly facing perimeter walls, the chambers positioned at the forefoot and the heel areas of the footbed, respectively;
wherein the insole includes two, viscoelastic inserts, each of the inserts received in respective ones of the chambers, the viscoelastic inserts having respective outer perimeters and corresponding circumferences, the outer perimeters spaced about their respective circumferences from the inwardly facing perimeter walls of respective ones of the chambers to form a gap between the inserts and the inwardly facing perimeter walls;
wherein the gap has a dimensional value when the insole is in an unloaded state, the dimensional value of the gap in the unloaded state being preselected to maintain spacing between the outer perimeters of the viscoelastic inserts and the inwardly facing perimeter walls of the chambers when the insole is subjected to a predetermined, maximum weight associated with the person;
whereby, when the device is worn during ambulation, in response to a given compressive force on the forefoot area and heel area of the footbed, the corresponding insert compresses more slowly during a given unit of time than portions of the stratum adjacent the corresponding insert, and in response to lessening of a given compressive force during toe-off phase of the ambulation, the insert rebounds more quickly per the given unit of time than the portions of the stratum adjacent the corresponding insert; and
whereby the heel area and the midfoot area of the footbed experience at least 30% less average maximum pressure over the given unit of time than if the footbed were without the insole.
2 . The ambulatory protective device of claim 1 , comprising:
a frame extending from the footbed, the frame comprising posterior and anterior portions, and configured to control ankle movement of the lower extremity, the frame having distal and proximal ends adapted to operatively engage portions of the foot and calf of the user, respectively;
an anterior ankle-foot orthosis configured to be selectively fittable to, and manually removable from, the anterior portion of the frame;
wherein the anterior ankle-foot orthosis comprises a longitudinally extending stay and at least one pair of transversely extending fingers; and
wherein the at least one pair of transversely extending fingers comprise finger engagement areas; and
wherein the proximal end of the frame comprises engagement portions located to oppose the finger engagement areas when the anterior ankle-foot orthosis is fitted to the frame.
3 . The ambulatory protective device of claim 2 , wherein the device further comprises a collar assembly configured to be selectively fittable to, and manually separable from, the proximal end of the frame.
4 . The ambulatory protective device of claim 3 , wherein the frame and footbed are configured to receive a lower-extremity, brace device.
5 . The ambulatory protective device of claim 4 , wherein the brace device is selected from the group consisting of a cast, a splint, and a bandage.
6 . The ambulatory protective device of claim 5 , wherein the brace device is interposed between the collar assembly and the lower extremity when worn on the lower extremity and received in the frame, and wherein the collar assembly has an engagement area oriented and configured such that when the collar assembly is fitted to the proximal end of the frame, the engagement area contacts an opposing surface of the brace device.
7 . The ambulatory protective device of claim 6 , wherein a distance between the distal and proximal ends of the frame define a first lever arm having a first length, wherein the frame is configured to reduce force on the foot during gait as a function of the first lever arm, and wherein the engagement area is configured to extend to locations proximal to the proximal end of the frame and to engage the brace device at said locations to define a second lever arm having a second length greater than the first length, thereby reducing force on a plantar surface of the foot when received in the ambulatory protective device.
8 . The ambulatory protective device of claim 1 , wherein the first layer consists essentially of ethylene vinyl acetate and the third layer consists essentially of polyurethane.
9 . The ambulatory protective device of claim 8 , wherein the ethylene vinyl acetate exhibits the following physical properties under associated ASTM test methods: compression set of 30%+/−10%, rebound of 46%+/−5%, split tear of 8.4 pounds per inch+/−4 pounds per inch, tensile strength of 21 psi+/−10 psi, elongation of 100-150%, density of 11 pounds per cubic foot+/−1.5 pounds per cubic foot.
10 . The ambulatory protective device of claim 1 , wherein the viscoelastic inserts consist essentially of a gel having a viscosity ranging between 350 to 450 centipoise.
11 . The ambulatory protective device of claim 10 , wherein the gel exhibits the following physical properties under associated ASTM testing methodologies: compression set of 10%+/−1%, rebound of 5%+/−1%, split tear of 11.2 lbs per inch+/−1 lb per inch, tensile strength of 14.06 psi+/−1 psi, elongation of 300%+/−10%, and density of 80 lbs per cubic foot+/−3 lbs per cubic foot.
12 . The ambulatory protective device of claim 1 , wherein the ambulatory protective device is selected from the group consisting of a CAM walker, a protective shoe, a protective boot, a brace, and a cast.