Walking boot for diabetic and other patients

Abstract

An orthopedic walking boot promotes rapid healing of diabetic foot ulcerations by lowering the maximum peak pressure imposed upon the foot. The walker has a hard unyielding shell which is designed for walking. The shell closely and rigidly supports a mid-sole in a foot-shaped bed. The mid-sole has a foot-shaped cavity with rounded sides adapted to form resilient support for the heel, arch and sides of a foot in addition to the bottom of a foot. A conformable inner-sole is adapted to fit over the foot-shaped cavity in the mid-sole and be compressed in response to foot pressure between the sides and bottom of the foot and the sides and bottom of the foot-shaped cavity in the mid-sole thereby compensating for small differences between the shape of the foot and the shape of the cavity. Weight applied to the foot is transferred to the walking shell by contact between the sides of the foot, arch, and heel and the arch, heel and sides of the foot-shaped cavity as well as the bottom of the cavity thereby decreasing the peak or maximum unit pressure on the plantar surface of the foot. A breathable bootie which wraps the foot and lower leg in a protective “cocoon” is preferably secured to the upper surface of the insole thereby preventing foreign materials from entering the foot cavity.

What is claimed:  
     
         1 . An improved walking boot, comprising: 
 a walking shell having an inner and an outer surface wherein the outer surface is a walking surface and the inner surface is a foot bed designed to receive and support a mid-sole;    a premolded mid-sole having a lower outer surface mounted on the foot bed, the mid-sole having an upper surface comprising a foot shaped cavity having a bottom surface with upwardly curving sides which rise to a foot shaped opening;    an inner-sole having a foot receiving upper surface and a bottom surface adapted to fit over the upper surface of the mid-sole, the inner-sole having a self-molding characteristic in response to pressure from a foot that allows the inner-sole to mold itself closely to a foot and tightly against the upwardly curving walls of the mid-sole; and    whereby support for a foot is provided around the heel and sides of the foot as well as under the foot.    
     
     
         2 . An improved walking boot according to  claim 1 , wherein: 
 the mid-sole has a lower outer surface, which is supported by the inner surface of the walking shell to prevent spreading of the mid-sole by contact between the mid-sole and the inner surface of the walking shell in response to foot pressure.    
     
     
         3 . An improved walking boot according to  claim 2 , wherein: 
 the walking shell has upwardly turned edges along at least the sides and heel areas which provide support to the lower outer surface of the mid-sole to prevent spreading of the mid-sole.    
     
     
         4 . An improved walking boot according to  claim 2 , wherein: 
 the mid-sole is secured to the walking shell against sliding of the mid-sole relative to the walking shell.    
     
     
         5 . An improved walking boot according to  claim 1  wherein the inner-sole is secured to the mid-sole in a manner that prevents shifting movement.  
     
     
         6 . An improved walking boot according to  claim 1 , wherein: 
 the inner-sole has a peripheral flange extending laterally substantially all around the foot shaped opening; and    a durable and resilient soft support comprising a protective bootie for extending around the lower leg and foot wherein the bootie has an open bottom having bottom edges secured to the peripheral flange of the inner-sole to restrict hard foreign objects from reaching the foot.    
     
     
         7 . An improved walking boot according to  claim 1 , wherein: 
 the mid-sole is formed from material having the characteristic that it will rebound from pressure force and will not take a compression set; and    the inner-sole is formed from a soft spongy material having the characteristic that it does not readily rebound from pressure force and will take a compression set in response to foot pressure.    
     
     
         8 . An improved walking boot according to  claim 7 , wherein: 
 the inner-sole comprises an elastomeric foam material having a skinned outer surface.    
     
     
         9 . An improved walking boot according to  claim 1 , wherein: 
 the mid-sole is formed from material having the characteristic that it will rebound from pressure force and will not take a compression set thereby essentially retaining its premolded shape after use.    
     
     
         10 . An improved walking boot according to  claim 8 , wherein: 
 the cross-sectional thickness of the mid-sole is selected to be a lesser thickness under those parts of the foot having bony protrubences, as opposed to other boney parts of the foot cushioned with more tissue, thereby minimizing leg height differential and any relative motion between the foot and sides of the foot shaped cavity supporting the foot caused by periodic compression of the mid-sole in response to foot loading while walking.    
     
     
         11 . An improved walking boot according to  claim 9 , wherein: 
 the foot shaped opening is nearly the size of a selected average foot, but larger than the projected shape of said foot onto a flat surface and wherein the size and shape of the foot shaped cavity is selected so that the foot is preloaded along the sides before the foot is loaded on the bottom.    
     
     
         12 . An improved walking boot according to  claim 10 , further including: 
 a durable and resilient soft protective bootie secured to the inner-sole and extending around the lower leg and foot to protect the foot from injury and enclose the foot to prevent extraneous particles of foreign material from entering the area where the foot is protected.    
     
     
         13 . An improved walking boot according to  claim 11 , wherein: 
 the walking shell has an outer lower surface which is closely supported unyieldingly on the bottom and sides by the foot-shaped bed of the walking shell to prevent spreading of the mid-sole in response to foot pressure in the foot-shaped cavity.    
     
     
         14 . An improved walking boot, comprising: 
 a walking shell having an inner surface having an upturned edge portion which forms an unyielding foot-shaped bed adapted to support a mid-sole;    a mid-sole supported in the foot-shaped bed, the mid-sole having a foot-shaped cavity with rounded sides adapted to provide form resilient support for the heel and sides of a foot in addition to the bottom of a foot;    a conformable inner-sole adapted to fit over the foot-shaped cavity in the mid-sole and be compressed in response to foot pressure between the sides and bottom of the foot and the sides and bottom of the foot-shaped cavity in the mid-sole thereby compensating for small differences between the shape of the foot and the shape of the cavity; and    whereby weight applied to the foot is transferred to the walking shell by contact between the sides of the foot and heel and the sides of the foot-shaped cavity as well as the bottom of said cavity.    
     
     
         15 . The improved walking boot of  claim 14 , wherein: 
 the mid-sole has an outer lower surface which is supported closely and unyieldingly on the bottom and sides by the foot-shaped bed of the walking shell to prevent spreading of the mid-sole in response to foot pressure in the foot shaped cavity.    
     
     
         16 . The improved walking boot of  claim 15  wherein: 
 the upturned edge portion and inner surface of the walking shell extends around the heel and sides of the foot shaped bed and wherein the lower outer surface of the mid-sole and the inner surface of the foot-shaped bed are surfaces conforming with each other to provide firm unmoving support for the mid-sole.  
 
     
     
         17 . The improved walking boot of  claim 14  wherein: 
 the mid-sole is premolded with the foot-shaped cavity, from material having the characteristic that it will rebound from pressure force and will not take a compression set thereby essentially retaining its premolded shape after use.  
 
     
     
         18 . The improved walking boot of  claim 17  wherein: 
 the cross-sectional thickness of the mid-sole is selected to be a lesser thickness under those parts of the foot having bony protrubences, as opposed to other boney parts of the foot cushioned with more tissue, thereby minimizing leg height differential and any relative motion between the foot and sides of the foot shaped cavity supporting the foot caused by periodic compression of the mid-sole in response to foot loading while walking.  
 
     
     
         19 . The improved walking boot of  claim 17 , wherein: 
 the foot shaped cavity has a foot shaped opening nearly the size of a selected average foot, but larger than the projected shape of said foot onto a flat surface and wherein the size and shape of the foot shaped cavity and the thickness of the conformable inner-sole are selected so that the foot is preloaded along the sides before the foot is fully loaded on its bottom.    
     
     
         20 . The improved walking boot of  claim 19  wherein the conformable inner-sole is secured to the mid-sole.  
     
     
         21 . The improved walking boot of  claim 20  wherein: 
 the conformable inner-sole is secured to the mid-sole by means of a peripheral flange which extends laterally outwardly relative to the foot-shaped opening of the mid-sole.  
 
     
     
         22 . The improved walking boot of  claim 21  further including a durable and resilient soft protective bootie adapted for extending around the lower leg and foot and having an open bottom portion having sides all around the foot that are secured to the peripheral flange of the inner-sole to form a soft protective bootie around the foot and lower leg.  
     
     
         23 . The improved walking boot of  claim 19 , further including: 
 a durable and resilient soft protective bootie secured to the inner-sole and extending around the lower leg and foot to protect the foot from injury and enclose the foot to prevent extraneous particles of foreign material from entering the area where the foot is protected.    
     
     
         24 . An improved walking boot, comprising: 
 a walking shell having an inner surface having an upturned edge portion which forms an unyielding foot-shaped bed adapted to support a mid-sole;    a mid-sole supported in the foot-shaped bed, the mid-sole being premolded to form a foot-shaped cavity with upwardly and outwardly rounded sides to form a resilient but non-compressively setting support for the sides of a heel and sides of a foot in addition to the bottom of a foot;    a conformable inner-sole formed from pliable but compressibly settable material wherein the conformable inner-sole is adapted to fit over the foot-shaped cavity in the mid-sole and be compressed in response to foot pressure between the sides and bottom of the foot and the sides and bottom of the foot-shaped cavity in the mid-sole thereby compensating for small differences between the shape of the foot and the shape of the foot-shaped cavity;    whereby weight applied to the foot compresses and molds the conformable inner-sole to fit tightly between the heel and sides of the foot thereby preloading the foot along the heel and the sides of the foot before the foot is fully loaded by fully compressing the inner-sole and the mid-sole at the bottom of the cavity.    
     
     
         25 . An improved walking boot according the  claim 24  wherein the foot-shaped cavity in the mid-sole has a foot-shaped opening near the size of a selected average foot and where the size and the shape of the foot-shaped cavity and the thickness of the conformable inner-sole are selected to assure that the foot is preloaded along the sides of the foot-shaped cavity before the foot is fully loaded on its bottom.  
     
     
         26 . An improved walking boot according to  claim 25  wherein the conformable inner-sole comprises an elastomeric foam having a skinned outer surface to prevent penetration by moisture or other liquids.  
     
     
         27 . An improved walking boot according to  claim 25  wherein the cross sectional thickness of the mid-sole in the highly loaded areas under the heel and ball of the foot are selected to be a minimum thickness in order to minimize leg height differential and any relative motion tending to be caused by compression of the mid-sole, which might occur between the foot and sides of the foot-shaped cavity supporting the foot, arising because of periodic compression of the mid-sole in response to foot loading while walking.  
     
     
         28 . An improved walking boot according to  claim 27  further including a durable and resilient soft protective bootie secured to the inner-sole and extending around the lower leg and foot to protect the foot from injury and enclose the foot to prevent extraneous particles of foreign material from entering the area where the foot is protected.  
     
     
         29 . The improved walking boot according to  claim 28  wherein the mid-sole has an outer lower surface which is closely supported unyieldingly on the bottom and sides by the foot-shaped bed of the walking shell to prevent spreading of the mid-sole in response to foot pressure in the foot-shaped cavity.  
     
     
         30 . The improved walking boot according to  claim 29  wherein the walking shell has a pair of upstanding struts which serve to secure the walking boot and bootie on the leg of the wearer.  
     
     
         31 . A method of supporting an injured foot, comprising: 
 providing a walking shell having inner and outer surfaces wherein the outer surface is a walking surface and the inner surface is a foot bed designed to receive and support a mid-sole;    mounting a premolded mid-sole in the foot-bed, the mid-sole having a foot shaped cavity having a bottom surface with upwardly curving sides which rise to a foot shaped opening;    placing a self-molding inner-sole having a foot receiving upper surface and a bottom surface adapted to fit over the upper surface of the mid-sole in a manner that allows the inner-sole to conform itself closely to a foot and fit tightly against the upwardly curving walls of the mid-sole;    placing a foot on the foot receiving upper surface of the self-molding inner-sole over the foot receiving cavity in the mid-sole; and    putting weight on the foot, thereby conforming and compressing the self-molding inner-sole closely against the foot between the bottom and sides of the foot and the foot-shaped cavity to shift some of the weight to the side portions of the foot before the bottom of the foot is loaded, thereby minimizing unit pressure applied to the foot.    
     
     
         32 . The method of  claim 31 , wherein: 
 the step of providing a walking shell having a foot bed and mounting a premolded mid-sole in the foot bed are accomplished by providing conforming mating surfaces where the mid-sole contacts the foot bed; and    the step of putting weight on the foot is not accompanied by the step of spreading the mid-sole outwardly in response to the weight.    
     
     
         33 . The method of  claim 32 , wherein: 
 the step of mounting a premolded mid-sole in the foot-bed comprises includes the step of providing a mid-sole prepared from a material having the characteristic of yielding without taking a compression set; and    the step of putting weight on the foot is accompanied by the step of some non-permanent yielding of the mid-sole which is substantially less than the compression of the self-molding inner-sole in conforming to the foot in response to loading applied to the inner-sole by the foot.    
     
     
         34 . The method of  claim 33  further comprising the step of surrounding the lower leg and foot with a durable and resilient soft protective bootie.  
     
     
         35 . The method of  claim 34  further including the step of protecting the foot from hard foreign particles which may be encountered when walking by securing the self-molding inner-sole to the bottom portion of the protective bootie.