US 3905135 A
An adjustable size boot for covering a surgical foot cast. The boot is of bendable construction and comprises an insole of resilient, closed cell sponge laminated to a waterproof sponge out sole. The boot is attachable to the cast by means of a single piece upper fully covering the sides and heel portions of the cast and provided with a cushion adapted to protect the heel of the cast from impact forces.
Description (OCR text may contain errors)
United States Patent [191 Debusk 1 Sept. 16, 1975 [5 1 BOOT FO A FOOT CAST  Inventor: Autrey O. V. Debusk, 7324 Afton 'Dr., Knoxville, Tenn. 37918  Filed: July 10, 1974  Appl. No.: 486,993
 U.S. Cl 136/25 R  Int. Cl. A43B 00/00  Field of Search 36/7.1 R, 7.1 A, 8.1, 11.5, 36/25 R  References Cited UNITED STATES PATENTS 2,725,648 12/1955 Kirk et al. 36/25 R 3,566,487 3/1971 Beightol 336/25 R Primary Examiner-Patrick D. Lawson Attorney, Agent, or Firm-Fitch, Even, Tabin & Luedeka [5 7] ABSTRACT An adjustable size boot for covering a surgical foot cast. The boot is of bendable construction and comprises an insole of resilient, closed cell sponge laminated to a waterproof sponge out sole. The boot is attachable to the cast by means of a single piece upper fully covering the sides and heel portions of the 'cast and provided with a cushion adapted to protect the heel of the cast from impact forces.
5 Claims, 6 Drawing Figures PATENTEB 3905 1' 5 SHEET 1 [IF 3 \PATENTEDSEPWHYB 3,905,135
HEET 2 [1F 3 BooT FOR A FOOT CAST This invention relates to a protective boot for covering a surgical foot cast and more particularly to an adjustable size boot of bendable construction to be worn over a surgical cast encasing a foot.
Surgical casts are designed to immoblize the foot and/or leg during the process of healing. They are generally molded about the leg with plaster of Paris and gauze, and when dry the cast forms a rigid covering which immoblizes the injured member. While the surgical cast is a relatively durable structure, it is susceptible to damage by water and impact forces such as occur during the extended periods of continuous wear which normally accompany such casts. Casts are especially susceptible to damage by repeated exposure to concentrated pressure in a given area, such pressure often resulting in a breakdown of the cast wall and loss of immoblization. Such breakdown of the cast is promoted when the cast structure is weakened by exposure to water, as when the wearer walks on damp ground.
The heel area of the cast is particularly susceptible to damage due to frequent exposure to impact forces such as occur when the wearer moves to a sitting position and extends his leg to rest the immoblized limb. In this position, the weight of the cast and the wearers leg is brought to bear upon the heel of the cast which rests on the floor or other surface. When unprotected, as in the prior art, the impace of the cast heel against the floor, especially after numerour such impacts, breaks down the cast in the region of the heel. In the course of such breakdown of the cast, portions of the inner wall of the cast chip away but are not able to escape from the inside of the cast. These chips bear against the wearers foot, causing pain and discomfort.
It is therefore an object of this invention to provide a boot covering a surgical foot cast.
It is another object to provide a boot of the kind described having a resilient inner sole andheel cushion providing protection from impact forces and pressure brought to bear upon the sole and heel region of a surgical foot cast during the normal course of wear.
It is another object to provide a boot of the kind described which has a waterproof bendable outersole that is contoured to facilitate walking.
Another object of this invention is to provide an inexpensive and easily constructed boot of the kind described which is attachable to a surgical foot cast with maximum ease and of universal fit.
FIG. 1 is a perspective view ofa boot showing various features of the invention;
FIG. 2 is a perspective view of a boot as disclosed herein attached to a surgical cast;
FIG. 3 is a side view of the boot shown in FIG. 1;
FIG. 4 is a sectional view taken generally along line 4-4 of FIG. 3;
FIG. 5 is a plan view of an upper for the boot of FIG. 1; and 3 FIG. 6 is a side view of the boot with a section of the boot upper cut away.
In accordance with this invention there is provided a bendable boot for a surgical foot cast, the boot comprising an insole of resilient closed sponge laminated to an outsole of waterproof sponge. The boot is releasable attachable to the cast by means of a single piece upper provided with a cushion adapted to protect the heel of the cast from impact forces.
As shown in FIG. 1, the disclosed boot, generally designated as 10, includes a single piece upper 12 joined to a sole 14. A protective heel cushion 16 and means for attaching the boot to a surgical cast 18 (See FIG. 2) are provided on the boot upper.
The sole 14 of the boot 10 includes a generally bifacial outsole 20 (FIG. 6) ofa wear-resistant, flexible material. One suitable material is a high-styrene styrene/- butadiene closed cell sponge sheet material of about inch uniform thickness. This material has a specific gravity of between about 0.27 and 0.43, a resilience of about 20%, a compression deflection of between about 15 and 23 pounds per square inch, and a flex life of 100,000 flexes plus as determined in accordance with ASTM D105255. It is tough and resists abrasion. The exposed bottom face 24 of the outsole is adapted to frictionally engage the ground 21 or other supporting surface. To this end the bottom face 24 is provided with a roughened surface which in the depicted embodiment comprises a plurality of projections 26 extending outwardly from the bottom face.
The outsole 20 is overlaid with and bonded to a similarly contoured insole 28 which is tapered at its forward end 30 and, in one embodiment, is about A inch shorter in length than the outsole. The insole defines the upper face 31 of the sole l4 and when the boot is applied over a cast, this face 31 engages the sole 32 of the cast.
The preferred insole 28 is of a material which exhibits substantial resiliency and which rebounds quickly and substantially completely to its original shape following the removal of a comprssive force applied thereto. Such compressive forces may take the form of impact forces as when the cast is struck against a relatively sharp object, or the form of a more gentle compressive force as when the cast with the foot on it is placed generally flat upon a suporting surface as when standing. A preferred material for the insole 28 is a closed cell rubber or polymeric sponge. On suitable closed cell polymeric sponge is styrene/butadiene (SBR) sheet having a thickness of about inch. This material exhibits a compression deflection of between about 5 and 13 pounds per square inch and an average specific gravity of between about 0.16 and 0.29. A A inch thick sample of this material compressed 50% for 22 hours at F. and allowed to recover for 24 hours has an average compression set between about 20 and 30%. Its mean resilience is about 45% and its water absorption is less than about 5% by weight. These properties of the material provide. an insole which is pliable and substantially more resilient than the outsole, thereby having the capacity to absorb substantial compressive forces. This materialhas a flex life in excess of 1 X 10 flexes (ASTM D105255) indicating its ability to withstand numerous compressions and rebounds.
As shown in FIG. 5, the boot includes a generally simicircular, unitary upper, generally designated at 12. As shown in FIGS. 2, 3 and 6, the upper 12 is formed about the perimeter of the sole 14 with the central portion of the upper defining the heel 40 of the boot. The bottom straight edge 42 of the upper preferably has several triangular darts 44 removed from its bottom edge 42 and is split at spaced locations 46 to facilitate forming of the upper to the perimetral contour of the sole. In the illustrated embodiment, the upper 12 is secured to the sole 14 by inserting the bottom edge 42 of the upper 12 between the outer margin of the interface 48 between the outsole 20 and the insole 28 and bonding these members together as by an adhesive (not shown). The preferred upper is of vinyl sheet material 34 laminated by a suitable adhesive to a liner 36, such as circle-knit nylon disposed on the inner surface of the upper. This supported vinyl 34, is waterproof and protects the sides and rear of the foot portion of the surgical cast which would normally be exposed to moisture or splashing water when walking on damp or wet surfaces. The upper extends above the sole 14, a distance sufficient to shield the cast to at least about ankle height against normally encountered exposure to water. A height of approximately inches between the sole 14 and the top edge 38 of the upper in the heel region 40 has been found sufficient to provide the desired coverage and protection of the ankle region of the cast. In addition to its support function, the preferred liner material 36 for the inner surface of the upper reduces the frictional engagement of the upper to the rough cast thereby allowing the boot to be readily fitted over the cast.
When the upper 12 is secured to the sole 14, the opposite ends 50 and 52 of the upper 12 terminate short of the forward end 30 of the sole to leave an opening 56 in the forward end of the boot through which the wearers toes may protrude leaving them exposed to the ambient atmosphere as is desired to provide a degree of ventilation to the cast. The sides 58 and 60 of the attached upper overlie the opposite sides of the cast to provide a continuous waterproof covering from the toe region fully around the sides and the heel region of the cast.
The semicircular portion of the perimeter of the boot upper 12 is reinforced with bias binding 66 which extends along the semicircular edge 68 and terminates approximately 1 inch beyond each end of the bottom edge 42 as shown in FIG. 5. The extensions 70 and 72 of the bias binding provide means for insuring adequate retention of the opposite ends 50 and 52 of the upper in their respective positions of attachment to the boot sole 14.
The boot is attached to the surgical cast as by means of one or more releasable straps such as Velcro straps 74 and 76 depicted in FIG. 2. In the preferred embodiment, two cooperating straps 74 and 76 are attached to the boot upper by sewing one end of each strap to the bias binding 66. Two cooperating Velcro pads 78 and 80 are sewn to the boot upper on the opposite side thereof to receive the Velcro straps as shown in FIG. 5. The cooperating straps and pads are readily fastened together in any of many relative positions, thereby permitting the sides 58 and 60 of the upper to be fitted snugly against the sides of a cast and secured in such snug fitting positions. By this means, the boot is substantially of a universal size within the limits of the length and breadth dimensions of the sole.
Referring to the embodiment shown in the Figures, the upper is provided with a shock-absorbent cushion 16 on its inner surface 54 in the heel region of the cast and in juxtaposition to the sole of the cast. In the preferred embodiment the heel cushion 16 is of the same closed cell sponge material as the insole. conveniently, the cushion is rectangular and attached to the boot upper 12 as shown in FIG. 4 by an adhesive. One suitable adhesive is a general purpose neoprene adhesive as known in the art. As depicted, the heel cushion is centered to the rear of the cast heel (FIG. 4) with the lower edge 82 of the heel cushion 16, located a short distance, for example one-half inch, above the upper planar surface 31 of the insole 28 (also see FIG. 3). In this position the heel cushion l6 absorbs impact forces such as are occasioned by the wearer assuming a seated position and extending the injured limb forward and bringing the weight of the cast and injured limb to bear upon the heel region of the cast 18, thereby protecting the cast against crushing of the cast wall and resultant pain due to loosened portions of the inner cast wall digging" into the injured limb.
In combination with the resilient outsole 20, the insole 28 provides protection to the cast from the recurring compressive forces, and particularly repetitive impact forces, to which a cast is commonly subjected.
When compressed as by the application of pressure thereto, as when the wearer of the cast to which the boot is attached stands or walks, the insole diminishes in thickness to absorb a substantial portion of the forces acting upon the cast. The cells of the disclosed sponge material used in forming the insole (and the outsole) are relatively small and substantially each is closed with gaseous material trapped inside the cell. Each cell thus responds to applied compressive forces by reduction of the cell size and compression of the entrapped gas. Repetition of this response by many cells provides for absorption of substantial compressive forces. Upon release of such compressiveforces, the individual cells, hence the insole, rebound their original uncompressed state and size, returning the insole to its initial thickness, ready to receive and absorb subsequent compressive forces. Because the sponge cells remain closed and keep the gas entrapped therein, the insole remains active over extended periods of use.
Further, each of the cells of the disclosed sponge material of the insole has a resilient cell wall so that the cell expands and contracts in response to applied compressive forces. The resistance of any given cell to a compressive force is in part determined by the support given such cell by its neighboring cells. Accordingly, in the present insole, an applied compressive force is transferred in part from one cell to another such that the degree of compression of the cells decreases as the location of the cell from the location of pressure application increases. In the present boot, the result is that in addition to the ability of the insole to absorb repetitive compressive forces of the type generally experienced during the action of one walking while the boot is attached to the cast, the preferred closed cell sponge material of the insole functions to distribute compressive forces over an area substantially larger than the actual area of contact between the boot and the object or surface that bears against the boot. In the present insole, this force distribution is enhanced by choosing a closed cell sponge that possesses a resiliency such that when the wearer of the cast places his weight upon the cast, the contoured cast sole 32 deforms the insole and causes it to wrap around and contact the full area of the cast sole thereby supplying lateral as well as vertical support to the cast. This enhanced contact between the cast and insole permits vertical forces to be distributed to the rounded sides of the cast sole and further reduces localization of forces exerted against the cast.
By reason of its flexible nature, the outsole 20 enhances distribution of the weight of the wearer over a relatively large area of the sole 14 of the cast 18. In the position of the cast shown in FIG. 6, the weight of the wearer bears upon that area of the surgical cast 18 and the outsole 20 between vertical lines D and E. In contrast to a rigid outsole as taught in the prior art, the weight of the wearer of a cast fitted with the disclosed boot is spread over a relative large area of the cast sole 32, thereby distributing the impact forces and/or other pressures experienced during walking movements over a relatively large area of the cast and decreasing the deleterious effect of forces upon the cast sole and cast wall.
As noted above, in the depicted boot, the forward end 30 of the insole 28 is tapered in thickness to prevent the toe of the boot from bearing against the supporting surface during walking movements and developing inordinately large pressures over the relatively small and unsupported front edge 86 of the cast. The preferred taper provides an angle A with the horizontal of between about and 45. The apex of the angle in the preferred embodiment is between about 1 inch and l /2 inches rearwardly of the forward edge 88 of the insole. The remainder of the insole preferably is of uniform thickness for economy of material cost and ease of manufacture. Similarly, the outsole is of uniform thickness. The outsole, however, in one embodiment, is about inch longer than the insole. ln bonding the outsole 20 to the insole 28, the rear ends 90 and 92 of the insole and outsole, respectively, are aligned flush with each other. As the outsole is pressed into contact with the insole, there being adhesive disposed therebe tween, the outsole is bend upwardly at its forward end to follow the taper on the insole. In the completed laminate sole, the forward ends of the insole and outsole, the forward ends of the insole and outsole are also aligned flush with each other. This difference in lengths and the relative stiffnesses of the outsole and insole develop an upward bow in the booth sole when the bent outsole is released after being bonded to the insole.
This bow enhances the conformity of the insole to the normal contour of a cast sole and aids in the transfer of compressive or shock forces to the boot.
What is claimed is: l. A flexible boot for covering a surgical foot cast having heel, toe and side portions, said boot comprising flexible sole means including flexible outsole means of a wear-resistant, waterproof, flexible material and insole means of a resilient, closed cell sponge material overlaid on and bonded to said outsole,
unitary upper means having a generally semicircular plan including a generally straight bottom edge. said bottom edge of said upper means being formed about the side and heel perimetral portion of said insole means and joined to said sole means along a portion of the perimetral margin of said sole means, the remainder of said upper means extending upwardly from said sole margin to define a generally U-shape that substantially encloses the sides and heel portions of said cast to approximately ankle height while leaving the toe portion of said boot open, and
heel cushion means carried by said upper means on the inner surface thereof in juxtaposition to the heel portion of said cast.
2. The boot of claim 1, wherien said insole is tapered upwardly at its forward end.
3. The boot of claim 1, wherein said outsole is of greater length than said insole and the respective ends of said outsole and insoole are aligned flush with each other when bonded together.
4. A boot as set forth in claim 1, wherein said upper is formed of supported vinyl sheet.
5. The boot of claim 1 and including means adapted to removably secure said boot to said cast.