Title:
PROTECTIVE COVER FOR PLASTER CAST
United States Patent 3735759
Abstract:
A flexible waterproof plastic cover comprises an open-topped sleeve intended to be used over a plaster cast on a person's foot and ankle. The sleeve is formed from two edge-interconnected plies of flexible waterproof material. The plies are interconnected along rear and bottom edges as well as along a front edge which is formed in two sections. The first section of the front edge of the sleeve extends generally perpendicularly upwardly from the bottom edge for a distance equal to at least about half the length of the bottom edge and the second section extends obliquely upwardly and rearwardly toward the rearward edge so that the size of the largest foot cast which can be inserted into the sleeve is primarily determined by the minimum separation between its rear edge and the top end of the second section of its front edge. A panel of abrasion-resisting material is usefully bonded to the cover along its bottom edge effectively to provide a ground-engaging sole.
US Patent References:
Foot covering
Baxter - June 1967 - 3324580
/1258024.html
Laybourn - March 1918 - 1258024
Protector for shoes and stockings
Herrick - March 1926 - 1577716
One-piece foldable overshoe
Hardman - September 1953 - 2652637
BOOTEE FOR HARD CASTS
Rivera - March 1970 - 3497875
Foot covering
Baxter - June 1967 - 3324580
/1258024.html
Laybourn - March 1918 - 1258024
Protector for shoes and stockings
Herrick - March 1926 - 1577716
One-piece foldable overshoe
Hardman - September 1953 - 2652637
BOOTEE FOR HARD CASTS
Rivera - March 1970 - 3497875
Application Number:
05/140377
Publication Date:
05/29/1973
Filing Date:
05/05/1971
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
36/8.100, 36/7.200, 2/239
International Classes:
A61F13/04; A43B3/18; A41B11/00; A61F5/00
Field of Search:
128/82,83,83.5,157,165 2/61,239,DIG.7 36/8.1,7.1R,7.3,7.4,70
US Patent References:
| 2493878 | Hosiery guard | January 1950 | Kirtz |
Primary Examiner:
Gaudet, Richard A.
Assistant Examiner:
Frinks, Ronald L.
Claims:
What I claim is
1. A generally waterproof cover for a foot cast within a predetermined size range which cover comprises an open-topped sleeve of two plies of flexible waterproof material extending from a common foldline down the rear edge thereof, and said two plies being interconnected to form said sleeve along a common bottom edge having a length x, being oriented to extend along about the centerline of said cover, and along a first section of a front edge continuous with said bottom edge and extending upwardly therefrom along about the centerline of said cover for a distance equal to at least about 0.4x to a top end thereof and being spaced apart forwardly from said rear edge, and along a second section of said front edge continuous with said first section of said front edge at said top end thereof and extending obliquely rearwardly and upwardly therefrom toward said rear edge, said plies being mutually separable along generally co-extensive top edges thereof extending forwardly from said rear edge and along generally co-extensive forward edges extending from respective forward ends of said top edges to a top end of said second section of said front edge to provide flaps having generally triangular configurations defined by said top edges and said forward edges whereby said flaps can be folded outwardly about lines extending generally from an upper end of said rear edge downwardly and forwardly to said top end of said second section of said front edge, said interconnection of said plies along said bottom edges and along said first and second sections of said front edge being exterior of said cover and including a welt strip of flexible waterproof material folded over and stitched to said two plies around the exterior thereof to embrace the edges of the individual plies, and further individual welt strips of flexible waterproof material are folded over and stitched to said top edges and said forward edges of said flaps, and co-operating securement means on said flaps generally at said forward edges thereof for fastening said cover about a wearer's lower leg, whereby the size of the largest foot cast which can be inserted into said cover is primarily determined by the minimum separation between said top end of said second section of said front edge and said rear edge, and, an abrasion-resisting wear surface panel of flexible waterproof material bonded to outer surfaces of both said two plies, said panel being substantially centered along said bottom edge to extend upwardly from either side thereof along said outer surface of said plies.
2. A generally waterproof cover as claimed in claim 1 in which the minimum separation m between said top end of said second section of said front edge and said rear edge has a value of at least about 0.5 x and in which said first section of said front edge has a length t of at least about 0.5 x.
3. A generally waterproof cover as claimed in claim 2 in which said rear edge has a height equal to at least about 1.0 x.
4. A generally waterproof cover as claimed in claim 1 in which said plies are integrally formed at least partially along said rear edge of said sleeve from a single sheet of said flexible waterproof material.
5. A generally waterproof cover as claimed in claim 4 in which each said ply comprises a sheet of a vinyl plastic material.
6. A waterproof cover as claimed in claim 1 in which said wear surface panel is formed of a sheet of metallized polyester material adhesively bonded to both said plies.
1. A generally waterproof cover for a foot cast within a predetermined size range which cover comprises an open-topped sleeve of two plies of flexible waterproof material extending from a common foldline down the rear edge thereof, and said two plies being interconnected to form said sleeve along a common bottom edge having a length x, being oriented to extend along about the centerline of said cover, and along a first section of a front edge continuous with said bottom edge and extending upwardly therefrom along about the centerline of said cover for a distance equal to at least about 0.4x to a top end thereof and being spaced apart forwardly from said rear edge, and along a second section of said front edge continuous with said first section of said front edge at said top end thereof and extending obliquely rearwardly and upwardly therefrom toward said rear edge, said plies being mutually separable along generally co-extensive top edges thereof extending forwardly from said rear edge and along generally co-extensive forward edges extending from respective forward ends of said top edges to a top end of said second section of said front edge to provide flaps having generally triangular configurations defined by said top edges and said forward edges whereby said flaps can be folded outwardly about lines extending generally from an upper end of said rear edge downwardly and forwardly to said top end of said second section of said front edge, said interconnection of said plies along said bottom edges and along said first and second sections of said front edge being exterior of said cover and including a welt strip of flexible waterproof material folded over and stitched to said two plies around the exterior thereof to embrace the edges of the individual plies, and further individual welt strips of flexible waterproof material are folded over and stitched to said top edges and said forward edges of said flaps, and co-operating securement means on said flaps generally at said forward edges thereof for fastening said cover about a wearer's lower leg, whereby the size of the largest foot cast which can be inserted into said cover is primarily determined by the minimum separation between said top end of said second section of said front edge and said rear edge, and, an abrasion-resisting wear surface panel of flexible waterproof material bonded to outer surfaces of both said two plies, said panel being substantially centered along said bottom edge to extend upwardly from either side thereof along said outer surface of said plies.
2. A generally waterproof cover as claimed in claim 1 in which the minimum separation m between said top end of said second section of said front edge and said rear edge has a value of at least about 0.5 x and in which said first section of said front edge has a length t of at least about 0.5 x.
3. A generally waterproof cover as claimed in claim 2 in which said rear edge has a height equal to at least about 1.0 x.
4. A generally waterproof cover as claimed in claim 1 in which said plies are integrally formed at least partially along said rear edge of said sleeve from a single sheet of said flexible waterproof material.
5. A generally waterproof cover as claimed in claim 4 in which each said ply comprises a sheet of a vinyl plastic material.
6. A waterproof cover as claimed in claim 1 in which said wear surface panel is formed of a sheet of metallized polyester material adhesively bonded to both said plies.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to a cover intended for use over a plaster cast applied to a person's foot for immobilizing that foot following injury thereto and more particularly to an inexpensive cover intended for use over such a cast for the purpose of protecting that cast from damage by moisture and dust during outdoor perambulation of the patient.
Plastic sleeve protectors intended to be worn over the feet have heretofore been suggested for a variety of reasons. For instance, plastic sleeve foot covers have been suggested for use by military personnel and others for anti-contamination purposes when such personnel have been required to perform in the presence of poisonous gases or other noxious substances. Plastic sleeve shoe coverings have also previously been suggested for protecting ladies' shoes from damage from puddles on sidewalks and roads.
Such previously proposed protective coverings are, however, unsuitable for use for protecting plaster casts applied to the feet following injury thereto since such known coverings include top end openings which are so restricted that a person's foot immobilized in a plaster cast could not be inserted into such a covering while still ensuring positive fastening of the covering about the case.
It is accordingly a principal object of this invention to provide a generally waterproof cover intended to be worn by a person whose foot is contained in a plaster cast and immobilized thereby so as to enable that person to perambulate out of doors even under adverse weather conditions.
A further object of this invention is to provide a a protective cover for the aforesaid purpose and which cover can be positively fastened about a foot cast so as to be retained thereon during perambulation of the patient.
Another object of this invention is to provide a protective cover for the aforesaid purpose which cover is particularly characterized by its low manufacturing cost and the simplicity of its construction.
Yet another object of this invention is to provide a protective cover of the specified type and which cover can be manufactured from low cost vinyl plastic sheeting and which is provided with an abrasion-resisting wear surface panel intended to constitute a ground-engaging sole for such a cover.
Other objects of the invention will become apparent as the description herein proceeds.
SUMMARY OF THE INVENTION
Broadly, the present invention provides a generally waterproof cover for a foot cast within a predetermined size range which cover comprises an open-topped sleeve of two plies of flexible waterproof material interconnected to form said sleeve, said two plies being interconnected along a bottom edge having a length x, along a rear edge continuous with said bottom edge and extending upwardly therefrom, along a first section of a front edge continuous with said bottom edge and extending upwardly therefrom for a distance equal to at least about 0.4 x to a top end thereof and being spaced apart forwardly from said rear edge, and along a second section of said front edge continuous with said first section of said front edge at said top end thereof and extending obliquely rearwardly and upwardly therefrom toward said rear edge, said plies being mutually separable along generally co-extensive top edges thereof extending forwardly from said rear edge and along generally co-extensive forward edges extending downwardly from respective forward ends of said top edges to a top end of said second section of said front edge to provide flaps having generally triangular configurations defined by said top edges and said forward edges whereby said flaps can be folded outwardly about lines extending generally from an upper end of said rear edge downwardly and forwardly to said top end of said second section of said front edge, and co-operating securement means on said flaps generally at said forward edges thereof for fastening said cover about a wearer's lower leg, whereby the size of the largest foot cast which can be inserted into said cover is primarily determined by the minimum separation between said top end of said second section of said front edge and said rear edge.
Specific dimensions for typical covers in accordance with this invention will be set down hereinafter after the structure of the particular embodiment of a cover as illustrated in the accompanying drawing has been described.
Other features and advantages of the invention will become apparent as the description herein proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described merely by way of illustration with reference to the accompanying drawings in which:
FIG. 1 is a side view of one embodiment of a generally waterproof cover in accordance with this invention showing that cover in use for protecting a plaster cast on a person's foot and lower leg;
FIG. 2 is a side view of the generally waterproof cover of FIG. 1 illustrating the manner in which a person's foot with a plaster cast applied thereto for the purpose of immobilization is introduced into that cover;
FIG. 3 is a plan view of a sheet of flexible waterproof material showing the manner in which that sheet is precut during the manufacture of the cover shown in FIGS. 1 and 2;
FIG. 4 is a side view of the cover shown in FIGS. 1 and 2 when disposed in a flattened generally planar configuration and included herein for the purpose of identifying in more detail some important relative dimensions of such a cover, and,
FIG. 5 is an enlarged fragmentary section taken as indicated by the arrows 5--5 of FIG. 1 showing in more detail one useful way of interconnecting the separate plies of that cover along their co-extensive edges.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The generally waterproof cover indicated at 10 in FIGS. 1 and 2 of the accompanying drawings includes an open-topped sleeve 11 and is intended to be used for protecting a plaster cast generally indicated at 12 and fitted on a person's lower extremity as shown in phantom outline at 14.
The sleeve 11 shown in the accompanying drawings is usefully formed from a single sheet of flexible waterproof material as indicated generally at 16 in FIG. 3 and which sheet is folded about the line A-B to provide two overlying plies 18 and 19 with the fold line A-B constituting a rear edge 20 of the finished sleeve. In a manner yet to be described, the front and bottom edges of the plies 18 and 19 are interconnected to form the open-topped sleeve 11.
Since the sleeve 11 is deformed somewhat when placed over a plaster cast as shown in FIGS. 1 and 2, the dimensions of that sleeve will be identified herein with particular reference to FIG. 4 in which the sleeve is shown in a flattened generally planar disposition with the two plies 18 and 19 in essentially co-extensive overlying surface abutment with each other.
The sleeve 11 is defined by the aforementioned rear edge 20 which is continuous with a bottom edge 21 from which the rear edge extends upwardly therefrom and by a front edge generally indicated at 22, the two plies 18 and 19 being interconnected in any appropriate manner along their bottom and front edges 21 and 22 respectively. For the particular sleeve 11 shown in the accompanying drawings, the rear edge 20 extends at an angle of 90 β to the bottom edge 21 as will readily be understood by reference to FIG. 4. Referring now in more detail to the front edge 22, it will be seen that the front edge 22 essentially comprises a first section 24 which is continuous with the aforementioned bottom edge 21 and which extends upwardly therefrom so as to be spaced apart forwardly from the rear edge 20. It can be usefully indicated at this juncture that a cover in accordance with this invention will normally be formed so that the first section 24 of the front edge thereof has a height t which is equal to at least about 0.4 x and more generally to a value equal to at least about 0.5 x, wherein x represents the length of the bottom edge 21. The rear edge 20 will normally have a height h equal to at least about 1.0 x.
The front edge 22 also includes a second section 26 which is continuous with the first section 24 thereof and which extends upwardly and obliquely rearwardly therefrom at an angle α toward the rear edge 20 to terminate at a top end indicated at 27. The minimum separation m between the top end 27 of the second section 26 of the front edge 22 and the rear edge 20 will have a value of [(t + s. cosineα) tan β + x-s.sineα]cosine β wherein s represents the length of the second section 26 of the front edge 22. Normally, the minimum separation m will have a value of at least about 0.5x.
The sleeve 11 also comprises mutally separable and essentially co-extensive top edges 30 and 31 of the plies 18 and 19 respectively which top edges extend generally forwardly from the rear edge 20 and which, with mutually separable and essentially co-extensive forward edges 32 and 33 of the plies 18 and 19 respectively, define flaps 34 and 35 respectively which can be flexed outwardly (as shown in FIG. 2 for the flap 34) about lines B-C and B-D respectively extending from the top end B of the rear edge 20 to the top end 27 of the second section 26 of the front edge 22 for a purpose which will be more readily understood as the description herein proceeds.
Referring now to FIG. 3, it will be seen therefrom that, for the particular sleeve 11, a dart 40 is cut out of the lower edge of the sheet 16 to provide a curved heel edge 41 when the two plies 18 and 19 are interconnected and that the front edge 22 is formed with a forwardly directed convex curvature throughout its first section 24 although such features are not absolutely essential in a cover constructed in accordance with this invention.
It is further to be noted that the forward edges 32 and 33 of the flaps 34 and 35 respectively usefully extend at a small angle forwardly relative to the second section 26 of the front edge 22.
For the particular cover 10 shown in the accompanying drawings, the separate plies 18 and 19 of the sleeve 11 are interconnected along the bottom edge 21 and along the first and second sections 24 and 26 respectively of the front edge 22 by a welt strip 44 of appropriate flexible waterproof material and by stitching 45 in a manner which will be readily understood by reference to FIG. 5. When a heel dart 40 is provided as shown, the welt strip 44 and stitching 45 will also extend around that dart as actually shown in FIGS. 1 and 2. The invention is not, however, restricted to the hereinbefore described method of interconnecting the plies 18 and 19 and it is, for example, equally within the scope of this invention to secure the two plies together by heat sealing or by the use of a suitable adhesive.
An additional single welt strip 46 is provided along the forward edges 32 and 33 and along the top edges 30 and 31 of the flaps 34 and 35 respectively of the individual plies 18 and 19 respectively to provide some degree of additional rigidity to those edges of those flaps. Metal eyelets 47, 48, 49 and 50 are also provided in the flaps 34 and 35 slightly inwardly of the forward edges 32 and 33 respectively of those flaps so that the cover 10 can be tied about the wearer's lower leg by means of a lace 52 as will be readily understood by reference to FIG. 1.
The cover 10 also includes an abrasion-resisting wear surface panel generally indicated at 56 which is suitably secured to the outer surfaces of the plies 18 and 19 along the lower edge 21 thereof so as to extend upwardly along the outer surfaces of those plies to form a ground-engaging sole when the cover 10 is disposed around a foot cast as shown in FIG. 1. The panel 56 can be secured in any appropriate manner although the use of adhesive bonding has proved effective in practice when the sleeve 11 is formed from a plasticized polyvinyl chloride sheet of the type conventionally used for protective seat covers in automobiles and the panel 56 is itself formed of a metallized sheet of the polyethylene terephthalate polyester commercially available under the trade mark "Mylar."
Having described the structure of the cover 10, the manner in which that cover 10 is used for protecting a cast, such a plaster cast 12, will now be explained. For such a purpose, with the lace 52 untied, the patient's foot with the cast thereon is inserted into the open upper end of the sleeve 11. Obviously the patient's foot cannot be flexed at that time since the whole purpose of the cast 12 is to immobilize the patient's ankle. During such insertion of his foot, the minimum separation m (FIG. 4) between the top end 27 of the second section 26 of the front edge 22 and the rear edge 20 of the sleeve 11 determines whether or not the cast can be inserted into the cover 10. It will particularly be seen from FIG. 2 that, by the provision of the hereinbefore defined double-section structure for the front edge 22, the patient's foot can move freely into the sleeve 11 provided that his heel is able to move through the gap defined by the point 27 and the nearest point on the rear edge 20. In practice, it has been found to be necessary for the purpose of meeting most practical demands to manufacture four sizes of sleeves, the specific dimensions in inches for each such size being indicated in Table I for a sleeve in which the angle α equals 40° and the angle β equals 7° .
TABLE I
SIZE x L t s m Child 10.25 13.5 7 6 7.75 Small Adult 10.25 15.5 7 6 7.75 Medium Adult 12 15.5 7.5 5 10 Large Adult 14 15.5 8 4 12.75
The dimensions of the wear-surface panel 56 provided on a protective cover in accordance with this invention are not critical although it will be readily understood that such a panel will usefully extend over that part of the lower surface of such a cover which is likely to be worn away by contact with the ground.
Although the cover 10 of this invention has hereinbefore been described as being formed from a single sheet 16 of resilient waterproof material, it is equally within the scope of this invention to form such a cover from two separate sheets of such a material, a seam then also being provided along the rear edge between the two plies.
The covers of this invention can be formed from any sheet material having the desired flexibility and waterproof properties but plasticized vinyl plastic sheet having a thickness of about 0.010 inch has proved to be particularly suitable as well as providing the additional advantages of low cost and ready availability.
It is equally within the scope of this invention to utilize means other than the lace/eyelet means hereinbefore described for releasably fastening the flaps 34 and 35 of the cover 10 about a wearer's leg. It is, for example, equally possible to provide a hook and loop type fabric fastener of the type commercially available under the trade name "Velcro."
Other variations in the described structure will be readily apparent to those conversant with the relevant technologies.
The present invention relates to a cover intended for use over a plaster cast applied to a person's foot for immobilizing that foot following injury thereto and more particularly to an inexpensive cover intended for use over such a cast for the purpose of protecting that cast from damage by moisture and dust during outdoor perambulation of the patient.
Plastic sleeve protectors intended to be worn over the feet have heretofore been suggested for a variety of reasons. For instance, plastic sleeve foot covers have been suggested for use by military personnel and others for anti-contamination purposes when such personnel have been required to perform in the presence of poisonous gases or other noxious substances. Plastic sleeve shoe coverings have also previously been suggested for protecting ladies' shoes from damage from puddles on sidewalks and roads.
Such previously proposed protective coverings are, however, unsuitable for use for protecting plaster casts applied to the feet following injury thereto since such known coverings include top end openings which are so restricted that a person's foot immobilized in a plaster cast could not be inserted into such a covering while still ensuring positive fastening of the covering about the case.
It is accordingly a principal object of this invention to provide a generally waterproof cover intended to be worn by a person whose foot is contained in a plaster cast and immobilized thereby so as to enable that person to perambulate out of doors even under adverse weather conditions.
A further object of this invention is to provide a a protective cover for the aforesaid purpose and which cover can be positively fastened about a foot cast so as to be retained thereon during perambulation of the patient.
Another object of this invention is to provide a protective cover for the aforesaid purpose which cover is particularly characterized by its low manufacturing cost and the simplicity of its construction.
Yet another object of this invention is to provide a protective cover of the specified type and which cover can be manufactured from low cost vinyl plastic sheeting and which is provided with an abrasion-resisting wear surface panel intended to constitute a ground-engaging sole for such a cover.
Other objects of the invention will become apparent as the description herein proceeds.
SUMMARY OF THE INVENTION
Broadly, the present invention provides a generally waterproof cover for a foot cast within a predetermined size range which cover comprises an open-topped sleeve of two plies of flexible waterproof material interconnected to form said sleeve, said two plies being interconnected along a bottom edge having a length x, along a rear edge continuous with said bottom edge and extending upwardly therefrom, along a first section of a front edge continuous with said bottom edge and extending upwardly therefrom for a distance equal to at least about 0.4 x to a top end thereof and being spaced apart forwardly from said rear edge, and along a second section of said front edge continuous with said first section of said front edge at said top end thereof and extending obliquely rearwardly and upwardly therefrom toward said rear edge, said plies being mutually separable along generally co-extensive top edges thereof extending forwardly from said rear edge and along generally co-extensive forward edges extending downwardly from respective forward ends of said top edges to a top end of said second section of said front edge to provide flaps having generally triangular configurations defined by said top edges and said forward edges whereby said flaps can be folded outwardly about lines extending generally from an upper end of said rear edge downwardly and forwardly to said top end of said second section of said front edge, and co-operating securement means on said flaps generally at said forward edges thereof for fastening said cover about a wearer's lower leg, whereby the size of the largest foot cast which can be inserted into said cover is primarily determined by the minimum separation between said top end of said second section of said front edge and said rear edge.
Specific dimensions for typical covers in accordance with this invention will be set down hereinafter after the structure of the particular embodiment of a cover as illustrated in the accompanying drawing has been described.
Other features and advantages of the invention will become apparent as the description herein proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described merely by way of illustration with reference to the accompanying drawings in which:
FIG. 1 is a side view of one embodiment of a generally waterproof cover in accordance with this invention showing that cover in use for protecting a plaster cast on a person's foot and lower leg;
FIG. 2 is a side view of the generally waterproof cover of FIG. 1 illustrating the manner in which a person's foot with a plaster cast applied thereto for the purpose of immobilization is introduced into that cover;
FIG. 3 is a plan view of a sheet of flexible waterproof material showing the manner in which that sheet is precut during the manufacture of the cover shown in FIGS. 1 and 2;
FIG. 4 is a side view of the cover shown in FIGS. 1 and 2 when disposed in a flattened generally planar configuration and included herein for the purpose of identifying in more detail some important relative dimensions of such a cover, and,
FIG. 5 is an enlarged fragmentary section taken as indicated by the arrows 5--5 of FIG. 1 showing in more detail one useful way of interconnecting the separate plies of that cover along their co-extensive edges.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The generally waterproof cover indicated at 10 in FIGS. 1 and 2 of the accompanying drawings includes an open-topped sleeve 11 and is intended to be used for protecting a plaster cast generally indicated at 12 and fitted on a person's lower extremity as shown in phantom outline at 14.
The sleeve 11 shown in the accompanying drawings is usefully formed from a single sheet of flexible waterproof material as indicated generally at 16 in FIG. 3 and which sheet is folded about the line A-B to provide two overlying plies 18 and 19 with the fold line A-B constituting a rear edge 20 of the finished sleeve. In a manner yet to be described, the front and bottom edges of the plies 18 and 19 are interconnected to form the open-topped sleeve 11.
Since the sleeve 11 is deformed somewhat when placed over a plaster cast as shown in FIGS. 1 and 2, the dimensions of that sleeve will be identified herein with particular reference to FIG. 4 in which the sleeve is shown in a flattened generally planar disposition with the two plies 18 and 19 in essentially co-extensive overlying surface abutment with each other.
The sleeve 11 is defined by the aforementioned rear edge 20 which is continuous with a bottom edge 21 from which the rear edge extends upwardly therefrom and by a front edge generally indicated at 22, the two plies 18 and 19 being interconnected in any appropriate manner along their bottom and front edges 21 and 22 respectively. For the particular sleeve 11 shown in the accompanying drawings, the rear edge 20 extends at an angle of 90 β to the bottom edge 21 as will readily be understood by reference to FIG. 4. Referring now in more detail to the front edge 22, it will be seen that the front edge 22 essentially comprises a first section 24 which is continuous with the aforementioned bottom edge 21 and which extends upwardly therefrom so as to be spaced apart forwardly from the rear edge 20. It can be usefully indicated at this juncture that a cover in accordance with this invention will normally be formed so that the first section 24 of the front edge thereof has a height t which is equal to at least about 0.4 x and more generally to a value equal to at least about 0.5 x, wherein x represents the length of the bottom edge 21. The rear edge 20 will normally have a height h equal to at least about 1.0 x.
The front edge 22 also includes a second section 26 which is continuous with the first section 24 thereof and which extends upwardly and obliquely rearwardly therefrom at an angle α toward the rear edge 20 to terminate at a top end indicated at 27. The minimum separation m between the top end 27 of the second section 26 of the front edge 22 and the rear edge 20 will have a value of [(t + s. cosineα) tan β + x-s.sineα]cosine β wherein s represents the length of the second section 26 of the front edge 22. Normally, the minimum separation m will have a value of at least about 0.5x.
The sleeve 11 also comprises mutally separable and essentially co-extensive top edges 30 and 31 of the plies 18 and 19 respectively which top edges extend generally forwardly from the rear edge 20 and which, with mutually separable and essentially co-extensive forward edges 32 and 33 of the plies 18 and 19 respectively, define flaps 34 and 35 respectively which can be flexed outwardly (as shown in FIG. 2 for the flap 34) about lines B-C and B-D respectively extending from the top end B of the rear edge 20 to the top end 27 of the second section 26 of the front edge 22 for a purpose which will be more readily understood as the description herein proceeds.
Referring now to FIG. 3, it will be seen therefrom that, for the particular sleeve 11, a dart 40 is cut out of the lower edge of the sheet 16 to provide a curved heel edge 41 when the two plies 18 and 19 are interconnected and that the front edge 22 is formed with a forwardly directed convex curvature throughout its first section 24 although such features are not absolutely essential in a cover constructed in accordance with this invention.
It is further to be noted that the forward edges 32 and 33 of the flaps 34 and 35 respectively usefully extend at a small angle forwardly relative to the second section 26 of the front edge 22.
For the particular cover 10 shown in the accompanying drawings, the separate plies 18 and 19 of the sleeve 11 are interconnected along the bottom edge 21 and along the first and second sections 24 and 26 respectively of the front edge 22 by a welt strip 44 of appropriate flexible waterproof material and by stitching 45 in a manner which will be readily understood by reference to FIG. 5. When a heel dart 40 is provided as shown, the welt strip 44 and stitching 45 will also extend around that dart as actually shown in FIGS. 1 and 2. The invention is not, however, restricted to the hereinbefore described method of interconnecting the plies 18 and 19 and it is, for example, equally within the scope of this invention to secure the two plies together by heat sealing or by the use of a suitable adhesive.
An additional single welt strip 46 is provided along the forward edges 32 and 33 and along the top edges 30 and 31 of the flaps 34 and 35 respectively of the individual plies 18 and 19 respectively to provide some degree of additional rigidity to those edges of those flaps. Metal eyelets 47, 48, 49 and 50 are also provided in the flaps 34 and 35 slightly inwardly of the forward edges 32 and 33 respectively of those flaps so that the cover 10 can be tied about the wearer's lower leg by means of a lace 52 as will be readily understood by reference to FIG. 1.
The cover 10 also includes an abrasion-resisting wear surface panel generally indicated at 56 which is suitably secured to the outer surfaces of the plies 18 and 19 along the lower edge 21 thereof so as to extend upwardly along the outer surfaces of those plies to form a ground-engaging sole when the cover 10 is disposed around a foot cast as shown in FIG. 1. The panel 56 can be secured in any appropriate manner although the use of adhesive bonding has proved effective in practice when the sleeve 11 is formed from a plasticized polyvinyl chloride sheet of the type conventionally used for protective seat covers in automobiles and the panel 56 is itself formed of a metallized sheet of the polyethylene terephthalate polyester commercially available under the trade mark "Mylar."
Having described the structure of the cover 10, the manner in which that cover 10 is used for protecting a cast, such a plaster cast 12, will now be explained. For such a purpose, with the lace 52 untied, the patient's foot with the cast thereon is inserted into the open upper end of the sleeve 11. Obviously the patient's foot cannot be flexed at that time since the whole purpose of the cast 12 is to immobilize the patient's ankle. During such insertion of his foot, the minimum separation m (FIG. 4) between the top end 27 of the second section 26 of the front edge 22 and the rear edge 20 of the sleeve 11 determines whether or not the cast can be inserted into the cover 10. It will particularly be seen from FIG. 2 that, by the provision of the hereinbefore defined double-section structure for the front edge 22, the patient's foot can move freely into the sleeve 11 provided that his heel is able to move through the gap defined by the point 27 and the nearest point on the rear edge 20. In practice, it has been found to be necessary for the purpose of meeting most practical demands to manufacture four sizes of sleeves, the specific dimensions in inches for each such size being indicated in Table I for a sleeve in which the angle α equals 40° and the angle β equals 7° .
TABLE I
SIZE x L t s m Child 10.25 13.5 7 6 7.75 Small Adult 10.25 15.5 7 6 7.75 Medium Adult 12 15.5 7.5 5 10 Large Adult 14 15.5 8 4 12.75
The dimensions of the wear-surface panel 56 provided on a protective cover in accordance with this invention are not critical although it will be readily understood that such a panel will usefully extend over that part of the lower surface of such a cover which is likely to be worn away by contact with the ground.
Although the cover 10 of this invention has hereinbefore been described as being formed from a single sheet 16 of resilient waterproof material, it is equally within the scope of this invention to form such a cover from two separate sheets of such a material, a seam then also being provided along the rear edge between the two plies.
The covers of this invention can be formed from any sheet material having the desired flexibility and waterproof properties but plasticized vinyl plastic sheet having a thickness of about 0.010 inch has proved to be particularly suitable as well as providing the additional advantages of low cost and ready availability.
It is equally within the scope of this invention to utilize means other than the lace/eyelet means hereinbefore described for releasably fastening the flaps 34 and 35 of the cover 10 about a wearer's leg. It is, for example, equally possible to provide a hook and loop type fabric fastener of the type commercially available under the trade name "Velcro."
Other variations in the described structure will be readily apparent to those conversant with the relevant technologies.