US3702999A - Partial weight bear warning device - Google Patents

Abstract

A device for warning a patient when he exceeds a predetermined amount of weight on his foot during locomotion comprising two force-sensitive electrical contactors disposed one each in predetermined positions beneath the heel and ball of the foot. The contactors are secured in a thin pad shaped to conform to the bottom of the shoe or footwear of the patient. Each electrical contactor includes a pair of flat circular metal plates separated by a resilient member and connected to a battery-powered alarm.

Description

United States Patent Gradisar i PARTIAL WEIGHT BEAR WARNING DEVICE Y [72] Inventor: Ivan A. Gradisar, 3629 Greenwich Road, Barberton, Ohio 44203 [22] Filed: Feb. 22, 1971 [21] Appl. No.: 117,509

[52] US. Cl ..340/272, 36/85 51 I t. Cl. ..G08b 13/10 [58] Field of Search ..340/272; 200/85; 36/25 Y, 36/25 AC, 8.5, 1; 33/3 R, 3 A; 73/172 [56] References Cited UNITED STATES PATENTS 3,008,038 11/1961 Dickens et al ..200/85 R X SIGNAL BOX [ 5] Nov. 14, 1972 3,548,134 12/1970 HarthanJrn ..200/86.5

Primary Examiner-Donald J. Yusko Attomey-Michael L. Gill [57] ABSTRACT A device for warning a patient when he exceeds a predetermined amount of weight on his foot during locomotion comprising two force-sensitive electrical contactors disposed one each in predetermined positions beneath the heel and ball of the foot. The contactors are secured in a thin pad shaped to conform to the bottom of the shoe or footwear of the patient. Each electrical contactor includes a pair of flat circular metal plates separated by a resilient member and connected to a battery-powered alarm.

21 Claims, 3 Drawing Figures PATENTEDuuv 14I972 3. 7 02.9 9 9 'eeimse 5:41am.

INVENTOR E IVAN A. GRADISAR ATTORNEY PARTIAL WEIGHT BEAR WARNING DEVICE This invention relates to devices for aiding patients during convalescence and in particular to a device for permitting a patient to bear partial weight on his leg.

There are many situations in which a patient should continuously and repeatedly place a certain amount of weight on his leg or foot in order to speed up the healing process. It is usually important, however, that he does not exceed another certain amount of weight on the leg since this might damagethe repair or injury.

One example of such a situation is a period of convalescence following a mold arthroplasty repair of the femoral head and vitalium cup or ball and socket joint in the hip. This operation involves separating the ball and socket and removing damaged or deteriorated material. An artificial cup is placed over the ball and it is placed back in the socket. Exercise and use of the hip joint helps the bones to develop a new layer of cartilage. Too much force or weight on the hip in the early stages of convalescence, however, can damage the ball or socket. The patient is, therefore, placed on crutches and told to put a certain amount of weight on his leg, say about twenty pounds. In order, that the patient know how much twenty pounds is, it has been the practice to have the patient step on a scale or walk over a force-sensing device in the laboratory. This has a decided disadvantage since once the patient leaves the scale or laboratory he no longer can check his weight and soon forgets or loses his appreciation of how much weight he is actually placing on his leg and hip as he walks around on crutches.

It is, therefore, desirable to have a device or means which would permit the patient to place a certain amount of weight on his leg or foot while he is walking but at the same time signal or warn him when he exceeds a predetermined amount of weight. The device should be lightweight, reliable, and not uncomfortable to the patient since he will be continuously carrying or wearing it during locomotion or walking.

It is, therefore, an object of this invention to provide a device for permitting a patient to bear up to a certain amount of weight on his leg or foot but warn him when he exceeds the certain amount.

It is also an object of this invention to provide such a device which is lightweight and comfortable to the user.

It is a further object to provide such a device which can be used in conjunction with normal footwear.

Other objects will be in part apparent and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the con struction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

IN THE DRAWING FIG. 1 is a sectional elevational view of a device constructed in accordance with this invention, illustrated in use in conjunction with the shoe of the patient;

FIG. 2 is a view of the device of FIG. 1, taken substantially along line 2-2 of FIG. I; and

FIG. 3 is an enlarged sectional view of a portion of the device of FIG. 2 taken substantially along line 3-3 of FIG. 2.

With reference to the drawing and in particular to FIG. 1, a device according to the present invention comprises afoot pad assembly 10* and a signal box or alarm 11. Thefoot pad assembly 10 and signal box 11 are operably connected by a pair of flexible insulatedelectrical wires 52, 54. Thefoot pad assembly 10 is thin and shaped to fit or conform to the bottom of the shoe 12 of the patient.

Referring now to FIGS. 1 and 2, thefoot pad assembly 10 comprises athin pad 24 of soft resilient material, such as sponge rubber, and a pair of pressure or force-sensing means 20 and 22 located respectively in the heel l4 andtoe 16 of the shoe 12 when thefoot pad assembly 10 is located in the shoe l0 beneath thefoot 18 of the patient. Each force-sensing means 20, 22 is secured in thepad 24 in a predetermined position such that one force-sensing means 20 is centered beneath the heel oros calcis 62 of the patent and the other force-sensing means 22 is centered beneath the ball ormetatarsal heads 64 of thefoot 18 of the patient.

More particularly, and with reference to FIG. 3, there is an enlarged view of the force-sensing means 22. Both force-sensing means 20 and 22 are the same with the exception that the force-sensing means 22 is larger in diameter than the force-sensing means 20. An illustration and description of one, therefore, will suffice for both.

In the particular embodiment illustrated, the forcesensing means 22 comprises a contactor assembly having a lower flat circularmetal contact plate 32 and an upper flatcircular plate 30. Theplates 30 and 32 are thin and held apart in vertical spaced apart relationship by a resilientdielectric member 34. In the particular embodiment illustrated, thedielectric member 34 is a rubber O-ring which is generally rectangular in crosssection. The twoplates 30, 32 and the O-ring member 34 are centered with respect to each other and have a common vertical axis.

Theupper plate 30 has acircular hole 46 therein and a threadednut 38 secured thereto by any suitable means, such as aweld 42 or soldering. Thenut 38 is positioned on the side of theupper plate 30 that is closest to thelower plate 32, and located coaxially with respect to the twoplates 30, 32 and the O-ring 34. Thenut 38, therefore, extends downwardly from theupper plate 30 into thehole 40 of the O-ring 34 and toward thelower contactor plate 32. Thehole 46 is also positioned coaxially with respect to theplates 30, 32, the O-ring 34 andnut 38, and thus permits the passage of aset screw 44 through theupper plate 30. Theset screw 44 is threadably engaged with thenut 38 and thus can be moved toward and away from thelower contactor plate 32 by screwing it in and out of thenut 38. A rounded lower end orcontactor 45 is provided on theset screw 38 to engage with thelower plate 32 at itscenter 47 when theupper plate 30 andnut 38 are forced downwardly as illustrated in dotted lines in FIG. 3. Theset screw 38 is short such that when it is retracted into thenut 38 to a point at which only thecontactor 45 protrudes out of the bottom of thenut 38, thescrew 38 will not protrude out of the top of thefoot pad assembly 10.

Each pressure-sensing means orcontactor assembly 22 or 20 is received in theresilient pad 24 to secure the contactor assembly in a predetermined position beneath the foot. The O-ring 34 is disposedin ahole 36 in thepad 24 while the upper andlower plates 30 and 32 located on opposite sides of the O-ring somewhat compress thepad 24 in the area radially outwardly of the O-ring 34. Thepad 24 is substantially softer than the O-ring 34 and offers little resistance to the force of the foot as compared to O-ring 34.

With reference to FIGS. 2 and 3, a flat braided,flexible wire 50 extends along the top side of thepad 24 and is connected to'bothtop plates 30 in the twocontactor assemblies 20 and 22. A second flat, flexible braidedwire 48 extends along the bottom side of thepad 24 and is connected to bothbottom plates 32 in the two contactor assemblies. Thepad 24 which separates thewires 48 and 50 is a dielectric and, therefore, insulates thewires 48 and 50. A pair ofwires 52 and 54 are connected to thewires 48 and 50, respectively, and extend to the signal box 1 1.

Thecomplete pad 24 andcontactor assemblies 20 and 22 are covered on top by a suitable thin sheet ofmaterial 26. A hole is provided in thematerial 26 above theset screw 44 in eachcontactor assembly 20, 22 to permit adjustment of theset screw 38. A similar thin sheet ofmaterial 28 is provided on the bottom of thepad 24 andcontactor assemblies 20, 22. The sheets ofmaterial 26 and 28 are adhered to thepad 24 andrespective plates 30 and 32 to maintain the foot pad assembly as a unit.

With reference to FIG. 3, in the particular embodiment illustrated the signal box 11 or means to wam the patient includes anaudible alarm 60. Also included in the signal box 11 is abattery 56 and rheostat 58. Thebattery 56,rheostat 58, and alarm 68 are connected in series with the ends of thewires 52 and 54 opposite theflexible wires 48 and 50. Thebattery 56,rheostat 58, andalarm 60 should be small and neatly fitted into a small container which can be conveniently carried by the patient, say for example in a pocket. While thealarm 60 in the particular embodiment illustrated is an audible alarm, it could be any other means for alerting the patient, such as a light. Therheostat 58 is provided to permit adjustment of the volume of thealarm 60.

When theupper plate 30 is forced toward thelower plate 32 until thecontactor 45 engages thelower plate 32 as illustrated in dotted lines in FIG. 3, the circuit is completed through the contactor assembly or 22 through thewire 50,wire 54,rheostat 58,alarm 60,battery 56,wire 52, andwire 48, and cause thealarm 60 to sound.

The amount of force required to cause thecontact tip 45 to touch thelower contact plate 32 can be adjusted by turning theset screw 44 in and out of thenut 38 and change the spacing between thecontactor tip 45 and theplate 32. If the spacing is large, it will take a large force to compress the O-ring 34 enough to cause thecontactor tip 45 to touch theplate 32. Likewise, if the spacing is small, the force required for contact will be small.

In the use of the device, the foot pad assembly is removed from the shoe or footwear l2 and placed on a table or fiat surface. Theset screw 38 in onecontactor assembly 20 or 22 is adjusted away from thelower plate 32 until the head of the set screw is flush with the outer surface of theplate 30. Theset screw 38 is then adjusted toward thelower plate 32 just until the alarm rings, when a weight equal to the maximum permitted on the leg or foot is placed on the contactor assembly. The process is then repeated with the other contactor assembly.

Thefoot pad assembly 10 is then reinserted into the shoe 12. The patient places his foot in the shoe and places the signal box in his pocket with thewires 52 and 54 extending down to the shoe. As he walks, maximum weight is placed successively on his heel and ball of his foot and if he exceeds the predetermined limit in either position, the alarm will momentarily sound.

It should be noted that while the specific embodiment illustrated is shown in conjunction with a left" shoe, the same device can be used with a right shoe by turning thefoot pad assembly 10 over. When thepad assembly 10 is turned over, it will fit neatly into a right shoe. Also, it will be appreciated that while it is preferred that theplates 30, 32 be circular, they could be any generally flat configuration which is expedient.

While a certain representative embodiment and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

1. A device for permitting a patient to bear part of his weight on his foot but warning him when he places at least a predetermined weight on said foot comprising, sensing means for detecting a weight on said foot including means for adjusting the minimum weight which is detected by said sensing means to said predetermined weight, means for maintaining said sensing means in a predetermined position adjacent the bottom of said foot so that said sensing means will detect said predetermined weight when said patient bears said predetermined weight on said foot; and, means operably connected to said sensing means to signal said patient when said predetermined weight is placed on said foot.

2. A device as claimed in claim 1, wherein said means for detecting a weight includes a pair of electrical contacts held apart by a resilient member.

3. A device as claimed inclaim 2, wherein said electrical contacts include a pair of coaxially spaced apart, generally flat circular plates and said resilient member is an elastomeric ring disposed centrally between said plates.

4. A device as claimed inclaim 3, wherein said contacts further include a contactor adjustably mounted on one of said plates and located centrally with respect to the hole in said ring so that the distance between said contactor and the other said plate can be adjusted.

5. A device as claimed in claim 4, wherein said contactor is a screw threadably mounted on said one of said plates so that turning said screw in said one of said plates moves said screw toward and away from said other plate.

6. A device as claimed in claim 1, wherein said sensing means includes two force detectors disposed one each generally beneath the heel and ball of said foot.

7. A device as claimed inclaim 2, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

8. A device as claimed inclaim 3, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

9. A device as claimed in claim 4, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

10. A device as claimed in claim 5, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

1 1. A device as claimed in claim 1, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

12. A device as claimed inclaim 2, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

13. A device as claimed inclaim 3, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

14. A device as claimed in claim 4, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

15. A device as claimed in claim 5, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to :fit into the footwear of said patient.

16. A device as claimed in claim 6, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

17. A device as claimed in claim 7, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

18. A device as claimed in claim 8, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

19. A device as claimed in claim 9, wherein said means for maintaining said sensing means in a' predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

20. A device as claimed inclaim 10, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

21. A device as claimed inclaim 20, wherein said means operably connected to said sensing means includes an electrically operated audible alarm connected to said contact.

Claims (21)

1. A device for permitting a patient to bear part of his weight on his foot but warning him when he places at least a predetermined weight on said foot comprising, sensing means for detecting a weight on said foot including means for adjusting the minimum weight which is detected by said sensing means to said predetermined weight, means for maintaining said sensing means in a predetermined position adjacent the bottom of said foot so that said sensing means will detect said predetermined weight when said patient bears said predetermined weight on said foot; and, means operably connected to said sensing means to signal said patient when said predetermined weight is placed on said foot.

2. A device as claimed in claim 1, wherein said means for detecting a weight includes a pair of electrical contacts held apart by a resilient member.

3. A device as claimed in claim 2, wherein said electrical contacts include a pair of coaxially spaced apart, generally flat circular plates and said resilient member is an elastomeric ring disposed centrally between said plates.

4. A device as claimed in claim 3, wherein said contacts further include a contactor adjustably mounted on one of said plates and located centrally with respect to the hole in said ring so that the distance between said contactor and the other said plate can be adjusted.

5. A device as claimed in claim 4, wherein said contactor is a screw threadably mounted on said one of said plates so that turning said screw in said one of said plates moves said screw toward and away from said other plate.

6. A device as claimed in claim 1, wherein said sensing means includes two force detectors disposed one each generally beneath the heel and ball of said foot.

7. A device as claimed in claim 2, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

8. A device as claimed in claim 3, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

9. A device as claimed in claim 4, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

10. A device as claimed in claim 5, wherein there are two pairs of said electrical contactors disposed one each generally beneath the heel and ball of said foot.

11. A device as claimed in claim 1, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

12. A device as claimed in claim 2, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

13. A device as claimed in claim 3, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

14. A device as claimed in claim 4, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

15. A device as claimed in claim 5, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

16. A device as claimed in claim 6, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

17. A device as claimed in claim 7, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

18. A device as claimed in claim 8, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

19. A device as claimed in claim 9, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

20. A device as claimed in claim 10, wherein said means for maintaining said sensing means in a predetermined position includes a resilient pad adapted to hold said sensing means and to fit into the footwear of said patient.

21. A device as claimed in claim 20, wherein said means operably connected to said sensing means includes an electrically operated audible alarm connected to said contact.

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