US3494355A

US3494355A - Leg cast with means for adjusting the amount of weight supported by the patient's foot during walking

Info

Publication number: US3494355A
Application number: US688761A
Authority: US
Inventors: Milton P Wolpow
Original assignee: M P W ASSOCIATES Inc
Current assignee: M P W ASSOCIATES Inc; Mpw Associates Inc
Priority date: 1967-12-07
Filing date: 1967-12-07
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10

Description

' M. P.- woLP'oW 3,494,355

Feb. 10, 1970 I 1 LEG CAST WITH MEANS FOR ADJUSTING THE AMOUNT OF WEIGHT SUPPORTED BY THE PATIENTS FOOT DURING WALKING Filed Dec. 7, 1967 FIG.2

10 a I g I 59 29 INVENTOR,

Milton Rwolpovg United States Patent Oil tice 3,494,355 Patented Feb. 10, 1970 US. Cl. 12883.5 Claims ABSTRACT OF THE DISCLOSURE The sole region of a cast encasing a patients leg, has a vertical cylinder therethrough carrying two slidable pistons which are normally biased to be close to each other, and between which pistons, air under adjustable pressure can be introduced. The lower face of the lower piston is always below the cast. Atop the upper piston, within the cast, is a foot-supporting saddle. An ischial weight-bearing ring or a thigh clamp at the upper end of the cast, makes the cast to shunt the full body weight when the patient stands, and there is no pressure within the cylinder. When such pressure is present, the lower piston becomes a floating heel, and the intensity of such pressure determines the extent of the load borne by the injured leg.

The present invention relates to, and its principal object is to provide a novel and improved leg cast construction including mechanism aifording the patient the capability to practice walking, and so arranged that the injured leg shall support a part of the body Weight, which burden is adjustable, and finally to carry the entire body weight at some subsequent practice session.

A further object thereof is to provide a novel and improved leg cast and operating system of the character described, which can be made for a reasonable cost, easy to manipulate and eflicient in carrying out the purposes mentioned.

Other objects and advantages will become apparent as this disclosure proceeds.

For one practice of this invention, the sole of an ischialbearing cast, is provided with an upright cylinder therethrough having two pistons between which a pressurized gas may be fed to build up a pressure which is adjustable. The upper piston carries a foot-supporting saddle within the cast, in a slight space allowing movement thereof along the vertical. In the absence of pressure within the cylinder, the pistons assume close relation, and in taking a step with the encased leg, the entire body weight is borne by the cast and imposed on the hip bone. Upon feeding compressed gas into the cylinder, the pistons move in opposite directions. The lower piston extends always below the cast. A valve means controls the gas feed from a supply source, and the pressure is indicated by a suitable gage in the feed line. The cast may be an assembly of plastic sections which can be taken apart, or in one piece of plaster, arranged with rigid reinforcement structure.

In the accompanying drawing forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

FIG. 1 is a side elevational view of a plastic cast encasing a leg; said cast being of a construction and associated with mechanism embodying the teachings of this invention, The components of the system are shown in disproportionate relation in order to include them in the limited space available on the sheet.

FIG, 2 is a side elevation of a plaster cast with rigid reinforcement structure, and embodying similar mechanism as taught herein.

FIG. 3 is an enlarged fragmentary central longitudinal section of the cast structure shown in FIG. 1. Here, pressurized air has been admitted into the cylinder.

FIG. 4 is an enlarged central sectional view of a valve means suitable to control the air system.

In a preferred embodiment shown in the drawing, the numeral 15 designates a leg encased in a surgical cast indicated generally by the numeral 16. This cast is a shell structure provided at its mouth with an ischial weight-bearing ring 17, which as is well known, makes the cast able to shunt and support the full body weight when the patient stands, so no part of the weight is borne by the injured limb. The cast 16 is of plastic, molded to fit the leg, and is made in

sections

18, 19, having facing perimetrical flanges 18, 19', which are bolted together, and of course, such sections are separable, This cast 16 is sufficiently strong and sturdy to support the full body weight. When however, the cast is of plaster as 20,

rigid reinforcement rings

21 and 22, around the top and bottom respectively, and

vertical bars

23, 24, along each side of the cast, are joined to form a unitary cage structure, for instance of aluminum bar stock, which is sufficient to support the body weight when the wearer stands up. There may be a central ring 22'.

For the practice of this invention, the cast is provided with a vertically positioned cylinder 26, securely mounted through the sole region of the cast, in substantially axial alignment with the legs axis. There are two

pistons

27, 28, slidably fitted in the cylinder 26, and connected by tension coil springs as shown at 29, to keep them normally close together with a slight space between them for the admission of compressed air from a supply tank 30, whose output is controlled by a suitable valve 31, and the pressure in the feed line is indicated by a gage 32. A two way valve device indicated generally by the numeral 33 is provided to direct compressed air into the cylinder 26, by a metal tube 34, which is preferably imbedded in the casts wall; said tube being connected at its lower end to the intake port 35 of the cylinder 26,

and at its upper end is exposed for connection by a hose 36, to the radial port 37 in the stator 38 of the valve 33. Said port 37 is equi-distant and intermediate two other radial ports 40 and 41, in the valve stator 38. The rotor 42 of this valve has a socket 43 in its periphery, of sufiicient size to span the central port 37 with either of the adjacent ports. The port 41 is connected to the air supply tank 30, by a tube 44, while the port 40 is open to the atmosphere. A handle 45 is provided to turn the rotor 42. O-

rings

46 and 47 having elastic quality, serve as piston rings.

The lower piston 28, at its very bottom, has an outward flange 43, which normally bears against the lower rim of the threaded bushing which serves as the cylinder 26. The lower face of said lower piston is always below the cast 16. A chain 49 connects the pistons to maintain the lower one associated with the cylinder. The upper piston 27, mounts a foot-supporting saddle 50 which is in a space 51 within the cast, to permit a vertical movement of said saddle and its associated piston. The permitted movement of the pistons, is suggested to be at most, about one-quarter of an inch.

Although an ischial bearing cast is preferred, this invention contemplates a cast reaching up partway on the thigh, where a ring clamped to the thigh, bears on the mouth rim of the cast, like 17 on 16. Such slight modification in structure is believed understood without the necessity of further illustration.

A patient, fitted with the cast herein taught, on an injured leg for the purpose of immobilizing said limb, or else on a leg which has been inactive for any reason whatever, can practice walking, preferably at first with :he aid of a crutch, cane or walker device; the system nerein provided, allowing the patient to control the ex- ;ent to which the injured leg will bear of the burden of his full body weight, from nil to full weight, according his requirements and comfort.

It is evident that when no pressure is furnished within the cylinder 26, the flange 48 of the lower piston 28, will bear against the lower rim of the cylinder, and so the cast will shunt the entire body weight. By applying compressed air into the cylinder, the

pistons

27 and 28 will move apart, thereby providing a pneumatic cushion for the impact of his step, afforded by the floating heel offered by the lower piston 28.

So, he then shifts the valve rotor 42 to the position shown in FIG. 4, and opens and adjusts the valve 31, so compresed air of five pounds per square inch pressure is entered into the cylinder. In taking a step, the sick leg will bear an impact equal to the pressure on the pistons which, for instance, are of an area of two square inches, so the leg will be subject to an impact of ten pounds, while the balance of his weight will be shunted by the cast and borne by his hip bone. If the impact is too much for the patient to tolerate with comfort, he will reduce the pressure in the cylinder 26, by shifting the handle 45 so the cavity 43 spans the ports 37, 40, which will empty the cylinder. Then he will manipulate the

valves

31 and 33, to furnish the cylinder with a supply of compressed air at a lower pressure, which he will note by reading the gage 32. At subsequent practice sessions, he will successively increase such pressure of the medium supplied into the cylinder 26, so the shunting by the cast will be in modulated decreases, while the burdens borne by the leg will be in modulated increments, finally reaching full body weight. The greater the pressure is in the cylinder, a greater portion of the total body weight will be borne by the leg.

If the patient has both legs injured, then he will have the equipment described herein in duplicate. If only on one leg, then the other shall be shod with a shoe, for walking practice.

A compressed air or carbon dioxide supply in a small tank 30, or an aerosol canister for such supply of pressurized medium, and the valve and gage equipment, may be carried on a belt worn by the user, thereby making the outfit portable and convenient.

I claim:

1. In combination, a shell cast for encasing a patients leg, a cylinder fixed in upright position through the sole of said cast substantially coaxially with the longitudinal axis of said cast, upper and lower pistons slidably carries in the cylinder, a foot-supporting saddle within said cast, free for slight vertical movement therein; said saddle being fixed atop the upper piston, first means holding the lower piston so its lower face is below the cast when the pistons are closest to one another, second means maintaining the lower piston in association with the cylinder; said cylinder having a port for the admission of a pressurized medium between said pistons, and a third means at the upper end of the cast, adapted to engage the patient and support the patients weight when a step is taken by the patient on the cast-encased leg.

2. The combination as defined in claim 1, wherein the first means is an outward flange on the lower end of the lower position.

3. The combination as defined in claim 1, wherein the second means comprises a foldable member of predetermined length within the cylinder and connecting said pistons.

4. The combination as defined in claim 1, wherein the third means is an ischial weight-bearing ring.

5. The combination as defined in claim 1, including spring means within the cylinder, connecting the pistons and biasing them towards each other.

6. The combination as defined in claim 1, wherein the pistons are always in spaced relation.

7. The combination as defined in claim 1, wherein said port extends through the Wall of the cast.

8. The combination as defined in claim 7, wherein that part of said port which is through the cast, comprises a passage extending from the cylinder, thence upwardly, in and along the Wall of the cast; opening in the upper art of said cast, for connection to a supply of pressurized medium.

9. The combination as defined in claim 1, wherein the cylinder is an exteriorally threaded bushing, threadedly engaged with the cast.

10. The combination as defined in claim 1, including a supply of pressurized fluid medium, means connecting said supply to said port, and valve means interposed in such connecting means to selectively control the admission of said medium into the cylinder and to make said cylinder communicative with the atmosphere.

References Cited UNITED STATES PATENTS 739,634 9/1903 Allen 128--83.5 874,446 12/1907 Slater 12883.5 XR 2,206,234 7/1940 Murray 12883.5

L. W. TRAPP, Primary Examiner