GB2069845A

GB2069845A - Artificial limb

Info

Publication number: GB2069845A
Application number: GB8105596A
Authority: GB
Original assignee: Blatchford & Sons Ltd
Current assignee: Blatchford & Sons Ltd
Priority date: 1980-02-22
Filing date: 1981-02-23
Publication date: 1981-09-03
Also published as: GB2069847A; GB2069847B; GB2069845B

Abstract

A stump socket (1) for an artificial leg is connected to a hip joint (19) by a support arm (15) fastened to the outer surface of the wall (16) of the socket (1). Adjustment of the position of the hip joint axis (20) in the anterior-posterior direction relative to the socket (1) is conveniently performed by pivoting the support arm (15) about the pivoted connection (25) without having to detach the arm (15) from the socket (1). The alignment of the arm may then be fixed by driving rivets through the holes (26) in the end portion of the arm (15). <IMAGE>

Description

SPECIFICATION Improvements in artificial limbs This invention relates to an artificial limb with a stump socket, and to the attachment of the socket to a rotatable joint.

Until recently artificial limb sockets have normally been made of wood or metal, or moulded in a thermoset plastics material. However techniques have now been developed whereby a socket for an artificial leg can be vacuum formed in a thermoplastics material, for example polypropylene, and in particular whereby the socket can be vacuum formed over a cast impression of the patient's stump. Polypropylene socket containers can be moulded in a similar manner, using the socket itself as part of the mould. In addition, polypropylene is now being used in the manufacture of adjustable diameter sockets suitable mainlyfortemporary use by the patient while an individual socket for permanent use is being made up.

The development of the thermoplastics socket has given rise to difficulties in attaching the socket to the remainder of the artificial limb structure, since conventional attachment methods used with sockets made of other materials are not suitable, due particularly to the relative thinness of the thermoplastics socket wall and the lack of effective adhesives for use with some thermoplastic materials.

In the case of a thermoplastics above-knee socket for an artificial leg it is necessary to attach a hip joint to the upper part of the socket The joint commonly has an upper support arm which is attached to a pelvic band and a lower support arm which is attached to the wall of the socket by, for example, rivets. When the leg is fitted to the patient, it is often necessary to adjust the position of the hip joint axis relative to the socket. This involves removing the rivets or other fastening devices from the support arm and moving itto a different position on the socket wall. The adjustment is a somewhat awkward operation and makes a controlled, accurate alignment relatively difficult to achieve. In addition, if several adjustments are made, the thermoplastics wall of the socket may be significantly weakened by the several fixing holes.

It is an object of this invention to provide an improved means of connecting a rotatable joint to a socket.

According to one aspect of this invention an artificial limb includes a stump socket with an open end for receiving a patient's stump, wherein the socket is connected to a rotatable joint by a support member which is mounted on the wall of the socket or a socket container and which includes means for pivotally adjusting the position of the member relative to the socket.According to another aspect of the invention there is provided a method of producing an artificial leg component including a stump socket for an above-knee amputee and a support member which carries an artificial hip joint, wherein the method includes: (i) attaching the support member to the lateral wall of the socket by means of pivotal connection; (ii) adjusting the position of the hip joint axis relative to the socket in the anterior-posterior direction by pivoting the support member about the said con nection so as to establish a required hip joint location; and (iii) establishing a fixed connection between the support member and the socket to preserve the required hip joint location.

In the case of an artificial leg for an above-knee amputee, the support member constitutes the lower arm of a hip joint and is attached to a planar surface region on the lateral side of the socket or socket container. A large planar surface on the medial side of the arm engages the said surface region on the soc ket, and a rivet, bolt, or pin driven through both the arm and the socket wall in the centre of the planar region defines an adjustment pivot axis generally perpendicular to the socket wall. Thus, prior to and during fitting the hip joint axis can be adjusted in the anterior-posterior direction along an arc centred on the pivot axis.This significantly aids the prosthetist when the limb is being fitted to the patient, since accurate adjustments can be made quickly and eas ily without the need to punch several holes in the socket or socket container each time the support arm is moved.

Further aspects of the invention are: (i) an artificial limb component comprising a stump socket with an open end for receiving the patient's stump, and a support member including a rotatable joint, wherein the support member is mounted on a portion of the wall of the socket adja cent the open end and is pivotally adjustable relative to the socket about an axis generally perpendicular to the socket wall portion; and (ii) a method of reinforcing the wall of a vacuum formed thermoplastics artificial limb socket or socket container, wherein a reinforcing plate is introduced between the mould on which the socket or container is vacuum formed thereby to produce an internal recess in the wall of the socket or container for hous ins the plate.

The invention will now be described by way of example with reference to the drawings in which :- Fig. 1 is a side view of an artificial hip joint with a lower support arm attached to the wall of a vacuum formed adjustable-diameter socket; Fig. 2 is a sectional view of a reinforced portion of the socket of Fig. 1; and Fig. 3 is a sectional view of the hipjoint bearing of Fig. 1.

Referring to Fig. 1 a hip joint for connecting an above knee socket 1 to a pelvic band comprises a lower arm 15 attached to the lateral wall 16 of the socket, an upper arm 17 having tongues 18 which are secured in the pelvic band (not shown), and a rotating bearing 19 connecting the upper and lower arms and defining a pivot axis 20 for the joint. The socket 1 is a thermoplastics adjustable width socket which, on the lateral side has an outer wall 16, terminating at an edge 21, overlapping an inner wall 22.

The wall of the socket or container is reinforced by a relatively rigid pad or plate 23, seen in section in Fig.

2, which is held against the inner surface of the wall 16, thereby trapping the wall 16 between the plate 23 and the lower end portion of the arm 15. In Fig. 1 the outline of the reinforcing plate is visible as the edge 24 of a raised planar area in wall 16. The plate 23 is retained in the wall 16 by using the plate as part of the mould over which the socket or container is vacuum formed, the edges of the plate being chamfered as shown in Fig. 3 so thatthe wall 16 grips the edges.

Note that the inner surface of the plate 23 is flush with the exposed inner surface of the wall 16.

The reinforced area of the wall 16 forms a rigid portion for mounting the lower arm 15 of the hip joint. This avoids the inherent weakness of a riveted connection between the lower arm of a hip joint and a relatively thin and flexible unreinforced socket wall. It also enablesthe lowerarm 15 to be rotatably mounted on the socket 1 to provide for anterior/posterior adjustment of the pivot axis 20 relative to the socket 1. Prior to the fitting of the artificial leg to the patient, the arm 15 is secured to the socket 1 by a rivet or bolt inserted through the centre hole 25 and corresponding holes in the wall 16 and the plate 23, the arm 15 being clamped to the socket 1 so that the arm may be pivoted against frictional resistance.During fitting, the arm 15 is set to the required position and rivets are driven through the three circumferentially spaced holes 26 to eslabl ish a permanent connection. The centre bolt may then, if required, be removed orthe fixation at that point made permanent using a rivet. This method of adjustment replaces the known technique whereby rivets or temporary bolts attaching the arm to the wail have to be removed and the arm shifted horizontally on the socket if the prosthetist decides that an adjustment to the hip joint position is necessary.

The variation in the height of the pivot axis 20 during adjustment can be neglected.

A feature of the hip joint illustrated in Fig. 1 is the rotating bearing 19 which is visible in more detail in the sectional view of Fig. 3. This bearing comprises a bolt 27 with a tapered head and a conical nut 28 which are screwed togetherto clamp the two arms 15 and 17 together. The conical bearing surfaces of the joint have a relatively large surface area in comparison with similar known hip joint bearings which provide greater stability and durability. The bolt 27 has a central hole 29 to reduce the weight of the bearing. The bolt head and nut lie virtually flush with respect to the outer surfaces of the arms.

Claims

1. An artificial limb including a stump socket with an open end for receiving a patient's stump, wherein the socket is connected to a rotatable joint by a support member which is mounted on the wall of the socket or a socket container and which includes means for pivotally adjusting the position of the member relative to the socket.

2. An artificial limb according to claim 1, wherein the support member includes means for adjustment about a pivoting axis which is generally perpendicular to the socket or socket container wall adjacent the support member.

3. An artificial limb according to claim 2, wherein the wall of the socket or socket container has a sub- stantially planar outer surface portion which engages a planar surface of the support member.

4. An artificial limb according to any preceding claim which is an artificial leg for an above-knee amputee, the rotatable joint being a hip joint connected to the socket or socket container by a support member in the form of a support arm which is mounted on the lateral side of the socket, and includes pivot means for carrying out an anteriorposterior adjustment of the position of the hip joint axis.

5. An artificial limb according to claim 4, wherein the hip joint connects the support arm to a pelvic band.

6. An artificial limb according to claim 4 or claim 5, wherein the support arm has a plate-like end portion which engages the outer surface of the socket, the said end portion having a generally central pivoted connection means for pivotally adjusting the support arm relative to the socket, and at least one fixing hole spaced from the central connection for fixing the position of the arm relative to the socket after adjustment has been performed.

7. An artificial limb according to claim 6 wherein the end portion of the arm has a plurality of circumferentially spaced fixing holes.

8. An artificial limb according to any of claims 4 to 7 wherein the hip joint comprises a pair of overlapping support arms held together by a bolt with a countersunk head and a countersunk threaded nut providing conical bearing surfaces which engage corresponding conical surfaces in the support arms.

9. An artificial limb according to any preceding claim wherein the socket or socket container on which the support member is mounted is made of a thermoplastics material.

10. An artificial limb according to claim 9 wherein the socket or socket container is vacuum formed and wherein the wall of the socket or socket container is reinforced in the region of the support member by a plate recessed into the inside surface of the wall.

11. A method of reinforcing the wall of a vacuum formed thermoplastics artificial limb socket or socket container, wherein a reinforcing plate is introduced between the mould on which the socket or container is vacuum formed thereby to produce an internal recess in the wall of the socket or container for housing the plate.

12. An artificial limb component comprising a stump socket with an open end for receiving the patient's stump, and a support member including a rotatable joint, wherein the support member is mounted on a portion of the wall of the socket adjacent the open end and is pivotally adjustable relative to the socket about an axis generally perpendicular to the socket wall portion.

13. An artificial leg component according to claim 12 for an above knee amputee, wherein the rotatable joint is a hip joint with an axis of rotation generally parallel to the adjustment axis, and wherein the support member is mounted on a planar surface on the lateral side of the socket.

14. A method of producing an artificial leg component including a stump socket for an above-knee amputee and a support member which carries an artificial hip joint, wherein the method includes: (i) attaching the support member to the lateral wall of the socket by means of pivotal connection; (ii) adjusting the position of the hip joint axis relative to the socket in the anterior-posterior direction by pivoting the support member about the said con nection so as to establish a required hip joint location; and (iii) establishing a fixed connection between the support member and the socket to preserve the required hip joint location.

15. An artificial limb component constructed and arranged substantially as herein described and shown in Fig. 1 of the drawings.

16. A method of producing an artificial leg component substantially as herein described with reference to the drawings.