GB2592374A

GB2592374A - A prosthetic limb

Info

Publication number: GB2592374A
Application number: GB2002618.3A
Authority: GB
Inventors: Laura Walker Kate
Original assignee: Exphand Prosthetics Ltd
Current assignee: Exphand Prosthetics Ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2021-09-01
Also published as: GB202002618D0

Abstract

A prosthetic limb 14 is provided comprising a telescopic member 21 such that the length of the limb is adjustable. The telescopic member 21 comprises a proximal portion 42 and distal portion 36 which are telescopically connected and secured by fastening means. The telescopic members may be fastened relative to one another by pins passing through any of a plurality of pairs of holes 10. The limb may be used as an arm or a leg, with an attached hand 16 or foot. As a prosthetic arm, wires may pass through the length of the arm which terminate at the ends of the fingers (Figure 17), wherein bending the elbow contracts the fingers to form a fist. The fingers may be resiliently biased towards an open position. The hand may be modular in construction.

Description

A Prosthetic limb

Field of the invention

This invention relates to a prosthetic limb. In particular, but not exclusively, the present invention relates to a limb prosthesis that can be adjusted and adapted to fit a patient, and to a limb prosthesis having a pivot joint that can be operated in two configurations.

Background

Every year there arc more than 1,000,000 amputations leading to a total of 30 million people in need of prosthetics across the world. When a limb reduction or amputation has occurred, a prosthesis can be fitted to provide additional length and functionality to the user. There are three types of prosthetic, cosmetic, body powered and myoelectric. Typically, children arc offered a cosmetic prosthesis which has no function and is purely used for body symmetry and to allow the child to get used to wearing something on their residual limb.

Body powered prostheses are operated using the movement of the body and typically enable a pincer movement in a split hook. Myoelectric prostheses are the most advanced form of prostheses as these use sensors attached to the residual limb to create complex movements and motions in the prosthesis. These are typically only given to adults due to their high price and the high level of control which is required to operate them.

Current development in prosthetics is heavily focused around myoelectric devices with little development seen in body powered devices in the past 50 years. As a consequence of this, many children and young adults do not have adequate access to suitable prosthetics due to the high price of newly developed prostheses and the lack of development in body powered devices, in addition to this, children and adolescents face further restrictions and limitations in the usefulness of prospective devices due to their rapid growth rate which causes their prosthetics to have a shortened useful lifetime and increases the number of prosthetics required during any given time period compared to an adult with a similar limb reduction.

It is an object of the present invention to provide a body powered prosthetic which is able to adapt to the growth of a child or adolescent in order to increase the length of its useful lifetime.

Summary

According to a first aspect of the invention. there is provided a prosthetic limb comprising a telescopic member such that a length of the prosthetic limb is adjustable.

The telescopic member comprises a proximal portion and a distal portion which are telescopically connected and secured in position by one or more fastening means.

The telescopic member is advantageous since it allows the length of the prosthetic limb to be adjusted, for example to account for the rapid growth of a child. This means that a prosthetic can be used for a longer time without requiring replacement.

The proximal portion and distal portion may be secured by a pair of fastening means.

Using a pair of fastening means rather than a single fastener may reduce unwanted pivoting about the single fastener, and hence provide a more secure and rigid connection.

It may be that the proximal portion has a plurality of pairs of holes each configured to receive a fastener for securing the proximal portion to the distal portion, wherein the spacing between the pairs of holes is greater than the spacing between holes within each pair.

The distal portion may have regularly spaced holes configured to receive the fasteners, and the spacing between the holes in the distal portion is equal to the spacing between holes within each pair of holes in the proximal portion.

A continuous pattern of regularly spaced holes on the distal member may increase the number of different possible lengths of the telescopic member as opposed to having pairs of holes on both the proximal member and the distal member It may be that the distal portion is slidably received inside the proximal portion.

Receiving the distal portion slidably inside the proximal portion ensures that dirt, which is more often present near the distal end of the limb is less likely to be trapped in the prosthetic.

The prosthetic limb may comprise a second telescopic member having a distal portion and a proximal portion which are telescopically connected. It may further be that the second telescopic member is spaced from the first telescopic member in a direction substantially perpendicular to the lengths of the telescopic members.

It may be that the distal portion of one of the telescopic member and the second telescopic members is configured to hingedly connect to a prosthetic hand or foot at a distal end of the distal portion, such that changes in the width of residual limbs may be accommodated. It may further be that the distal portion of the other of the telescopic member and the second telescopic members is configured to rigidly connect to a prosthetic hand or foot at a distal end of the distal portion Thc prosthetic limb may comprise a forearm including a prosthetic hand connected at a distal end of the telescopic member(s).

It may be that the hand includes fingers and thumbs hingedly connected to a palm and that the movement of the fingers and thumbs is controlled by control wires secured at the distal ends of the fingers, such that the prosthetic limb is body powered.

It may be that the fingers and thumb each have a hinged knuckle configured to allow them to bend in response to tension in the control wires.

The fingers and thumb may be biased to return to a neutral position by resiliently biased members.

The prosthetic limb may include an upper member connected to the proximal end of the proximal portion by a pivot joint. The pivot joint may allow the telescopic member to pivot relative to the upper member, about an axis perpendicular to its length.

It may be that the control wires are anchored on a proximal side of the pivot joint and pass through the telescopic member such that bending the elbow joint increases the path length of the wires which pulls on the ends of the fingers and thumb and hence pulls the fingers and thumb in towards the palm to form a fist.

The distal forearm portion may comprise a channel through which the wires pass.

It may be that the wires are anchored by a whippletree assembly mounted on the upper member, the whippletree assembly being configured to allow the load to be unevenly distributcd between the wires such that irregularly shaped objects can be gripped.

The prosthetic hand may have a modular construction and the palm, fingers, and thumbs may be interchangeable.

According to a second aspect of the invention, there is provided a body powered prosthetic limb comprising: a first elongate member; a second elongate member; a pivot joint configured to allow the first elongate member to rotate relative to the second elongate member; and an anchor on one of the first elongate member and second elongate member, for securing one or more control wires, the control wires for actuating one or more digits on the other of the first elongate member and second elongate member. The pivot joint defines a path for the one or more control wires to pass from the anchor to the one or more digits. The pivot joint rotates about a rotational axis perpendicular to the path. and comprises one or more wire deflection portions configured to deflect the control wires by a first amount as the joint rotates by a first angle in a first rotational direction, and deflect the control wires by a second amount, different to the first amount as the joint pivots by the first angle in a second direction opposite the first.

Typically, joints in limb will only bend in a single direction from a neutral position.

The joint of the second aspect can be used in two different orientations. Depending on the orientation of the body powered prosthetic, it may be in a high geared setting or a low geared setting. This allows the prosthetic to be configurable for individual users. For example, someone with little experience of controlling body powered prosthetics may prefer to use the low gearing since relatively significant movement is needed at the pivot joint to actuate the digits. Meanwhile, a user with more experience of prosthetics may want a finer amount of control over the digits, and will be capable of providing more precise movements at the pivot joint to actuate the digits.

The pivot joint may comprise: a first cylindrical member rigidly formed on an end of the first elongate member, the first cylindrical member having a cylindrical wall defining central passage extending along the rotational axis; and a second cylindrical member rigidly formed on an end of the second elongate member, the second cylindrical member having a cylindrical wall extending along the rotational axis, at least part of the second cylindrical member received within the passage of the first cylindrical member, the first and second cylindrical members arranged to rotate about the rotational axis, relative to each other, wherein the path is defined through radially extending openings in the cylindrical walls of the first and second cylindrical members.

It may be that the first cylindrical member has a pair of diametrically opposed openings in the cylindrical wall, defining the path, the openings providing an inlet and outlet for the one or more control wires.

It may be that the openings are substantially circular in shape. The openings are sized such that they are approximately the same size as the plurality of control wires required to actuate the digits of the hand or foot.

The pivot joint may have a neutral position, wherein in the neutral position, the angular distance from the one or more wire deflection portions to the nearest of the pair of diametrically opposed holes is greater in the first rotational direction that in the second rotational direction It may be that the wire deflection portions are located such that when the pivot joint is rotated in the first rotational direction, the wire deflection portions do not contact the wire and the path of the wire through the joint is substantially linear, and when the pivot joint is rotated in a second direction, the wire deflection portions manipulate the wire into an 'S' shaped path through the joint.

The wire deflection portions may compr se a pair of port ons of the cylindrical wall of the second cylindrical member.

It may be that the cylindrical wall of the second cylindrical member comprises elongate openings between the wire deflection portions, wherein the path extends through the pair of openings in the first cylindrical member and the elongate openings in the second cylindrical member, between the wire deflection portions.

The wire deflection portions may be located radially opposite each other.

It may be that in the neutral positon, the pair of openings in the first cylindrical member are aligned with the elongate openings in the second cylindrical member; and the wire deflection portions are arranged such that when the pivot joint rotates in the first rotational direction, the elongate openings in the second cylindrical member remain aligned with the pair of openings in the first cylindrical member but when the pivot joint rotates in the second rotational direction, the elongate openings rotate out of alignment with the pair of openings in first cylindrical member, such that at least a portion of the path passes circumferentially between the first and second cylindrical members.

The second cylindrical member may have flanges at both ends. The flanges may have diameter greater than the diameter of the central passage to retain the second cylindrical member with respect to the first cylindrical member.

It may be that the first and second elongate members, including the first and second cylindrical members are manufactured as a single part incorporating the pivot joint.

The body powered prosthetic limb may be manufactured using additive manufacturing techniques.

It may be that the first elongate member includes the anchor, and the second elongate member is a telescopic member such that a length of the prosthetic limb is adjustable, the telescopic member comprising a proximal portion and a distal portion which are telescopically connected and secured in position by one or more fastening means, the distal portion connected to a prosthetic hand having one or more digits, the one or more control wires anchored at the digits.

The body powered prosthetic limb of the second aspect may have the features of the prosthetic limb of the first aspect, with the telescopic member forming the member without the whippletree.

It will be understood that any feature discussed in relation to a particular aspect may also be applied to any other aspect, mutatis mutant/is.

Brief description of the drawings

The invention is shown, by way of example, in a series of drawings with an accompanying description which details the intricacies of an embodiment of the invention. The drawings include: Figure 1 is a perspective view of a prosthetic limb according to an embodiment of the invention, with the limb in tension, and the forearm in an extended position; Figure 2 is a perspective view of thc prosthetic limb of Figure 1 with the limb in tension, and the forearm in a retracted position; Figure 3 is a cross sectional view of the palm and wrist of the prosthetic arm of Figure 1, showing the internal hinge; Figure 4 is a perspective view showing further detail of the wrist hinge shown in Figure 3; Figure 5 is a top down view of a palm showing an alternative connector to that shown in Figures 3 and 4; Figure 6 is a cross sectional view of the elbow joint of the prosthetic arm of Figure 1; Figure 7 is a perspective view of the proximal forearm portion of the prosthetic limb of Figure I. including the outer section of the elbow joint; Figure 8 is a cross sectional view of the elbow joint of the prosthetic limb of Figure 1, showing the wires when the limb is in a neutral position; Figure 9 is a cross sectional view of the elbow joint of the prosthetic limb of Figure I, showing the wires when the limb is in tension in low gearing; Figure 10 is a cross sectional view of the elbow joint of the prosthetic limb of Figure I showing the wires when the limb is in tension in high gearing; Figure 11 is a perspective view of the whippletree assembly of the prosthetic limb of Figure I. in its neutral position, attached to the upper arm member; Figure 12 is a perspective view of the whippletree assembly of the prosthetic limb of Figure 1, in its taut position, attached to the upper arm member; Figure 13 is a perspective view of the whippletree of the prosthetic limb of Figure 1, assembly in its taut position; Figure 14 is a perspective view of the whippletree assembly of the prosthetic limb of Figure 1, in its neutral position; Figure 15 is a perspective view of the interior of the hand assembly of the prosthetic limb of Figure 1, when the limb is in tension with a varied force grip; Figure 16 is a perspective view of the exterior of the hand assembly of the prosthetic limb of Figure 1, when the limb is in its neutral position; Figure 17 is a cross sectional view of a Finger of the prosthetic limb of Figure 1 showing the internal wire pathway and joints; Figure 18 is a perspective view of a thumb of the prosthetic limb of Figure 1 showing the three thumb portions; Figure 19 is a perspective view of the prosthetic limb in a neutral position, and the forearm is in an extended position; Figure 20 is a perspective view of part of the arm assembly of the prosthetic limb of Figure 1; and Figure 21 is a top down view of the palm of the prosthetic limb of Figure I. in three sizcs.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

Detailed description

In the following description, reference will be made to proximal and distal ends/regions/portions. It will be appreciated that proximal refers to the end/region/portion closer to the body of the user and distal refers to the end/region/portion farther from the body of the user.

Referring to Figure I. a perspective view of the prosthetic limb is illustrated and referred to with numeral 14. The prosthetic limb 14 is formed of multiple subassemblies, including a hand assembly 16, a whippletree assembly 18 and a pair of arm assemblies 20a,20b, in the illustrated embodiment, the prosthetic limb 14 comprises an upper body limb, namely an arm, with the hand assembly 16 being disposed at the distal end of the arm assemblies 20a,20b. The hand assembly 16 comprises a palm 26, fingers 24, and a thumb 28.

Each of the arm assemblies 20 comprises a forearm member 21, a pivot joint (elbow) 38, and an upper arm member 34. A distal end 35 of the upper arm member 34 is connected to a proximal end 41 of the forearm member 21 by the pivot joint 38 which is discussed in more detail below. The angle of rotation of the pivot joint 38 can be described by the angle between the upper arm member 34 and the proximal forearm portion 42. For example, an angle of 180 degrees represents a straight arm (as shown in Figure 19). Figures 1 and 2 show a prosthetic arm with a 90 degree rotation in the pivot joint 38.

Each forearm member 21a,b is comprised of two portions: a distal forearm portion 36, and a proximal forearm portion 42. The distal and proximal forearm portions 36, 42 are arranged telescopically, as will be discussed in more detail below. As such, the forearm member 21 can be considered a telescopic member.

The hand assembly 16 is connected to a distal end 37 of the telescopic forearm members 21a,b. A first arm assembly forms an outer arm assembly 20a, that connects to the back side of the hand assembly 16. A second arm assembly forms an inner arm assembly 20b, that connects to the palm side of the hand assembly 16.

The arm assemblies 20a,b will now be described in more detail.

As shown in Figures 6, 11 and 12, the upper arm members 34 of the outer arm assembly 20a and the inner arm assembly 20b have opposing planar surfaces 40a, 40b. A first surface is an outer surface 40a that, in use, faces away from the residual limb of the user, and the second surface 40b is an inner surface that faces towards the residual limb of the user. The opposing surfaces 40a.b are substantially rectangular in shape, and are separated by a thickness. The upper arm member 34 has a length perpendicular to the thickness, running from a proximal end 39 to a distal end 35, and a width perpendicular to the thickness and the length. The thickness is less than the length and width of the upper arm member 34, such that the upper arm member 34b is substantially flat. The length is also larger than the width and thickness, so the member 34 can be considered elongate.

At or near its proximal end 39, the upper arm member 34b includes an attachment point 142. The attachment point 142 is in the form of an eyelet or hoop projecting from one a first of the planar surfaces 40a in a direction parallel to the thickness.

As will be discussed in more detail below, a first portion of the elbow joint 38 is formed on the proximal end 39 of the upper am n member 34.

The upper arm member 34a of the outer arm assembly 20a (shown in Figures 11 and 12) further comprises an integrally formed connector 72 to which the whippletree mount 32 is fastened. The whippletree assembly 18 will be discussed in more detail below. The whippletree connector 72 is omitted from the upper arm member 34b of the inner arm assembly 20b.

Each proximal forearm portion 42 has a cross section defining a width and a thickness perpendicular to the width. The thickness extends between an outer surface 46a and an inner surface 46b, in a similar manner to the upper arm member 34. Each proximal forearm portion 42 also has a length running from a proximal end 41 to a distal end 45, the length perpendicular to the thickness and width.

As best shown in Figure 7, the cross section of the proximal forearm portion 42 is discorectangular in shape, with a hollow core defining a passage extending along the length of the proximal forearm portion 42. The proximal forearm portion 42 is closed at its proximal end 41 and open at its distal end 45. The major dimension of the discorectangular cross section (i.e. the longest straight line between opposing sides) is along the width of the proximal forearm portion 42.

With the pivot joint 38 in the neutral position (rotation of 180 degrees), the length of the proximal forearm portion 42 extends parallel to the length of the upper arm member 34, the width of the proximal forearm portion 42 extends parallel to the width of the upper arm member 34, and the thickness of the proximal forearm portion 42 extends parallel to the thickness of the upper arm member 34.

The axis of rotation of the elbow joint 38 is parallel to the thickness of both the upper arm member 34 and the proximal forearm portion 42 In the illustrated embodiment the proximal forearm portion 42 includes a second portion of the elbow joint 38 at its proximal end 41. Each proximal forearm portion 42 includes four attachment points 142. The attachment points 142 on the proximal forearm portions 42 are arranged in pairs, where the attachment points 142 of a single pair are located on opposite sides of the width of the proximal forearm portion 42, at the same position along the length. A first pair of eyelet attachment points 142 is located at or near the proximal end 41 of the proximal forearm portions 42, and the second pair is located substantially halfway between the proximal end 41 and distal end 45 of the proximal forearm portion 42.

In use, the attachment points 142 on the upper arm members 34a,b face outward from the residual limb, and the attachment points 142 on the proximal forearm portions 42a,b extends perpendicular to the attachment points 142 on the upper arm members 34a,b.

In use, the inner surface 40b of the upper arm member 34 and the inner surface 46b of the proximal forearm portion 42 rest against the residual limb of the user. The prosthetic limb 14 is attached to the user's residual limb using an elasticated loop strap (omitted for clarity) which is passed through the attachment points 142 on each of the upper arms 34 and around the residual limb, above the elbow on the residual limb.

Below the elbow on the residual limb, the prosthetic arm 14 is secured to the residual limb by a loop strap which passes through one eyelet 142 in the first pair of the proximal forearm portion 42a, b, in a direction away from the residual limb, around the proximal forearm portion 42a,b, and then back through the other eyelet of the pair in a direction towards the residual limb. This sequence is then repeated on the first pair of attachment points 142 on the other proximal forearm portion 42b,a, which is directly opposite the first mentioned pair, along the length of the residual limb. Thus, the strap loops around both proximal forearm portions 42a,42b and the forearm of the residual limb. A further strap is fitted in the same way using the second pairs of eyelets 142 on the proximal forearm members 42. Therefore, in the illustrated embodiment, three straps are used to attach the prosthetic limb 14 to the user's residual limb, two on the proximal forearm 42, and one on the upper arm member 43. Straps are threaded through attachment points 142 that are directly above/below and opposite each other to ensure a secure loop is made around the user's residual limb.

Although the description discussed above uses elastic loop straps. Other straps may be used such as hook and loop straps, and other forms of belt or strap.

Each distal forearm portion 36 has a discorectangular cross section arranged to form a tight fit inside the channel of the proximal forearm portion 42. The distal forearm portion 36 has a length extending parallel to the length of the proximal forearm portion 42, a width extending parallel to the width of the proximal forearm portion 42 and a thickness extending parallel to the thickness of the proximal forearm portion 42.

The distal forearm portion 36 extends into the open end 45 of the proximal forearm portion 42, and can slide along the direction parallel to the length of the forearm portions 36, 42. The forearm portions 36, 42 are held at a chosen length. This can be considered a telescopic connection, as it allows the total length of the forearm member 21 (from the distal end 37 of the distal arm portion 36 to the proximal end 41 of the proximal arm portion 42 to be varied.

In order to secure the forearm portions together, both the distal 36 and proximal 42 forearm feature holes 10a, 10b which extend through their thicknesses. The holes 10a, 10b can be aligned to enable bolts (omitted for clarity) to be passed through the proximal 42 and distal 36 forearms and engage with nuts (omitted for clarity), to secure the telescopic forearm member 21 at a suitable extension length. The holes 10a and/or 10b may be threaded, and a screw may used in place of a bolt to engage with the screw thread of the holes In this way, a nut may not be necessary to ensure the screw is secure.

In the illustrated embodiment, both the proximal forearm portion 42 and the distal forearm portion 36 comprise pairs of holes 10a, lob, the separation between the holes 10a, 10b within the pair being smaller than the separation between adjacent pairs. The proximal forearm portion 42 includes elliptical projections 47 on the outer surface 46a, in which the pairs of holes 10a are formed. Both holes 10a, 10b in a pair are intended to be used to receive fasteners at the same time. By using a pair of fastening points, the proximal 42 and distal 36 forearm may be more securely and rigidly fastened.

The holes 10b on the distal forearm 36 may not be in pairs, and may instead be evenly spaced, the spacing between each hole 10b being equal to the spacing within each pair of holes 10a on the proximal forearm 42.In this way, there would be more possible lengths and so such an arrangement would increase the adjustability of the forearm 21. Ensuring that the separation between the holes 10b on the distal forearm 36 matches the spacing within each pair of holes 10a on the proximal forearm 42 means that a pair of holes 10a can still be used to fasten each proximal forearm 42 and distal forearm 36 together, as discussed above. in some, but not all, embodiments the spacing between pairs of holes 10a on the proximal forearm 42 is a multiple of the spacing between holes 10a within pairs such that, when the distal forearm portion 36 is sufficiently received within the proximal forearm portion 42, more than one pair of holes 10a may be used to fasten the proximal 42 and distal 36 forearm portions together. Other fastening means, such as pins or screws for example, may be used in place of nuts and bolts, and will be apparent to the person skilled in the art.

In the illustrated embodiment, each of the proximal 42 and associated distal 36 forearm portions has a discorectangular cross-section. The proximal 42 and distal 36 forearm portions may be of substantially the same or of different cross-sectional shapes. One or each may, for example be of a tubular cross-section, such as a circular or rectangular cross section or of a 'C' section channel shape or elliptical, provided the distal forearm portion 42 can slide within the channel of the proximal forearm portion 36.

Referring to Figures 1 and 2, the prosthetic limb 14 is illustrated in two positional configurations. Figure 1 shows the prosthetic limb 14 in a First extended 35 configuration. Figure 2 shows the prosthetic limb 14 in a second, shorter, configuration. Extension of each telescopic forearm member 21 facilitates lengthening of the prosthetic limb 14, as needed, such as to accommodate the rapid growth of a child, for example.

As discussed above, the hand assembly 16 is connected to the distal end of the telescopic forearm members 21a,b, which is formed by the distal end 37 of the distal forearm portion 36 As best shown in Figure 15 and 16, the hand assembly 16 includes a pair of connectors 22a,b for connecting the palm 26 to corresponding arm assemblies 20a,b.

The connectors 22 include sleeves 23 haying an open end shaped to receive the distal end 37 of the distal forearm portions 36. Holes 50 in the distal forearm portions 36 align with holes 52 in the connectors 22, which allows a bolt or other fastening means to be passed through the lower forearms 36 and the connectors 22, the bolts being secured with respective nuts to ensure the two parts remain attached.

In an outer connector 22a, the sleeve 23, which receives the distal forearm portion 36a of the outer arm assembly 20a, is rigidly connected to the back of the hand assembly and does not feature any rotation.

In an inner connector 22b, the sleeve 23, which receives the distal forearm portion 366 of the inner arm assembly 20b, is connected to the palm 26 by a pinet hinge 33. The pinet hinge 33 is configured to rotate about a single axis perpendicular to the length of the forearm member 21 and to the thickness of the forearm member 21. it may alternatively be that the pinet hinge 33 is located on the outer connector 22a, and the connector 22b on the inner side of the prosthesis 14 does not feature any rotation and is fixed.

Figure 3 features a cross sectional view of the inner connector 22b. The sleeve 23 includes a projection 32 extending from its distal end (opposite the open end that receives the distal forearm portion 36b) in a direction parallel to the length of the forearm 21. The projection 31 includes a pair of cylindrical or conical protrusions 136 extending perpendicular to the length 21 of the forearm, defining the angle of rotation of the hinge 33. internal recesses 134 on the palm 26 can be seen, which are configured to engage with protrusions 136 formed on the projection 31 of the sleeve portion 23. The engagement allows rotation of the protrusions 136 within the recesses 134. Figure 4 shows the sleeve and projection 31, in detail.

Adjustment of the width of the prosthetic limb 14 is facilitated by adjusting the separation of the two arm assemblies 20. The arm assemblies 20a,b are only connected at the hand assembly 16 at their distal end 37, and by elastic or adjustable loop straps at or near their proximal end. Therefore, adjustment of the separation between the arm assemblies 20 occurs at the inner connector 22b on the hand assembly 16. The pinet hinge allows the inner arm assembly 20b to pivot about an axis substantially perpendicular to both the length and thickness of the distal forearm member 36b. The angle of the two arm assemblies 20 with respect to each other is therefore adjustable and hence the distance between the two assemblies at the upper arm members 34, where the prosthetic arm 14 is attached to the residual limb, is adjustable. This adjustment allows the prosthetic arm 14 to adjust in width when fitted to a user, to accommodate differences in the width of the residual limb Figure 5 features a top down view of palm 26 having an alternative connector 22. The connector 22 of Figure 5 includes a pair of holes 52. The sleeve 23 has on its outer face an elliptical projection 47 through which the holes 52 are formcd. This arrangement is similar to that of the holes 10b in the proximal forearm portion 42. In embodiments including a connector 22 as shown in Figure 5, two holes 50 in the distal forearm member 36 may be provided. In this way, a pair of fastening means can be used to fasten the hand assembly 16 to the distal forearm 36. Such an arrangement will provide a more rigid connection. The holes 50 may be the two most distal holes 106 in the distal forearm portion 36.

Figure 16 shows the hand assembly 16 in detail, whilst Figure 17 shows a finger 24 and Figure 18 the thumb 28. The hand assembly 16 includes the palm 26, palm top 78, thumb 28 and fingers 24. The thumb 28 is comprised of three moving parts, the thumb top 80, thumb middle 82 and thumb base 84. The thumb 28 is connected to the palm 26 via a threaded bar that is inserted from the wrist through a channel in the palm and allows rotation about one axis. The threaded bar pivotally joins the thumb base 84 to the palm 26. The thumb base 84 is able to pivot about the axis of the threaded bar, mimicking the movement of the Carpometacarpal joint. The screw thread on the threaded bar engages with internal thread in the channel through the palm 26. In other embodiments, the channel may not be threaded, and the bar may be held in place with an external nut.

The thumb can be best seen in Figure 18, in the illustrated embodiment, the three parts 80, 82, 84 are connected with integrally formed pinet hinges 86 which cannot be separated. The fingers 24 are comprised of two moving parts which are connected with integrally formed pinet hinges 128 and hence cannot be separated. The pinet hinges 128 have the same internal construction (with protrusions and recesses) as explained in relation to hinge 33 on the connector 22b. The four fingers 24 are joined to the palm 26 at joint 130. This joint is formed using the same threaded bar arrangement that joins the thumb 28 to the palm 26. A single threaded bar passes through the base of all four fingers, and engages with internal threads in the channel through the palm 26, in other embodiments, the channel may not be threaded, and the bar may be held in place with an external nut.

The movement of the digits (fingers 24 and thumb 28) is controlled by control wires 54. The wires 54 are connected at or near the distal ends of the digits 24, 28 (shown in Figure 17), and are also anchored at the wh ppletree 30 on the proximal side of the pivot joint 38a. Rotation of the pivot joint 38, such that the forearm 21 and upper arm member 34 are not parallel (i.e. the angle of rotation is less than 180 degrees), increases the path distance of the wires 54. This increased path distance increases tension in the wires 54, and causes the wires 54 to pull on the ends of the digits 24, 28 which bends the pinet hinges 86, 128 in the digits, such that the hand 16 begins to form a fist, which eventually closes with sufficient tension in the wires 54.

Both the thumb 28 and the fingers 24 feature inbuilt channels 88 shown in Figure 17 that allow a wire 54 to be passed therethrough. This wire 54 creates movement in the digit by translating the rotational movement of the pivot joint 38 about its axis into movement of the digit 24, 28 due to tensioning the wire 54. Figure 1 shows the prosthesis 14 in its tensed position whilst Figure 17 shows the prosthesis 14 in its neutral position. In the neutral position, a certain amount of tension exists in the wires 54, but this is increased in the tensed position.

As shown in Figure 17, the wire 54 is attached to the prosthesis 14 as follows: A first end of a wire 54 is secured at the tip 92 of a first finger 24 through an inbuilt attachment point 94 (for example by knotting). This wire 54 is then passed through a channel 88 in the finger 24 and through a channel in the palm 26. From the palm 26, the wire 54 is passed through a channel 98 in the wrist connector 22a, into a channel 100 in the distal forearm 36a, as seen in Figure 20. The channel 100 in the distal forearm 36a is offset from a centreline defined bisecting the width of the distal forearm 36a since the central region of the distal forearm 36a is occupied with the holes for fastening it to the proximal forearm 42a and connector 22a. The wire 54 is then passed through the channel 100 in the distal forearm portion 36a where it continues along its path through the proximal forearm portion 42a, passing within the same channel in which the distal forearm portion 36 slides. At the proximal end of the proximal forearm portion 42, the control wire 54 passes through a hole 102, into the elbow joint 38a. As with the channel in the distal forearm portion 36a, the hole 102 is offset from the centreline of the forearm 21. The wire 54 is then passed across the elbow joint 38, passing perpendicular to the axis of rotation, and through a hole 70 in the opposite (proximal) side of the elbow joint 38. From the hole 70 on the proximal side of the elbow joint 38 the wire 54 is passed along the upper arm member 34a to the whippletree 30.

From the whippletree 30, the wire 54 completes the same journey in reverse, passing through a second finger 24, adjacent the first finger 24. The second end of the wire 54, opposite the first end, is secured to the attachment point 94 of a second finger 24, adjacent the first finger.

The index finger 24a (first finger from thumb) and middle finger 24b (second finger from thumb) arc connected by a single piece of wire 54 that passes through the whippletree 30 and the ring finger 24c (third finger from thumb) and little finger 24d (fourth finger from thumb) are also connected by a single piece of wire 54 that passes through the whippletree 30. The wire 54 connecting the thumb 28 to the whippletree 30 follows the same path as that of the wire 54 connected to the fingers 24. However, the second end of the wire is secured to the whippletree 30 and is not passed through the prosthesis 14 on a return journey.

The palm top 78 is removable to allow the wires 54 to be threaded along their respective paths. Figure 16 shows the palm 26 with the top 78 removed.

In the embodiment discussed above, the control wires 54 are passed through the outer arm assembly 20a, in alternative embodiments, the control wires 54 may extend through the inner arm assembly 20b, in which case the proximal forearm portion 42b and associated distal forearm portion 36b of the inner arm assembly 20b may define a protective passageway through which the control wires 54 extend. Furthermore, in alternative embodiments, single wires 54, secured to the finger 24a-d at one end and the whippletree 30 at the other end, may be used.

Figures 11-14 illustrate the whippletree assembly 1/1 in further detail. The whippletree assembly 18 comprises a connector 72 which is integrally formed on the upper arm member 34a of the outer arm assembly 20a, the whippletree body 30, and the whippletree mount 32.

The whippletree body 30 is a solid triangular shaped element. The whippletree body 30 is pivotally connected to the whippletree mount 32 at one apex of the body 30, and the whippletree mount 32 is rigidly connected to the connector. Therefore, the whippletree body 30 is able to rotate with respect to the whippletree mount 32 and the upper arm member 34, about an axis perpendicular to the axis of rotation of the pivot joint 38, and the surfaces of the upper arm member 34 The whippletree body 30 comprises three internal passages which act as loop points about which the control wires 54 for the fingers 24 and thumb 28 can be looped. The loop points retain the wires with respect to the whippletree 30, thus anchoring the wires 54, in the example shown, each loop point comprises a pair of adjacent holes 140 formed in the body of the whippletree 30. The holes 140 of the loop points are internally connected by an arcuate passage such that a wire 54 can be threaded into the whippletree body through the first hole of a pair and then back out of the body 30 through the second hole of the pair.

As discussed above, the wires 54 attached to the fingers 24 loop around a loop point at the whippletree 30 and then pass back down the arm assembly 20 to the adjacent finger. The wire 54 which is attached to the thumb loops around a loop point, but is then tied off at the exit of the second hole of the pair, anchoring the wire 54 at the whippletree 30.

It will be appreciated that for embodiments where each finger 24 has a separate control wire 54, additional anchor points may be provided for each wire. Furthermore, any suitable type of anchor point may be used. For example, the passages which form the loop points may pass straight through the entire whippletree, such that a wire passes into the first passage at the distal end of the whippletree 30, out of the first passage at the proximal end of the whippletcree, then back into a second passage at the proximal end and out of the second passage at the distal end, forming a loop. Other anchor points such as pegs or the like may also be used.

Rotation of the whippletree 30 varies the path length of each wire 54 (or portion of wire) between the whippletree 30 and digit 24. This enables a varied grip whereby there is a difference in the amount of travel undertaken by the index finger 24a compared to the little finger 24d. This can be necessary when grasping irregular shaped items which have a significant variation in diameter, such as conical objects.

When holding a regular shaped object, (for example a cylinder) the whippletree body 30 is symmetrically oriented with respect to the with respect to the whippletree mount 32 and upper ann member 34, as shown in Figures 11 and 14.

However, when an uneven object is held, the whippletree body 30 rotates about its pivot point. For example, when holding a conical item with the larger end near the thumb, the index finger 24a requires much less travel that the little finger 24d the whippletree body 30 rotates in a first direction to ensure a secure grip. Similarly, if the conical item is held the opposite way around, the whippletree body 30 rotates in the opposite direction. The whippletree 30 facilitates an uneven grip as the rotation of the whippletree 30 creates additional slack in the wires 54 connected to one side of the hand 16 whilst tensioning the wires 54 on the opposite side of the hand 16. This creates an uneven distribution of force across the wires 54 and therefore allows for a variation in the travel of the fingers 24 and thumb 28. This is shown in Figure 15 where the little finger 24d has increased travel compared to the index finger 24a.

In addition to adjusting the length and width of the prosthesis 14, the palm 26, thumb 28 and fingers 24 are modular and hence removable and replaceable. The use of a single threaded bar to join all four fingers 24 to the palm 26 means that the fingers 24 are quick and easy to remove and replace. This enables a suitably sized hand 16 to be attached that is in proportion with the user's body. Figure 21 shows three differently sized interchangeable palms 26 next to each other. Though the palm 26, thumb 28 and fingers 24 are available in a variety of sizes, the connection points 90 remain the same size to enable them to be easily interchanged to allow for customisation of the prosthesis 14. Fingers 24 of various sizes can be fitted to any palm 26 to allow a completely customisable prosthesis 14 that is suitably sized for the user. When this is used in combination to the adjustable width and length of the arm assembly 20, the user has the ability to resize and refit their prosthesis 14 whenever required using their current prosthesis 14 and the components contained within it, as well as new components that have been purchased.

The wires 54 are taut when the prosthesis 14 is in its neutral position as shown in figure 19. When the elbow joint 38 is bent, meaning that the upper arm member 34 and proximal forearm 42 are no longer collinear, the tension on the wire 54 is increased causing the fingers 24 and thumb 28 to be pulled inwards towards the palm 26 creating a fist, as seen in Figure I. When the tension is decreased, the fingers 24 and thumb 28 return to their neutral position with the aid of elastic bands 108 on the knuckle side of the fingers 24 which act as biasing means.

Figure 19 shows the prosthesis 14 in its neutral position. The prosthesis 14 uses elastic bands 108 (shown in Figure 16), in this case small circular elastic bands akin to dental elastics used for securing braces, to ensure the fingers 24 and thumb 28 remain in the neutral position unless tension is applied to the wires 54. In alternative embodiments elasticated wire could be used to provide the same functionality. in the neutral position, all elastic bands 108 are visible and the recesses 110 in which they sit can easily be viewed. These recesses 110 have a cross section of a right-angled trapezoid with an undercut, whereby the sloped edge undercuts the central section and allows the elastic 108 to contract. This shape reduces the likelihood of the elastic bands 108 coming loose and pulling out of their recess 110, it will be appreciated that any suitable resiliently biased member may be used to secure bias the digits back to the neutral position.

Each finger 24 features recesses for two separate elastic bands 108, one elastic band 108 tensions the finger knuckle 128 (proximal interphalangeal joint), whilst the other elastic band 108 tensions the palm knuckle 130 (metacarpophalangeal joint). In the illustrated embodiment the distal interphalangeal joints 132 have been fused and therefore do not have any movement as they are in a permanent fixed position. in alternative embodiments, the distal interphalangeal joints 132 may be hinged in the same way as the other finger joints 128, 130. The thumb 28 features recesses 110 for three separate elastic bands 108, tensioning both thumb knuckles 128, 130 (mctacarpophalangeal joints) and the carpometacarpal joint 86 between the palm 26 and the thumb 28. The elastic bands 108 act as biasing means and pull the fingers 24 and thumb 28 back to a neutral position after they have been in tension.

As discussed above, the upper arm members 34 are connected to the proximal forearm portions 42 via pivot joints 38. In the illustrated embodiment (an arm) the pivot joint 38 is an elbow joint 38. The elbow joint 38 will now be described in more detail, with reference to Figures 1, 2, 6 to 11 and 19.

The elbow joint 38a comprises an inbuilt reyolute joint 56, 58 formed as a single part.

This may be, for example by 3D printing or other additive manufacturing process. During the printing process, support material separates the moving components. The support material is then removed after the print is complete, providing parts that can move relative to each other, whilst being formed as a single integral component.

The joint 38 comprises an inner cylindrical member 58 and an outer cylindrical member 56, arranged around the inner member 58. Figure 6 shows the upper arm member 34, with the joint 38 shown in cutaway (such that the forearm member 21 extends into the page) With reference to, for example, Figure 11, the upper arm member 38 includes the inner cylindrical member 58 of the elbow joint 38a. In the illustrated embodiment, the inner cylindrical member 58 is integrally formed with and rigidly connect to the upper arm member 34. The inner cylindrical member 58 is formed by a cylindrical sidewall 51 defining a central passage 66a. The sidewall 51 extends from the first surface 40a of the upper arm member 34, in the same direction as the connection points 42. A central axis of the cylinder defines the axis of rotation of the joint 38.

At each end of the cylindrical wall 51 there is a flange 55 projecting radially outward from the sidewall 51. In the example shown, the flange 55 extends around the entire circumference of the cylindrical wall 51. A pair of slots 60 are formed through the sidewall 51, extending a portion of the length of the wall 51 between the flanges 55. The slots 60 are situated diametrically opposite each other around the cylindrical wall 51. Each slot 60 extends for approximately 90 degrees around the circumference of the sidewall 51, such that they are considered elongate. Wire deflection portions 59 are defined by the sidewall 51 between the slots 60 Figure 7 shows the proximal forearm portion 42 which features the outer member 56 of the elbow joint 38a, in the illustrated embodiment, the outer member 56 is integrally formed with and rigidly connected to the proximal forearm member 42. The outer member 56 is formed by a cylindrical sidewall 53, defining a central passage 66b. The sidewall 53 is formed as a hoop at the proximal end 41 of the proximal forearm portion 42, with the primary axis of the hoop extending perpendicular to the length and width of the forearm member 21.

The length of the cylindrical sidewall 53 along its primary axis is substantially equal to the spacing between the flanges 55 of the inner cylindrical member 58. The inner diameter of the outer cylindrical member 56 is greater than the outer diameter of the inner cylindrical member 58. In this way, the inner cylindrical member 58 may be received within the central passage 66a of the outer section cylinder 56. In the illustrated embodiment, the inner diameter of the outer section cylinder 56 is smaller than the outer diameter of the flanges 55 on the inner cylindrical member 58. The flanges 55 therefore hold the inner section cylinder 58 in place along the axial direction, within the outer cylindrical member 56.

To ensure stable rotation about a single axis only, the outer diameter of the inner cylindrical member 58 is a tight fit to the inner diameter of the outer cylindrical member 58. This prevents wobbling, whilst still allowing rotation. The outer diameter of the outer cylindrical member 56 is the same as the outer diameter defined by the flanges 55.

Furthermore, in order to provide a stop on the rotation of the elbow joint 38, the proximal forearm portion 42 includes a projection 48 extending along its length. The projection 48 ends short of the proximal end 41 of the proximal forearm portion. The spacing of the projection 48 from the elbow joint 38 and the shaping of the end of the projection 48 is arranged such that the projection contacts the flange 55 of the inner cylindrical member 58 projecting from the inner surface 40b of the upper arm member 34 once the joint has rotated by a certain amount, preventing further rotation.

In one example, the elbow joint 38 and proximal forearm portion 42 may be arranged to limit rotation to just over 90 degrees (for example 95 degrees). However, it will be appreciated that the arm may rotate anywhere between 0 degrees and 180 degrees in either a clockwise Z, or anticlockwise Z1 direction.

The outer cylindrical member 56 comprises two holes 102, 70 extending through the cylindrical wall 53, at diametrically opposed positions on the sidewall 53. The first hole 102 passes from within the passage 66b of the cylindrical sidewall 53, into the channel 100 of the proximal forearm portion 42. The first hole 102 is elongate, extending around a portion of the circumference of the sidewall 53. The first hole 102 aligns asymmetrically with the centreline of the proximal forearm portion 42a, and allows the control wires 54 to pass from inside the proximal forearm 42a into the elbow joint 38a. The hole 102 is asymmetric around the centreline of the proximal forearm 42a since the channel 100 in the distal forearm 36a is offset from the centreline of the distal forearm 36a. The second hole 70 is circular and is located directly in line with the centreline of the proximal forearm 42a. The second hole 70 extends through the sidewall 53, and allows the control wires 54 to exit the elbow joint 38a such that they can be anchored at the whippletree 30.

The diameter of the second hole 70 is approximately equal to the height of the first hole 102 and the slots along the axial direction of the cylindrical sidcwalls 51, 53.

On the inner surface of the cylindrical wall 53, there is a groove 57 which extends around the entire circumference of outer cylindrical member 56. In the illustrated embodiment, hole 102 is larger than hole 70. This is to minimise the risk of wires 54 catching or snagging during movement of the elbow 38a.

In the assembled joint, the inner cylindrical member 56 is received within the passage of the outer cylindrical member 58, such that their primary axes coincide. Therefore, the passages 66a, 66bformed in the cylindrical members 56, 58 also coincide, forming a central passage 66 of the elbow joint having a primary axis along the axis of rotation of the joint.

In the neutral (unbent) position, as shown in Figures 8 and 19 (180 degree angle of rotation), the holes 70, 102 in the outer cylindrical member 56 align with an end of the slots 60 in the inner cylindrical member 58. Thus wire deflection portions 59 are located such that when the elbow 38a is in the neutral position, the wire deflection portions 59 are on either side of the wires 54, and are close to touching them such that the angular distance from each wire deflection portion 59 to the nearest hole 102, 70 is much greater in a first rotational direction, for example anticlockwise Z1 in Figure 8, than in a second rotational direction, for example clockwise Z2 in Figure 8. Therefore, when the cylindrical members 56, 58 are rotated relative to each other, about their coincident primary axes, the holes 70, 102 remain aligned with the slots, whilst when rotated in the opposite direction, the holes 70, 102 move out of alignment with the slots 60.

In the neutral position, the wires 54 enter the elbow joint 38a from the proximal forearm 42a, and then pass first through the first hole 102. The wires 54 then pass through the slots 60, between the wire deflection portions 59, and out of the second hole 70. The path of the control wires 54 is therefore substantially straight, along a diameter of the cylindrical portions 56, 58.

Consider rotating the proximal forearm member 42 relative to the upper arm member 34 in directions Z1 (anticlock wise) and Z2 (clockwise) shown in Figure 8. Figure 9 shows the elbow joint 38a with the proximal forearm member 42 rotated through 90 degrees in direction Z1, such that the holes 70, 102 remain aligned with the slots 60. When the prosthesis 14 is in tension (i.e. the elbow joint is bent), the wires 54 are still able to pass across the central passage 66 of the elbow joint linearly but additional tension is created due to the increased travel between the elbow exit hole 70 and the whippletree 30, as shown in figure 9.

Figure 10 shows the elbow joint 38a rotated through 90 degrees in the opposite rotational direction (Z2). In this case, the control wires 54 pass along the extended path length from the whippletree 30 to the exit hole 70 as discussed above. In this configuration, the control wire 54 cannot pass straight across the central passage 66 of the joint 38. Instead, the wire 54 passes through the hole 70, around a portion of the groove 57, before passing out a first slot 60. The wire 54 then extends diametrically across the central passage 66, in through a second slot 60, around a further portion of the groove 57 and out the hole 102 into the proximal arm portion 42. Now, when the prosthesis 14 is in tension, the wires 54 pass through the elbow joint 38a in an shape, therefore increasing the path length of the wires 54 when the elbow 38a is bent, compared to Figure 9.

Therefore, in the second configuration, rotation in the second direction Z2 causes a greater change in the path length (and therefore applies a greater tension) than the same amount of rotation in the first direction Z1. Alternatively, this increased path length in the second configuration means that less rotation is required at the elbow 38a to move the digits (fingers 24 and thumb 28) by the same amount than is required when the elbow 38a is bent in the first configuration. This arrangement means that when the elbow joint 38a is rotated in one direction, the wire deflection portions 59 move away from the wires 54 and so do not affect the path length (low gearing), but when the elbow joint 38a is rotated in the opposite direction, the wire deflection portions 59 contact the wires 54 immediately and then carry the wires 54 through their rotation, forming the "S" shaped path discussed above (high gearing).

As discussed above, elbow joints 38 tend to bend in a single direction. Therefore, dependent on the orientation of the installed elbow joint 38a the prosthesis can be set at either high or low gearing which determines the amount of movement required at the elbow joint 38a to fully open and close a fist. With low gearing, shown in Figure 9, more movement at the elbow 38a is required to open and close the fist. High gearing, shown in Figure 10, however increases the distance the wires 54 must travel during elbow contraction and therefore less movement is required in the elbow 38a to open and close the fist.

in the illustrated embodiment, the elbow joint 38a through which the wires 54 pass is provided on the outer arm assembly 20a (i.e. the arm assembly on the side of the residual limb away from the body of the user). The joint 38a in the Figures is configured to provide low gearing on a right arm when the inner surface 40b of the upper arm member 34 is provided against the residual limb. The same joint 38a would therefore provide high gearing if used as a left arm since the arm assembly 20a would have to be flipped such that inner surface 40b of the upper arm member 34a was in contact with the residual limb, and so the relative rotational direction would also flip (from Zito Z2), To provide an elbow joint 38a which is configured to provide high gearing on a right arm and low gearing on a left arm, the arrangement of the slots 60 in the sidewall 51 is mirrored in the centreline of the forearm. In one example, the elbow joint 38b of the inner arm assembly 20b may have this mirrored arrangement, so that to switch between high gearing and low gearing, the inner and outer arm assemblies 20ab, may be swapped (and the control wires 54 re-wired in the new outer arm assembly 20a). To achieve this, both upper arm members 34a,b may include whippletree assemblies 18, or at least whippletree connectors 72 to allow the whippletree assembly 18 to also be switched.

In an alternative example, the proximal elbow joint 38b of the illustrated embodiment does not include any slots 60 or holes 70, 102, since the control wires 54 do not pass through the proximal joint 38b. As such, to switch between high gearing and low gearing, a separate outer arm assembly 20a is required.

In a further alternative example, the outer arm assembly 20a may simply be flipped over to switch between high gearing and low gearing, such that the outer surface 40a of the upper arm member 34 and the outer surface 46a of the proximal forearm member 42a are now in contact with the residual limb. In yet a further example, the elbow joint 38 may be able to be disconnected, to allow just the upper arm member 34a to be exchanged or flipped.

The above description sets out one way of implementing a telescopic forearm member 21. It will be appreciated by the person skilled in the art that any suitable telescopic coupling between the two portions 36, 42 of the form arm may be used to allow the length of the forearm member 21 to be modified.

Furthermore, in the example discussed above, pinet joints 33 are used at one of the connectors 22b from the forearm member 21 to the hand 16, and at the joints within the hand. However, it will be appreciated that this is by way of example only, and any suitable hinged joint may be used. Optionally the joint may have a single axis of rotation.

In the above example, a whippletree joint mechanism is used to anchor the control wires 54 at the proximal end 39 of the arm. it will be appreciated that this is by way of example only. Any suitable anchor point for fixing the control wires 54 may be used. The anchor may be rigid or pivoted to allow variation in tensions in the control wires 54 as the prosthetic arm 14 is bent.

In the illustrated embodiment two arm assemblies 20 are provided. It is envisioned that the prosthetic 14 may comprise a different number of arm assemblies 20, for example there may be only a single arm assembly 20, or three or more arm assemblies.

In the above embodiment, the parts are formed using additive manufacturing techniques. It will be understood that any suitable manufacturing technique may be used such as casting, milling, carving for example.

In the illustrated embodiment, the prosthesis 14 is a prosthetic arm. It is envisioned that the prosthesis 14 may be configured to replace another limb, such as a leg, with a foot at the distal end. The pivot joint 38 may be a knee joint.

In the illustrated embodiment, a prosthetic hand assembly 16 is fitted to the distal end of the telescopic member. It is envisioned that other attachments may be used, such as a split hook. Embodiments with a split hook may not have a whippletree assembly 18 since the split hook is not capable of variable grip and so uneven tension in the wires 54 is not required.

It is preferable that the connector 22 through which the control wires 54 pass forms a rigid connection to the hand assembly 16 whilst the other connector 22 comprises a pinet hinge, however it is envisioned that the control wires 54 may pass through a connector 22 comprising a pinet hinge. For example, the wires 54 may pass through passages formed in the projection forming the pinet joint 33.

In the illustrated embodiment, the distal forearm 36 is at least partially received within the proximal forearm 42, it is envisioned that the proximal forearm 42 may instead be received within the distal forearm 36.

In the above embodiment, a pair of holes is used to receive fastening means to lock the telescopic member in place. In other embodiments, more or fewer holes may be used. For example, triplets of holes may be used.

In the illustrated embodiment, the inner 58 and outer 56 elbow sections are integrally formed with the upper arm member 34 and the proximal forearm 42 respectively. In alternative embodiments, this may be the other way around such that the inner section 58 is integrally formed with the proximal forearm 42 and the outer section 56 is integrally formed with the upper arm member 34. it is also envisioned that one or both of the pivot joint sections 56, 58, may not be integrally formed with an arm member, and may instead be provided as separate parts. In this case, the inner cylindrical member needs to be formed in separate parts to allow the joint to be assembled. The joint 38 may be assembled using welding, adhesive, clips, friction fits or the like.

In the illustrated embodiment, two wire deflection portions 59 and two slots 60 are provided on the inner section 58 of the pivot joint 38. In other embodiments, different numbers of slots 60 and wire deflection portions 59 may be provided. For example, only a single slot 60 and wire deflection portion 59 may be provided.

Furthermore, the elbow joint 38a may be arranged such that rotation in either direction is low gearing and rotation in the other direction is high gearing, by changing the relative rotational positions of the wire deflection portions 59 in the neutral position. The high gearing direction will always be in the same direction as the shorter distance between the holes 70 102 in the outer cylindrical member 58 and the wire deflection portions 59.

In addition, the elbow 38 may be arranged to have a configuration that has low gearing over a first range of rotation in a first direction, and then high gearing over a second range of movement in the same direction (for example low gearing over the 0 to 15 degrees and high gearing over rotation over 15 degrees in the same direction).

This may be accomplished by modifying the alignment of the holes 70, 102 in the outer cylindrical member 58 and the slots 60 in the inner cylindrical member in the neutral position. For example, if the holes 70, 102 are arranged such that, in the neutral position, the holes are 15 degrees from one end of the slots 60, there is a range of movement over which low gearing is maintained, before the high gearing commences.

Thus, but varying the amount the joint 38 can rotate before the holes 70, 102 and slots arc no longer aligned, direction in the same direction can have both low and high gearing is made.

In the opposite direction, there is a range of the remainder of the slot (in the example discussed above 75 degrees) before high gearing is adopted. Alternatively, the rotational length of the slot may be increased to maintain low gearing across a longer or shorter extent Embodiments may be provided without the groove 57 in the outer cylindrical member 58.

In the illustrated embodiment, the control wires 54 are housed inside the palm 26, fingers 24, and thumb 28. In other embodiments, these components may be solid and the wires 54 may be provided on the outside surface of the digits.

Although the invention has been described with different features in combination with one another it is to be understood that one or more features may be provided separately from others in a prosthetic limb or in another application and also that one or more features may be provided in combination with alternatives of other described features in a prosthetic limb. For example, the telescopic forearm member 21 may be used with any elbow joint 38, and the elbow joint 38 may be used with any forearm member 2 I. It will be appreciated by the person skilled in the art that various modifications may be made to the above described embodiment without departing from the scope of the present invention.

Claims

Claims 1. A prosthetic limb comprising a telescopic member such that a length of the prosthetic limb is adjustable, the telescopic member comprising a proximal portion and a distal portion which are telescopically connected and secured in position by one or more fastening means.
2. A prosthetic limb according to claim 1, wherein the proximal portion and distal portion are secured by a pair of fastening means.
3. A prosthetic limb according to claim 2, wherein the proximal portion has a plurality of pairs of holes configured, each configured to receive a fastener for securing the proximal portion to the distal portion, wherein the spacing between the pairs of holes is greater than the spacing between holes within each pair.
4. A prosthetic limb according to claim 3, wherein the distal portion has regularly spaced holes configured to receive the fasteners, and the spacing between the holes in the distal portion is equal to the spacing between holes within each pair of holes in the proximal portion.
5. A prosthetic limb according to any preceding claim, wherein the distal portion is slidably received inside the proximal portion.
6. A prosthetic limb according to any preceding claim, comprising a second telescopic member having a distal portion and a proximal portion which are telescopically connected, the second telescopic member spaced from the first telescopic member in a direction perpendicular to the lengths of the telescopic members.
7. A prosthetic limb according to claim 6, wherein the distal portion of one of the telescopic member and the second telescopic members is configured to hingedly connect to a prosthetic hand or foot at a distal end of the distal portion, such that different arm widths may be accommodated.
8. A prosthetic limb according to claim 7, wherein the distal portion of the other of the telescopic member and the second telescopic members is configured to rigidly connect to a prosthetic hand or foot at a distal end of the distal portion.
9. A prosthetic limb according to any preceding claim wherein the limb comprises a forearm including a prosthetic hand connected at a distal end of the telescopic member(s).
10. A prosthetic limb according to claim 9, wherein the hand includes fingers and thumbs hingedly connected to a palm and wherein the movement of the fingers and thumbs is controlled by control wires secured at the distal ends of the fingers, such that the prosthetic limb is body powered.
11. A prosthetic limb according to claim 10, wherein the fingers and thumb each have a hinged knuckle configured to allow them to bend in response to tension in the control wires.
12. A prosthetic limb according to claim 10 or claim 11, wherein the fingers and thumb are biased to return to a neutral position by resiliently biased members.
13. A prosthetic limb according to any preceding claim, including an upper member connected to the proximal end of the proximal portion by a pivot joint wherein the pivot joint allows the telescopic member to pivot relative to the upper member, about an axis perpendicular to its length.
14. A prosthetic limb according to claim 13 when appended to claim 10, wherein the control wires are anchored on a proximal side of the pivot joint and pass through the telescopic member such that bending the elbow joint increases the path length of the wires which pulls on the ends of the fingers and thumb and hence pulls the fingers and thumb in to form a fist.
15. A prosthetic limb according to claim 14, wherein the distal portion comprises a channel through which the wires pass.
16. A prosthetic limb according to claim 14 or claim 15, wherein the wires are anchored by a whippletree assembly mounted on the upper member, the whippletree assembly being configured to allow the load to be unevenly distributed between the wires such that irregularly shaped objects can be gripped.
17. A prosthetic limb according to claim 10 or any claim dependent thereon, wherein the prosthetic hand has a modular construction and the palm, fingers, and thumbs are interchangeable.