GB2488760A - Prosthetic hand with digits actuated by muscles via strings - Google Patents

Abstract

A prosthetic hand for a forearm amputee is disclosed. It comprises at least one prosthetic digit member 50 pivotally connected to a prosthetic metacarpal portion 70, which is supported by or attached to the stump, usually via a wrist box 175. A set of strings or wires 80 is provided to actuate the digit 50 according to flexion and extension. Anchoring elements such as rings or studs are provided to attach the strings 80 to the tendons or the muscles of the remaining stump, so the strings are mechanically linked to the tendons or muscles, thus allowing the prosthetic finger 50 to be moved. Extension elements 167, 168 may be implanted into the radius or ulna to provide extensions as required. Also disclosed is a prosthetic wrist, rigidly connected to the radius 165 (see figure 14) but rotatably connected to the ulna 166 so that the wrist can be rotated by rotating the radius around the ulna.

Description

I

Prosthetic hand The present invention relates to a prosthetic hand, particularly to a prosthetic hand designed for surgical implantation to a forearm stump of an amputee.

Mechanical hand prostheses are known in the prior art. They operate completely mechanically in that they do not use electrical or electronic actuation, or body electrical impulses to command movement. Some fully mechanical hand prostheses respond to and/or are actuated by movement drawn from undamaged joints, such as an elbow, or a shoulder. This is made possible by a mechanical connection between the shoulder, or elbow, and the prosthesis.

However, these mechanical prostheses typically provide only a basic, limited, grasping functionality to the patient, similar to that provided by a claw, or a clamp, To exemplify, the amputee can, under his command, open one finger element of the prosthesis -or more finger elements together -while the closing force that is required to return the *prosthetic fingers to their original, neutral, position is passively provided by a return spring. Likewise, it is possible, to provide a spring to return the prosthetic hand in the opened position, with the amputee actively controlling the closing, or flexing, of one or more fingers together. In both cases, however, while clamp-type prostheses at least mimic the basic function of a hand (i.e. that of grasping an object), they offer limited movements to the amputee. Further, the elbow and shoulder are anatomically designed for larger scale movements, and it is therefore mechanically difficult to "reduce" those movements to smaller scale movements such as those required by the hand.

For this and other reasons, more sophisticated hand prostheses have been developed in the prior art. Some hand prostheses are electrically or electronically actuated by the patient to provide finely controlled movements according to multiple degrees of freedom. Some hand prostheses operate in response to sensed parameters, such as the position or acceleration of the arm. Some other hand prostheses -more technologically advanced -employ body electrical impulses in order to provide electrical signals which operate servo-systems for controlling movements of the prostheses (bionic or myoelectric hands). The electrical impulses known as myoelectric potentials are detected by mounting appropriate electrodes on the skin overlapping appropriate remaining muscles of the stump, and are then processed and/or amplified for generating the electrical signals that drive the servo mechanisms, Thus, the motive force of such prostheses is provided by servo-mechanisms in response to electrical stimulus from the body of the patient.

An upside of all of these prostheses is that they do often allow independent movement of the prosthetic fingers. However, a major drawback is that -as their technological sophistication increases -so does their cost, and the cost of maintaining them throughout their life. The weight of these prosthetic limbs, given by the weight of both their electrical and mechanical parts, and the need for an external attachment to the torso or upper arm are additional drawbacks in themselves. Furthermore, training the amputee to a correct use of these prostheses can be troublesome.

From the above, it is clear that known hand prostheses have limited functions compared to those of a real hand. Furthermore, when this obstacle is addressed and hand prostheses are provided to offer to the patient more-than-basic functions, they tend to become highly complicated and expensive, mainly because of the complexity and cost of their actuation systems and methods.

Traditionally, hand prostheses are mounted on sockets which are then attached to the forearm stump. Attachment of the stump socket to the stump presents several options according to the length of the stump, and regularity of the soft tissues remaining in the stump. Factors that affect the choice of stump attachment are for example the presence or absence of deformation due to scar tissue, the amount of subcutaneous fat in the stump and/or the presence of mal-united bones in the stump.

Stump sockets need be custom designed to fit properly to the stump. Further, stump sockets need to be cleaned regularly to prevent the build up of impurities on the interface between the socket and the stump. The stump and socket method requires attachment to the upper limb by straps and buckles to the torso and/or upper arm.

All of the above are reasons why direct bone attachment has been explored in the humerus and tibia. However, while direct bone attachment in prosthetic applications is known, it has not been described for the forearm.

It is therefore an object of the present invention that of providing an improved prosthetic hand compared to those known in the prior art. Thus, the hand prostheses of the present invention will offer attractive functions for the patient, whilst being light, resistant and structurally simple and, therefore, relatively inexpensive to produce.

lt is another object of the present invention to provide an improved prosthetic device for implantation to the forearm stump of an amputee. The so-attached prosthesis represents a step forward towards resolving, or at least mitigating, at least one of the disadvantages of the prior art linked to the socket attachment method.

In particular, it is an additional object of the present invention to provide a prosthetic hand that can offer a good degree of articulation for the patient, especially in relation to the movements of the prosthetic wrist and/or the prosthetic fingers.

It is also an object of the present invention to provide an improved prosthetic hand which can be more conveniently and easily connected to the stump. Such a connection is also expected to be physiologically, mechanically and cosmetically advantageous for the patient.

It is a further object of the present invention to provide a prosthetic hand which has a good degree of compliance to any movements that may be externally imposed to the hand, or required of the hand.

It is yet another object of the present invention to provide a hand prosthesis that is user friendly and that requires minimal training for the amputee to achieve correct and full use.

Therefore, according to an aspect of the present invention there is provided a prosthetic hand for a forearm amputee, comprising: at least one prosthetic digit member; a prosthetic metacarpal portion to which each prosthetic digit member is pivotally connected, the metacarpal portion being configured for being supported in cooperation with the stump; at least one elongate actuating member connected to one of the digit members and operable to move the digit member; and at least one anchoring element attached or attachable to the at least one elongate actuating member, which can be used for connecting the elongate actuating member to remaining portions of tendons or muscles of the stump.

Preferably, the prosthetic hand further comprises: at least one additional elongate actuating member forming, with the at least one elongate actuating member, a set of elongate actuating members comprising flexor and extensor actuating members, wherein at least a pair of flexor and extensor actuating members is connected to one of the digit members and wherein the flexor member of said pair is operable to move the digit member to a first configuration, and the extensor member of said pair is operable to move the digit member to a second configuration; and at least one additional anchoring element forming, with the at least one anchoring element, a set of anchoring elements that can be used for connecting a pair of elongate actuating members to remaining portions of tendons or muscles of the stump, wherein one anchoring element is attached or attachable to the flexor actuating member of said pair of actuating members, and another anchoring element is attached or attachable to the extensor actuating member of said pair of actuating members, so that when the prosthesis is in place the digit member can be bent and extended by the amputee using the remaining tendons and/or muscles.

Preferably, the prosthetic hand comprises: at least two prosthetic digit members, at least. two of which are configured in opposition with respect to one another to allow grasping of objects therebetween; and at least two pairs of flexor and extensor actuating members, wherein a first pair of flexor and extensor members is connected to one digit member, and wherein a second pair of flexor and extensor members is connected to another, opposing digit member, and wherein the flexor members of said pairs are operable to move the respective digit members to a first, grasping configuration, and the extensor members of said pairs are operable to move the respective digit members to a second, release configuration.

Preferably, the prosthetic hand comprises five prosthetic digit members and five respective pairs of flexor and extensor members, wherein a prosthetic index, middle, ring and little finger are arranged substantially parallel to each other along a prosthetic metacarpo-phalangeal line, and wherein a prosthetic thumb is arranged substantially in opposition with respect to any of the prosthetic index, middle, ring and little fingers.

Preferably, at least one of the prosthetic digit members comprises at least two pivotally interconnected prosthetic phalangeal members, so that a further point of articulation for the prosthetic hand is present.

Preferably, at least one of the prosthetic digit members includes three pivotally interconnected prosthetic phalangeal members including proximal, distal and intermediate phalanges, so that the natural arrangement of the human hand is more closely reproduced.

Preferably, each prosthetic phalangeal member has an associated pair of actuating flexor and extensor members operably connected thereto in order to move the corresponding prosthetic phalanx angularly around its proximal pivot.

Preferably, at least one prosthetic phalanx comprises an elongated shell extending in the direction of the finger, so that the shell can tidily house and protect any elongate actuating members passing through said phalanx.

Preferably, the shell is tubular, so that the elongate actuating members are fully laterally enclosed in the tubular shell.

Preferably at least one elongated actuating member is arranged to run through the tubular shell and adjacent to a wall thereof, so that the elongate member is further tidily arranged in the prosthetic phalanx, and so that any force transmitted by the elongate member can more easily move the associated finger or phalanx.

In some embodiments, the metacarpal portion is formed from a single sheet of material, so that this part can be manufactured conveniently and cheaply. The material can be, for example, a sheet of metal. In particular, brass and aluminium are especially suitable materials, due to the fact that they are easy to shape.

In some embodiments, a prosthetic wrist portion will also be present, and this wilt have a seat configured for accommodating and supporting a bone extension, the extension being connectable to a bone of the stump, so that the hand prosthesis can be directly attached to a bone of the stump. This kind of attachment leaves ample room for the attachment of the anchoring elements to the muscles or tendons of the hand.

When the prosthesis is directly attached to the bones of the stump, very preferably the prosthetic wrist portion comprises a further seat and a further extension, the two extensions each having proximal and distal ends, one extension having its proximal end connectable to what remains of the ulna of the stump, and the other extension having its proximal end portion connectable to what remains of the radius of the stump, the distal portion of the ulnar extension being hingedly connected to the first seat of the wrist portion, and the distal portion of the radial extension being rigidly connected to the second seat of the wrist portion, so that the pronation and supination orientation of the hand prosthesis can be changed by rotating the radial extension around the ulnar extension.

Preferably, in the case of direct bone attachment, at least one extension is connectable to a bone by means of an implantable element designed for implantation in the bone itself according to the principles of osseointegration.

In certain embodiments, the elongated actuating members are strings or cables, which are easy to supply and can perform the required functions. Preferably, these strings or cables comprise intertwined multifilament metal wires, which are particularly strong and durable.

In some embodiments, the anchoring elements to be applied to tendons or muscles are percutaneous metallic rings, which are very suitable for their purpose as they are well accepted by the human body, are easy to source and come in a variety of sizes and materials. Alternatively, the anchoring elements can be percutaneous pins or studs, which also provide the required linking function, In some embodiments, at least two between: a prosthetic finger: a prosthetic phalanx: the prosthetic metacarpal portion; and the prosthetic wrist portion, are independently formed out of a single blank of material. This can make the manufacturing of the prosthetic hand even more simple and, thus, cheaper.

Preferably, the prosthetic finger or fingers, any prosthetic phalanx, the prosthetic metacarpal portion and the prosthetic wrist portion are each independently formed out of a single sheet of metal of maximum dimensions 450 by 300 mm. This makes the manufacturing of the prosthetics extremely simple and, potentially, very cheap. This can be especially suitable in the markets of poor or less developed countries.

Preferably, when a sheet of material is used to form components of the prosthetic hand, the blank is made of metal suitable for cold forming of the prosthetic hand's components.

In some embodiments, the prosthetic hand further comprises an external prosthetic cover portion generally provided in the shape of a glove, and configured for vesting the prosthetic hand.

Preferably, the prosthetic cover is made of rubber. Very preferably, said rubber has a thickness comprised in the range between 1 and 2.5 mm, so that the cover may confer a certain additional degree of rigidity to the prosthetic hand itself.

Preferably, the cover can be filled with, and hold or retain inside, a viscous substance, which protects and lubricates the internal components of the prosthetic hand, and also gives the prosthetic hand a natural feel.

In some embodiments, the prosthetic hand of the present invention may come as a kit.

The parts of the kit can be used, with a set of instructions, to assemble a prosthetic hand according to any of the above embodiments.

According to a further aspect of the present invention, there is provided a prosthetic hand for a forearm amputee, comprising: a distal prosthetic component having prosthetic fingers or the like; and a prosthetic wrist component connected to and supporting the upper prosthetic component, configured for being rigidly connected to what remains of the radius of the stump and for being rotatably connected to what remains of the ulna of the stump, wherein, in use, the prbnation and supination orientation of the hand prosthesis around a longitudinal axis of the stump can be varied by the patient by rotating the radius around the ulna. This configuration allows pronation and supination of the hand prosthesis according to the natural mechanism of pronation and supination in the forearm.

Preferably, the configuration of the prosthetic wrist component for being rigidly connected to the radius comprises a first extension-receiving portion, and the prosthetic hand further comprises a radius-connectable extension having proximal and distal ends, the proximal end of the radial extension being connectable to what remains of the radius of the stump, and the distal end of the radial extension being configured for being rigidly connected to the first extension-receiving portion of the wrist component, so that the length of the prosthesis can be made to match the length of the remaining limb.

Preferably, said first extension-receiving portion comprises an aperture, and the radial extension is configured for being received in the aperture by interference, which is a simple and convenient connection.

Alternatively, the rigid connection between the distal end of the radial extension and the first extension-receiving portion may comprise a bolted or threaded connection, which is also very convenient.

In some embodiments, the configuration of the prosthetic wrist component for being rotatably connected to the ulna comprises a second extension-receiving portion, and the prosthetic hand further comprises an ulna-connectable extension having proximal and distal ends, the proximal end of the ulnar extension being connectable to what remains of the ulna of the stump, and the distal end of the ulnar extension being configured for being hingedly connected to the second extension-receiving portion.

This configuration facilitates the rotation of the radial extension around the ulnar extension.

Preferably, the second extension-receiving portion comprises an aperture, and the ulnar extension is configured for being received in the aperture with clearance between the aperture and the uFnar extension so as to allow relative angular movement between the ulnar extension and the aperture.

Preferably, said aperture for the second extension-receiving portion is circular.

Preferably, the aperture receiving the radial extension comprises a 90 degrees angle, so that it can be readily distinguished from the aperture for the ulnar extension when this is circular.

In some embodiments, a bearing may be present between the distal end of the ulnar extension and the respective aperture to make the relative angular movement happen more smoothly.

Preferably, at least one of the radial or ulnar extensions is made of one of medical-grade titanium, stainless steel, brass, aluminium, gold and fibre reinforced composite.

Very preferably, at least one of the proximal ends of the extensions is configured for connection to the ulna or radius via an implantable element which can be implanted in the ulna or radius, wherein the proximal end of the extension is configured for attachment to the implantable element.

Very preferably, the prosthetic hand further comprises the implantable element, wherein the implantable element is an osseointegratable implantable element, and wherein said osseointegratable implantable element is designed for partial implantation into the ulna or radius with a distal portion of the implantable element being, in use, made available outside of the stump, and wherein the attachment to the implantable element is performed on said distal portion of the implantable element. These features will facilitate and enhance the surgical direct bone attachment of the hand prosthesis to the stump.

Preferably, the osseointegratable implantable element is made of medical-grade titanium, which is particularly suitable for bone implantation, as known in the art.

Preferably, the osseointegratable implantable element is hydroxy-apatite coated, which is also particularly suitable for bone implantation.

Very preferably, both of the proximal ends of the radial and ulnar extensions are configured for implantation via respective osseointegratable implantable elements, so that both elements can conveniently be implanted during the same surgical procedure.

In some particularly advantageous embodiments, at least one of the osseointegratable implantable elements may comprise an insertable portion having a triangular cross section sized for being inserted into an intramedullary canal of the stump's radius or ulna. This feature allows secure insertion of the implantable element with minimal destructiveness and intrusion into the bone fluid supply system.

Preferably, the size of the insertable triangular-cross portion is such that, in use, it cannot rotate inside the associated intramedullary canal -this allows for a secure and rigid connection.

Preferably, the prosthetic wrist component comprises a number of apertures for allowing elongate flexible members to pass therethrough in the proximal-distal direction, since direct-bone attachment of the hand prosthesis makes actuation of the prosthetic hand by connecting the elongate flexible members with the remaining tendons or muscles of the stump particularly attractive -this is because such muscles or tendons are located on the outer regions of the stump, which are directly accessible if the prosthesis is attached directly via the ulna and/or radius.

Preferably, the prosthetic wrist is in the shape of a shell-like structure, which is light, functional and easy to support and manufacture.

Preferably, the shell can be obtained by bending or cold forming a single blank of material into shape. Said material can be a metal, and the metal can be, advantageously, brass or aluminium.

In some embodiments, the shell may comprise proximal and distal walls, the distal wall being configured for connection with the distal prosthetic component, and the proximal wall being configured for connection with the ulna and radius, and at least two of said apertures of the wrist component may be organised one on the distal wall and one on the proximal wall directly opposite to each other in a substantially longitudinal direction with respect to the forearm, so as to allow easy passage of any actuating elongate flexible member.

Embodiments of the present invention will now be described in detail, for the purpose of enabling the invention to be carried out by the skilled person. Reference is made to the accompanying drawings in which: Figure 1 is a schematic view of a portion of a prosthetic hand according to the present invention, with a digit member in a first, extended, configuration; Figure 2 is a schematic view of the digit member of Figure 1 in a second, flexed, configuration; Figure 3 is a schematic view of a joint of the embodiment referred to in Figures 1 and 2; Figure 4 is a schematic sectional view of a distal interphalangeal joint of the embodiment referred to in Figures 1 and 2; Figure 5 is a sectional view along line V-V shown in Figure 4; Figure 6 is a top view of part of a prosthetic hand according to the present invention (with anchoring elements not shown); Figure 7 is a rear perspective view of the embodiment of Figure 6; Figure 8 is a bottom view of the embodiment of Figure 6; Figure 9 is a schematic top plan view of a sheet of metal for forming a prosthetic metacarpal part of a prosthetic hand according to the present invention; Figure 10 is a side perspective view of a finger element operated by a single pair of extensor and flexor strings according to an embodiment of the present invention, with the distal phalanx slightly tapered; Figure 11 is a perspective view of the sheet of metal of Figure 9, in a partially folded configuration; Figure 12 is a top perspective view of an embodiment of the present invention comprising a metacarpal part according to Figure 9, with the prosthetic fingers in a neutral, rest position (the prosthetic thumb is missing); Figure 13 is a side perspective view of the embodiment of Figure 12, with the prosthetic thumb and opposable digit members in grasping configuration; Figure 14 is a schematic top view of a hand prosthesis according to the present invention, with the prosthetic hand attached to what remains of the ulna and radius of a forearm stump; Figure 15 is a CAD front perspective rendering of a wrist box according to the embodiment of Figure 14, in folded configuration; Figure 16 is a CAD top plan view of the wrist box of figure 15 in fiat configuration; Figure 17 is CAD top plan view of a wrist box according to an embodiment of the present invention in flat configuration, with dimensions given in mm; Figure 18 is a front view of the wrist box of Figure 17, with dimensions given in mm; Figure 19 is a top perspective view of a part of an embodiment of the present invention, that part being a rubber cover for the prosthetic hand; Figure 20 is a top plan view of 5 sheets of metal positioned adjacent to each other forming a template for cutting individual prosthetic phalangeal, metacarpal and wrist elements of a prosthetic hand according to the present invention; Figure 21 is a top plan view of a prosthetic phalangeal member of Figure 18, with dimensions given in mm in 1:1 scale, in fiat configuration; Figure 22 is a bottom plan view of the prosthetic phalangeal member of Figure 19, in folded configuration; Figure 23 is a side view of the prosthetic phalangeal member of Figures 19 and 20; Figure 24 is a cross sectional view of the prosthetic phalangeal member of Figure 21; Figure 25 is a front perspective view of an educational tool for demonstrating the principle of a prosthetic hand according to the present invention; Figure 26 is a detail view of the educational tool of Figure 23; Figure 27 is a side view of an osseointegration insert for insertion and attachment to a bone of the stump according to an embodiment of the present invention, with dimensions in mm; Figure 28 is a perspective view of the osseointegration insert of Figure 25; Figure 29 is a front view of the osseointegration insert of Figure 26, with dimensions in mm; Figure 30 is a side view of an osseointegration trial for a hand prosthesis according to an embodiment of the present invention, with dimensions given in mm; Figure 31 is a perspective view of the osseointegration trial of Figure 28; Figure 32 is a front view of the osseointegration trial of Figure 29, with dimensions given in mm; Figure 33 is a detail view according to detail section "A" of Figure 30, with dimensions given in mm; Figure 34 is a side view of an osseointegration rasp for a hand prosthesis, according to an embodiment of the present invention, with dimensions given in mm; Figure 35 is a perspective view of the osseointegration rasp of Figure 32; Figure 36 is a detail view according to detail section "A" of Figure 32, with dimensions given in mm; Figure 37 is a front view of the osseointegration rasp of Figure 32, with dimensions given in mm; and Figure 38 is a detail view according to detail section "B" of Figure 35, with dimensions given in mm.

The present invention deals with a prosthetic hand designed for implantation to a forearm stump of an amputee, when the amputee has undergone an amputation of the type often referred to, in surgical terms, as "trans-radial" or "below-elbow" amputation.

Fig ures 1 and 2 show part of a prosthetic hand (in particular a finger and a metacarpal prosthetic portion) based on the concept of an exoskeleton, i.e. an external skeleton that houses and protects internal components. The prosthetic hand has been formed by joining substantially tubular members hinged together to provide joints. In particular, a metacarpal tube 1 is pivotally connected to a proximal phalanx tube 3 by way of a metacarpo-phalangeal hinged joint 5. As can be seen from the two Figures, the tubular members are arranged substantially end-to-end and the hinged joint 5 is positioned relatively closer to the dorsal side of the prosthetic hand. The pivot axis of the hinged joint is oriented substantially perpendicular to the axial directions of the two joined tubular members.

The hinged joint 5 includes a shaft 7 which passes through the inner tube 3, and is secured to the inner wall of the outer tube 1. Mounted on the shaft 7, within the tubes, is a roller 9, or pulley 9, which, as shown in Figure 3, is formed with inwardly curved annular recesses for supporting elongate operating members. These will be described below in more detail.

Either side of the joint 5, the tubes 1, 3 are cut away, or chamfered, to facilitate the relative pivoting movement between the adjacent tubes. The cut-away or chamfered portion is greater on the proximal side of the joint than on the distal. This will allow the prosthetic finger to flex according to a desired flexion angle under the action of the flexing strings.

In a similar manner to the metacarpal tube I and the proximal phalanx tube 3, the proximal phalanx tube 3 is hingedly connected to a middle phalanx tube 11 at a proximal interphalangeal joint 13, and the middle phalanx tube is hingedly connected to a distal phalanx tube 15 by way of a distal interphalangeal joint 17. The distal phalanx tube 15 is configured at the free end thereof to resemble a finger tip with a finger nail.

The region of the distal interphalangeal joint 17 is shown in more detail in Figures 4 and 5.

The hand is operated by way of a plurality of elongate operating members which are arranged in two groups, a set of extensor members for extending (or straightening) the finger or fingers, and a set of flexor members for flexing (or bending) the finger(s). In the present embodiment, the extensor members are provided by suitable strings, such as non-stretch multifilament wire strings. These can be made of any suitable material such as stainless steel or Keviar®. The diameter of these cables does not exceed 3 mm, so that they are easy to handle and sufficiently flexible. These cables should also allow the creation of loops, crimps or knots anywhere along their length. However, the reason for this requirement will be explained in more detail later. The extensor members pass through the regions located between the hinges and the outside or dorsal side of the prosthetic hand (upper side in Figure 1), and are guided by the annular recesses in the pulleys 9 so as to be able to extend the prosthetic finger. The flexor members pass through the regions located between the hinges and the inside (lower side in Figure 1) of the prosthetic hand, and do not require any further support (such as the one provided by the pulleys for the extensor members) to be able to flex the finger. The flexor members find housing in and along the substantially tubular members, which effectively guide the flexor strings, cords or wires through the prosthetic hand. The extensor members are also guided through the prosthetic hand in essentially the same way. However, the extensor strings and the flexor strings are located on opposite sides relative to the hinged joints located between adjacent tubular members. The strings effectively replace the hand motive functions that would have been provided by tendons and muscles in a real hand, thereby actuating the prosthesis.

More specifically, a first extensor member 19 passes over the pulley of the metacarpo-phalangeal joint 5 and is connected to the upper region of the proximal phalanx tube 3 not far from the joint 5 (see Figure 1) and serves to extend the proximal phalanx tube 3.

A second extensor member 21 passes over the pulleys of the metacarpo-phalangeal joint 5 and of the proximal interphalangeal joint 13 and is connected to the upper region of the middle phalanx tube 11, not far from the joint 13, and serves to extend the middle phalanx tube 11. A third extensor member 23 passes over the pulleys of the metacarpo-phalangeal joint 5, the proximal interphalangeal joint 13, and of the distal interphalangeal joint 17 and is connected to the upper/dorsal region of the distal phalanx tube 15 in a region not far from the joint 17, and serves to extend the distal phalanx tube 15.

A first flexor member 25 traverses the metacarpo-phalangeal joint 5 and is connected to the lower region of the proximal phalanx tube 3, in the region of the joint 5, and serves to flex the proximal phalanx tube 3. A second flexor member 27 traverses the metacarpo-phalangeal joint 5 and the proximal interphalangeal joint 13 and is connected to the lower region of the middle phalanx tube 11, in the region of the joint 13, and serves to flex the middle phalanx tube 11. A third flexor member 29 traverses the metacarpo-phalangeal joint 5, the proximal interphalangeal joint 13, and the distal interphalangeal joint 17 and is connected to the lower region of the distal phalanx tube in the region of the joint 17, and serves to flex the distal phalanx tube 15.

Due to the way in which each prosthetic finger flexes, the flexor strings 25, 27, 29 do not require a pulley or other retaining means. However, the extensor strings 19, 21, 23 require to run close to the outer or dorsal surface of the fingers, to maximise the distance between them and the hinges. This can be achieved in a number of different ways, such as the pulleys as previously described, or the extensor members may run in a tube or other string-guiding or cable-guiding item which is conveniently secured to the inner surface of the particular tube.

The flexor members too may run within a tube or other string-guiding item (such as a bracket or the like), if desired. To prevent the elongate members fouling with each other, the elongate members may run in individual tubes to ensure they remain separated from the other elongate members. A number of alternatives are possible for holding or encapsulating the wires, as it will be apparent to the skilled person.

The tubes forming the metacarpal and phalangeal parts of the prosthetic hand may be made of any convenient, hard-wearing material, such as stainless steel, while the elongate members may also be made of any suitable flexible, substantially inextensible cord or chain, as previously described. Polymeric materials may also be used. The strings will have to be secured to and within the tubes by any convenient means, such as knotting to studs or looping around gears or the like. It will also be apparent that a vast range of lengths and thicknesses for the elongate members is possible, compatibly with their purpose and function.

The hand prosthesis may be covered with a material designed to impart a suitable appearance, such as a glove of resilient or other flexible material to give the appearance of skin and nails (see description of Figure 17 below). The purpose of such covers may be cosmetic and/or functional. More details will be given below.

So far, a prosthetic hand has been described in which each of the prosthetic phalangeal members can be activated according to two directions -opening and closing1 i.e. respectively, extension and flexion -by strings or cable actuators.

However, if necessary, any one or more of these actuators may be substituted with passive actuators such as springs or other elastic return devices. As it will be explained below, this may be required when it is not possible to actuate the corresponding extension or flexion by means of an available tendon or muscle of the patient. Further, each actuated pivotal movement of the prosthetic fingers may be angularly limited by any appropriate limiting means, as known in the art.

The prosthetic digit can be provided according to the full, three tiers construction (i.e. with each prosthetic finger including three phalanges) as shown in Figures 1 to 5, or according to any other partial construction, i.e. fewer than three prosthetic phalanges may be provided for each prosthetic finger if desired, or if more appropriate for a certain patient having certain specific surgical requirements. Furthermore, fewer than five prosthetic fingers or digit members may be provided in the prosthetic hand, to simplify the prosthesis, if required. In a basic embodiment, just two prosthetic fingers can be provided: a thumb and any one of the other four fingers. This would however provide the basis for an opposition configuration (or claw-like or clamp-like configuration) of the prosthetic hand, which would still be suitable for grasping objects.

However, normally, four metacarpal tubes I are secured side-by-side onto a supporting structure (for example a prosthetic wrist box) to provide most of the hand prosthesis, together with a differently configured tube 1 to provide the hand prosthesis' thumb, in a manner which is readily apparent to the skilled person. The thumb will be configured in opposition relative to the other fingers, meaning that the flexion of the thumb member will be able to cooperate with flexion from any one of the other digit members to provide a grasping function similar, for example, to that used for holding a pen. In particular, to achieve this objective, the metacarpal component 70 may be provided with a slight curvature, so that all the fingers (index, middle, ring and little finger) are opposable to the prosthetic thumb. When the thumb is in retracted position, the fingers will be free to grip an object between the fingers and the palm of the prosthetic hand.

In the case of tendons or muscles of the hand, it is known that amputees, despite having lost a hand or digit, continue to be aware of the muscles and/or tendons which previously provided operation to the amputated hand or digit, or to be aware of the flexor and extensor muscles of an amputated limb. By asking a patient to imagine he or she is flexing or extending certain digits, or parts of an amputated limb, a surgeon or surgical technician can identify and label the appropriate muscles or tendons. A surgeon is then able, under local anaesthetic, to pierce the appropriate muscle or tendon percutaneously, and insert a suitable linking component, such as a ring, stud, pin or loop.

The linking or anchoring component can then be attached to the appropriate elongate member or string by way of a securing member provided at a free end of the elongate member to produce useful movement of the articulated components of the prosthesis as a result of voluntary muscle movement by the patient. There can be, for each actuation string, two securing components, one on the string side and one implanted on the patient's tendon or muscle. There can also be just one securing or anchoring component on either side -the choice will be surgical. However, there will be at least one securing or anchoring component and this can be a pin, loop, ring or stud or the like.

The structural complexity of the prosthesis (i.e. how many prosthetic fingers, phalanges, etc. will eventually be present) can be adapted to suit the residual capabilities of the patient, which residual capabilities often are a function of the degree of damage of the muscles and tendons caused by the injury which resulted in the amputation of the hand. For example, flexing and extending of an entire prosthetic finger could be effected with a single extensor member 23 and with a single flexor member 29, both connected to the same prosthetic phalangeal member, for example the distal phalanx. The complexity of the prosthesis will also be a function of the capabilities of movement required by the patient and by the surgeon. Also, as explained above, springs or other elastic or return mechanism may also be provided in conjunction with prostheses of the kind above described, to assist with flexing and/or extending any of the prosthetic fingers in the absence of appropriate muscles or tendons that may actively drive those return movements. It should also be mentioned that any spring or similar device may also be provided in addition to an actuating string, i.e. as an auxiliary, passive, actuation means that cooperates with the flexors or extensors. Therefore, partly active / partly passive actuation can also be implemented.

The motor functions of the hand prosthesis described above are the flexion and the extension of one or more of the prosthetic fingers and thumb. Forearm movements, however, can also be implemented, and they will be described later.

The existing, or remaining, musculo-tendinous structures in the forearm can be accessed by implanting percutaneous metallic rings or rods similar to those used in current popular cosmetic adornments, commonly seen implanted in the nose, the ears, the lips, the tongue and other parts of the anatomy. The perforations required to implant these devices will require the expertise of surgeons or medically qualified personnel, who can also identify the most suitable muscles and tendons for the purpose. In this respect, it would be feasible to use some muscles that may be anatomically not accurate for the purposes of the prosthetic hand -for example the flexors and extensors of the wrist, when not necessary for wrist movement, could be used for the flexion or extension of the fingers and thumb.

It is predictable, from past experience in the surgery of muscle transfers commonly used to improve function in patients suffering from paralysis due to poliomyelitis or leprosy, that motor control of a joint that has lost extension can be regained by the transfer of a flexor muscle and its tendon into the extension compartment of the limb. A typical example is the transfer of the tibialis posterior muscle, (which is normally a flexor of the ankle) from its position behind the medial malleolus of the ankle, into the dorsum of the foot to achieve extension in cases of paralytic dropped foot. Extension control in these cases can be regained by a process of learning, usually under the direction of a physiotherapist.

By creating a mechanical prosthetic hand device of the kind described above, the control of the fingers and thumb will almost certainly be less accurate that the normal hand, but this is not surprising, give that the complex musculo-tendinous arrangement of the normal anatomy of the hand will have certainly not been replicated within the exoskeleton of the prosthetic hand. Rather, the prosthetic hand provides a much simplified structure.

For example the intrinsic muscles of the hand, i.e. the lumbricals and interossei muscles, are redundant for the purpose of the prosthesis and a corresponding structure is therefore absent in the prosthesis. In the prosthesis, the flexion and extension of the metacarpo-phalangeal and interphalangeal joints can be achieved by a single flexor cable and return extensor springs or elastic extension bands, in a simplified configuration.

Better control, however, and some degree of proprioceptive function would probably be gained by utilising a single flexor and a single extensor cable for each finger attached to appropriate, corresponding, actual flexor and extensor muscles.

It should also be noted that the deep and superficial flexors of the fingers ("flexores digitorum profundus" and "flexores digitorum superficiales") need not be used separately in connection with the prosthetic hand, and may give stronger function if used together on the same percutaneous implant.

Motor control of the prosthetic hand will almost certainly be improved by utilising the existing activation and inhibition of pairs of flexors and extensors. If, for example the extensor indicis muscle and tendon can be identified in the amputated forearm and attached (via a ring and cable or string) to the extensor mechanism of the index finger of the prosthesis, and at the same time if the flexors of the index finger can be isolated from the other flexors of the fingers, and attached to a single ring and cable motivating flexion in the prosthetic index finger, the control of the index finger of the prosthesis is predicted to be ideal and would need very little training to gain nearly perfect function.

Similarly, an effort to identify the flexors and extensors of the thumb and attach them to appropriate and corresponding parts of the prosthesis is predicted to be ideal, and every effort to identify these structures accurately should be made at the time of surgery. This implies that the surgery should be done under local anaesthetic so that the patient's awareness and cooperation can be used in identifying the specific muscles involved, In other words, in order to use the patient's awareness the surgeon at the beginning of the operative procedure should ask the patient to imagine that he is flexing and extending the index finger, for instance. Dimpling under the skin gives the first indication of the locality of the muscle, as the tendon is often adherent to the subcutaneous tissues.

In these cases it should be relatively easily performed surgically to locate and perforate the tendon throughout minimally-invasive incision just large enough to introduce a temporary bar or ring and to leave this implant without attaching it to the cord or cable from the prosthesis for a period of two to three weeks to allow early healing. Longer periods in this respect may be required and this would need to be discussed with the patient at the time that consent for the operation is taken.

Figure 6 shows a prototype of a prosthetic hand. Each prosthetic finger 30, 40, 50, 60 (index, middle, ring and little fingers) has been formed with proximal, middle and distal prosthetic phalanges 31, 61, 32, 62, 33, 63. In addition, each prosthetic digit member 30, 40, 50, 60 is connected to its own metacarpal portion 71, 72, 73, 74. This prototype has been realised in principle according to the scheme shown in Figures 1 to 5.

However, there are some differences. For example, the finger metacarpal portions 71, 72, 73, 74 are integrally formed from a single sheet of metal. The sheet of metal is bent to provide a single metacarpal element 70 which comprises each of the metacarpal portions to which the fingers and thumb are or can be attached. Further, the hinged connections have now been formed using pins passing through sets of aligned holes formed at the distal ends of the "U" shaped sections forming the metacarpal portions 71, 72, 73, 74. These holes or perforations are aligned with corresponding holes or apertures formed through the proximal prosthetic phalanx, at its proximal end. In Figures 1 to 5, the hinges were provided by internally supported shafts, like the one shown in Figure 5. The prosthetic metacarpal portion 70 is attached to a prosthetic carpal or wrist portion 66. The attachment, in this embodiment, is by means of rivets, but alternative attachment methods are possible, such as by using adhesives, as it will be apparent to the skilled person. In this embodiment, the elongated members used for the flexion and extension of the prosthetic digits are strings made of a synthetic material 80. In total, 8 strings have been provided in this embodiment. A pair of strings is provided for each prosthetic finger, and, within each pair, one string will act as an extensor string and one string will act as a flexor string. Each pair of extensor and flexor strings has been attached to a corresponding distal phalanx, as it can be seen in Figure 8.

Figure 7 shows the prototype of Figure 6 from a different angle, which reveals back perforations in walls (back and front, or proximal and distal walls) of the shell-like structure that forms the prosthetic wrist portion 66. In the wrist portion 66, there is an array of five upper perforations 87 on the back or proximal wall. Four of them accommodate the four extensor strings 81, 82, 83, 84. There is also an array of five lower perforations 88. They accommodate the four flexor strings 91, 92, 93, 94. Each of the strings is accommodated into its own individual perforation or hole. There is one available perforation in each row. These are available for thumb strings (not present).

The ends of the strings 100 are visible at the back of the prosthetic hand. They are made available for attachment at the back of the prosthetic hand. This is where suitable anchoring elements will be positioned for attachment to the anchors, bars, pins or rings which have been surgically installed in the stump. The strings will be cut to appropriate lengths. At the back of the wrist portion 66 there are two further, wider, perforations 89, 90. One 89 such perforation is visible in Figure 7, while both 89, 90 are visible in Figure 8. These perforations serve to connect the prosthetic hand with any supporting means that may be provided for supporting the prosthesis on, or in cooperation with, the stump.

Figure 8 shows the prototype of Figures 6 and 7 as seen from the bottom to reveal the path of the actuating strings 80. They enter the wrist box 66 from its proximal end, where suitable perforations are present to allow access of the strings to the wrist box, and to support those strings 87, 88. Once the strings have entered the wrist box 66, they exit the wrist box through corresponding sets of perforations on the distal end or wall of the wrist box 66 (not clearly visible in Figure 8). The strings enter the metacarpal portion 70 of the prosthetic hand through another set of perforations on the metacarpal portion 70, at which point they are guided towards, and then divided according to, the prosthetic finger of competence. Thus, pairs of strings are visible in Figure 8 running through each individual metacarpal finger portion 71, 72, 73, 74; in each pair, one string is an extensor string and one string is a flexor string. The strings then run through the proximal and middle phalanx members, where they are supported by black plastic bands which help to keep the string tidy and fully housed in the proximal and middle prosthetic phalanges. With the upper or dorsal metallic part, the plastic bands form substantially tubular prosthetic digit members.

The strings enter, eventually, the respective distal phalanges, where they are attached on opposite sides relative to the hinge, as explained in conjunction with Figures 1 to S above. The metacarpal portion 70 has, at its proximal end, sets of perforations which, in use, i.e. when attached to the wrist box 66, match the position of the perforations on the distal end of the wrist box 66. Figure 8 also shows a prosthetic thumb 76 attached to the metacarpal box 70. In this prototype, the thumb comprises a single phalanx, which is anatomically inaccurate, as there are two phalanges in a thumb. However, the prosthesis need not reproduce accurately all the parts of the hand.

Figure 9 shows a plan view of a cut sheet of metal 101 for forming a metacarpal prosthetic portion. This portion is generally equivalent to the one seen in Figures 6 to 8.

With reference to the portion of sheet of metal 101 which will form the metacarpal part of a prosthetic thumb, we can see that the thumb metacarpal part is formed by two side parts 103, 104 which, when bent, form a "U" section in cooperation with the metacarpal thumb upper or dorsal part 102. These thumb elements are connected to the rest of the sheet by an intermediate portion 107. Extension support points 105, 106 are respectively formed on the distal ends of the thumb side parts 103, 104 (each or all of the extensions can take the form of a pin or shaft, or peg). The basic unfolded arrangement a) side part, b) upper or dorsal part, c) side part and d) inter-finger portion (which together form a prosthetic finger's metacarpal part) is then repeated in Figure 9 three times, respectively in correspondence of the index, middle and ring prosthetic metacarpal finger portions. This sequence is then concluded with the following sequence: a) side part, b) upper/dorsal part, and c) side part, for the little finger, as shown in Figure 9. The dimensions of the side parts 105, 106, 143, 144, upper parts 102, 112, 122, 132, 142, and inter-finger parts 107, 117, 127, are such that a natural relative positioning of the prosthetic fingers is achieved, when the sheet is folded along its folding lines 148.

Figure 11 shows the sheet of metal 101 of Figure 9 partiafly bent wh a view to eventually forming the prosthetic metacarpal portion. As it can be seen in Figure 11, the inter-finger portion 107 between the thumb and index is wide enough to allow the thumb to achieve its opposing configuration relative to the other fingers.

Figure 10 shows a prosthetic finger element 150 suitable for assembling with the metacarpal part provided by the bent sheet of metal 101 as shown in Figure 11. This element 150 comprises 3 phalanges, as usual for any of the four non-opposing fingers, and a pair of flexor and extensor strings connected to the distal phalanx in the usual way. Support and housing for the strings 154, 155 is now provided by metallic tubular members 151, 152, 153, rather than by tubular members partially obtained with tape or elastic bands or the like.

Figures 12 and 13 show the metacarpal portion of Figures 9 and 11 coupled with finger elements 134, 135, 136, 137 of the kind of Figures 6 to 8. The wrist box is missing. In Figure 12, the hand is shown in rest configuration, while resting over a surface. The hinges 118, 119, 120, 121 are formed by inserting headed pins into corresponding aligned holes in the metacarpal finger portions 112, 122, 132, 142 and the various phalanges. The strings are shown, in Figure 12, at the back of the metacarpal portion 101. Figure 13 shows the prosthetic hand in a functional configuration, where the ring 136 and little finger 137 elements of the prosthesis are partially flexed to achieve a grasping configuration in cooperation with the prosthetic thumb 138.

The prosthetic hand will need to be attached to, or in cooperation with, the stump. That can be done via a stump socket. Attachment of the stump socket to the stump will present several options according to the length of the stump, and regularity of the soft tissues, i.e. the presence or absence of deformation due to scar tissue, subcutaneous fat and mal-united bones. When the hand prosthesis is attached to the stump via a socket, the socket can have on its internal surface, which forms the interface with the stump, a set of internal grooves which allow the elongate flexible members to run along the stump. This provides for additional comfort for the amputee, in that the elongate members have sufficient space for their operation and are not pushed by the socket against the skin of the stump. However, in certain cases, attachment by means of a socket may not be viable.

When the two main bones of the forearm are intact, and the amputation has taken place through the wrist, a well-fitting stump socket moulded to the forearm stump could be used mechanically to support the hand prosthesis.

A new concept of hand prosthesis attachment is embodied schematically in Figure 14.

Here, the prosthesis is fixed to the stump by connecting or otherwise surgically installing, implanting or attaching two extensions 167, 168 to the cut off ends of the ulna and radius bones. The extensions can be stems, pins, bars, rods or the like. They can have uniform cross section (e.g. circular cross section, as shown in Figure 14), but embodiments with tapered or otherwise non-uniform cross sections are possible.

The attachment arrangement shown in Figure 14 allows an advantageous feature of the hand prosthesis. This is the active pronation and supination of the hand prosthesis.

Active pronation and supination of the prosthetic hand is an important functional feature. Pronation and supination allow the hand to pick up objects in pronation, to hold objects whilst supinating and to cradle an object in the supine position.

The implantable metal extensions 167, 168, or pins, are made of a material which is suitable for being inserted into the bone, e.g. titanium. It is an option to coat titanium inserts with hydroxy-apatite, so as to achieve a surface which is highly compatible with bones.

In some embodiments, the metal pins are simply screwed into the ulna and radius. In some embodiments, however, the inserts are designed according to the principles of osseointegration. This will be explained in more detail below.

In some embodiments, the ulna and radius may be attached directly to the wrist box, without extension bars. This is more likely to be the case where the amputation of the hand preserves to a good extent the extension of the ulna and radius. In this case, the ulna and the radius may be sufficient to support the prosthetic hand, without the need for extension means such as rods, bars or pins.

The extension bars are able to come in a variety of lengths according to the desired position of the hand relative to the opposite limb.

in Figure 14, the prosthetic hand 172 (or prosthetic upper or distal part) is riveted to a box 1751 the wrist box. Both the upper part of the prosthesis 172 and the wrist box 175 are formed from a sheet of metal. A preferred material for this is brass or aluminium.

Copper may also be used. There are holes in both the distal and proximal end walls 180, 181 of the wrist box 175 for the entry and exit of actuating members of the upper prosthesis. These actuating members are flexible elongate members 80 such as cords or strings (they can be made of a synthetic polymeric material or they can be made of multifilarnent metallic wire). In the illustrated embodiment, these actuating elongate members are designed for connection with remaining muscles and tendons of the stump proximally, and for connection with pivotal elements of the upper prosthesis 172, such as prosthetic fingers or the thumb.

As it can be seen from Figures 14 and 15, the wrist box itself 175 is not articulated, and it is attached firmly to the radius 165 by means of a threaded bolt or screw (not shown) screwed or otherwise fixed into the radius extension 167 or into the bone. The attachment is designed not to allow any rotation between the hand 172, the wrist 175 and the metallic radius extension 167. This is permitted by the rigid connection 176 between the wrist box and the radial insertion stem 167. Such rigid connection is obtained, in this embodiment, by interference fitting the radial stem 167 into the corresponding circular aperture 176 of the proximal wall 180 of the wrist box 175. In other embodiments, this joint can be implemented by using a threaded connection (e.g. by using a bolt so that the proximal wrist box wall 180 is sandwiched between a bolt and the radial extension pin, or a bolt with opposing nuts).

In anatomy, the rigid rotation of the radius 165, the wrist 175 and the hand 172 which allows supination and pronation of one's hand takes place at the level of the proximal radiohumeral and humeroulnar joints 170. Therefore, there is a site of rotation of the forearm at the elbow joint 170. Reciprocally, there is a further pronation and supination mechanism at the distal radio-ulnar joint, where the wrist bones reside. The hand and forearm both pronate and supinate at the radiohumeral joint proximally and the radio-ulnar joint distally. The prosthesis of Figure 14 allows pronation and supination of the prosthetic hand according to this mechanism. When the prosthetic hand is supine, the ulna and radius are configured substantially parallel to each other and the palm of the hand faces upwards when the hand is horizontally supported on a surface. In this position, the radius is external to the ulna, When the prosthetic hand is in pronation, the ulna and radius cross each other and the palm of the hand faces downwards with the hand is horizontally supported on a surface.

This mechanism is provided for, in this embodiment, by a loose (clearance) tubular joint 177 in the wrist box 175 (see Figure 2). When the radius 165 rotates around the ulna 166 at the distal radio-ulnar end or joint, the wrist box 175 rotates accordingly around the pivot or hinge created by the ulnar extension 168 and the wrist box cavity or tubular joint 177. This joint may be provided simply by a clearance fitting. The joint may be lubricated. Alternatively, a ball bearing or lubricated bushing may be inserted between io the ulnar extension rod 168 and the corresponding wrist box seat 177.

Figure 14 shows a hand in pronation. it is important to note that the radius 165 rotates its long axis at the elbow 170 and is fixed to the carpal box 175 (wrist box), whereas the ulna 166 is unable to rotate at the elbow and needs to have a rotation attachment, such as a bearing, at the joint 177 with the carpal box.

Attaching the hand prosthesis via the radial and ulnar bones is unknown in comparison with a socket attachment. In the applications of the present invention, where actuating strings are implanted in the stump in order to move prosthetic fingers of the prosthesis, the present method of attachment allows for additional tendon or muscle anchorage space compared to the socket method. This is because most of the appropriate muscles or tendons run closer to the surface of the stump than to the bones of the stump, in the stump's longitudinal direction. The present method of attachment leaves those areas or regions free. Furthermore, the bucket-like or socket-like attachment is isadvantageOU5 for other reasons -for example it may cause proximal and distal movement of the socket on the stump's skin (i.e. a "concertina" type of deformation), which would be mechanically unsound and may be liable to damage the skin of the stump.

Figure 15 shows the wrist box 175 of Figure 14 in isolation, in a folded configuration.

The box comprises a proximal plate 180 and a distal plate 181. in this embodiment the plates have a substantially semi-elliptical shape. Each plate has a number of perforations. Some perforations or apertures are smaller, because they only serve for the passage of the strings or cables of the prosthetic hand. The smaller apertures are disposed on either plate according to a matrix. In this case the matrix has two rows and ni five columns. A third array of perforations is present closer to a curved shell 182 of the box 175. Elongate actuation elements of the hand prosthesis, such as strings or cords, are therefore allowed to pass through the box in the longitudinal direction.

The larger-diameter perforations 176, 177 provide respective seats, or pin-receiving portions, for the radial and ulnar extension rods or pins, and their dimensions and tolerances are established accordingly. Each plate has two side flanges 183, 184. They allow the plates 180, 181 to be fixed to the curved shell 182, when folded, by means of retaining means (not showed in Figure 15). The retaining means work in conjunction with apertures formed on the flanges 183, 184 and with corresponding apertures formed on the curved shell. In this embodiment, the three tiers of perforations 185, 186 187 correspond to three tiers of prosthetic phalanxes in the upper prosthetic hand (as shown in Figure 14). In this embodiment, the perforations are designed to host pairs of flexor strings to represent flexores digitorum superficiales and profundes. The single perforations towards the dorsal part of the wrist box host the extensor tendons.

Figure 16 shows the wrist box of Figure 15 in flat configuration. The various fold lines 188 which allow the central rectangular part 182 to be formed into a curved shell are visible. The side plates 180, 181 are folded and closed up and against the folded rectangular part 182 to form a generally concave half shell which functions as the wrist box 175.

Figure 8 can also be interpreted as a prototype of an upper prosthetic hand 172 assembled to a wrist box 66, in an embodiment of the invention.

Figure 17 shows a slightly different embodiment, compared to the one described above, of a wrist box 275 in flat configuration. Dimensions are provided in millimeters.

Figure 18 shows frontally the wrist box 275 of Figure 17 in a folded configuration, with dimensions also given in millimeters. To distinguish the radial 276 and ulnar 277 extension seats where the radial and ulnar extension rods are housed, a different shape has been used. Therefore, the radial extension seat portion is square in shape 276 while the ulnar pin-receiving portion is still circular 277. The flanges 283, 284 which, from the distal and proximal walls 280, 281 of the shell 275, fold onto and against an inner side (in folded configuration) of the rectangular sheet 282 which forms the outer shell of the wrist box and to which the walls 280, 281 are attached, have also a different shape compared to the earlier embodiment. In particular they are narrower, thus easier to fold, and sharp corners of material have been removed therefrom. Fold lines on the rectangular sheet 282 are also there to allow this sheet to be folded in place. Two rows of perforations 285, 286 are present on either the proximal or distal walls 280, 281, instead of the three rows present in the other embodiment. This indicates that this wrist box may be designed for two tiers of phalangeal members in the prosthetic upper hand, if each perforation accommodates a pair of extensor and flexor strings. Alternatively, on each wall, one row of perforations can be dedicated to flexor strings (one per perforation) and the other row to extensor strings (one per perforation), and pairs of corresponding flexor and extensor strings can be connected to a respective phalanx. Slightly slanted or oblong perforations are also present on either side of said rows, to allow a degree of side movement for the strings serving the prosthetic thumb and little finger.

The new concept of attachment of the prosthesis to the stump is by attaching the prosthesis 172 directly to the radius 165 and ulna 166, or what remains of them. This concept is shown schematically in Figure 14, as discussed above. The implantable metal extensions 167, 168 can be made of a material which is suitable for screwing or for "fusing" into the bone according to the principles of osseointegration. An example of a metal having this property is titanium. Osseointegration will be described in more detail below.

Figure 14 shows that the prosthetic hand 172 is riveted to a wrist box 175. This is made from a sheet of metal, and it is similar to the prosthetic wrist portion already seen in Figures 6, 7 and 8. There are holes in the wrist box for the exit of the cords or strings from the phalanges of the prosthetic fingers and thumb. The wrist box itself 175 is not articulated, and -in this embodiment-it is attached firmly to the radius 165 by means of a bolt or screw (not shown) threaded or screwed into the radius extension 167 or into the bone. The attachment is designed not to allow any rotation between the hand 172, the wrist 175 and the metallic radius extension 167. This is permitted by a fixed or rigid connection 176 between the wrist box and the radial insertion stem 167. Fixing of the radius stem 167 to the wrist box can, for example, also be achieved by an interference fitting 176.

Osseointegration is a new method of attaching artificial limbs to the body. This method is also sometimes referred to as "exoprosthesis" or "endo-exoprosthesis". The method works generally by inserting a titanium implant into a bone at the end of the stump. The titanium can be hydroxy-apatite coated. After several months, the bone attaches itself to the titanium implant and a supporting component is attached to the titanium bolt. The supporting device extends out of the stump and the artificial limb is then attached to the supporting device.

Figure 27 shows an osseointegration supporting device, or insert or peg, for use with the present invention. The insert 300 has a rounded head 301 which can be accessed externally to drive the peg into the bone once a space has been prepared therein -this is usually done using a punch. The head 301 will remain outside the bone, once the bbdy of the peg 301 has been positioned inside the bone. To ensure that the insertion is effected up the right length, a shoulder or collar 310 is provided at the distal end of the insert's body 304. The head is configured for receiving an extension pin or rod of the above-discussed type, and it has a female threaded bore 302 on the outer side.

The head 301 could be equipped with different attachment means compared to those described in this embodiment. However, in this embodiment, the head 301 simply has a circular threaded bore extending to a certain depth. As a result, an extension pin can be inserted to the head 301. The implantable part of the insert 300 has a solid triangular cross section 303 terminating with a tapered end 306. On the triangular stem 303, a set of holes or apertures may be provided to allow the bone to heal in them, or to support a transversal reinforcement, if necessary.

It is important to think about the size and shape of the intramedullary osseointegratable implants, such as the one shown in Figures 27, 28 and 29, and the preparation for implanting them. In these applications, the intramedullary canals of the radius and ulna have a relatively small diameter, and in places the canal appears to be round in cross section. It therefore makes anatomical and physiological sense to design the implant stems 305 with a triangular cross section 303. The anatomical thinking behind this is the fact that the Haversian canals which supply the intra-osseous circulation run longitudinally in the bone and are less disturbed by the introduction of an implant with a triangular section 303, than by a screw or a tapered screw as has been tried on the femur and humerus up to date -it is perhaps appropriate to speculate that the reasons for the greater success of screw-in implants in dentistry is the fact the human jaw-bone is not a long bone, the implants are not implanted in the medullary canal and there is more cancellous bone rather than dense bone around a tooth implant.

The following specialised instruments are provided for the implantation of the S osseointegrated device 300: a. A set of intramedullary trials (Figures 30 to 33). Each trial instrument 400 consists of a handle 401, a stem 404, a collar 410 and a smooth triangular peg 403 of a certain size and depth. Each instrument is marked from size 1 to 6 to correlate with the correct size of the triangular rasp 500 (see below) and the peg/stem 300 of a sterile implant.

b. A set of triangular rasps 500 (Figures 34 to 38) correlated to the size of the intramedullary canal. Each rasp 500 is designed to be mounted on a punch. There is a collar 510 to prevent the rasp 500 from entering too deep into the medullary canal. For this purpose the collar on the rasp is designed to be positioned at a distance very slightly more proximal than the end of the peg 300 of the chosen implant. For the purpose of mounting the rasp on the punch the collar has an internal (female) thread 502 which matches the male thread on the punch.

c. Use of the rasp 500: following the choice of size, the appropriate size of triangular rasp is chosen. It is used to freshen the corners of the triangle to be occupied by the implant. The rasps 500 are designed to be slightly larger in their widest size 504 than the intramedullary trial 400 chosen. The rasp completes the exact fit of the appropriate hydroxy-apatite coated implant or titanium implant.

d. A threaded punch, consisting of a stem with a terminal thread to match the female thread 302 in the proximal side of the implant. The stem is cylindrical in shape with one flattened part to fit a spanner for mounting and removing the rasps and the final osseointegratable implant.

e. A light mallet to introduce the triangular rasp and the final implant into the medullary canal.

f. A forked hammer to engage on the stem of the punch for the introduction or removal of the rasps or implants from the medullary canal.

g. A stainless steel sterilising box into which the instruments fit for sterilisation.

As an example and with the purpose of setting the invention in the surgical context, a complete surgical procedure for implanting an osseointegrated prosthetic hand is described in detail below: L The first stage of the implantation -osseointegration of the foundation pegs.

a) Pre requisite for healthy soft tissues.

The amputation stump must be healthy and the original wound must have been closed with a healthy soft tissue covering over the ends of the radius and ulna bones. If there has been a history of an infected wound at the time of the original amputation it will be necessary to warn the patient that his or her forearm stump may be unsuitable for the implantation of an osseointegrated prosthesis.

To this end, it may be necessary to perform a preliminary operation to shorten the stump in order to ensure healthy skin and soft-tissue coverage. This would mean that three operations may be necessary to ensure a healthy stump.

b) The 3-stage elective procedure.

Having ensured that the soft tissues and bones are healthy, the first stage should be performed under local anaesthetic infiltration to facilitate the cooperation of the patient during the identification of the appropriate muscles and tendons which will be used for the flexors and/or extensors of the fingers and thumb.

c) Surgical approach.

The approach to the end of the healed stump should, wherever possible, be designed to follow the scar of the healed skin wound. It is important to avoid parallel wounds which may compromise the blood supply to the skin. One wound can be used for all of the procedures.

d) Preparation of the bone ends.

S

The ends of the radius and ulna bones are exposed and a few millimetres of bone are resected using an appropriate sterile saw to expose the intramedullary canal of the bone.

e) Implantation of the intramedullary osseointegrated device.

The ends of the bones are gently cleaned removing bone spicules and exposing their intramedullary canal for a distance of no more than the length of the triangular intramedullary peg of the prosthesis. Next, the size of the medullary canal including the width and depth of the appropriate implant is measured. This is done by using the set of triangular trials which not only measure the triangular size of the medullary canal, but also act as depth gauges to measure the ideal depth of the appropriate peg. The intramedullary canals should under no circumstances be reamed in a circular fashion to enlarge the lumen of the medullary canal. Reaming the medullary canal may endanger the intramedullary arterial and venous circulation, with the result that the biology of the bone may be affected. The integrity of the circulation of the bone induding the microcirculation through the Haversian systems should not be damaged.

It is contested that reaming may be counterproductive to the osseointegration of the implant.

o Use of the triangular rasps.

Following the measurement of the medullary canal an appropriately sized triangular rasp is chosen from the set, and mounted on the punch provided. By using the correct size of triangular rasp, the corners only of the medullary canal should be rasped to accommodate the angular corners of the triangular peg of the implant for a firm interference fit.

g) Sizing the intramedullary pegs of the titanium implant The correct size of the titanium osseointegration device is now mounted onto the punch having removed the rasp. The implant is inserted into the intramedullary canal, and by the use of a light mallet the punch should be tapped home until the collar of the implant engages with the cut end of the bone.

The plastic temporary cover is now screwed into the end of the implant, using the hexagonal standard screw driver provided for the purpose. This cover will remain for six months, and its purpose is to keep the internal threads of the implant clean and free of infection for that period.

h) Identifying the appropriate muscles and tendons.

The distal parts of the flexor and extensor muscles should be exposed. The flexor and extensor muscle and tendons to be used in the percutaneous implantation of the devices should be identified (and subsequently tagged) by asking the patient to flex and extend the "ghost digits".

i) Tagging the ends of the reciprocal tendons or muscles.

The reciprocal ends of the flexor and extensor tendons (e.g. the flexor pollicis longus and extensor pollicis longus) should be dissected free from surrounding scar tissue and adhesions. They should be" tagged" by suturing them together using coloured non-absorbable sutures, such as blue nylon monofilament sutures. Tagging the relevant muscles at this stage will facilitate easy retrieval at the second operative stage.

At this stage the percutaneous devices in the form a rings should not be implanted.

The skin is closed with subcutaneous and subcuticular absorbable sutures. Sterile dressings are applied and the patient is given antibiotic cover for a minimum of 7 days.

j) The interim period of waiting (expected 6 months).

The wound should be kept dry and left undisturbed for a period of 14 days. Following this the patients may get back to using a cosmetic prosthesis. X-rays should be taken at 3 monthly intervals and if the osseointegration appears to have occurred the next stage can be planned. The expected average time is 6 months, but this needs to be verified with experience.

If infection and loosening appears on X-ray and on clinical evaluation, the implant should be removed, if infection is suspected, culture specimens are obtained and the organism should be identified and appropriate antibiotic therapy should be initiated.

If the radiological appearance shows that osseointegration is incomplete, the next stage of the operation should be delayed by further intervals of three months until the appearance is satisfactory.

2. The second stage -attachment of the radius and ulna extensions to the foundafion pegs/elements.

At the stage when osseointegration between the implanted pegs in both the radius and ulna is complete, the next stage of attachment should be planned.

Surgical approach: The stump ends with the integrated foundation pegs will again be exposed by a surgical approach through the healed soft tissue wound.

The tendons of the extensor and flexor muscles that will be used for the implantation of the percutaneous devices (rings or dumb bells as the case may be), need to be separated and dissected so that the percutaneous devices can be passed through the skin and through the tendon or muscle (as the case may be) proximal to the skin edges of the stump.

In the case of flexor muscles and tendons the percutaneous devices will be implanted on the flexor aspect of the stump.

Conversely, if extensor muscles and/or tendons are being used they should be implanted on the extensor aspect of the amputation stump.

The temporary caps of the foundation pegs should be removed using the instrument designed for the purpose, exposing the inner thread which should have been kept clean by the temporary thread of the temporary cap.

The appropriate radius and ulna extensions are attached with the help of a pair of flats 311 that are present on the head 301 of the implantable stems (these are to prevent an excessive force to be allied to the bone during connection), and the skin wounds are closed around the junction of the osseointegration implanted device. Skin clips and percutaneous skin sutures are not recommended as they can be a source of infection.

It is recommended that absorbable subcutaneous and subcuticular sutures should be sued sparingly and should be reinforced with SteristripsTM and dry dressings such as Mepore®. The stump should be allowed to heal preferably without disturbing the dressing for two weeks. The patient should take antibiotics for two weeks so that any blood exuding from the wound will contain antibiotics.

3. ffhe Third Stage -attachment of the hanpghesis.

At two weeks postoperatively the wounds should be inspected. The skin should be cleaned with Hibitane or a similar antibacterial solution and the patient should be given strict instructions on how to manage the wound and how to keep it clean and sterile.

At this stage the hand prosthesis should be fitted and strings should be attached to the percutaneous rings in the forearm. The strings should be adjusted and the patient and those living with him should be warned of complications and instructed in the daily routine of keeping the wound clean and adjusting the strings attached to the percutaneous rings.

Maintenance of the prosthesis, the wounds and the cosmetic glove should be explained to the patient and his cohabitants and email and telephone contact should be maintained permanently.

Returning now to the description of the prosthetic hand, Figure 19 shows a rubber cover 190 that can be used in conjunction with any of the above-described embodiments of the hand prosthesis. The manufacturing process to obtain the glove 190 can be casting or blow moulding. The cover can be manufactured from a waterproof elastomer. The thickness of the sheet forming the cover can be up to 2.5 mm, and preferably between 1 and 2.5 mm. Further, the material in question can be pigmentable so that the best possible colour match with the patient's own skin can be achieved. In addition, the length of the cover extends preferably up to 150 mm up the forearm of the patient, beyond the wrist section. This kind of cover is worn by a patient as a glove would be worn for a real hand. The cover of Figure 19 is to be used in conjunction with a five-digit prosthesis, like the ones shown in Figures 13 or 14, whereby each finger of the glove 191, 192, 193, 194, 195 is associated with a prosthetic digit member. This kind of cover can make the hand prosthesis have an appearance similar to that of a real hand.

The cover 190 can certainly serve cosmetic purposes. The cover 190 comprises parts which resemble the parts of a real hand, such as a metacarpal portion 196, knuckle portions 199 and nail portions 200. A part of the glove will also cover the wrist 197. The finish of the outer part of the cover will also be similar to the roughness or texture of a real hand. The colour of a real hand should also be respected, as mentioned above.

However, the cover can also be functional. In order to achieve this, the rubber glove is made of a material (rubber or plastic) having a certain thickness both of which, in combination, are able to confer to the prosthetic hand an overall degree of rigidity that is comparable to that of a real hand. The hand prosthesis will therefore look and feel as natural as possible, and will be as similar as possible to a real hand. By coupling a relatively rigid glove with any of the above-described prosthetic hands, a prosthesis can be achieved that has an overall degree of rigidity similar to that of a real hand. This is obtained from a contribution to that overall rigidity coming from the internal prosthesis, and from a contribution coming from the cover 190. This would not be possible if, for example, the glove was a very thin glove made of latex: this cover would hardly have an appreciable effect on the overall rigidity of the glove. Instead, in this embodiment, the prosthetic hand with the glove 190 has, or is designed to have, an overall rigidity and overall feel very similar to that of a real hand.

In order to improve the overall rigidity of the hand prosthesis, a viscous filling could be added to the prosthesis inside the glove 190. The filling would also contribute to protect the internal metallic components from oxidisation.

Now, a convenient way of preparing a bespoke prosthetic cover for a patient will be described. A patient in need of a hand prosthesis, may have a glove similar to the one shown in Figure 19 made to measure for his remaining hand. An easy and convenient way to achieve this is by creating a cast of the remaining real hand, as known in the art. The made-to-measure glove can then be sent to a prosthesis workshop. The workshop will then produce the internal skeleton of the prosthesis on the basis of the glove. The resulting prosthesis will fit the glove and will therefore represent a hand having a correct size for the patient. It should be noted that the glove can be easily reversed, and can therefore represent both the right and left hands of the patient. In other words, a glove for a right hand can become one for a left hand if reversed.

Reversal of the initial glove, the one made on the basis of the real hand, will allow the workshop to produce a prosthesis based on an exact model of the amputated hand.

Figure 20 shows a step in the manufacturing process of the upper prosthetic hand (i.e. the prosthetic hand excluding the pins for attachment to the ulna and radius). The step in question is that of obtaining a template 200 from which flat parts or units can be obtained. These can then be folded and assembled to form the upper prosthesis (see for example Figure 6). In Figure 20, there are shown flat parts or units sufficient for manufacturing a complete single-hand prosthetic unit, with additional spare parts. The phalangeal units are allocated to two sheets of material 201, 202. The material in question is brass, and the sheets have a thickness of 0.3 mm. In total, there are 7 different designs of phalangeal units 206, 207, 208. In the first row of phalanges, across the two sheets 2011 202, we can see two designs of proximal phalanges 206; three units are present for each of the two designs. In the second row, the first five phalanges share a common design, while the last two have their own design. These are all intermediate phalangeal members 207. In the third row, there are three designs of phalanges: the first three units represent the first, the next two units represent the second, and the remaining two units represent the third, all the units in this row being distal phalanges 208. For the metacarpal part (or palm box), there are shown in Figure 20 two alternatives 210, 211. The alternatives are just different designs of the same part. Each is shown in a separate sheet 203, 204. Two flat wrist box parts 209 are also shown, one being intended just as a spare part. They have been sketched in one sheet of material 205.

Figure 20 shows that the upper prosthesis can be obtained in principle from a single sheet of metallic material, in this case brass (but it could be copper or aluminium), of size 470 by 320 mm. However, the parts can be further nested, and the nesting can be further optimised. Ultimately, a sheet of material of further reduced dimensions will be used to provide all the parts necessary to assemble a single prosthetic hand.

Ultimately, it is suggested that a single hand will be obtained from at feast a sheet of size 450 by 300 mm.

In Figure 20, the contours of the flat members to be obtained from the brass sheet are visible as solid fines. These contours 213 were obtained by chemical or laser etching.

The etching was such that the parts could easily be removed from the sheet. This is substantially equivalent to pre-cutting the parts. Chemical etching has also been used to obtain the fold lines 210 of Figure 20. These are visible as dashed lines.

Figure 21 shows a technical drawing, with dimensions, of one of the phalangeal flat units 206 of Figure 20. This is a proximal phalangeal unit (first row in Figure 20). At the centre, it is possible to distinguish the phalanx upper part 221, between two fold lines 224. The phalanx side parts 222, 223 are next to the upper part 221, on either side of the fold lines 224. Further out, there are two side flanges 229, 230, which serve to form the phalanx unit as a tubular member once the sheet of cut material has been wrapped. These are also folded along respective folding lines 239, 240, The fixation is made via the perforations 231, 232, 233, 234 in the flanges, but other methods would be possible such as using adhesives. The part 206 also has two proximal 225, 226 and two distal 227, 228 flanges. They carry perforations for creating the hinges between the phalanx and the metacarpal part and the phalanx and the intermediate phalanx respectively.

Figure 22 shows the phalanx of Figure 21 in a folded configuration, with the perforations of the side flanges 229, 230 aligned in place, ready for fixation. Figure 23 is a side view of the same component, detailing the position of the hinge perforations 241, 242. Figure 24 is a cross sectional view of the same component showing the wrapped or tubular arrangement.

Figure 25 shows an embodiment of prosthetic hand arranged vertically on a wood support 253 for use as an educational or demonstration tool 250. The prosthesis comprises four finger members 256 and a thumb 255, a metacarpal box 260 and wrist box 254. The prosthesis is fixed to the wood column 253 by means of two vertical bolts, with the respective screws passing through the wrist box 254. The fingers and thumb are operated according to the above-disclosed method of operation, i.e. via strings or other type of elongate members fixed to the phalanges of the prosthesis. The strings pass through the wood column and exit it at its base. Loops are then formed at the end of the strings. The strings are divided into flexors 252 and extensors 251, according to their function. A user of the educational tool 250 can pull the strings via the loops to actuate the fingers. That demonstrates the principles of operation of a real hand, where the movements of the fingers and thumbs are controlled by muscles and tendons.

Returning now to the upper portion of Figure 25, i.e. to the hand itself, it can be seen that the actuating strings are encapsulated in white plastic cables 258. Figure 26 shows an enlarged image of the cables. Each cable houses one string, thereby preventing the string to become entangled with other strings or cables (entanglement would prevent proper functioning of the actuation mechanism of the hand). The cables or guides 258 allow the actuating strings to be neatly delivered to the desired location. In this embodiment, the stings run to the distal phalanges through the metacarpal box 260, and the proximal and intermediate phalanges. Each pair of actuating strings 257 corresponding to a certain finger is connected to the distal phalanx of that finger on opposite sides with respect to the distal phalanx hinge.

There is also disclosed an educational tool for demonstrating the principle of a hand prosthesis for a stump of a patient with a forearm amputation of a hand according to any one of the preceding claims, comprising: at least one digit member; a metacarpal portion to which each prosthetic digit member is pivotally connected, the metacarpal portion configured for being supported by or attached to a base of the educational tool; at least one elongate actuating member connected to one of the digit members and operable to move the digit member; and at least one actuation element that can be used for pulling the respective actuating member.

The present invention has been described above purely by way of example.

Modifications in detail may be made to the invention within the scope of the daims appended hereto.

Claims (52)

1. CLAIMS: 1. A prosthetic hand for a forearm amputee, comprising: at least one prosthetic digit member; a prosthetic metacarpal portion to which each prosthetic digit member is pivotally connected, the metacarpal portion being configured for being supported in cooperation with the stump; at least one elongate actuating member connected to one of the digit members and operable to move the digit member; and at least one anchoring element attached or attachable to the at least one elongate actuating member, which can be used for connecting the elongate actuating member to remaining portions of tendons or muscles of the stump.
2. 2. A prosthetic hand for a forearm amputee according to claim 1, further comprising: at least one additional elongate actuating member forming with the at least one elongate actuating member a set of elongate actuating members comprising flexor and extensor actuating members, wherein at least a pair of flexor and extensor actuating members is connected to one of the digit members and wherein the flexor member of said pair is operable to move the digit member to a first configuration, and the extensor member of said pair is operable to move the digit member to a second configuration; and at least one additional anchoring element forming with the at least one anchoring element a set of anchoring elements that can be used for connecting a pair of elongate actuating members to remaining portions of tendons or muscles of the stump, wherein one anchoring element is attached or attachable to the flexor actuating member of said pair of actuating members, and another anchoring element is attached or attachable to the extensor actuating member of said pair of actuating members.
3. 3. A prosthetic hand for a forearm amputee according to claim 2, comprising at least two prosthetic digit members, at least two of which are configured in opposition with respect to one another to allow grasping of objects therebetween, and at least two pairs of flexor and extensor actuating members, wherein a first pair of flexor and extensor members is connected to one digit member, and wherein a second pair of flexor and extensor members is connected to another, opposing digit member, and wherein the flexor members of said pairs are operable to move the respective digit members to a first, grasping configuration, and the extensor members of said pairs are operable to move the respective digit members to a second, release configuration.
4. 4. A prosthetic hand for a forearm amputee according to claim 3 comprising five prosthetic digit members and five respective pairs of flexor and extensor members, wherein a prosthetic index, middle, ring and little finger are arranged substantially parallel to each other along a prosthetic metacarpo-phalangeal line, and wherein a prosthetic thumb is arranged substantially in opposition with respect to any of the prosthetic index, middle, ring and little fingers.
5. 5. A prosthetic hand for a forearm amputee according to claim 1 to 4, wherein at least one of the prosthetic digit members comprises at least two pivotally interconnected prosthetic phalangeal members.
6. 6. A prosthetic hand for a forearm amputee according to claim 5, wherein at least one of the prosthetic digit members includes three pivotally interconnected prosthetic phalangeal members including proximal, distal and intermediate phalanges.
7. 7. A prosthetic hand for a forearm amputee according to claim 5 or 6, wherein each prosthetic phalangeal member has an associated pair of actuating flexor and extensor members operably connected thereto in order to move the corresponding prosthetic phalanx angularly around its proximal pivot.
8. 8. A prosthetic hand for a forearm amputee according to claim 5, 6 or 7, wherein at least one prosthetic phalanx comprises an elongated shell extending in the direction of the finger.
9. 9. A prosthetic hand for a forearm amputee according to claim 8, wherein the shell is tubular.
10. 10. A prosthetic hand for a forearm amputee according to claim 9, wherein at least one elongated actuating member is arranged to run through an elongated tubular shell adjacent to a wall thereof.
11. 11. A prosthetic hand for a forearm amputee according to any one of the preceding claims, wherein the metacarpal portion is formed from a single sheet of material.
12. 12. A prosthetic hand for a forearm amputee according to claim 11, wherein the material is a metal.
13. 13. A prosthetic hand for a forearm amputee according to claim 12, wherein the metal is brass or aluminium.
14. 14. A prosthetic hand for a forearm amputee according to any one of the preceding claims, further comprising a prosthetic wrist portion having a seat configured for accommodating and supporting a bone extension, the extension being connectable to a bone of the stump.
15. 15. A prosthetic hand for a forearm amputee according to claim 14, wherein the prosthetic wrist portion comprises a further seat and a further extension, the two extensions each having proximal and distal ends, one extension having its proximal end connectable to what remains of the ulna of the stump, and the other extension having its proximal end portion connectable to what remains of the radius of the stump, the distal portion of the ulnar extension being hingedly connected to the first seat of the wrist portion, and the distal portion of the radial extension being rigidly connected to the second seat of the wrist portion, wherein the pronation and supination orientation of the hand prosthesis can be changed by rotating the radial extension around the ulnar extension.
16. 16. A prosthetic hand for a forearm amputee according to claim 14 or 15, wherein at least one extension is connectable to a bone by means of an implantable element designed for implantation in the bone according to the principles of osseointegration.
17. 17. A prosthetic hand for a forearm amputee according to any one of the preceding claims, wherein the elongated actuating members are strings.
18. 18. A prosthetic hand for a forearm amputee according to claim 17, wherein the strings comprise intertwined multifilament metal wires.
19. 19. A prosthetic hand for a forearm amputee according to any one of the preceding claims, wherein the anchoring elements are percutaneous metallic rings.
20. 20. A prosthetic hand for a forearm amputee according to any one of claims I to 18, wherein the anchoring elements are percutaneous pins or studs.
21. 21. A prosthetic hand for a forearm amputee according to any one of the preceding claims, wherein at least two between: a prosthetic finger, a prosthetic phalanx, the prosthetic metacarpal portion and the prosthetic wrist portion are independently formed out of a single blank of material.
22. 22. A prosthetic hand for a forearm amputee according to claim 21, wherein the prosthetic finger or fingers, any prosthetic phalanx, the prosthetic metacarpal portion and the prosthetic wrist portion are each independently formed out of a single sheet of metal of maximum dimensions 450 by 300 mm.
23. 23. A prosthetic hand for a forearm amputee according to claim 22, wherein the blank is a sheet of metal suitable for cold forming of the prosthetic hand's components.
24. 24. A prosthetic hand for a forearm amputee according to any one of the preceding claims, further comprising an external prosthetic cover portion generally provided in the shape of a glove, and configured for vesting the prosthetic hand.
25. 25. A prosthetic hand for a forearm amputee according to claim 24, wherein the prosthetic cover is made of rubber.
26. 26. A prosthetic hand for a forearm amputee according to claim 25, wherein the rubber has a thickness comprised in the range between I and 2.5 mm.
27. 27. A prosthetic hand for a forearm amputee according to claim 24, 25 or 26, wherein the cover can be filled with and retain a viscous substance.
28. 28. A kit for assembling a prosthetic hand for a forearm amputee according to any one of the preceding claims.
29. 29. A prosthetic hand for a forearm amputee comprising: a distal prosthetic component having prosthetic fingers or the like; a prosthetic wrist component connected to and supporting the upper prosthetic component, configured for being rigidly connected to what remains of the radius of the stump and for being rotatably connected to what remains of the ulna of the stump, wherein, in use, the pronation and supination orientation of the hand prosthesis around a longitudinal axis of the stump can be varied by the patient by rotating the radius around the ulna.
30. 30. A prosthetic hand for a forearm amputee according to claim 29, wherein the configuration of the prosthetic wrist component for being rigidly connected to the radius comprises a first extension-receiving portion, and wherein the prosthetic hand further comprises a radius-connectable extension having proximal and distal ends, the proximal end of the radial extension being connectable to what remains of the radius of the stump, and the distal end of the radial extension being configured for being rigidly connected to the first extension-receiving portion of the wrist component.
31. 31. A prosthetic hand for a forearm amputee according to claim 30, wherein the first extension-receiving portion comprises an aperture, and the radial extension is.configured for being received in the aperture by interference.
32. 32. A prosthetic hand for a forearm amputee according to claim 30, wherein the rigid connection between the distal end of the radial extension and the first extension-receiving portion comprises a bolted or threaded connection.
33. 33. A prosthetic hand for forearm amputee according to any one of claims 29 to 33, wherein the configuration of the prosthetic wrist component for being rotatably connected to the ulna comprises a second extension-receiving portion, and wherein the prosthetic hand further comprises an ulna-connectable extension having proximal and distal ends, the proximal end of the ulnar extension being connectable to what remains of the ulna of the stump, and the distal end of the ulnar extension being configured for being hingedly connected to the second extension-receiving portion.
34. 34. A prosthetic hand for a forearm amputee according to claim 33, wherein the second extension-receiving portion comprises an aperture, and wherein the ulnar extension is configured for being received in the aperture with clearance between the aperture and the ulnar extension.
35. 35. A prosthetic hand for a forearm amputee according to claim 34, wherein the aperture is circular.
36. 36. A prosthetic hand for a forearm amputee according to claim 35 when dependent on claim 31, wherein the aperture receiving the radial extension comprises a 90 degrees angle.
37. 37. A prosthetic hand for a forearm amputee according to claims 34, 35 or 36, wherein a bearing is present between the distal end of the ulnar extension, and the respective aperture.
38. 38. A prosthetic hand for a forearm amputee according to any one of claims 30 to 37, wherein at least one of the radial and ulnar extensions is made of one material among: medical-grade titanium, stainless steel, brass, aluminium, gold and fibre reinforced composite.
39. 39. A prosthetic hand for a forearm amputee according to any one of claims 30 to 38, wherein at least one of the proximal ends of the extensions is configured for connection to the ulna or to the radius via an implantable element that can be implanted in the ulna or radius, wherein the proximal end of the extension is configured for attachment to the implantable element.
40. 40. A prosthetic hand for a forearm amputee according to claim 39, further comprising the implantable element, wherein the implantable element is an osseointegratable implantable element, and wherein said osseointegratable implantable element is designed for partial implantation into the ulna or radius with a distal portion of the implantable element being, in use, made available outside of the stump, and wherein the attachment to the implantable element is performed on said distal portion of the implantable element.
41. 41. A prosthetic hand for a forearm amputee according to claim 40, wherein the osseointegratable element is made of medical-grade titanium.
42. 42. A prosthetic hand for a forearm amputee according to claim 40 or 41, wherein the osseointegratable element is hydroxy-apatite coated.
43. 43. A prosthetic hand for a forearm amputee according to claim 40, 41 or 42, wherein both of the proximal ends of the radial and ulnar extensions are configured for implantation via respective osseointegratable implantable elements.
44. 44. A prosthetic hand for a forearm amputee according to any one of claims 40 to 43, wherein the or each osseointegratable iniplantable element comprises an insertable portion having a triangular cross section sized for being inserted into an intramedullary canal of the stump's radius or ulna.
45. 45. A prosthetic hand for a forearm amputee according to claim 44, wherein the size of the insertable triangular cross section portion is such that, in use, it cannot rotate inside the associated intramedullary canal.
46. 46. A prosthetic hand for a forearm amputee according to any one of claims 29 to 45, wherein the prosthetic wrist component comprises a number of apertures for allowing elongate flexible members to pass therethrough in the proximal-to-distal direction.
47. 47. A prosthetic hand for a forearm amputee according to claim 46, wherein the prosthetic wrist is in the shape of a shell-like structure.
48. 48. A prosthetic hand for a forearm amputee according to claim 47, wherein the shell can be obtained by bending a single blank of material into shape.
49. 49. A prosthetic hand for a forearm amputee according to claim 48, wherein said material is a metal.
50. 50. A prosthetic hand for a forearm amputee according to claim 49, wherein the metal is brass or aluminium.
51. 51. A prosthetic hand for a forearm amputee according to any one of claims 47 to 50, wherein the shell comprises proximal and distal walls, the distal wall being configured for connection with the distal prosthetic component, and the proximal wall being configured for connection with the ulna and radius, and wherein at least two of said wrist-box apertures are organised one on the distal wall and one on the proximal wall directly opposite to each other in a substantially longitudinal direction with respect to the forearm.
52. 52. A prosthetic hand for a forearm amputee substantially as hereinbefore described with reference to any one or more of the accompanying drawings.