GB2488759A

GB2488759A - Intramedullar implant for prosthetic limb attachment

Info

Publication number: GB2488759A
Application number: GB1103593.8A
Authority: GB
Inventors: Angus Everett Strover
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-03-01
Filing date: 2011-03-01
Publication date: 2012-09-12
Also published as: GB201103593D0

Abstract

An implantable item 300 for osseointegration of a prosthetic device into a trans-amputated bone of a stump is disclosed. This is designed for frontal implantation into an intramedullary canal 4 and it comprises: a proximal, insertable portion 304 for insertion into the intramedullary canal 4 of the bone 5; and a distal, non-insertable portion 301. The proximal insertable portion 304 comprises anchor edges 12 for anchoring the item 300 to the intramedullary canal 4, and the distal portion 304 is configured for attachment to the prosthetic device. Alternatively, the prosthetic limb may be provided with the insertable portion.

Description

Surgically implantable elements and surgical tools for implantation thereof The present invention relates to an item for surgical implantation into bones. In particular, it relates to an osseointegratable item for surgical implantation of prosthetics to trans-amputated bones in limbs of the human body.

Trans-amputated bones are characterized by a truncation of the bones according to a cross sectional plane. The cross section of the bone revealed by the amputation can be used as the attachment location for direct bone attachment of bone extensions or other prosthetics.

In this type of surgical procedures, an osseointegratable, implantable item, element or insert is first connected to the bone at the amputation cross section. A portion of the element or insert is then left protruding out of the bone, while the skin of the patient can heal over the truncation and around said protrusion. Typically, a medical device, extension or prosthesis is attached to said protrusion to obtain the final implant or installation.

Direct bone attachment of the type described above has been explored, for example, in the humerus, tibia and femur.

In certain applications, the connection is realized by means of a screw screwed directly into a medullary canal of the bone. This has been shown not to be an ideal method of attachment, due to its intrinsic destructiveness as the screw is allowed to "self-tap' into the bone.

In other applications, the medullary canal -which typically has a variable and imperfect shape such as a generally imperfect oval, ovoidal or elliptical shape -is reamed first, to create a regular, round seat that can house a rod or circular peg or stem. However, this method of attachment, although perhaps less invasive that the screw, has also been proven not to be ideal, due to the inevitable removal of part of the Haversian canals of the bone -these canals supply the intra-osseous circulation, and, therefore, are fundamental for the health of the amputated bone. Furthermore, reaming makes the bone weaker.

Once the implant or insert has been installed, the bone can heal around the implant according to the principles of osseointegration until the implant is effectively "fused" into the bone.

S It should be pointed out that surgical implants of the types described above can vary greatly in detail according to specific surgical requirements.

The skin of the amputee too then heals around the insert. To do so, the skin will grow and inevitably come into contact with the insert in certain parts. These parts require constant cleaning, otherwise bacteria can develop in these sites. Cleaning these regions can be very cumbersome for the amputee. To prevent the healed skin to come into contact with dust or dirt, sometimes stump caps or other similar barriers are used.

It is therefore an object of the present invention to provide an improved surgically implantable osseointegratable item, element, device or the like, which may overcome at least one of the above disadvantages.

It is also an object of the present invention to provide an improved surgically implantable osseointegratable item, element, device or the like, which may favour intraosseous circulation for the amputated bone.

It is a further object of the present invention to provide an improved surgically implantable osseointegratable item, element, device or the like which can be more conveniently and easily connected to a stump of an amputee, and which may be more likely to be accepted physiologically, mechanically and cosmetically by the amputee, It is yet a further object of the present invention to provide a connection for an external item such as a prosthesis or other similar medical device which is or can be advantageous for the patient compared to the prior art.

It is also an object of the present invention to provide a connection for bone implantation to amputated limbs of an amputee which is less invasive and/or

troublesome compared to the prior art.

According to an aspect of the present invention, there is provided an implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, comprising: a proximal, insertable portion for insertion into the intramedullary canal of the bone; and a distal, non-insertable portion, wherein the proximal insertable portion comprises anchor edges for anchoring the item to the intramedullary canal, and wherein the distal portion is configured for attachment to the prosthetic device, so that the implantable item can be push fitted to the intrarnedullary canal with minimal invasiveness, and minimal destructiveness for the amputated bone.

Very preferably, the item comprises at least one side located between two of said edges, and said side is recessed compared to a notional cylindrical surface circumscribing the item through said two edges, so that the item can be inserted in the intramedullary canal without reaming it first, thereby maintaining a maximum number of Haversian canals around the intramedullary canal. In some embodiments, said side is a straight side, but in other embodiments said side can be an inwardly curving side, so as to allow additional space between the internal wall of the intramedullary canal and the item.

Preferably, there are three of said anchor edges, which is optimal for the equilibrium and the distribution of forces on the item when this is inside the intramedullary canal.

Preferably, said anchor edges are non coiled edges, so that push fitting of the item in the intramedullary canal is facilitated and does not require any twisting.

Preferably, said edges extend substantially longitudinally so that they are easy to guide inside the canal.

Preferably, said edges extend substantially axially compared to the body of the item, in accordance with the axial extension of the bone.

Preferably, two of said edges extend substantially parallel to each other, so that their insertion is further facilitated.

In some embodiments, the proximal insertable portion comprises a substantially polygonal cross section, which provides the required stiffness and solidity.

Preferably, said polygonal cross section is generally triangular, which is especially suitable for insertion in the ovoidal or generally elliptical cross section of the intramedullary canal. In addition, this geometry provides for good support, and minimises any chance of the item twisting inside the canal.

Preferably, the item comprises a collar, which is generally wider than the proximal insertable portion, so that the item can be inserted according to the correct length.

In some embodiments, the proximal insertable portion may comprise one or more apertures, which can be useful if reinforcement pegs, screws or the like have to be applied to the item, for increasing its strength.

Preferably, the distal portion comprises receiving means, so that a prosthetic device can be received therein after the item has been installed in the bone.

Preferably, the receiving means are adapted for receiving an end of a stem.

Preferably, the distal portion comprises a pair of flats, so that the item can be kept still, e.g. with a spanner, while the prosthetics is connected thereto.

In preferred embodiments, the proximal insertable portion is sized for insertion into the intramedullar-y canal of the radius or ulna.

Preferably, the item is made of medical grade titanium, which is known to provide the correct stiffness, and which is particularly suitable for osseointegration.

Preferably, the item or a part thereof is hydroxy-apatite coated, which is a substance that is particularly well accepted by bones, it being highly biocompatible with bones.

Preferably, the item or a part thereof is silver coated, so that bacteria are less likely to grow at the interface between the silver coated portion of the item and the re-grown skin of the patient.

In certain embodiments, the length of the insertable portion is comprised in the range to 65 mm, which gives good stability of the insert in the bone.

According to another aspect of the present invention, there is instead provided a kit for assembling a prosthetic hand for a stump of a patient with a forearm amputation of a hand comprising an implantable item comprising: a proximal, insertable portion for insertion into the intramedullary canal of the bone; and a distal) non-insertable portion, wherein the proximal insertable portion comprises anchor edges for anchoring the item to the intramedullary canal, and wherein the distal portion is configured for attachment to the prosthetic hand.

According to another aspect of the present invention, there is provided a kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for installation of a prosthetic device to a stump, the kit comprising at least one osseointegratable device comprising: a proximal, insertable portion for insertion into the intramedullary canal of the bone; and a distal, non-insertable portion, wherein the proximal insertable portion comprises anchor edges for anchoring the item to the intramedullary canal, and wherein the distal portion is configured for attachment to the prosthetic device, so that the implantable item can be push fit to the intramedullary canal with minimal invasiveness, and minimal destructiveness for the amputated bone.

Preferably, the kit further comprises a set of trial devices for said osseointegratable item, which will be used to gauge the size of the intramedullary canal.

Preferably one or more of the trial devices comprises a collar.

Preferably, one or more of the trial devices comprises a trial head.

In some embodiments, the kit further comprises a rasp for preparing the intramedullary canal.

Preferably, the rasp comprises a rasp stem for insertion of the rasp in the canal.

Preferably, the rasp comprises a rasp collar, so that the correct length of the rasp os inserted in the canal in preparation of the insertion of the item.

Preferably, the rasp comprises a rasp head.

Preferably, at least the trial and the item, or the rasp and the item, are compatibly sized for preparing and installing the osseointegratable item inside the intramedullary canal.

According to another aspect of the present invention, there is provided a prosthetic limb for osseointegration into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, comprising a proximal, insertable portion for insertion into the intramedullary canal of the bone, wherein the proximal insertable portion comprises anchor edges for anchoring the prosthetic limb to the intramedullary canal.

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 side view of an osseointegration insert for insertion and attachment to the ulna or radius of a forearm stump according to an embodiment of the present invention, with dimensions in mm; Figure 2 is a perspective view of the osseointegration insert of Figure 1; Figure 3 is a front view of the osseointegration surgically implantable element of Figure 2, with dimensions in mm; Figure 4 is a side view of an osseointegration trial for a prosthetic hand to be connected to the radius and ulna of a forearm amputee according to an embodiment of the present invention, with dimensions given in mm; Figure 5 is a perspective view of the osseointegration trial of Figure 4; Figure 6 is a front view of the osseointegration trial of Figure 4, with dimensions given in mm; Figure 7 is a detail view according to detail section "A" of Figure 62, with dimensions given in mm; Figure 8 is a side view of a rasp for freshening the intramedullary cavity of the ulna or radius of a forearm amputee for installing a hand prosthesis connected to the ulna and radius of the amputee, according to an embodiment of the present invention, with dimensions given in mm; Figure 9 is a perspective view of the osseointegration rasp of Figure 8; Figure 10 is a detail view according to detail section "A" of Figure 8, with dimensions given in mm; Figure 11 is a front view of the rasp of Figure 8, with dimensions given in mm; Figure 12 is a detail view according to detail section "B" of Figure 11, with dimensions given in mm; Figure 13 is a schematic cross sectional representation of a trans-radial amputation showing a typical shape of the intramedullary canal of the radius; Figure 14 is a schematic cross sectional representation of an osseointegratable insert according to the present invention while housed in the intramedullary canal of Figure 13; and Figure 15 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.

The present invention is described hereinbelow with reference to a new concept of attachment of a prosthetic hand to a forearm stump involving attachment of the prosthetic hand 172 directly to the radius 165 and ulna 166 of the stump, or what remains of them.

However, it will be understood that the invention can similarly be applied to any trans-bone amputation of any bone of a human limb including the humerus, tibia, fibula and femur amongst others, wherever an insert should be inserted in an intramedullary canal of the bone to form the basis, anchor or implant for an external prosthetic device.

With reference to Figure 13, an amputated cross section of a radius 5 is shown. An intramedullary canal 4 is visible in the middle of the bone. Around it, a cluster or system of osteons 2 is present, where Haversian canals 3 can be identified. The Haversian canals are fundamental for the health of the stump, in that they provide fluid supply to the resected bone.

The dash line in Figure 13 represents a reaming line 8, according to which some of the Haversiàn canals are removed when the intramedullary canal 4 is reamed to make space for a traditional circular osseointegration insert, which is push fitted to the bone 5.

The new concept of hand prosthesis attachment is embodied schematically in Figure 15. Here, a hand prosthesis is fixed to the stump by connecting or otherwise surgicafly installing or attaching two extensions 167, 168 into the cut off ends of the ulna and radius. The extensions can be stems, pins, bars or rods. They can have uniform cross section (e.g. circular, as shown in Figure 1), but embodiment with tapered or otherwise non-uniform cross sections are possible.

The attachment arrangement shown in Figure 15 allows an advantageous feature of the hand prosthesis. This is the active pronation and supination of the hand prosthesis.

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 1 shows an osseointegration supporting device, element, item, insert or peg -as it can be referred to -for use according to the present invention. The insert 300 has a rounded head 301 which can be accessed externally to drive the surgically implantable element into the bone once a space has been prepared therein -this is usually done using a punch.

The head 301 will remain outside of the bone, once the body of the surgically implantable element 301 has been positioned inside the bone. To help with this, certain embodiments, like the one shown in Figure 1, are equipped with a collar, shoulder or other abutment 310. This also ensures that the insertion is effected up the right length.

The shoulder or collar 310 is provided at the distal end of the insert's body 304.

At its proximal end 306, in this embodiment, a tapered segment 306 can be identified -this will help to position, accommodate or centre the insert 300 on the rim of the intramedullary canal.

The head is configured for receiving an extension pin or rod, for example of the type briefly discussed above. In this embodiment, for this reason, the head 301 has a female threaded bore 302 on an outer side thereof. The head 301 could be equipped with different attachment means compared to those described in this embodiment, such as a connector, hook, latch or any known compression or snap fitting. Any means for connection with another part may be provided on the head of the implant -this is after all the primary function of the implant, that of providing an interconnection device between the bone and a prosthetic part.

In this embodiment, the circular threaded bore 302 only extends to a certain depth in the head 301. As a result, an extension pin can be inserted in and screwed to the head 301.

The implantable part of the insert 300, in this embodiment, has a solid triangular cross section 303 terminating with the tapered end 306. This kind of cross section provides anchor edges 12 that can support the surgically implantable element inside the intramedullary canal. However, contrary to the inserts of the prior art, the recessed sides of the triangle compared to the wall of the intramedullary canal, allow the insert to be inserted in said canal without the need for reaming it. The Haversian canals are therefore maintained, and the chances for the amputated stump to keep healthy are correspondingly niaximised.

For the application of the hand prosthesis briefly described above, the length of the body 304 of the element is in the range 25 to 65 mm. However, for different applications, different lengths may be provided. The radius of the anchor edges in the embodiment in question is 1 mm. However, radiuses between 0.5 mm and 2 mm are preferred.

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 osseointegrated implants, such as the one shown in Figures 1, 2 and 3, 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 imperfectly round in cross section. As said above, it therefore makes anatomical and physiological sense to design the implant stems 305 with a recessed cross section that is, however, still able to hold itself onto the internal wall of the intramedullary canal to which it is implanted to, such as the triangular cross section 303.

To reinforce the concept behind the invention, the anatomical thinking is the fact that the Haversian canals 3 which supply the intra-osseous circulation run longitudinally in the bone and are less disturbed by the introduction of an implant with such a cross 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 osseointegrated device 300: a. A set of intramedullary trials (Figures 4 to 7). Each trial instrument 400 consists of a handle 401, a stem 404, a collar 410 and a smooth triangular element 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 8 to 12) 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 surgically implantable element 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 impiant. 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 is provided 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 rnedullary 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 the osseointegrated prosthetic hand briefly discussed above is described in detail below: 1. The first stage of the implantation -osseointegration of the fpundtion surgically irnffiantable element 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.

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 including the microcirculation through the Haversian systems should not be damaged.

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

f) 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, 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 foundation elements.

At the stage when osseointegration between the implanted elements 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 elements 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 elements 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. The Third Stage-attachment of the handprosthes.

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 filled 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.

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 claims appended hereto.

Claims

CLAIMS: 1. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, comprising: a proximal, insertable portion for insertion into the intrarnedullary canal of the bone; and a distal, non-insertable portion, wherein the proximal insertable portion comprises anchor edges for anchoring the item to the intramedullary canal, and wherein the distal portion is configured for attachment to the prosthetic device.
2. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to claim 1, wherein the item comprises at least one side located between two of said edges, and wherein said side is recessed compared to a notional cylindrical surface circumscribing the item through said two edges.
3. An implantable item for osseointegratiori of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to claim 2, wherein said side is a straight side.
4. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to claim 2, wherein said side is an inwardly curving side.
5. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 4, wherein said anchor edges comprise at least three anchor edges.
6. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 5, wherein said anchor edges are non-coiled edges.
7. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 6, wherein said edges extend substantially longitudinally.
8. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 7, wherein said edges extend substantially axially.
9. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 8, wherein two of said edges extend substantially parallel to each other.
10. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 9, wherein the proximal insertable portion comprises a substantially polygonal cross section.
11. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 10, wherein said polygonal cross section is generally triangular.
12. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 11 further comprising: a collar, wherein the collar is generally wider than the proximal insertable portion.
13. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 12, wherein the proximal insertable portion comprises one or more apertures formed therealong.
14. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 13, wherein the distal portion comprises receiving means.
15. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to claim 13, wherein the receiving means are adapted for receiving an end of a stem.
16. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 15, wherein the distal portion comprises a pair of flats.
17. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 16, wherein the proximal insertable portion is sized for insertion into the intramedullary canal of the radius or ulna.
18. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 17, wherein the item is made of medical grade titanium.
19. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims 1 to 18, wherein the item or a part thereof is hydroxy-apatite coated.
20. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, according to any one of claims I to 19, wherein the item or a part thereof is silver coated.
21. An implantable item for osseointegration of a prosthetic device into a trans-amputated bone of a stump, designed for frontal implantation into an intiamedullary canal, according to claim 17, wherein the length of the insertable portion is comprised in the range 25 to 65 mm.
22. A kit for assembling a prosthetic hand for a stump of a patient with a forearm amputation of a hand comprising an implantable item according to any one of claims 1 to 21.
23. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for installation of a prosthetic device to a stump, the kit comprising: at least one osseointegratable device according to any one of claims 1 to 21.
24. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to claim 23, the kit further comprising a set of trial devices for said osseointegratable item.
25. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic. device to a stump according to claim 24, wherein one or more of the trial devices comprises a collar.
26. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to claim 25, wherein one or more of the trial devices comprises a trial head.
27. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to any one of claims 23 to 26, the kit further comprising a rasp for preparing the intramedullary canal.
28. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to claim 27, wherein the rasp comprises a rasp stem.
29. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to claim 27 or 28, wherein the rasp comprises a rasp collar.
30. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to claim 27, 28 or 29, wherein the rasp comprises a rasp head.
31. A kit for performing implantation of an implantable element into an intramedullary canal of a trans-amputated bone for implantation of a prosthetic device to a stump according to any one of claims 23 to 30, wherein at least the tiial and the item, or the rasp and the item, are compatibly sized for preparing and installing the osseointegratable item inside the intramedullary canal.
32. A prosthetic limb for osseointegration into a trans-amputated bone of a stump, designed for frontal implantation into an intramedullary canal, comprising a proximal, insertable portion for insertion into the intramedullary canal of the bone, wherein the proximal insertable portion comprises anchor edges for anchoring the prosthetic limb to the intramedullary canal.
33. An implantable item for osseointegration of a prosthetic hand into a forearm stump of a patient substantially as hereinbefore described with reference to any one or more of the accompanying drawings.