WO2012028182A1

WO2012028182A1 - Orthopaedic implant system

Info

Publication number: WO2012028182A1
Application number: PCT/EP2010/062795
Authority: WO
Inventors: Stephanie Regula Margarethe Grassmann; Andreas Klockow
Original assignee: Smith & Nephew Orthopaedics Ag
Priority date: 2010-09-01
Filing date: 2010-09-01
Publication date: 2012-03-08

Abstract

An orthopaedic implant system is provided that comprises an orthopaedic implant (1; 11; 12; 29; 33, 34) for implantation within a human or animal body and that is adapted for the delivery of a therapeutic fluent material to an interface between the implant and the body. The implant (1; 11; 12; 32; 37; 40) defines at least one channel (7, 8; 19, 20; 23, 25; 43) that communicates with at least one aperture (9; 21; 24; 34; 39; 44) defined at the surface of the implant (1; 11; 12; 32; 37; 40). The implant (1; 11; 12; 32; 37; 40) is adapted for delivery of the therapeutic fluent material intra-operatively to said interface via one or more forces intrinsic to the construction of implant (1; 11; 12; 32; 37; 40) and/or applied extrinsically to the implant (1; 11; 12; 32; 37; 40). Preferably, the implant (1; 11; 12; 29; 33, 34) is adapted by virtue of its design and/or geometry and/or by virtue of its placement in vivo to deliver said therapeutic fluent material to said interface by means of hydraulic, capillary, gravitational or adhesive forces. The implant system may comprise a short-term implant, a long-term implant or a trauma implant.

Description

ORTHOPAEDIC IMPLANT SYSTEM

The present invention relates to an orthopaedic implant system adapted for the delivery a therapeutic fluent material to an interface between an implant and a human or animal body and in particular, but not exclusively, for delivery of a therapeutic fluent material faciHtetbig one or more of the following, namely healing, fusing of adjoining bones, inciting osteointegration of implants, combating infections, preventing inflammatory response and treating areas with tumours.

The use of therapeutic agents to improve healing of skeletal structures, fusing of adjoining bone and osteointegration of orthopaedic implants, and to prevent postoperative complications, for example deep infection of orthopaedic implants, is well accepted and is increasing in clinical use. The main reason for the failure of orthopaedic or trauma implants is thought to be owing to loosening of the implant, which is usually the result of inadequate or failed osteointegration, sepsis, deep infection or other conditions that limit the healing response of the surgically affected area, for example osteoporosis or bone metabolic disorders causing bone resorption. In order to assist osteointegration of implants, coatings of titanium or hydroxyapatite (HA) are sprayed on to implants during their production. Such surface coated implants have been shown to reduce the incident of loosening but not completely eliminate it. Another therapeutic agent, bone mineral proteins (BMP) have been shown to stimulate the osteogenic response to assist in the healing of fractured bones. BMP are usually used in combination with bone grafts or as a putty which has limited load-bearing capabilities. However, the use of BMP with orthopaedic implants is not in widespread use which for several reasons including undesirable ectopic bone formation proximal to the implant. In clinical practice, the placement of therapeutic agents has been generally limited to the coating of orthopaedic implants, for example HA coated implants, but since the therapeutic agent is present as a coating only skeletal tissue immediate to the implant comes into contact with the therapeutic material.

Therapeutic agents are sometimes incorporated within temporary implants or bioabsorbable materials. For deep infections, die surgeon removes an existing implant from an affected area and creates a temporary implant during surgery with antibiotic bone cement or uses a preformed antibiotic bone cement temporary implant. However, temporary implants may restrict the range of motion of patients and only limited weight bearing is allowed. Key to the healing and recovery of the patient is the early mobilization of the affected joint in order to limit the amount of scar tissue and joint stiffening. Bioabsorbable materials are known to have inferior loading carrying characteristics in comparison to long-term permanent orthopaedic implants. Bioabsorbable materials have also been shown in some cases to weaken proximal areas of skeletal tissue.

Implants are also known that have a reservoir enabling sustained delivery of therapeutic materials using various mechanisms. However, the quantity of therapeutic fluent material released and the time period of therapeutic fluent material delivery depends on the release mechanism of the implant. The condition of the surgically affected area immediately following surgery is usually considered to be key to successful healing with an orthopaedic implant. Such implants do not deliver therapeutic fluent materials instantaneously during surgery by the sturgeon.

It is therefore an object of the present invention to provide an orthopaedic implant system adapted for the delivery of a therapeutic fluent material to treat an interface between an implant and a human or animal body during the surgical procedure.

According to the present invention there is provided an orthopaedic implant system comprising an orthopaedic implant for implantation within a body that is adapted for the delivery of a therapeutic fluent material to an interface between the implant and the body, the implant defining at least one channel that communicates with at least one aperture defined at the surface of the implant, and characterised in that said implant is adapted for delivery of said therapeutic fluent material intra-operatively to said interface via

one or more forces intrinsic to the construction of implant and/or mtrinsic to the nature of the therapeutic fluent material, and/or

one or more forces applied extrinsically to the implant. Preferably, such an orthopaedic implant system provides for the delivery of a therapeutic fluent material by virtue of its design and/or geometry and/or by virtue of its placement in vivo to deliver said therapeutic fluent material to said interface by means of hydraulic, capillary, gravitational or adhesive forces both during and possibly after surgery. Such a deliver}' is expected to optimize the postoperative healing process.

Unlike some implant systems that employ extrinsic hydraulic forces to pump fluent material through channels in the implant to the interface, for example by use of an external pressurized injector that is temporarily attached to the implant during the operative procedure, the present invention uses one or more of the following to deliver the therapeutic fluent material to the interface:-

(1) mtrinsic properties of the implant;

(2) intrinsic properties of the therapeutic fluent material;

(3) intrinsic properties of the implant in combination with mtrinsic properties of the therapeutic fluent material itself;

(4) either of (1), (2) or (3) in combination with an extrinsic force applied directly to at least a part of implant itself rather than to the therapeutic fluent material.

The system enables the surgeon to deteoriine the correct quantity of therapeutic fluent material required for each particular case and either to select an implant pre-charged with that quantity of material for instantaneous delivery or to charge the implant with that quantity of therapeutic fluent material pre- or intra-operatively for immediate delivery. Hence, more or less fluent material can be used as required. The invention therefore enables the surgeon to control fluent material delivery in terms of amount delivered and its delivery location.

The channels and apertures may be created during one or more manufacturing processes for the implant. These processes may include a rapid prototyping process (i.e. laser sintering) and a coating process. The implant may be pre-charged with therapeutic fluent material by integrating it in one or more apertures or channels during one or more of these manufacturing processes. In some embodiments the implant may be adapted for delivery of said therapeutic fluent material via vibratory forces applied extrinsically to the implant. Alternatively or in addition, the implant preferably comprises one or more portions that are resiliently flexible or pliable whereby said therapeutic fluent material is delivered to said interface via squeezing or flexing said portion or portions or via the application of vibratory forces applied extrinsically to said portion or portions. In this case, this portion or portions preferably comprise a sponge-like, open-cell structure defining a plurality of said channels therethrough.

In other embodiments, the implant may incorporate an intrinsic piston mechanism for instantaneous, intra-operative delivery of said therapeutic fluent material to said interface. In this case the piston mechanism preferably comprises a piston located within an interior space of the implant and attached to one end of a piston rod to which said extrinsic force is applied to move the piston within the space and thereby deliver said therapeutic fluent material.

Preferably also, the piston rod is hollow and is in communication with the interior space whereby said interior space is chargeable with said therapeutic fluent material.

Preferably also, the piston mechanism is accommodated within the body of the implant after delivery of the therapeutic fluent material. Alternatively, the piston mechanism is adapted for removal from the implant after deployment.

Preferably also, said piston rod protrudes through a port in the implant prior to delivery of said therapeutic fluent material through which said therapeutic fluent material is introduced into said interior space.

Preferably also, a pressure plate is secured to the other end of the piston rod to which plate said extrinsic force is applied to move the piston within the space. Advantageously, the port is shaped to provide a countersink for the plate that thereby seals off the interior of the implant after deliver of the therapeutic fluent material. More generally, in all of the aforesaid embodiments the implant preferably comprises at least one port that is accessible mtra-operatively whereby said therapeutic fluent material is introduced into said channel or channels of said implant. In this case, preferably the port or ports each comprise a sealable means.

Alternatively or in addition, the implant is pre-charged with said therapeutic fluent material for deliver)' intra-operatively to said interface by virtue of its placement in vivo and/ or by virtue of forces applied extrinsically to the implant.

In some embodiments the implant is pre-charged with therapeutic fluent material adapted to undergo a phase change once located in vivo whereby said material is then delivered to said interface by forces created during said phase transformation.

It will be appreciated that the shape, the size, the position, the distribution, the uniformity and the number of apertures and channels can be determined dependent on the application of the implant. In this regard, preferably the implant comprises a plurality of apertures that communicate with said at least one channel. Advantageously, said at least one channel is a macro-, micro- or nano- channel. Alternatively or in addition, said at least one channel is formed by a hollow interior space within the implant with which said apertures are in communication. Similarly, the aperture or apertures may each comprise a macro-, micro- or nano- aperture and be in the form of any of the following, namely holes, gaps, slits, fenestrations and open pores.

Preferably also, a means is provided to selectively close one or more of said apertures. This means preferably comprises a sheath located in the interior space that selectively closes one or more of the apertures. Advantageously, the sheath is removably located within the space.

Preferably also, the exterior surface of at least part of the implant is coated with a porous coating. This coating preferably comprises a hydroxyapatite coating and/or titanium beads;

Preferably also, the implant comprises a natural or an artificial bone graft. Preferably also, the implant is adapted to comprise or be at least partially comprised of a radiographic material or to comprise a radiographic marker.

Preferably also, the implant comprises one of a short-term implant, a long-term implant and a trauma implant.

Preferably also, the implant comprises an arthroplasty implant or a part thereof. Alternatively, the implant may enable an arthrodesis (fixed joint).

The implant may comprises one of a screw, a nail, a plate and an internal/external fixation device. The implant may also comprise or form a part of an implant adapted for implantation in one of a hip joint, a knee joint, an ankle joint, a toe joint, a shoulder joint, an elbow joint, a wrist joint, a hand joint, a finger joint, and the spine. In this case, the implant may comprise any of the following: a femoral stem of a hip joint prosthesis; an acetabular shell;, a tibial tray; and an intervertebral disc prosthesis.

The present invention will now be described by way of example with reference to the accompanying drawing in which:

Fig. 1 is schematic plan view of first embodiment of the invention in the form of a tibial tray;

Fig. 2 is a sectional view along the line II-II of Fig. 1;

Fig. 3 is schematic side view of a second embodiment of the invention in the form of femoral stem of a hip joint prosthesis;

Fig. 4 is a is view similar to Fig. 3 but of another embodiment of a femoral stem of a hip joint prosthesis; Fig. 5 is a side view of a piston mechanism for use in the embodiment of femoral stem as shown in Fig. 4 and that is also similar to that shown in the following Fig. 6;

Fig. 6 is a schematic side view of a fourth embodiment of the invention in the form of an intervertebral disc prosthesis;

Fig. 7 is a schematic side view of a fifth embodiment of the invention also in the form of an intervertebral disc prosthesis;

Fig. 8 is a schematic cross-sectional view of a sixth embodiment of the invention in the form of a hip acetabular shell pre-assembled with a liner to form an acetabular implant; and

Fig. 9 is an exploded side view of the implant shown in Fig. 8.

In a first embodiment of the invention a knee joint prosthesis comprises a tibial component in the form of a tibial tray 1, as shown in Figs. 1 and 2. The tibial tray 1 comprises a platform-like tray 2 defining a superior surface 3 and an inferior surface 4 and an inferiorly extending tibial stem 5. The tibial stem 5 is adapted to be implanted in a corresponding opening made by a surgeon in a proximal tibia. In the present embodiment the stem 5 is integrally formed with the tray 2. A porous coating 6, for example a coating comprising a hydroxyapatite coating and/ or one including titanium beads may be disposed on the inferior surface 4 of the tray 2 and over the stem 5. In accordance with the invention, formed within the body of the tray 2 and the stem 5 are channels 7, 8. Preferably, one or more channels 7 each communicate with a plurality of capillary channels 8 that are small-bore micro- or nano- channels having , for example, a diameter of 600μπι or less. Each of these capillary channels 8 communicates with an aperture 9 defined at the inferior surface 4 of die tray 1 or at the surface of the stem 5. These apertures 9 may be macro-, micro- and/or nano -apertures. The channels 7 communicate with a port 10 located on the superior surface 3 of the tray 2 that permits the tray 1 to be charged with therapeutic fluent material and sealed by a plug, which may be a self-sealing plug, a resealable plug or cap. The tray 1 can either be pre-charged with therapeutic fluent material prior to an operative procedure and retained in an orientation with the stem 5 uppermost so that the material cannot penetrate into the channels 8. Then, during and shordy after implantation capillary and gravitation forces will draw the therapeutic fluent material into the channels 8 from whence it will run out of the apertures 9 for dispersal via the porous coating 6 to treat the interface between the tray 1 and the tibial tissue into which it is implanted. Alternatively, the tray 1 is implanted and then charged with therapeutic fluent material intra-operatively. Again, capillary and gravitation forces will act to draw the therapeutic fluent material from the manifold channel 7 into the channels 8 and out through the apertures 9.

It is envisaged that some conventional tibial trays could be adapted by traditional machining techniques to introduce the channels 7, 8, the apertures 9 and at least one port.. However, preferably, trays 1 will be especially manufactured and the channels 7, 8 srzed and orientated within the tray 2 and stem 5 to achieve maximal and even spread of the therapeutic fluent material to the interface between the bone and the implant. Such trays 1 will also enable a port to be incorporated that comprises a micro- screwhole that sits flush with the superior surface 4 of the tray 2. The port 9 can then be adapted to connect to a delivery means for the therapeutic fluent material.

Turning now to the embodiments of the invention shown in Figs. 3 and 4, these both show an embodiment 11 and 12 respectively of a femoral stem of a hip joint prosthesis. In both embodiments, in conventional fashion the stem 11, 12 comprises a neck 13 and an anchoring blade 14 that tapers towards a distal end 15. The blade 14 widens conically from the distal end 15 in the direction of the proximal end. The neck 13 is terminated by a conically tapering pin 16 on which a spherical joint head (not shown) can be located. On the side of the blade 14 opposite the neck 13, the cone widens out and then defines a trochanter wing 17 before merging, via a shoulder 18, into the neck termination plane. The cross-sectional profile of the blade 14 is preferably rectangular, but may also be circular, trapezoidal, rhombic or any other appropriate shape. However, in accordance with the invention, in the embodiment shown in Fig. 3 a manifold channel 19 is formed within the blade 14 of the stem 11 that communicates via small-bore channels 20 with apertures 21 defined in the surface of the blade 14. A port providing access to the channel 19 is positioned in the shoulder 18 of stem 11 and is closeable by a plug 22. The shape, size, position, distribution, uniformity and the number of apertures 21 is variable as appropriate. The bore of the channels 20 may also be chosen as appropriate dependent on the viscosity of the therapeutic fluent material and is preferably optimized. In use, the channel 19 may be either pre~charged with therapeutic fluent material or such material may be introduced into the channel 19 intra-operatively. The therapeutic fluent material may be delivered to the interface between the blade 14 and the femoral tissue by capillary and gravitational forces as described above. However, this embodiment is particularly well suited to delivery of the therapeutic fluent material via vibratory forces applied extrinsically to the blade 14 in the direction of arrow F, for example by applying a vibrating apparatus to the shoulder 18 of the blade 14. Such forces will shake therapeutic fluent material from the manifold channel 19 into the channels 20 and thence out of the apertures 21.

The embodiment of stem 12 shown in Fig. 4 differs from that shown in Fig. 3. Here, the interior of the blade 14 defines a hollow interior space 23 with which a plurality of apertures 24 defined in the surface of the blade 14 is in communication. A channel 25 communicates the space 23 with a port 26 located on the shoulder 18 of the stem 12. A piston mechanism 27, as shown separately in Fig. 5, is fitted through the port 26 and comprises a piston 28 that is located within the space 23, a hollow piston rod 29 attached to the piston 28 that passes to the exterior of the implant through the channel 25, and an upper pressure plate 30 that is secured to the protruding end of the rod 29. The open end of the rod 29 adjacent the plate 30 is sealable by a cap or plug 31.

In this embodiment, the space 23 may be pre-charged with therapeutic fluent material or may be filled intra-operatively by the surgeon through the hollow rod 29, which communicates with an aperture in the piston 28 with the space 23. The open end of the rod 29 is then sealed by the plug 31 and the piston mechanism is deployed when appropriate by pressing down on the pressure plate 30. This moves the piston 29 in the space 23 and forces the therapeutic fluent material out of the stem 12 through the apertures 24. The length of the rod 29 is chosen so that after operation of the piston mechanism 27 the pressure plate 30 locates into the port 26, which is shaped so as to provide a countersink for the plate 30 . The plate 30 is therefore also used to seal off the interior of the stem 12 after delivery of the therapeutic fluent material.. The piston mechanism 27 is, therefore, accommodated within the implant 12 after delivery of the therapeutic fluent material.

The piston mechanism may be adapted such that as pressure is applied to the pressure plate 30, the fluent material flows around to the back side of the piston 29 between the wall of the piston 29 and the inner walls of the implant and out through the apertures 34 at the rear of the piston 29 as well as being forced out of the apertures below the piston 29, A plate or seal is provided in this case to prevent the fluent material from leaving the implant during pressure application.

In a modification of this embodiment, if the channel 25 and the space 23 have the same diameter, the piston mechanism 27 can be removed from the stem 12 after deployment and the port 23 sealed off by a separate cap or plug .

In this embodiment the apertures 24 may be in the form of pores, as shown in Fig. 4, or of elongated fenestrations. The apertures 24 are also only located in the distal part of the blade 14. This stem 12 has, therefore, been adapted only to treat areas of the skeletal structure that will be in the proximity of this part of the blade 14 after implantation.

The embodiment shown in Fig. 6 comprises an intervertebral disc prosthesis, a prosthetic disc 32 being shown between two vertebrae 33. As with the other embodiments of the invention, channels (not shown) are formed within the disc 32 that terminate in apertures 34 defined in the surface of the disc 32. At their other end the channels communicate with a hollow interior space 35 within the disc 32 in which is located a piston mechanism 36 that is similar in construction and operation to that described above with reference to Fig. 4 and as shown in Fig. 5. The same reference numerals have therefore been used in Fig. 6 for similar parts of the mechanism 36 to those used above with reference to Figs. 4 and 5. It will be appreciated, however, that the size and shape of the mechanism 36 have been adapted for use in an intervertebral disc prosthesis. As described above with reference to Fig. 4, the space 35 may be pre- charged with therapeutic fluent material or may be filled intra-operatively by the surgeon through the hollow rod 29, which communicates with the space 35. The piston mechanism 36 is then deployed in exactly the same way as the mechanism 37 to deliver the therapeutic fluent material to the interface between the disc 32 and the body. In particular, the piston mechanism may again be adapted such that as pressure is applied to the pressure plate 30, die fluent material flows between the walls of the piston 29 and the inner walls of the implant and out through the apertures 34, a plate or seal being provided to prevent the fluent material from leaving the implant during pressure application.

As before, if the space 35 and the piston 28 have the same diameter, the piston mechanism 36 can be removed from the stem disc 32 after deployment and the space 35 sealed off by a separate cap or plug.

In some implants, movement of the joint itself can be used to pump therapeutic fluent material through and out of the implant. Such movement could activate an internal piston mechanism similar to that described above or squeeze a resiliendy flexible or pliable portion of the implant.

In another embodiment of intervertebral disc prosthesis 37 as shown in Fig. 7, the intervertebral disc prosthesis 37 is again shown between two vertebrae 33. However, in this prosthesis 37, a port 38 is positioned at the posterior side of the disc through which the disc 37 is charged with therapeutic fluent material pre- or intra- operatively. Alternatively, the therapeutic fluent material may be integrated in one or more apertures and/or channels during one or more manufacturing processes.

However, whereas the implants described above are all rigid implants, typically being comprised of any or a mixture of the metals, namely titanium, titanium alloy, stainless steel, stainless steel alloy, cobalt chrome alloy, polymer or polymer composite. The implant system shown in Fig. 7 may be comprised, at least in part, of a sponge or sponge-like material with an open-cell structure that is porous so as to define a plurality of channels therethrough. As in previous embodiments, the shape, size, position, distribution, uniformity and the number of apertures 39 is variable as appropriate but in this particular embodiment the apertures may comprise holes, gaps, slits, fenestrations or open pores. However, more generally, the sponge or sponge-like portion of this implant is preferably resiliently flexible or elastic so that when it is compressed either by pressure exerted by the vertebrae 33 or by the application of extrinsic force by a surgeon intra-operatively therapeutic fluent material is forced out through the apertures 39 to treat the interface between the disc 37 and the vertebrae 33, It will be appreciated that such an implant may continue to deliver therapeutic fluent material to the interface postoperatively when compressed by the adjacent vertebrae 33 when the spine is flexed and/ or straightened as the patient moves.

The embodiment of implant shown in Figs. 8 and 9 comprises an acetabular shell 40 forming part of an acetabular implant 41 adapted for implantation into the acetabulum of a hip such that it can receive a head of a femoral stem such as, for example, that shown in Figs. 3 and 4. It is possible, however, for the implant 41 to be adapted for interaction with a natural femoral head. The implant 41 comprises two components, namely the acetabular shell 40 and a liner 42. Usually, the acetabular shell 40 is metal and the liner 42 is a plastics material, such as an ultra high molecular weight polyethylene, but the shell 40 and the liner 42 may each be formed from any desirable material. However, as in the other embodiments of the invention channels 43 are formed within the body of the shell 40. These channels 43 will typically be small-bore channels, for example micro- or nano-channels with a diameter less than 600μιτι. The channels 43 communicate with apertures 44 defined on the exterior surface of the shell 43. These apertures 44 may also be micro- or nano- apertures.

In one embodiment of the shell 40, therapeutic fluent material is integrated in one or more apertures 44 and/ or channels 43 during one or more manufacturing processes of the shell 40. It will be appreciated that in this case a port through which the therapeutic fluent material is poured into the shell 40 is not necessarily required as the therapeutic fluent material may be deposited in the shell 40 via the apertures 44 themselves. Such therapeutic fluent material may be deposited in a solid or gel form, for example, and adapted to undergo a phase change once implanted or located in vivo. The therapeutic fluent material is then delivered to the interface between the shell 40 and the acetabulum by forces created during said phase transformation. Adhesive forces between the acetabulum and therapeutic fluent material may also assist in delivery of the material. In this case, it will be appreciated that forces intrinsic to the nature of the therapeutic fluent material deHver the latter to the interface between the shell 40 and the body. Alternatively or in addition, the therapeutic fluent material may be delivered by press- fitting the shell 40 into the acetabulum and, prior to fitting of the liner 42, an impactor with a shape complementary to the interior of the shell 40 used to strike the shell 40 with blows intended to shake or vibrate the therapeutic fluent material out of the apertures 44 and/ or channels 43.

In another embodiment of the shell 40, one or more ports 45 may be located on the rim of the shell 40 through which the shell 40 may be charged with therapeutic fluent material either pre- or intra- operatively. Delivery of this material may then take place by one or more of hydraulic, gravitational and capillary forces. As with the other embodiments, the port or ports 45 may be sealed by means of a sealing means such as a plug, cap or similar.

The acetabular shell 40 of the invention may be used with different types of liner 42, as appropriate. Typically, the implant 41 is assembled by press fitting the liner 42 into an interior cavity of the shell 40 intra-operatively but it may be secured in any appropriate manner. In some cases the shell 40 and the liner 42 will be pre-assembled to form the implant 41 by the manufacturer. The shell 40 may also comprise a retaining ring 46 that can be used to secure additional components to the implant 41, as desired.

In a modification of any of the embodiments described above, an implant system according to the invention may comprise a natural or artificial bone graft.

It will also be appreciated that the methods described above for delivery of the therapeutic fluent material to an interface between the implant and tissues of the body may be employed with any of the other embodiments of implant systems described above. All of these implant systems enable, in accordance with the invention, a therapeutic fluent material to be delivered to a surgically affected area during surgery and sometimes for a period of time thereafter. The delivery of therapeutic fluent materials direcdy during surgery is expected to optimize the healing process postoperative and it will be appreciated that a surgeon may detenriine during a surgical procedure the amount of therapeutic fluent material required. Hence, the invention enables intraoperative control of therapeutic fluent material delivery in terms of amount delivered and its delivery location.

The nature of the therapeutic fluent material to be used can be determined by the surgeon as appropriate. It is expected that such materials will be biological, biocompatible, bioactive material or therapeutically active agents. Such agents include bone slurry, bone morphogenic protein (BMP), bone growth factor, a pallet gel, antiinflammatory agents, analgesic agents, anti-microbial, anti-viral agents, oncological drug, chemotherapeutic agent, antibiotic agent, osteogenic agent, osteoinductive agent, osteoconduction agent, osteostimulative agent or a combination of these.

The implant systems, dependent on their nature, may be available in different lengths and geometries including thickness and cross-sectional shape, according to the characteristics of the patient, the patient bone or the requirements of the surgical procedure. The surface of the implant system as a whole or its components may be surface treated or surface roughened to assist the osteointegration of the implant. This treatment may include, for example, adding surface layer(s) of titanium, hydroxyapatite, biocompatible phase-ttansforming material or other, pressure or grit blasting with zirconium oxide or other grit material(s). Alternatively, the surface of the implant may also be produced with rapid prototype or manufacturing procedures, i.e. laser sintering.

The implant system may enable an arthrodesis (fixed joint).

In some embodiments, the implant system may comprise or be at least partially comprised of a radiographic material or comprise a radiographic marker.

The implant system may comprise a short-term implant, a long-term implant or a trauma implant and it is primarily, but not exclusively, intended that the therapeutic fluent material will facilitate one or more of the following, namely healing, fusing of adjoining bones, inciting osteointegration of implants, combating infections, preventing inflammatory response and treating areas with tumours. The system in accordance with the invention may be utilized intra-operatively or postoperatively when intervention is required to combat deep infections, to treat tumours or to improve a healing response. In the case of trauma implants, the affected area may be treated with a therapeutic fluent material to assist its healing process prior to explantation of the trauma implant.

Reference Numerals

1 Tibial tray

2 Tray

3 Superior surface of tray

4 Inferior surface of tray

5 Stem

6 Porous coating

7 Channels

8 Capillary channels

9 Apertures

10 Port

11 Femoral stem

12 Femoral stem

13 Neck

14 Blade

15 Distal end

16 Pin

17 Trochanter wing

18 Shoulder

19 Manifold channel

20 Small-bore channel

21 Apertures

22 Plug

23 Hollow interior space

24 Apertures

25 Channel 26 Cylinder

27 Piston mechanism

28 Piston

29 Piston rod

30 Pressure plate

31 Cap

32 Prosthetic disc

33 Vertebrae

34 Apertures

35 Interior space

36 Piston mechanism

37 Prosthetic disc

38 Port

39 Apertures

40 Acetabular shell

41 Acetabulat implant

42 Liner

43 Channels

44 Apertures

45 Port

46 Retaining ring

Claims

1. An orthopaedic implant system comprising an orthopaedic implant (1; 11; 12;

32; 37; 40) for implantation within a body that is adapted for the delivery of a therapeutic fluent material to an interface between the implant (1; 11; 12; 32; 37; 40) and the body, the implant defining at least one channel (7, 8; 19, 20; 23, 25; 43) that communicates with at least one aperture (9; 21; 24; 34; 39; 44) defined at the surface of the implant (1; 11; 12; 32; 37; 40), and

characterised in that

said implant (1; 11; 12; 32; 37; 40) is adapted for delivery of said therapeutic fluent material intra-operatively to said interface via

one or more forces intrinsic to the construction of implant (1; 11; 12; 32; 37; 40) and/or intrinsic to the nature of the therapeutic fluent material, and/or

one or more forces applied extrinsically to the implant (1; 11; 12; 32; 37;

40) .

2. A system as claimed in Claim 1, wherein said implant (1; 11; 12; 32; 37; 40) is adapted by virtue of its design and/or geometry and/or by virtue of its placement in vivo to deliver said therapeutic fluent material to said interface by means of hydraulic, capillary, gravitational or adhesive forces.

3. A system as claimed in Claim 1 or Claim 2, wherein said implant (1; 11; 12; 32;

37; 40) is adapted for delivery of said therapeutic fluent material via vibratory forces applied extrinsically to the implant (1; 11; 12; 32; 37; 40).

4. A system as claimed in any of Claims 1 to 3, wherein said implant (37) comprises one or more portions that are resiliently flexible or pliable whereby said therapeutic fluent material is delivered to said interface via squeezing or flexing said portion or portions or via the application of vibratory forces applied extrinsically to said portion or portions.

5. A system as claimed in Claim 4, wherein said one or more portions comprise a sponge-like, open-cell structure defining a plurality of said channels therethrough.

6. A system as claimed in Claim 1 or Claim 2, wherein said implant (12; 32) incorporates a piston mechanism (27; 36) to which force is applied extrinsically for instantaneous, intra-operative delivery of said therapeutic fluent material to said interface.

7. A system as claimed in any of Claims 1 to 6, wherein the implant (1; 11; 12; 32;

37; 40) comprises at least one port (10; 26; 38; 45) that is accessible intra- operatively whereby said therapeutic fluent material is introduced into said channel or channels (7, 8; 19, 20; 23, 25; 43) of said implant (1; 11; 12; 32; 37; 40).

8. A system as claimed in Claim 7, wherein said port or ports (10; 26; 38; 45) each comprise a sealable means (22).

9. A system as claimed in any of Claims 1 to 8, wherein said implant (1; 11; 12; 32;

37; 40) is pre-charged with said therapeutic fluent material for delivery intra- operatively to said interface by virtue of its placement in vivo and/or by virtue of force applied extrinsically to the implant.

10. A system as claimed in Claim 9, wherein said implant (1; 11; 12; 32; 37; 40) is pre-charged with therapeutic fluent material adapted to undergo a phase change once located in vivo whereby said material is then delivered to said interface by forces created during said phase transformation

11. A system as claimed in any of Claims 1 to 10, wherein said implant (1; 11; 12;

32; 37; 40) comprises a plurality of apertures (9; 21; 24; 34; 39; 44) that communicate with said at least one channel (7, 8; 19, 20; 23, 25; 43).

12. A system as claimed in any of Claims 1 to 11, wherein said aperture or apertures (9; 21; 24; 34; 39; 44) are in the form of any of the following, namely holes, gaps, slits, fenestrations and open pores.

13. A system as claimed in any of Claims 1 to 12, wherein said aperture or each of said apertures (9; 21; 24; 34; 39; 44) is a macro-, micro- or nano- aperture.

14. A system as claimed in any of Claims 1 to 13, wherein said at least one channel (7, 8; 19, 20; 23, 25; 43) is a macro-, micro- or nano- channel.

15. A system as claimed in any of Claims 1 to 14, wherein said at least one channel is formed by a hollow interior space (19; 23, 35) within the implant (11; 12; 32) with which said apertures (21; 24; 34) are in communication.

16. A system as claimed in Claim 15 when dependent on Claim 6, wherein the piston mechanism (27; 36) comprises a piston (28) located within said interior space (23; 35) and attached to one end of a piston rod (29) to which said extrinsic force is applied to move the piston (28) within the space (23; 35) and thereby deliver said therapeutic fluent material.

17. A system as claimed in Claim 16, wherein said piston rod (29) is hollow and is in communication with the interior space (23; 35) whereby said interior space (23; 35) is chargeable with said therapeutic fluent material.

18. A system as claimed in Claim 16 or Claim 17, wherein the piston mechanism (27; 36) is accommodated within the body of the implant after delivery of the therapeutic fluent material.

19. A system as claimed in Claim 16 or Claim 17, wherein the piston mechanism (27) is adapted for removal from the implant (12) after deployment.

20. A system as claimed in any of Claims 16 to 19, wherein said piston rod (29) protrudes through a port (26) in the implant prior to delivery of said therapeutic fluent material through which said therapeutic fluent material is introduced into said interior space (23; 25).

21. A system as claimed in any of Claims 16 to 20, wherein a pressure plate (30) is secured to the other end of the piston rod (29) to which plate (30) said extrinsic force is applied to move the piston (28) within the space (23; 35).

22. A system as claimed in Claim 21 when dependent on Claim 18, wherein said port (26) is shaped to provide a countersink for the plate (30) that thereby seals off the interior of the implant (12; 32) after deliver of the therapeutic fluent material.

23. A system as claimed in any of Claims 1 to 22, wherein a means is provided to selectively close one or more of said apertures (9; 21; 24; 34; 39; 44) .

24. A system as claimed in any of Claims 1 to 23, wherein the exterior surface of at least part of the implant (1; 11; 12; 32; 37; 40) is coated with a porous coating (6).

25. A system as claimed in Claim 24, wherein said porous coating (6) comprises a hydroxyapatite coating and/ or titanium beads.

26. A system as claimed in any of Claims 1 to 25, wherein said implant (1; 11; 12;

32; 37; 40) comprises a natural or an artificial bone graft.

27. A system as claimed in any of Claims 1 to 26, adapted to comprise or be at least partially comprised of a radiographic material or to comprise a radiographic marker.

28. A system as claimed in any of Claims 1 to 27, wherein said implant (1 ; 11; 12;

32; 37; 40) comprises one of a short-term implant, a long-term implant and a trauma implant.

29. A system as claimed in any of Claims 1 to 28, wherein , said implant (1; 11; 12; 32; 37; 40) comprises one of a screw, a nail, a plate and an internal/external fixation device.

30. A system as claimed in any of Claims 1 to 29, wherein said implant (1; 11; 12;

32; 37; 40) comprises an arthroplasty implant or a part thereof.

31. A system as claimed in any of Claims 1 to 29, adapted to enable an arthrodesis (fixed joint).

32. A system as claimed in any of Claims 1 to 30, wherein said implant comprises or forms a part of an implant (1; 11; 12; 32; 37; 40) adapted for implantation in one of a hip joint, a knee joint, an ankle joint, a toe joint, a shoulder joint, an elbow joint, a wrist joint, a hand joint, a finger joint, and the spine.

33. A system as claimed in Claim 32, wherein said implant comprises any of the following: a femoral stem (11; 12) of a hip joint prosthesis; an acetabular shell (40); a tibial tray (1); and an intervertebral disc prosthesis (32; 37).