AN IMPLANTABLE DEVICE

Abstract

An intramedullary bone device which has an internal lumen defined by a sidewall is described. The sidewall includes first and second perforated regions having respective first and second openings. The device also includes fluid flow directing features to direct the flow of a fluid from the internal lumen of the device through the openings in the sidewall of the device. The device may be part of a system with a fluid introducer member inserted through the internal lumen of the device. A method of securing and/or stabilising a bone including a fractured bone is also described.

Claims

1. An intramedullary bone device extending from a first end to a second end and having a sidewall defining an internal lumen, said sidewall comprising a first perforated region at or adjacent to the first end and a second perforated region at or adjacent the second end, said first perforated region comprising first openings in the sidewall and the second perforated region comprising second openings in the sidewall, the first and second openings in fluid communication with the internal lumen, wherein the device further includes a first flow directing feature associated with at least one of the first openings and a second flow directing feature associated with at least one of the second openings and wherein the first flow directing feature directs the flow of a fluid from the internal lumen through the first openings in a first direction and the second flow directing feature directs the flow of a fluid from the internal lumen through the second openings in a second direction which is different to the first direction.

2. The intramedullary bone device of claim 1 further comprising an intermediate region between the first and second perforated regions wherein the intermediate region is devoid of openings in the sidewall.

3. The intramedullary bone device of claim 1 wherein at least some of the first openings and/or second openings are helically arranged around the sidewall.

4. The intramedullary bone device of claim 1, wherein a first flow directing feature comprises part of the sidewall of the intramedullary bone device near an associated first opening.

5. The intramedullary bone device of claim 4 wherein the part of the sidewall extends into the internal lumen of the intramedullary bone device to form a first fluid guide member.

6. The intramedullary bone device of claim 5, wherein the first fluid guide member extends into the internal lumen at an angle relative to the sidewall of the intramedullary bone device.

7. The intramedullary bone device of claim 5 wherein the first fluid guide member extends from a connection end connected to the sidewall to a second free end.

8. The intramedullary bone device of claim 7, wherein the connection end is connected to part of the sidewall defining an associated first opening and wherein the first fluid guide member extends from said connection end towards the second end of the intramedullary bone device to define a flow channel in the internal lumen to the associated first opening.

9. The intramedullary bone device of claim 5, comprising a plurality of first fluid guide members arranged to define an internal passage within the internal lumen of the first perforated region.

10. The intramedullary bone device of claim 9, wherein the internal passage is substantially centrally positioned within the internal lumen and sized to receive a fluid introducer member.

11. The intramedullary bone device of claim 1 wherein at least one second flow directing feature comprises part of the sidewall of the intramedullary bone device near an associated second opening.

12. The intramedullary bone device of claim 11, wherein the second fluid guide member extends into the internal lumen at an angle relative to the sidewall of the intramedullary bone device.

13. The intramedullary bone device of claim 10 wherein the second fluid guide member extends from a connection end connected to the sidewall to a second free end.

14. The intramedullary bone device of claim 13, wherein the connection end is connected to part of the sidewall defining an associated second opening and wherein the second fluid guide member extends from said connection end towards the first end of the intramedullary bone device to define a flow channel in the internal lumen to the associated second opening.

15. The intramedullary bone device of claim 10, comprising a plurality of second fluid guide members arranged to define an internal passage within the internal lumen of the second perforated region.

16. The intramedullary bone device of claim 15, wherein the internal passage is substantially centrally positioned within the internal lumen and sized to receive a fluid introducer member.

17. The intramedullary bone device of claim 1, when made from a polymeric material.

18. The intramedullary bone device of claim 17, wherein the polymeric material is a biocompatible resorbable polymer.

19. The intramedullary bone device of claim 18, wherein the biocompatible, resorbable polymer comprises one or more of poly(-hydroxy esters), poly(caprolactone), poly(p-dioxanone), poly(trimethylene carbonate), poly(oxaesters), poly(oxaamides), and their co-polymers and blends.

20. The intramedullary bone device of claim 18, wherein the biocompatible resorbable polymer comprises one or more of tyrosine derived poly amino acids, poly(arylates), poly(imino-carbonates), phosphorous containing polymers, poly(ethylene glycol) [PEG] based block co-polymers, poly(-malic acid), poly(ester amides), or polyalkanoates.

21. The intramedullary device of claim 18, wherein the device is made from a co-polymer of poly(lactide), and poly(glycolide).

22. The intramedullary bone device of claim 21 further including trimethyl carbonate.

23. The intramedullary bone device of claim 18, wherein the biocompatible resorbable polymeric material is blended with a pH modifying agent which modifies the pH profile of the intramedullary bone device as it is resorbed.

24. The intramedullary bone device claim 18, wherein the biocompatible resorbable polymeric material further comprises bioglass.

25. The intramedullary bone device of claim 1 wherein the fluid is a biocompatible, resorbable fluid.

26. The intramedullary bone device of claim 25, wherein the fluid comprises a biocompatible, resorbable bone cement.

27. The intramedullary bone device of claim 26, wherein the resorbable bone cement includes calcium.

28. The intramedullary bone device of claim 27, wherein the resorbable bone cement comprises calcium phosphate.

29. The intramedullary bone device of claim 27, wherein the resorbable bone cement comprises one or more of dicalcium phosphate, tricalcium ( and ) phosphate, or tetracalcium phosphate hydroxyapatite.

30. The intramedullary bone device of claim 27, wherein the resorbable bone cement comprises one or more of heptacalcium phosphate, octocalcium phosphate, calcium pyrophosphate, oxyapatite, calcium metaphosphate, dahlite, carbonatoapatite, monocalcium phosphate anhydrous, amorphous calcium phosphate, calcium deficient hydroxyapatite, fluorapatite; a calcium silicate ceramic, a calcium sulfate salt, or plaster of Paris.

31. The intramedullary bone device of claim 27, wherein the resorbable bone cement has a resorbing pH profile which is basic.

32. An intramedullary bone system comprising: a device which extends from a first end to a second end and comprises a sidewall defining an internal lumen, said sidewall including a first perforated region adjacent said first end and a second perforated region adjacent the second end, said first perforated region comprising first openings in the sidewall and the second perforated region comprising second openings in the sidewall, the first and second openings in fluid communication with the internal lumen, wherein the device further includes a first flow directing feature associated with the one or more first openings and a second flow directing feature associated with the one or more second openings and wherein the first flow directing feature directs the flow of a fluid from the internal lumen through the first openings in a first direction and the second flow directing feature directs the flow of a fluid from the internal lumen through the second openings in a second direction which is different to the first direction; a fluid introducer member positioned substantially within the internal lumen of the device, said fluid introducer member comprising a first end having an entry portal to receive the fluid, a second opposed end having at least one exit portal, and an internal channel fluidly connecting the entry and exit portals.

33. A method of stabilising and/or securing a bone including; preparing an entry point in the bone; inserting a guidewire into the intramedullary canal of the bone; reaming a length of the intramedullary canal over the guidewire; advancing a device over the guidewire, the device extending from a first end to a second end and having a sidewall defining an internal lumen, said sidewall comprising a first perforated region adjacent the first end and a second perforated region adjacent the second end, the first perforated region comprising first openings in the sidewall and the second perforated region comprising second openings in the sidewall, the first and second openings in fluid communication with the internal lumen wherein the device further includes a first flow directing feature associated with the one or more first openings and a second flow directing feature associated with the one or more second openings; withdrawing the guidewire when the device is desirably positioned within the bone; introducing a fluid into the internal lumen of the device such that the first flow directing feature directs the flow of the fluid from the internal lumen through the first openings in a first direction and the second flow directing feature directs the flow of the fluid from the internal lumen through the second openings in a second direction which is different to the first direction.

34. A method of stabilising and/or securing a bone including; preparing an entry point in the bone; inserting a guidewire into the intramedullary canal of the bone; reaming a length of the intramedullary canal of the bone over the guidewire; advancing an intramedullary bone system over the guidewire, the intramedullary bone system comprising; an intramedullary device extending from a first end to a second end and having a sidewall defining an internal lumen, said sidewall comprising a first perforated region adjacent the first end and a second perforated region adjacent the second end, the first perforated region comprising first openings in the sidewall and the second perforated region comprising second openings in the sidewall, the first and second openings in fluid communication with the internal lumen wherein the device further includes a first flow directing feature associated with the one or more first openings and a second flow directing feature associated with the one or more second openings; and a fluid introducer member positioned substantially within the internal lumen of the intramedullary bone device, said fluid introducer member comprising a first end having an entry portal to receive the fluid, a second end having at least one exit portal, and an internal channel fluidly connecting the entry and exit portals and wherein the exit portal of the fluid introducer member is positioned within the second perforated region of the intramedullary bone device; withdrawing the guidewire when the intramedullary bone system is desirably positioned within the bone; introducing a fluid into the internal channel of the fluid introducer member such that said fluid flows from the exit portal of the fluid introducer member and is directed by at least one second flow directing feature through at least one second opening in a second direction; withdrawing the fluid introducer member until the exit portal is positioned within the first perforated region of the intramedullary bone device such that the fluid flows from the exit portal of the fluid introducer member and is directed by at least one first flow directing feature through at least one first opening in a first direction, the first direction being different to the second direction.

35. The method of claim 34, wherein the intramedullary bone device stabilises and/or secures a fracture in a bone of a subject.

36. The method of claim 34, wherein the bone includes the femur, tibia, fibula, humerus, radius or ulna.

37. The intramedullary bone system of claim 32, wherein the fluid is a biocompatible, resorbable fluid.

38. The intramedullary bone system of claim 37, wherein the fluid comprises a biocompatible, resorbable bone cement.

39. The intramedullary bone system of claim 38, wherein the resorbable bone cement includes calcium.

40. The intramedullary bone system of claim 38, wherein the resorbable bone cement comprises calcium phosphate.

41. The intramedullary bone system of claim 38, wherein the resorbable bone cement comprises one or more of dicalcium phosphate, tricalcium ( and ) phosphate, or tetracalcium phosphate hydroxyapatite.

42. The intramedullary bone system of claim 38, wherein the resorbable bone cement comprises one or more of heptacalcium phosphate, octocalcium phosphate, calcium pyrophosphate, oxyapatite, calcium metaphosphate, dahlite, carbonatoapatite, monocalcium phosphate anhydrous, amorphous calcium phosphate, calcium deficient hydroxyapatite, fluorapatite, a calcium silicate ceramic, a calcium sulfate salt, plaster of Paris, or a mixture thereof.

43. The intramedullary bone system of claim 38, wherein the resorbable bone cement has a resorbing pH profile which is basic.

44. The method of claim 34, further providing a suction force to assist in drawing the fluid from the fluid introducer member.

45. The intramedullary bone system of claim 42, wherein the resorbable bone cement comprises one or more of calcium orthosilicate, wollastonite, dicalcium silicate, diopside, bioglass (any composition), -calcium sulfate hemihydrates, -calcium sulfate hemihydrates, calcium sulfate dehydrate or a mixture thereof.

46. The intramedullary bone device of claim 30, wherein the resorbable bone cement comprises one or more of calcium orthosilicate, wollastonite, dicalcium silicate, diopside, bioglass (any composition), -calcium sulfate hemihydrates, -calcium sulfate hemihydrates, calcium sulfate dehydrate or a mixture thereof.

47. The intramedullary bone device of claim 20, wherein the biocompatible, resorbable polymer comprises one or more of poly(DTH carbonates), poly(phosphoesters), poly(phosphazenes), PEG-poly(lactic acid), PEG-poly(propylene glycol), PEG-poly(butylene terephthalate), poly(hydroxybutyrate (HB) copolymers, or poly(hydroxyvalerate) (HV) copolymers.

48. The intramedullary bone device of claim 19, wherein the biocompatible, resorbable polymer comprises poly(lactide) or poly(glycolide).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0222] FIG. 1A is a side view of a stent and sheath of the disclosure;

[0223] FIG. 1B is a side view of a stent and sheath which has been filled with a cement;

[0224] FIG. 2A is a schematic view of a stent of the disclosure;

[0225] FIG. 2B is a schematic view of the stent of FIG. 2A, filled with cement;

[0226] FIG. 3 is a schematic view of the stent of FIG. 2A when implanted in a clavicle bone of a subject;

[0227] FIGS. 4A to 4D show side views of embodiments of an introducer rod of the present disclosure;

[0228] FIG. 5 shows a side view of an introducer gun of the disclosure with an exemplary introducer rod attached;

[0229] FIG. 6 is a side view of an intramedullary bone device of the present disclosure;

[0230] FIG. 7 is a sectional view of part of the intramedullary bone device of FIG. 6, including a view of an introducer rod;

[0231] FIG. 8 is a sectional view of a further part of the intramedullary bone device of FIG. 6, including a view of an introducer rod;

[0232] FIG. 9 is a sectional view of a first perforation region of the intramedullary bone device of the present disclosure;

[0233] FIG. 10 is an enlarged view of the region marked B shown in FIG. 9;

[0234] FIG. 11 is an enlarged view of the region marked A in FIG. 9;

[0235] FIG. 12A is an image of a femur with the intramedullary bone device of the disclosure inserted through the intramedullary canal;

[0236] FIG. 12B is a radiographic image of the femur of FIG. 12A;

[0237] FIGS. 13A to 13D are schematic depictions of a femur and the process of inserting an intramedullary bone device across a fracture of the femur;

[0238] FIG. 14A is a photograph image of an anterior view and posterior view of the fractured sawbone of Experiment 1;

[0239] FIG. 14B shows radiographs of the sawbone shown in the photograph of FIG. 14A in the anterior and posterior views; and

[0240] FIGS. 15A to 15C are graphs providing the results of Experiment 2.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE DISCLOSURE

[0241] In one embodiment, a bone stent 10 is made up of a series of struts 11 which define apertures 12.

[0242] The stent 10 is radially expandable from a compressed to an expanded configuration when deployed in a bone.

[0243] Stent 10 extends from a proximal end 13 to a distal end 14. In the embodiment shown in FIGS. 1A and 1B, for example, stent 10 also includes a sheath 15 which extends around the stent and covers the distal end 14. Proximal end 13 is not fully covered which allows for the delivery of a substance to the stent 10. This can be seen in FIG. 1A and FIG. 1B wherein sheath 15 has an inlet 16 at a region adjacent proximal end 13.

[0244] In one embodiment, stent 100 depicted in FIG. 2A has flared regions 117 at both the proximal end 113 and the distal end 114.

[0245] Stents 10, 100 are substantially straight whereas an example of a curved stent 200 deployed in a clavicle 210 is shown in FIG. 3.

[0246] As shown in FIG. 1B, the stent 10 and sheath 15 arrangement may be filled with a cement 20. The cement 20 is typically introduced through inlet 16 of sheath 15 and into the interior of the stent 10. The cement 20 is in a flowable form as it is introduced and thus migrates through apertures 12 to fill the stent 10 and the space around the stent 10 contained by sheath 15.

[0247] FIGS. 4A to 4D show a further embodiment of an introducer rod 30 for implantation in a bone of a subject. Introducer rod 30 comprises a tubular structure defining a lumen (not depicted) and which extends from a proximal end 31 to the distal end 32. The introducer rod 30 has a series of apertures 33 to allow fluid inserted into the lumen to exit the rod 30.

[0248] The apertures may be arranged a number of different way. For example, in FIG. 4A, the apertures are arranged helically along a majority of the length of rod 30. In FIG. 4B, an alternative embodiment is provided in which there are two separate groupings of apertures, 33a and 33b and a portion 34 of rod 10 which is devoid of apertures. In this embodiment, it may be advantageous to deploy the rod such that portion 34 is positioned at the region of fracture of a bone so that any fluid introduced into the rod 30 does not leak at this portion and through the fractured bone. The length of portion 34 may vary depending upon the size of bone and degree of fracture. As shown in FIG. 4C, the length of portion 34 is less than portion 34 of the device depicted in FIG. 4B.

[0249] In FIG. 4D only a length of rod 30 adjacent the distal end 32 comprises apertures 33.

[0250] The introducer rod may comprise an entry portal 37 to receive a fluid. In this embodiment, the entry portal comprises part of a luer lock system for attachment to a fluid source.

[0251] In FIG. 5, an introducer gun 40 is depicted which is shown coupled to a proximal end 31 of rod 30. The particular embodiment shown relates to the introducer rod 30 shown in FIG. 4C although any of the embodiments of 4A to 4D may be attached to such an introducer gun 40. The coupling is depicted as a luer lock connection with a luer component 49 of gun 40 connecting with the entry portal 37 but could be any form of coupling suitable for the purpose. The introducer gun 40 comprises a handle 41 and a plunger mechanism 42, the plunger mechanism 42 connected to an actuator lever 43 of handle 41. Plunger mechanism 42 comprises an elongate piston 44 and an end plunger head 45. The introducer gun also includes a barrel 46 which is dimensioned to hold a sufficient volume of fluid for introduction into the introducer rod 30.

[0252] When a user pulls actuator 43 in a direction of handle 41, the plunger head is driven distally towards the rod 30 to force a fluid in barrel 46 into the lumen of rod 30.

[0253] In embodiments, wherein the fluid is a bone cement, the coupling between rod 30 and actuator gun 40, may include a motor (not depicted) to cause rotation of the rod 30 around a longitudinal axis as the cement is introduced from the barrel and into the lumen of rod 30.

[0254] In another embodiment of the present disclosure, a carrier device 300 may be used to deliver a carrier substance to a desired location. In this embodiment the location may not be within a bone but could be a surface bone region or other area of the body. The carrier device may be any suitable configuration and could include, for example, the stent 310 of FIG. 2B. The carrier 300 is configured to receive and hold a carrier substance 311 which has a pre-determined viscosity to allow it to be retained in stent 310 for a preferred period of time.

[0255] The carrier substance 311 of this embodiment may be a high viscosity liquid carrier material (HVLCM).

[0256] In addition to the viscosity of the HVLCM, apertures 312 of stent 310 are sized and/or shaped to provide an optimal surface tension to retain the carrier substance 311 within stent 310.

[0257] In embodiments to promote bone growth or graft new bone, the HVLCM will be loaded with an agent or a plurality of agents which gradually elute to enhance bone growth.

Intramedullary Bone Device

[0258] In an exemplary embodiment, the disclosure relates to an intramedullary bone device 400 which extends from a first end 401 to a second end 402 and has a sidewall 403 defining an internal lumen 404.

[0259] The sidewall 403 of the intramedullary device 400 comprises a first perforated region 405 adjacent the first end 401 and a second perforated region 406 adjacent the second end 402.

[0260] The first perforated region 405 comprises a plurality of first openings 407 in the sidewall 403 and the second perforated region 406 comprises a plurality of second openings 408 in the sidewall 403. The first 407 and second 408 openings are in fluid connection with the internal lumen 404.

[0261] The intramedullary bone device 400 further includes a first flow directing feature 420 associated with the first openings 407 and a second flow directing feature 440 associated with the second openings 408.

[0262] The first flow directing feature 420 directs the flow of a fluid from the internal lumen 404 through the first openings 407 in a first direction as shown by arrows 5a and 5b and the second flow directing feature 440 directs the flow of a fluid from the internal lumen 404 through the second openings 408 in a second direction which is different to the first direction, as shown by arrows 6a, 6b and 6c.

[0263] The intramedullary bone device 400 is tubular and extends along a first axis 7. The first perforated region 405 and the second perforated region 406 are separated by an intermediate region 409. Intermediate region 409 does not have openings in the sidewall 403.

[0264] In the embodiment shown in FIG. 6, the first openings 407 and the second openings 408 are helically arranged along a length of sidewall 403 of the intramedullary bone device 400.

[0265] A first flow directing feature 420 as shown in FIGS. 10 and 11, for example, comprises part of the sidewall 403 of the intramedullary bone device 400 near an associated first opening 407.

[0266] Similarly, a second flow directing feature 440 as shown in FIG. 8 comprises part of the sidewall 403 of the intramedullary bone device 400 near an associated second opening 408.

[0267] The first flow directing feature 420 may comprise a first fluid guide member 421. First fluid guide member 421 extends inwardly and at an angle from an attachment with an internal surface of sidewall 403 and into internal lumen 404.

[0268] In one embodiment, first fluid guide member 421 depends from a connection end 422 connected to the sidewall. The connection end 422 in this embodiment comprises part of an upper edge 423 of an associated first opening 407.

[0269] The first fluid guide member 421 extends from the connection end 422 towards the second end 402 of the intramedullary bone device 400 and to a second end 424.

[0270] A first fluid guide member 421 as depicted in, for example FIG. 10, is substantially curved across its width and along its length from the connection end 422 to second end 424. This provides a curved fluid engagement surface 425. The curved fluid engagement surface 425 provides an increased surface area for subsequent bonding with a fluid.

[0271] A plurality of first fluid guide members 421 may be arranged internally in the first perforated region 405 of the intramedullary bone device 400 as shown in, for example, FIG. 9. Each fluid guide member 421 is associated with a first opening 407.

[0272] The first fluid guide members 421 as arranged internally in FIGS. 7 and 9 together define a narrower passage 430 within the internal lumen 404 of the first perforated region 405. The narrow passage is shown as the passage between dashed lines 431a and 431b in FIGS. 7, 8 and 9.

[0273] The intramedullary bone device 400 may receive an introducer rod 500. The introducer rod 500 may be configured to connect to a fluid source and sized such that it is insertable into the intramedullary bone device 400 and into the internal lumen 404 at first end 401. As the introducer rod 500 is progressed toward second end 402 of intramedullary device 400, it is confined to the narrower passage 430 defined by the multiple first fluid guide members 421. In the embodiments shown in for example FIGS. 7 and 9, the narrower passage 430 is relatively central and thus centralizes the introducer rod 500 within the intramedullary bone device 400.

[0274] The first fluid guide members 421 as shown in the drawings are substantially identical in shape and/or orientation relative to each other to provide a uniform flow pattern of fluid therethrough. However, it is noted that the first fluid guide members 421 may comprise different shapes relative to each other and/or may extend at different angles relative to the sidewall 403.

[0275] The second flow directing feature 440, in one embodiment comprises a second fluid guide member 441. Second fluid guide member 441 is typically the same shape as the first fluid guide member 421. However, as noted from FIG. 8, the second fluid guide members 441 have a different orientation relative to the first fluid guide members 420 which are shown in FIG. 7.

[0276] In the depicted embodiments, the intramedullary bone device 400 is insertable in a medullary cavity of a fractured bone to stabilise the bone during healing of the fracture. To further stabilise the bone, the fluid of the disclosure is a bone cement which is introduced via introducer rod 500. The bone cement is introduced in a relatively flowable state but wherein the cement substantially hardens upon delivery.

[0277] The intramedullary bone device 400 is shown in FIGS. 12A and 12B stabilising a fracture of a femur 600. The femur 600 of this embodiment comprises a saw bone deliberately fractured at site 601 as part of an experiment to observe the flow of a cement through the device 400.

[0278] The intramedullary bone device depicted is a bioresorbable device and the cement used in FIGS. 12A and 12B is a bioabsorbable bone cement.

[0279] Intramedullary bone device 400 is implanted as shown in FIGS. 12A and 12B by drilling an entry hole in the greater trochanter 602 of the femur 600 and inserting a guidewire 650 through the intramedullary canal. The process is also schematically represented in FIGS. 13A to 13D. A reaming device may be inserted over the guidewire 650 (this step is not shown) to ream a passage through the intramedullary canal. The intramedullary device 400 is then inserted over the guidewire and advanced towards the distal epiphysis 603 of the femur 600. The second end 402 is positioned distally relative to the fracture site 601 while the first end 401 extends from the entry hole in the greater trochanter 602. Intermediate portion 409 spans the fracture site 601.

[0280] In one embodiment, prior to insertion of the intramedullary device 400 over the guidewire, an introducer rod 500 is inserted into the internal lumen 404 at the first end and advanced towards the second end 402 of the intramedullary bone device 400. Introducer rod 500 extends from a first end 501 to a second end 502. An inner lumen 503 is formed through introducer rod 500 from the first end 501 to the second end 502. First end 501 is connectable to a fluid source which, in the embodiment depicted in FIG. 7, comprises a source of cement shown as arrow 8.

[0281] Second end 502 comprises an exit portal 504 as shown, for example in FIG. 8. The cement introduced into the first end 501, flows through lumen 503 and eventually exits via exit portal 504.

[0282] The introducer rod 500 is typically inserted into the intramedullary bone device 400 until the exit portal 504 is positioned in the second perforated region 406. The exit portal 504 may be aligned with the furthest second openings 408, that is the second openings closest to the second end 402 of device 400.

[0283] Once the device 400 and introducer rod 500 are optimally positioned, a cement source is coupled to the first end 501 of introducer rod 500 and cement introduced such that it flows towards second end 502. As the cement starts to flow from exit portal 504 it is channeled by second fluid guide members 441 towards second openings 408. The positioning of second guide members 441 is such that the cement flows in the direction of arrows 6a, 6b and 6c. The direction of flow in the second perforated region is therefore towards the second end 402 of the intramedullary device 400. When is use, this is important because it directs the cement away from a fracture site such as 601 in FIG. 12B.

[0284] It can be seen from the radiographic image of FIG. 12B that the cement (showing as brighter white than the device 400 and femur 600) is localised around the second perforated region 406.

[0285] The introducer rod 500 is gradually retracted from the second end 402 of the intramedullary bone device 400 towards the first end 401. FIG. 8 shows the introducer rod 500 as it is being retracted towards the first end 401 of the intramedullary bone device 400 as indicated by arrow 9.

[0286] The intermediate region 409 of the intramedullary bone device 400 is positioned bridging fracture site 601 in FIG. 12B. The absence of openings in intermediate region 409 prevents the flow of cement to the fracture site 601 and instead the cement is contained within the internal lumen 404.

[0287] The introducer rod 500 is further retracted until exit portal 504 is positioned within the first perforated region 405. As the cement continues to flow from the exit portal 504, it is channeled by the first fluid guide members 421 in a direction shown by arrows 5a and 5b, that is, towards the first end 401 of the intramedullary bone device 400. This directing of the cement towards the first end 401 of the device 400 urges the cement away from the fracture site. Again, as can be seen from the X-ray in FIG. 12B, the cement introduced in the first perforated region 405 is substantially localised to said region and does not extend into fracture site 601.

[0288] The introducer rod 500 may then be removed fully from the intramedullary bone device 400 and the fracture held until the cement has substantially set.

EXPERIMENTS

Experiment 1

[0289] A pilot bench experiment was performed with a paediatric tibia sawbone (Pacific Research Laboratories, Inc. Washington USA). The sawbone was subjected to a bending force and fractured. A 6.5 mm medullary canal was created by drilling through a region of the sawbone adjacent a proximal region and an entry portal of 2 mm created proximally in the medial aspect of the metaphysis. A vent hole in the bone was created distally.

[0290] A metallic stent was inserted and a calcium phosphate cement injected through the entry portal, filling the medullary canal. After a 10 minute curing time the bone was seen to be well fixed.

[0291] Radiographs were taken in the anterio-posterior and lateral projection and are shown in FIG. 14B. These clearly show the medullary canal filled with calcium phosphate cement, with the more dense loops of the metallic stent are seen crossing the fracture and reinforcing the cement. The pilot hole and venting hole can also be seen.

Testing

[0292] Four point non-destructive bend testing was carried out at a rate of 2 mm/min to a limit of 60N with a 1 kN load cell on an Instron 5944 mechanical testing machine (Instron; Melbourne, Australia) and the stiffness of the fractured, treated sawbone with the cement filled stent in situ was 85% of the stiffness of an intact (unfractured) sawbone.

Experiment 2

[0293] This experiment aimed to test the strength and stiffness of calcium phosphate cement against a polymer device filled with the cement.

[0294] Cylinders of calcium phosphate cement (Hydroset, Stryker) were produced and allowed to cure for 24 hours.

[0295] 3 Groups were tested:

[0296] 1. Hydroset alone

[0297] 2. Hydroset cylinder surrounded by a polycaprolactone (PCL) intramedullary bone device as herein disclosed

[0298] 3. Hydroset together with polyester (PE) mesh peripheral reinforcing

Testing

[0299] Four point bend destructive testing was carried out at a rate of 2 mm/min with a 1 kN load cell on an Instron 5944 mechanical testing machine (Instron; Melbourne, Australia). Inner span length was 10 mm with outer 30 mm.

Energy to Failure Under Four Point Bending

[0300] The brittle calcium phosphate cement of group 1 failed relatively very early, absorbing only a small amount of energy in bending before failure. As shown in FIG. 15A, the increase in energy to failure in the PCL introducer of group 2 in situ was 10 fold higher than group 1, and the group 3 combination of mesh and hydroset provided a further 2.5 fold increase in energy to failure.

Maximum Load to Failure Under Four Point Bending

[0301] As shown in FIG. 15B, the maximum load to failure was increased over two-fold above the group 1 results and by a factor of four for group 3.

Stiffness Under Four Point Bending

[0302] The stiffness results as shown in FIG. 15C demonstrate the brittle nature of the calcium phosphate cement of group 1. While stiff, its energy to failure is very low causing it to easily break.

Post Testing

[0303] The calcium phosphate of group 1 behaved in a chalk like manner and was separated into pieces. Both examples of group 2 and group 3 kept their structure and were still able to take load.

[0304] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.