Method to introduce an implantable device to fill a bone void whilst minimising pressurisation

Abstract

Disclosed is an invention that provides a method of treating a bone void of a patient through the use of an implantable device whilst minimising the potential for an increase in pressure within the bone void thus avoiding embolization of the void contents into the patient's bloodstream.

Claims

1. A method of reconstructing a bone void in a patient, the method comprising introducing into a bone void of one or more implantable devices, each of which one or more implantable devices are substantially cylindrical, having a convex, domed or semi-spherical shaped ends; contain one or more longitudinal channels where the one or more longitudinal channels create a venting path allowing for depressurisation of any contents of the bone void, the one or more longitudinal channels each intersecting a surface of the device and extending towards an axial centerline thereof, and being tapered such that the width of the one or more longitudinal channels opening on an outer, circumferential edge of the implantable device is greater than its width at a base thereof; and have a flat surface on an opposing longitudinal side to the one or more longitudinal channels; whereby introduction of the one or more implantable devices reconstructs bone in the bone void in the patient.

2. The method of claim 1 where the one or more implantable devices comprise a hardened bone substitute material.

3. The method of claim 1 where the bone void is a contained bone void.

4. A method of claim 2 where the one or more implantable devices are moulded through the use of a multi-cavity flexible mould mat or by 3D printing.

5. A method of claim 1 where the one or more implantable devices are inserted into the bone void by being digitally packed.

6. A method of claim 1 where the one or more implantable devices are inserted into a bone void by the use of an introducer comprising a guide tube and a pusher.

7. A method according to claim 1 where the bone void is a long bone intramedullary canal of a patient.

8. A method according to claim 7 where the bone void is a long bone medullary canal that is reamed out to a diameter to slidingly accept the one or more implantable devices or the guide tube.

9. A method according to claim 7 where the bone void is debrided prior to insertion of the one or more implantable devices.

10. A method according to claim 1 where the one or more implantable devices contains a medicament.

11. A method according to claim 10 where the medicament is an antimicrobial intended to prevent or treat an infection.

12. A method according to claim 11 where the infection is bacterial, fungal or parasitic.

13. A method according to claim 10 where the medicament is an antineoplastic agent for treating a bone tumour, such as a giant cell tumour of bone.

14. A method according to claim 10 where the medicament is a bone morphogenetic protein to aid in bone regeneration.

15. A method of reconstructing a bone void in a patient while reducing pressurisation of the bone void, the method comprising introducing into a bone void of one or more implantable devices through the use of a guide tube and a pusher that facilitates the one or more implantable devices being freely inserted into the intramedullary canal; where the one or more implantable devices comprise: 1) a capsule shape, having convex, domed or semispherical shaped ends; and 2) one or more longitudinal channels extending the entire length of the implantable device; wherein the one or more longitudinal channels create a venting path allowing for the depressurization of any contents of the bone void, the one or more longitudinal channels each intersecting a surface of the device and extending towards an axial centerline thereof, and being tapered such that the width of the one or more longitudinal channels opening on an outer, circumferential edge of the implantable device is greater than its width at a base thereof, and have a flat surface on an opposing longitudinal side to the one or more longitudinal channels; whereby introduction of the one or more implantable devices reconstructs bone in the bone void while reducing pressurisation of the bone void in the patient.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various features of the invention, which are applicable as appropriate to all aspects, will now be described in more detail with reference to the following drawings, where:

(2) FIG. 1 shows plan, end and isometric views of an implantable device for use in the instant invention with a spherocylindrical or capsule shape and a longitudinal channel.

(3) FIG. 2A shows a multi-cavity flexible mould mat with cavities that, when filled with bone substitute material, can be used to form the implantable device(s).

(4) FIG. 2B shows a cross-section view of the multi-cavity flexible mould mat.

(5) FIG. 3A shows multiple implantable devices of the present invention together in series.

(6) FIG. 3B shows multiple implantable devices of the present invention together in series. A venting path is shown where the void contents may exit the bone void or the IM canal during device insertion, helping to minimise pressure build-up within the void and thus minimise the potential for an embolism.

(7) FIG. 4 shows an inserter (guide tube and engaged pusher) with implantable devices being dispensed.

(8) FIG. 5 shows an inserter being used to dispense implantable devices in to an intramedullary canal.

(9) FIG. 6 shows a cross sectional view of an intramedullary canal containing an implantable device.

(10) FIG. 7 is an X-ray of a tibia showing the implantable devices contained within the medullary canal.

DETAILED DESCRIPTION OF THE DRAWINGS

(11) FIG. 1 shows an implantable device 10 of the present invention, which is capsule shaped, having domed, convex or semispherical shaped ends 20. A longitudinally aligned channel 30 intersects the surface of the implantable device and extends towards the cylindrical axis 40 of the implantable device.

(12) FIG. 2A shows a multi-cavity flexible mould mat 60 which has cavities 70 in rows 80. Each cavity has a shape that corresponds to the shape of the implantable device 10.

(13) FIG. 2B shows a cross-sectional view of the multi-cavity flexible mould mat 60, of a row of cavities 80. The shape of the cavities 80 corresponds to that of the implantable devices 10, with the longitudinal channels 30 visible.

(14) However, while the multi-cavity flexible mould mat 60 constitutes a typical method of manufacturing the implantable devices 10, the implantable devices 10 may be alternatively produced by a method not described herein, by methods which will be readily apparent to the person skilled in the art.

(15) FIG. 3A shows multiple implantable devices 10 of the present invention together in series, showing the longitudinal channels 30 for venting the contents of the bone void or IM canal which form part of the venting path 50 through the longitudinal channel 30 and domed, convex or semispherical shaped ends 20.

(16) FIG. 3B shows multiple implantable devices 10 of the present invention together in series. A continuous venting path 50 for the contents of the bone void or IM canal is shown through the longitudinal channels 30 and domed, convex or semispherical shaped ends 20, thus helping to minimise pressure build-up within the void and thus minimise the potential for an embolism.

(17) FIG. 4 shows a guide tube 170 with a handle 100, for the insertion of the implantable devices in to the bone void or IM canal, and a funnel 120 at the proximal end to help guide insertion of the implantable devices 10 and subsequently the pusher 110. The outside diameter of the guide tube 170 is less than the inside diameter of the medullary canal to be treated. The distal end of the guide tube 170 has a flexible retainer 160 which retains the implantable devices 10 within the guide tube 170 until pressure is applied by the pusher 110 at its proximal end 130 to the implantable devices 10 which will cause the retainer 160 to flex allowing the implantable devices 10 to exist the guide tube 170 at its distal end.

(18) FIG. 5 shows a guide tube 170 and pusher 110, inserted into an IM canal 180 of a patient, where the outer diameter of the pusher 110 is less than the internal diameter of the guide tube 170. The pusher 110 has a circular handle 130 to allow the Surgeon to maintain pressure on the implantable devices 10 whilst retracting the guide tube 170 to dispense the devices 10 into the IM canal 180. The guide tube 170 has a flexible retainer 160 which retains the implantable devices 10 until the surgeon applies pressure on the pusher handle 130. Once pressure is applied by the surgeon the fluid contents 200 of the IM canal can be seen exiting the proximal end of the guide tube 170.

(19) FIG. 6 shows a sectional representation of an IM canal 70 and cortex 150, containing an implantable device 10 that has been inserted therein. The longitudinal channel 30 has a taper angle 140.

(20) FIG. 7 shows an X-ray of the tibia 190 of a patient which contains a series of implantable devices 10 lined up end-to-end within the IM canal 180.

(21) It is to be understood that various modifications may be made to the method(s) disclosed herein without departing from the scope of the invention, which may include, but are not limited to, the following:

(22) The method may be directed to treating infected long bone non-unions.

(23) The longitudinal channel cross section may be semi-circular.

(24) The longitudinal channel cross section may be a straight line.

(25) The longitudinal channel may have some other shape.

(26) Bone cement may be used to form the implantable devices.

(27) It is of course to be understood that the present invention is not intended to be restricted to the foregoing examples which are described by way of example only.

EXAMPLES

(28) A long bone medullary canal requiring treatment is prepared as follows:

(29) Ream the canal to the required depth and diameter, the diameter slidingly exceeding the outside diameter of the introducer. An intramedullary canal that has had an intramedullary nail removed may be suitable without the need for reaming. Alternatively, reaming may be required to remove necrotic, infected or cancerous tissues.

(30) Use the flexible mould to produce implantable devices using a bone void filler such as STIMULAN Rapid Cure (Biocomposites Ltd). Follow the mixing instruction for STIMULAN Rapid Cure. A typical quantity required to fill an adult subjects' long bone would be about 20 cc when formed into implantable devices according to the instant invention.

(31) Prepare the STIMULAN Rapid Cure and place the STIMULAN paste on the area of the mat containing the cavities using the paste applicator.

(32) Once filled, lift the mat and then tap on a solid surface to dislodge and release any trapped air bubbles. Remove excess material from the surface of the mat using the paste applicator or other suitable scraper. Allow the material to set according to the STIMULAN Rapid Cure instructions and then remove devices from the mat by flexing. Ensure the implantable devices remain in the sterile field. The implantable devices placed end-to-end should be sufficient to fill the IM canal to the required depth. The maximum outside diameter of the implantable devices should be slidingly less than the inside diameter of the guide tube while the outside diameter of the guide tube should be slidingly less than the inside diameter of the reamed IM canal.

Example 1

(33) The implantable device(s) may be digitally inserted, one at a time, in to the IM canal.

Example 2

Load the Guide Tube In Situ

(34) Insert the guide tube in to the IM canal.

(35) Digitally load the guide tube with implantable devices, one at a time, ensuring that the first device added is pushed to the distal end of the guide tube using the pusher and subsequent devices added are pushed forward to abut the previous device. Ensure that the number of devices added is sufficient to fill the IM canal to the required depth.

(36) When the guide tube is populated with sufficient devices, re-insert the pusher to engage the proximal end of the most proximal device.

(37) Apply a positive pressure onto the last implantable device placed into the guide tube using the pusher. Whilst maintaining a positive pressure, pull the guide tube back along the pusher to leave the implantable device(s) in the bone void.

Example 3

Pre-Load the Guide Tube

(38) Digitally load the guide tube with implantable devices, one at a time, ensuring that the first device added is pushed to the distal end of the guide tube and subsequent devices added are pushed forward to abut the previous device. Ensure the number of devices is sufficient to fill the IM canal to the required depth.

(39) Transfer the pre-loaded guide tube to the bone void.

(40) Insert the guide tube slowly into the bone void.

(41) Insert the pusher into the guide tube to engage the most proximal device and apply a light, positive pressure onto the device. Whilst maintaining a positive pressure, pull the guide tube back along the pusher to leave the implantable device(s) in the bone void.

(42) A number of embodiments of the invention have been described. However it is to be understood that various modifications may be made without departing from the scope of the invention.

(43) References:

(44) Akhtar, S., Fat embolism. Anesthesiol Clin, 2009. 27(3): p. 533-50.

(45) Issack, P. S., et al., Fat embolism and respiratory distress associated with cemented femoral arthroplasty. Am J Orthop (Belle Mead N.J.), 2009. 38(2): p. 72-6.

(46) Shaikh, N., Emergency management of fat embolism syndrome. J Emerg Trauma Shock, 2009. 2(1): p. 29-33.

(47) Hampson, F., Fat embolism. J Clin Pathol Suppl (R Coll Pathol), 1970. 4: p. 121-2.

(48) Rebellow, M. M., et al., Venting alone is insufficient in preventing complications in the prophylactic nailing of femoral metastases, in 49th Annual Meeting of the Orthopaedic Research Society. 2003: New Orleans, La., USA.

(49) Knott, L. Fat Embolism Syndrome. 2014; Available from: http://patient.info/doctor/fat-embolism-syndrome.