TriPore Delivery Device

Technical Field

[1] The application relates to apparatus for preparing a biological composite and to

methods for using the apparatus.

[2] Composites, such as those comprising a ceramic inorganic substrate such as a

calcium phosphate inorganic material are generally known in the art for the repair of bone caused by, for example, tumour growth or degenerative disease, physical damage, or congenital malformation. Material is utilised as a bone graft and supports new tissue growth by providing the bone and blood cells with a matrix through which bone and blood cells reconnect the bone. A wide range of materials are generally known in the art. However, materials based on calcium phosphate such as beta-tricalcium phosphate ('β-TCP') and hydroxyapatite ( ¹ HA'). They are increasingly being used in surgical methods. One example of such bone graft material is shown in, for example, WO 2004/101013. This describes a biomaterial comprising a ceramic material, the ceramic material, the ceramic material having a plurality of micropores, larger midipores, and elongated macropores.

[3] The use of such materials can be improved by adding a biological component, such as blood, cell growth factors such as bone morphogenic proteins (BMPs), stem cells and bone marrow aspirate ( ¹ BMA'). The BMA is the most bioactive and cost effective technique for this application. This procedure involves the collection of semi-liquid bone marrow. The aspirate is typically from the back of the hip bone or posterial iliac crest for general orthopaedic application. In the spinal fusion surgery the BMA can be taken from pre-drilled pedicle screw hole in the vertebral body. Typically, an aspirate needle is inserted through the skin until it abuts the bone. The needle is then advanced through the bone into the marrow cavity. Once the needle is in the marrow cavity a syringe is usually attached and used to aspirate liquid bone marrow. Bone marrow aspirate contains a number of cells and other factors which encourage osteogenesis if used with the ceramic material. This encourages bone formation and the integration of the ceramic material into the site of the bone repair or bone graft.

[4]

Background Art

[5] Solid pieces of ceramic material have been used to repair bone. However, it has also been known to make the ceramic material into granular or powdered material and add bone marrow aspirate to form a putty-like material which can be moulded and inserted into the site of repair by a surgeon. One such device for mixing a ceramic material with a bone marrow aspirate to form a biological composite is shown in US 7,052,517. [6] US 7,052,517 discloses an apparatus for delivering a biological composition comprising a plunger and chamber. The chamber contains calcium phosphate material. The document shows that a needle is attached to one end of the apparatus and bone marrow aspirate is drawn into the material at one of the material via a vacuum applied by partially withdrawing the plunger from the chamber. This requires a relatively large amount of pressure and sheer forces to be applied to the aspirate in order to force the aspirate through the bore of the needle and the aperture of the point at which the needle is attached to the chamber. Moreover, the aspirate has to be drawn through the calcium phosphate material from one end. This increases the stresses on the cells in the aspirate and also results in inconsistencies in the amount of wetting of the material with the aspirate.

Disclosure of Invention

Technical Problem

[7] The inventor identified a need to improve the mixing of the bone marrow aspirate with the ceramic material. There is a need to ensure that there is consistent mixing of the two materials and also to reduce the amount of pressure required to pass the bone marrow aspirate into the ceramic material. Reducing the pressure and therefore shear forces reduces the amount of damage to cells within the bone marrow aspirate as they are passed into the apparatus.

Technical Solution

[8] The inventor has utilised a diffuser to improve mixing of the materials and reduce the pressure and sheer force applied to the bone marrow aspirate.

Advantageous Effects

[9]

Description of Drawings

[10] The invention will now be described by way of example only with reference to the following figures:

[11] Figure 1 shows the apparatus according to the invention from one side;

[12] Figure 2 shows perspective view of the hollow body;

[13] Figure 3 shows perspective views of one example of an end cap.

[14] Figure 1 shows an example of the apparatus according to the invention. The

apparatus (10) comprises a hollow body (12), plunger (14) and end cap (16).

[15] The plunger (14) is inserted into a first end of hollow body (12). The plunger

comprises a plunger handle (18) and end piece (20). End cap (16) comprises a diffuser (22) extending into the hollow body (12). The interior of the hollow body (24) in use contains ceramic material, such as granulated or powdered calcium phosphate or hydroxy apetite material. End cap (16) additionally comprises a female Luer-lock (26) attached to the end of it. The Luer-lock (26) is hollow and communicates with an aperture in the end of the end cap (16) and through the aperture to the diffuser (22).

[16] Figure 2 shows a perspective view of a preferred hollow body (12) that shows the first end (28) and second end (30). A pair of radially-extending flanges (32) are also shown. In use, this allows the body to be easily utilised by placing body between two fingers, the edges of the flange resting on the fingers whilst the plunger (14) is depressed to expel material from the apparatus.

[17] Figure 3 shows perspective views of the end cap (16). This shows a preferred embodiment in which the diffuser (22) comprises four rods (34) which in use extend into the interior of the hollow tube (12). The rods (34) are spaced apart from one another to form four slits or channels (36) extending from a centre space between the rods (34) which extends through to the aperture (38). In the embodiment shown in Figure 3(a) the aperture (38) does not have a Luer-lock, but instead comprises a slip fitting into which a male slip fitting of a syringe may be inserted to allow transfer of bone marrow aspirate through aperture (38) and diffuser (22) into the interior (24) of the hollow tube (12). The end cap (16) additionally comprises a plurality of raised mouldings (40). These assist the user of the apparatus to grip and remove the press-fit end cap (16) from the hollow tube (12).

Best Mode

[18] The invention provides an apparatus for preparing a biological composite, the

apparatus comprising:-

[19] (i) a hollow tube having a first end and a second end;

[20] (ii) a moveable plunger arranged at least partially in the hollow tube at the first end; and

[21] (iii) an end cap mounted on the second end of the hollow tube, the end cap

comprising a first aperture and a diffuser element, the diffuser element extending from the end cap into the hollow tube, the diffuser element adapted to enhance diffusion of a liquid from the aperture into the hollow tube.

[22] The hollow tube may comprise granular or powdered ceramic material. This may be added immediately prior to use, for example by removing the end cap or plunger and replacing the end cap or plunger, or inserted at the point of manufacture and packaging of the apparatus. The first aperture may be sealed by a suitable closure such as a stopper or cap.

[23] The ceramic material is preferably a calcium phosphate or hydroxyapatite material, such as β-TCP or for example materials such as that disclosed in WO 2004/101013, incorporated herein in its entirety. Such material is generally known in the art.

[24] Such material is typically less than 5mm, less than 3mm or less than lmm in

diameter. [25] The first aperture in the end cap and the diffuser are preferably coaxial with the hollow tube. The diffuser may be hollow. The diffuser is preferably an elongated diffuser which extends into the hollow tube so that in use it is surrounded by the ceramic material. Preferably the diffuser is adapted to diffuse liquid radially outwardly from the diffuser into the hollow tube and the surrounding ceramic material. The arrangement of the diffuser may, for example, be a helical coil or spring extended into the hollow tube. In use, bone marrow aspirate pass through the first aperture then passes through the hollow interior of the diffuser and passes radially outwardly through the gaps in the coil or spring. Alternatively, the diffuser may be a tube comprising one or more slits or apertures which allow the dispersion of the bone marrow aspirate radially outwards from the diffuser into the hollow tube. The tube, coil or spring may have a closure toward the first end of the diffuser, or alternatively may not be closed, allowing material to also diffuse axially through the end of the diffuser.

[26] The diffuser may also comprise a plurality of rods extending from the end cap which form a passage from the aperture and form a plurality of slits between the rods into the hollow tube. Two, three, four, five, six or more rods may be used. Preferably four rods are used which when viewed in transverse cross-section produce a 'cross'-like arrangement of the passage and slits. The slits typically extend axially along the diffuser.

[27] A moveable plunger is typically slideable along the axis of the hollow tube to allow, for example, material to be expelled from the second end of the hollow tube. The plunger may be arranged in a similar manner as for conventional syringes. It typically contains an end piece which assists in sealing the first end of the hollow tube by restricting the exit of the surrounding material and/or bone marrow aspirate.

[28] The apparatus preferably contains one or more additional apertures which allow the exit of air or liquid from the hollow tube. In use, bone marrow aspirate is passed through the first aperture, through the diffuser into the hollow tube. This means that either the plunger should be displaced to allow the ingress of the material into the tube, or alternatively the apertures are provided to allow the egress of air from the hollow tube. Preferably, the one or more additional apertures are provided in the end cap. This arrangement is useful because it allows the apparatus to be filled with the first end of the hollow tube placed vertically downwards. Bone marrow aspirate is passed through the first aperture in the end cap until aspirate is seen at the additional apertures in the end cap. Typically two or more apertures are provided in the end cap.

[29] The end cap itself is preferably removable and may simply be a push-fit onto the end of the hollow tube. Alternatively, it may be screw-fit onto the end of the hollow tube.

[30] The end cap may comprise a Luer-lock fitting and/or a slip fitting to the first

aperture. This allows, for example, a syringe containing bone marrow aspirate to be screwed onto the Luer-lock fitting. Alternatively, the tapered end of a syringe may simply be inserted into the slip fitting to connect the syringe containing the bone marrow aspirate to the apparatus. Typically, the Luer-lock fitting is a female Luer-lock fitting.

[31] The first end of the hollow tube may comprise a plurality of flanges extending

radially outwards from the hollow tube. This allows, for example, the hollow tube to be placed between two fingers with the end flanges extending over the fingers to allow the plunger to be easily depressed and expel the contents of the hollow tube. The tube may have a substantially circular cross-section.

[32] The invention also provides an end cap for attachment to end of a hollow tube, the end cap comprising an aperture and a diffuser extending from the end cap, which in use would be extending into the hollow tube. The structural arrangement of the end cap and diffuser are preferably as described above.

[33] The apparatus may be made of any suitable material. Typically, the device is made of plastics materials. For example, the cap may be formed from ABS to assist with rigidity and tolerance to gamma radiation for sterilisation purposes. The syringe barrel may be made of low density polyethylene. The end piece of the plunger may be made of a silicon rubber or for example a low density polyethylene, and be attached to a plunger handle made from, for example, high density polyethylene.

[34] A further aspect of the invention provides a method of preparing a biological

composite comprising an apparatus according to the invention, introducing bone marrow aspirate through the first aperture of the end cap, through the diffuser element and into the granular or powdered ceramic material to form the biological composite; removing the end cap from the hollow tube; and expelling the biological composite material from the hollow tube by moving the plunger from the first end of the hollow tube towards the second end of the hollow tube to expel the composite material. The aspirate may be maintained within the hollow tube in contact with the ceramic material for sufficient time to allow wetting of a composite material at least partial coalescence of the bone marrow material within the composite.

[35] Sufficient bone marrow aspirate is usually provided wet the granular or powdered ceramic material.

[36] The bone marrow aspirate itself may be obtained using conventional methods and introduced into the apparatus via, for example, connection of a male Luer-lock on the syringe containing the bone marrow aspirate onto the female Luer-lock of the end cap of the apparatus. Alternatively, a slip connection may be used.

[37] Typically, the apparatus is maintained in a vertical arrangement with the first end of the apparatus downwards. In this arrangement, with apertures in the end cap, it is possible to tell whether sufficient bone marrow aspirate has been inserted into the apparatus by the eventual egress of excess aspirate through the additional apertures. [38]

Mode for Invention

[39]

[40] In use, granulated or powdered ceramic material is placed into the hollow part (24) of the body (12). The end cap (16) is then placed over the end of the hollow tube (12). Bone marrow aspirate is removed from a patient by conventional methods, typically utilising a syringe. The syringe may be connected to the end cap (16) via, for example, a Luer-lock (26) or slip-fitting (as shown in Figure 3(a)). The material is passed through the aperture (38) and diffuser (22). The bone marrow aspirate passes along the diffuser (22) and out through the radially-extending slits (36) into the ceramic material. This arrangement reduces the amount of pressure required to force the bone marrow aspirate through the aperture and into the material. It also ensures greater homogeneity of the diffusion or the bone marrow aspirate into the ceramic material.

[41] Typically the end cap (16) will comprise one or more additional apertures (not

shown). This allows the escape of air displaced from the hollow body (12) by movement of the bone marrow aspirate into the interior (24) of the hollow body. The addition of sufficient bone marrow aspirate is typically shown by escape of excess bone marrow aspirate from such additional apertures. The bone marrow aspirate and the ceramic material may be incubated for several minutes to ensure that the ceramic material is wetted properly. End cap (16) is then removed. The removal of the end cap material may be assisted by slightly tapering the external surfaces of the rods (34) from the second end towards the interior end of the diffuser (22).

[42] Once the end cap is removed, the biological composite comprising the bone marrow aspirate and the ceramic material may then be expelled by pressing on the plunger handle (18). This forces the end plunger (20) against the composite material which expels it out of the hollow tube (12). The composite material may then be utilised by a surgeon for the repair of, for example, damaged bone as is generally known in the art. Industrial Applicability

[43]

Sequence List Text

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