AU2007203182A1 - Cortical and cancellous allograft cervical fusion block implant - Google Patents

Description

10-JUL-2007 14:27 A J PARK 64 9 3566990 P.04 Regulsaion 3.2

AUSTRALIA

PATENTS ACT, 1990 COMPLETE

SPECIFICATION

FOR A STANDARD

PATENT

ORIGINAL

Name of Applicant MUSCULOSKELETAL TRANSPLANT

FOUNDATION

Actual Inventor: YOLANDA DENISE SHEPARD Address for service in A J PARK, Level 11, 60 Marcus Clarke Street, Canberra ACT Australia: 2601, Australia Invention Title: Cortical And Cancellous Allograft Cervical Fusion Block Implant The following statement is a full description of this invenion, including the bcs method of perfomning it known to us.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:27 A J PARK 64 9 3566990 Sla 0 00 RELATED

APPLICATION

There are no related applications.

S MFIELD OF INVENTION The present invention is generally directed toward a surgical implant product and O more specifically is a shaped allograft cortical cancellous bone block implant for the fusion of vertebral bones which is introduced between two vertebral bones to be fused.

0 BACKGROUND OF THE INVENTION The use of substitute bone tissue dates back around 1800. Since that time research efforts have been undertaken toward the use of materials which are close to bone in composition to facilitate integration of bone grafts. Developments have taken place in the use of grafts to use materials such as corals, hydroxyapatites, ceramics or synthetic materials such as biodegradable polymer materials. Surgical implants should be designed to be biocompatible in order to successfully perform their intended function Biocompatibility may be defined as the characteristic of an implant acting in such a way as to allow its therapeutic functionto be manifested without secondary adverse affects such as toxicity, foreign body reaction or cellular disruption.

Human allograt tissue is widely usedin orthopaedic, neuro-, raxillofacial, podiatric and dental surgery. The tissue is valuable because it is biocompatible, strong, biointegrates in time with the recipient patient's tissue and can be shaped either by the surgeon to fit the specific surgical defect or shaped commercially in a manufacturing environment. Contrasted to most synthetic absorbable or nonabsorbable polymers or metals, allograft tissue integrates with the surrounding tissues.

Allograft bone is a logical substitute for autologous bone. It is readily available and precludes the surgical complications and patient morbidity associated with obtaining autologous bone as noted above. Allograft bone is essentially a collagen fiber reinforced hydroxyapatite matrix containing active bone morphogenic proteins (BMP) and can be provided in a sterile form. The demineralized form of allograft bone is naturally both osteoinductive and osteoconductive. The demineralized allograft bone tissue is fully incorporated in the patient's tissue by a well established biological mechanism. It has been used for many years in bone surgery to fill the osseous defects previously discussed.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:27 A J PARK 64 9 3566990 P.06 S2 0 O Allograft bone occurs in two basic forms; cancellous and cortical. The cancellous bone includes void areas with the collagen fiber component contributing in part to torsional and t tensile strength. The less dense cancellous bone provides an excellent matrix for rapid bone

O

regeneration and repair.

Manydevices ofvarying shapes and forms are fabricated fromallograft corticaltissue Cx- by machining. Surgical implants such as pins, rods, screws, anchors, plates, intervertebral spacers 00 and the like have been made and used successfully inhuman surgery. These pre-engineered shapes 3 are used by the surgeonin surgery to restore defects in bone to the bone's original anatomical shape.

Injury or disease processes to the head, neck, or shoulders can cause abnormalforces o to be applied on the cervical vertebra. Arthritis, motion induced "whiplash", or other trauma create N this malfumction. This situation is often treated surgically by a procedure intended to fuse the two adjacent cervical or spinal vertebrae to each other. Such fusion relieves the pressure the partially displaced vertebrae place on the adjacent spinal nerves.

Many surgical devices have been developed andused successfully to imobilize and fuse the misalgned vertebrae. Metal plates screwed into the adjacent vertebrae work well but after sometime post-operatively, the stress rise occurring at the screwposition causes erosion ofthe bone and resultant slipping. This has been improved by placing load-bearing spacers between the two (or more) misaligned vertebrae- The spacer is both load-bearing and of a material which will induce, or at least support, fusion between the vertebrae.

Removal of damaged or diseased discs, restoration of disc space height and fusion of adjacent vertebrae to treat chronic back pain and other ailments are known medical techniques.

Implants such as intervertebral spacers are often implanted in the disc space engaging the vertebrae to maintain or reestablish disc space height after removal of all or a portion of the disc. The spacers are formed of a variety of both resorbable and non-resorbable materials, including, for example, titanium, surgical steel, polymers, composites and bone. It is currently considered desirable to promote fision between the vertebral bodies that are adjacent to the damaged or diseased discs.

Typically, an osteogenic material is combined with a spacer and inserted in the disc space to facilitate and promote bone growth. While the selection of the implant configuration and composition can depend upon a variety of considerations, it is often desirable to select a resorbable material that does not shield the bone ingrowth. Bone and bone-derived components can provide suitable material to prepare the implants. However, bone material and in particular cortical bone acceptable for use in implants is a scarce resource, being derived from limited number human tissue donor resources.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:28 A J PARK 64 9 3566990 P.07 3 SSuitable bone or bonederived material for use implants, in general, is almost 3 exclusively obtained fom allograft and xenograft sources both of which com from a limited Ssupply. Since intervertebral spacers must withstand the compressveloads exertedbythe spine, tese implants are often cortical bone which has the mechanical strength suitable for use in any region of the spine. Cortal spacers are often shaped from corticallong bones, which are prkarily foud in C the lower limbs and include, for example, femur, fibula, and the tibia bones. However, these long c bones makeup onlyafractionofthe available bone source- Cancellous bone, because ofits superor 8 osteoinductive properties, would be desirable to sue in the spinal implant. However, the lower mechanicalstrength ofcancelloubone prohibitsituse mm ysurgicalapplicati Thus, sources Sof bon suitable for structural intervertebral spaces are extremely limited. The scarcity of desired N donor bone makes it difficult to provide implants having the desired size and configuration for implantationbetween vertebrae, which canrequie relatively large irplats. It is further anticipated that as the population ages there will be an increased need for correction for spinal deformities and a concomitant increase in the demand for bone-derived components. Therefore, these structural bone portions mst be conserved and used effciently to provide iplants. The scarcity of suitable bone material has also hindered efforts to design and manufacture varying configurations of suitable implants for arthodesis of the spine. Further, various implant configurations have not been physiologically possible to obtain giventhe structural ad geometrical constraints of available donor bone.

One known treatment for fusing two vertebrae is the insertion of a suitably shaped dowel ito a prepared cylindrical cavity which reaches the two vertebrae to be sed. The dowel used is preshaped bone or allograft bone.

A number of allograft bone spacers have been used in surgery as spacers. They are commonly called the ACF spacer constructed as a cortical bone cross section, shaped like a washer withteethto discourage graft explusion and an axial center hole; aVG3 cervical spacer constructed with two ramp shaped cortical plates held together with cortical pins, the top and bottom surfaces being ridged to discourage graft expulsion; an ICW spacer constructed with an elongated C spaced cortical portion with a cancellous inside to allow rapid ingrowth (slice of iliac crest) and a SBS spacer constructed with a single piece cortical member with serrated top and bottom surfaces and ah axial center hole.

The ICW (iliac crest wedge) has been used for a long time for cervical spine fusion and has a total load bearing force around 4500 Newtons. Testing has noted that cervical vertebrae fail in compression at about 2000 Newtons. The ICW spacer suffrs from high unit variability COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:28 A J PARK 64 9 3566990 P.08 4 0 O because of its natural, anatomic variations.

SUnited States Patent No. 5,972,368 issued on October 26, 1999 discloses the use c' of cortical constructs a cortical dowel for spinal fusion) which are cleaned to remove all of 0 the cellular material, fat, free collagen and non-collagenous protein leaving structural or bound collagen which is associated with bone mineral to form the trabecular struts of bone. The shaped CI bone is processed to remove associated non-collagenous bone proteins while maintaining native bound collagenmaterials and nturaly associated bone minerals. The surface ofamacined cortical bone is characterized by a wide variety of openings resulting from exposure by the machining c process ofthe Haversian canals present throughout cortical bone. These canals serve to transport 0 fluids throughout the bone to facilitate the biochemical processes that occur at variable angles and Cl depths within the bone.

An attempt to solve the increasing bone supply problems using a combined cortical and canoellous bone block is shown in United States Patent Number 4,950,296 issued August 21, 1990 which uses a cubically configaued cortical shell defining a through going internal cavity and a cancelous plug fitted into the cavity so that the end surfaces of the cancelous plug are exposed.

Another reference, WIPO Patent PublicationNumber WO 02/24122 A2, published Mareh28, 2002 owned by SDGI Holdings Inc. showvarious intervertebral spacers formed ofcortical andcancellous bone composites such as sandwiches, with intersecting ribs and rods.

U.S. Patent Number 6,294,187 issued September 25, 2001 is directed toward an shaped osteimplant of compressed bone particles. The shaped implant is disc shaped and has a number of holes drilled therein for macroporosity and the holes can be filled with an osteogenic putty material.

Conversely, WIPO Patent PublicationNumber WO 02/07654 A2, published January 31, 2002 discloses intervertebral spacers formed ofdense cancellous human or animal bone. In one embodiment, a cortical rod or cortical rods are placed in bores cut through a cancellous bone block to provide load bearing strength with the ends of the rods being exposed on both sides of the cancellous bone block. Another embodiment shows a C shaped cortical block with a cancellous plug inserted into the recess of the C to form a rectangular spacer. A pin is inserted through a bore cut through the legs of the C block and through the cancellous plug to keep the cancellous plug positioned withthe recess of the cortical component. U.S. Patent Number 6,379,385 issued April 2002 also discloses the use of a spongy block having a plurality of cortical rods mounted in through going bores out through the bone block. In another embodiment, a X-shaped cortical support member is mounted therein to provide structured strength to the composite implant.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:29 A J PARK 64 9 3566990 P.09 0 o It is also knownto mate various bone components together to form a single implant.

In this regard, see, Albee, Bone Graft Surger in DiseaseInjury and Deformity, (1940), pp. Swhich uses a tongue in groove and dove tail to hold separate pieces of bone together for implant 0 use, and U.S. PublicationNo. US2002/0029084 Al, published March 7,2002, which shows a three component implant with a center core surrounded by two outer semicircular portions. The outer Sportions have alternative dove tail joints on adjacent bone portions to secure the outer portions 00 together foring a dowel shaped bone implant.

r C Consequently, there is a need for an implant which should have with a load bearing C, compressive strength of 1000 to 5000 Newtons with a compressive load to be a minimum of 3000 0 Newtons as a safety factor. There is also a need to have a portion of canellous bone immediately C0 adjacent to the load bearing cortical zone to permit rapid ingrowthofapatient's owanewbone with the cancellous bone forming the major part of the implant.

SUMMARY OF THE INVENTION The composite allograft cervical fusion block is directed toward a two piece, mated bone fusion block or spacer constructed with one component member of load bearing material preferably cortical bone and the other component member made of cancellous bone for use in orthopedic surgical procedures. The cortical bone member defines a dove tail shaped projection extending from its outer surface with the cancellous component member having a dove tail recess cut therein to receive the dove tail projection ofthe cortical member. A plurality of bores are cut through the cortical bone member and into the cancellous member to hold pins which are angularly inserted into the bores along opposite sides ofthe dove tail projection and recess and through the head of the cortical member to limit axial and lateral movement.

Additional embodiments include the use of a single throughgoing pin, a single transverse throughgoing pin, multiple dove tails, a bulbous projection substituted for the dove tail and opposing load bearing members.

It is an object ofthe invention to use a bone block geometry to provide a composite bone block ofcanccllous and corticalbone components having performance characteristicsthatmeet or exceed conventional spinal fusion requimrments.

It is another object of the invention to utilize a shaped cortical cancellous bone implant blockwhichprovides the mechanial strength characteristics that can withstand compression forces and provide overall strength and durability to the structure.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 1-JUL-007 14:29 A J PARK 64 9 3566990 6 0 SIt is stillanother object of the inventionto provide a spinal fusionimplaut which uses a load bearing componet member to take up the highforces whh can arise between two vertebral t bodies and a relatively porous cancellous component member to accelerate the healing process.

It is yet another object of the inventionto provide a pre-machined shaped allograft bone structure which can effectively promote new bone growth and accelerate healing.

C'I It is also an object of the invention to create a sterile bone fusion implant, which is Ssterile and which can be easily handled by the physician during surgery which eliminates or o signiicantly reduces the physician fom having to carve or modify the respective bone blocks.

These and other objects, advantages, and novel features ofthe present invention will 0 become apparent when considered with the teachings contained in the detailed disclosure. This N disclosure, along with the accompanying drawings and description, constitutes a part of this specification and illustrates embodiments of the invention which serve to explain the principles of the invention.

BRggIE DESCRPTION OF THE DRAWINGS Figure 1 is a perspective view of the inventive composite cortical and cancellous component bone implant; Figure 2 is a top plan view of the implant of Figure 1; Figure 3 is a perspective view iuphantom ofthe cancellous component of Figure 1; Figure 4 is an enlarged top plan view of the cancellous component of Figure 3 showing the bores in phantom; Figure 5 is an enlarged front right side elevationalview ofthe cancellous component of Figure 3; Figure 6 is a right side elevational view of the cancellous component of Figure 3; Figure 7 is a top plan of the cortical component of Figure 1; Figure 8 is a front elevational view of the cortical component of Figure 7 showing the dove tail in phantom; Figure 9 is a side elevational view ofthe cortical component of Figure 7; Figure 10 is a perspective view of an alternative embodiment of the composite cortical and cancelous bone implant with a single throughgoing bore running along the center axis of the dove tail; Figure II is a top plan view of the implant of Figure 10 showing the bore in phantom; COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-007 14:29 A J PARK 64 9 3566990 P.11 7 0 0 Figure 12 is a perspective view of an alternative embodiment of the composite 3 cortical and cancellous bone implant with a single throughgoing bore running transverse the axis of t s fthe dove tail; Figure 13 is a top plan view of the implant of Figure 12 showing the bore in pbantom; NC Figure 14 is a perspective view ofan alternate embodiment ofthe composite cortical 0 0 and cancellous composite bone implant with multiple dove tails; o Figure 15 is a top plan view of the implant of Figure 14; Figure 16 is a perspective view of an altemative embodiment of the composite o cortical and cancelous composite bone implant with a truncated ellipsoid interconnection; Figure 17 is a top plan view of the implant of Figure 16; Figure 18 is a perspective view of the embodiment of Figure 16 with two angled bores; Figure 19 is atop plan view of the implant of Figure 18; Figure 20 is a perspective view ofan alternate embodiment ofthe composite cortical and cancellous composite bore implant with a wider dove tail engagement structure; Figure 21 is a top plan view of the implant of Figure Figure 22 is a perspective view ofthe implant of Figure 20 with a single bore parallel to the center axis of the implant; Figure 23 is a top plan view of the implant of Figure 22 with the bore shown in phantom; Figure 24 is aperspective view of an alternate embodiment ofthe composite cortical and cancellous composite bone implant with load bearing members positioned at both ends; Figure 25 is a top plan view of the implant of Figure Figure 26 is a perspective view of the implant of Figure 24 showing two throughgoing bores: Figure 27 is a top plan view of the implant of Figure 26 with the bore shown in phantom; Figure 28 is a perspective view of the implant of Figure 24 showing a single throughgoing bore; and Figure 29 is a top plan view of the implant of Figure 28 showing the bore in phantom.

DETAILED DESCRIPTION OF THE INVENTION COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-207 14:30 A J PARK 64 9 3566990 P.12 8 0 N The preferred embodiment and best mode of the present invention is shown in 3 Figures 1 through9. The composite bone implant block 10 is shown in Figure I in accordance with o the present invenion.

The composite cortical cancellous bone block body or intervertebral spacer 10 is preferably constructed with a first component member 12 of denser cancellous bone taken from 00 donors age 45 or less cut into a truncated triangle shape. This component accounts for a large portion of the graft and provides a large area for bone fusion to occur. The component member o body has a fiat planar front end surface 14 and is provided with a dove tail shaped recess 16 cut r thereininto the interior ofthe cancellous component body. The dove tail shaped recess 16 extends O from the access port or opening 15 to the base wall 17 forming the rear of the recess. The access entrance opening 15 is preferably about twice as wide as the base 17 ofthe recess and the sidewalls 19 ofthe recess are angled from 76' to 95° outward from the entrance opening 15. The cancellous bone is harvested from a bone such as a tibia, humerus, patella, calcaneus or femur. The side walls 18 of the cancellous member 12 are tapered or angled from 1000 to 110°, preferably at 101 with a tapered distal side section 20 running into a planar rear wall surface 22. The cancellous member 12 when implanted in the patient's body encourages tissue, vascularation and deposition of new bone.

The cortical cancellous bone block 10 has aT shaped cortical component member with a cross piece 31 having planar outer surface 32 and two tapered or curved side sections 33 which lead to an inner flat planar surface 34. A dove tail shaped projection 36 which has approximately the same dimensions as dove tail recess 16 cut into the cancellous member extends outward from the planar surface 34. The projection or mating member 36 has angled side walls 37 extending outward at an angle ranging from 70 to 75° to mate with the recess 16. The end 38 of the dove tail projection36 is planar. The cortical member 30 has superior wall strength for support between load bearing body structures such as vertebrae. While it is noted that wall surfaces 14 and 34 are fiat, these surfaces can be provided with any kind of complementary construction.

Whenthe composite assembly is lyophilized, the pieces shrink with the corticalbone shrinking about 3% and the cancellous bone shrinking a greater amount ranging from 4% to 8%.

Thus, the dove tail projection 36 will loosely fit into the dove tail recess 16 to hold the two components together. The cortical member 30 has superior wall strength for support betweenload bearing body structures such as vertebrae and has a compressive load ranging from 2000 to 5000 Newtons, preferably in excess of 3000 Newtons. The composite bone block body 10 height can COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 1-JUL-007 14:30 A J PARK 64 9 3566990 P.13 9 0 range from 8-12 nn preferably 10 mm depending upon patient needs with a corresponding length ranging from 12 to 20 mm, prferably 16 mm with a width ranging from 10 mm to 14 mm preferably 12 mm, again depending upon surgeonpreference and the size of the fusion block which Swill be used on the individual patient.

Preferably, the bad bearing member accounts for about 15% to 40% of the outside N exposed area of the implant, preferably around 20%, witha vohluetric area ofabout 10% to about 00 ofthe implant, preferably around 10% to o If desired, pins 40 and 42 can be inserted in a through going bores 44 and 46 cut through both component members 12 and 30 to increase stability to the graft The pins 40 and 42 Sare preferably constructed ofcorticalbone but can be constructed from any bio-compatible material C having the necessary strength requirements including metals, plastics compositions and the like and are friction fit in the respective bores 44 and 46. The cortical front is mated to the cancellous component with the crosspiece inner planar suface being adjacent the cancellous component The cortical or load bearing component bears not only a compressive load but also serves as an impaction surface. Thus, the surgeon can tap on the anterior cortical surface while impacting the graft without damaging the more brittle cancellous portion of the graft.

In an alternate embodiment ofthe invention, a single bore 60 is formed through the center of the dove tail and the base ofthe U as is seen in Figures 10 and 11. A pin 62 is inserted through the axially aligned bores of the corticalload bearing member 30 and the cancellous member 12.

In Figures 12 and 13, a bore 70 is cut transverse to the axis ofthe dove tail shaped stem and across the legs ofthe cancellous member 12 to receive a pin 72 whichprovides additional seurity to the composite implant.

In Figures 14 and 15, the load bearing member 30 is formed with two dove tail shaped projections 80 and 82 which fit into correspondingly formed recesses 81 and 83, formed in cancellous member 12.

In Figures 16 and 17, the load bearing member 30 is formed with a bulbous or truncated ellipsoid projection 90 which fits into a similarly configured recess 92 of the cancellous member 12. In Figures 18 and 19, the construction of Figure 16 is shown with-two angled bores 94 and 96, cut through the load bearing member 30 and into the cancellous member 12 holding pins and 97.

Another modification of the invention is shown in Figures 20 and 21 in which a COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-207 14:30 A J PARK 64 9 3566990 P.14 1 O widened dove tail mating member 100 extends from the load bearing member 30. This widened dove tail member is at least double the size ofthe originally shown dove tail member in Figure 1 and l' fits into a similarly sized recess 102 in cancellous meber 12 as shown in Figure 21. An added S feature to the Figare 20 embodiment discloses a bore 110 is cut through the load bearing member and centered on the widened dove tail 102. The throughgoing bore 110 holds pin 114.

C A double sided load bearing implant is shown in Figures 24 through 29. In this 00 embodiment, the load bearing members 30 and 130 are mounted on opposite sides of the cancellous o member 12 which has coiresponding recesses 132 and 134 to hold dove tail projections 133 and 135. The cacellous member 112 is substantially I shaped Additional component security can be Saccomplished by providing two throughgoing bores 140 and 142 to bold respective pins 141 and C' 143, as is showninFigures 26 and 27. A pin variation is shown in Figures 28 and 29. This variation uses a single bore 150 running through the center midpoint of the load bearing members 30 and 130 and the central stem of the I shaped member 112. A pin 152 is inserted into the aligned bore 150.

It should be noted that all ofthe embodiments shown in Figures 1 through 29, that the sidewalls of the cancellous member are tapered from 1000 to 110° and when two facing load bearing members and 130 are utilized that member 130 has a smaller inner flat surface 136 than the flat surface 138 of load bearing member 30 withthe respective member 130 having a smaller area size than the load bearing member While the embodiments shown in Figures 1 through 23 have a volumetric ratio in which the load bearing member accounts from 10% to 40% of the mass volume of the composite, the double load bearing embodiment shown in Figures 24 through 29 has a higher volumetric mass in that the load bearing surfaces account for about 30% to about 45% of the total vohame of the component.

While this operation has been discussed in terms of using the prefeed embodiment namely, llograf cortical andcancellous component members ofthe bone blocks, alternative sources ofthe components ofthe components ofthe bone blocks may be substituted such as xenograft bone or synthetic graft materials. With any of these alternatives, the bone blocks may be shaped as described above. The devices provide the surgeon with a graft that has the combined and best characteristics of both cortical and cancellous bone materials.

The cancellous component can be of partially demineralized or mineralized bone and the load bearing component can be fbrmed of partially srface demineralized or mineralized bone.

COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-200l7 14:31 A J PARK 64 9 3566990 11 0 O The spacers of the present invention were prepared by machining cancellous bone from donors, preferably under 45 years of age which have a denser cancellous structure. Suitable c- bones which canbe used are calcaneus patella, femoral head, long bone condyles and talus. Cortical o bone was prepared by machining and was taken from any acceptable donor age. Suitable bones are the radius, ulna, femur, tibia, humerus and the talus.

C4 The unique features ofallograft bone that make it desirable as a surgical material are, 0_ its ability to slowly resorb and be integrated into the space it occupies while allowing the bodies own c healing mechanism to restore the repairing bone to its natural shape and function by a mechanism Ci known in the art as creeping substitution.

ro It is well known that bone contains osteoinductive elements known as bone C, morphogenetic proteins (BMP). These BMP's arepresent withinthe compound structure ofcortical bone and are present at a very low concentrations, e.g. 0.003%. The BMP's are present in higher concentrations in cancelious bone. BMP's direct the differentiation ofpluripotential esenchymal cells into osteoprogenitor cells which form osteoblasts. The ability of freeze dried demineralzed bone to facilitate this bone induction principle using BMP present in the bone is well known in the art. However, the amount ofBMP varies in the bone depending on the age of the bone donor and the bone processing. Based upon the work of Marshall Urist as shown in United States Patent Number 4,294,753, issued October 13, 1981 the proper demineralization of cortical bone will expose the BMP and present these osteoinductive factors to the surface of the demineralized material rendering it significantly more osteoinductive. The removal of the bone mineral leaves exposed portions ofcollagen fibers allowing the addition ofBMP's and other desirable additives to be introduced to the demieralized outer treated surface ofthe bone structure and thereby enhances the healing rate of the cortical bone in surgical procedures. In cancellous bone the structure is not as dense as cortical boe exposing the naturally occurring BMP's rendering the entire structure with biological properties similar to full demineralized bone (DBM).

It is also possible to add one or more rhBMP's to the bone by soaking and being able to use a significantly lower concentration ofthe rare and expensive recombinant human BMP to achieve the same acceleration of biointegration. The addition of other useful treatment agents such as vitamins, hormones, antibiotics, antiviral and other therapeutic agents could also be added to the bone.

Any number of medically useful substances can be incorporated in the cancellous component member or load bearing member by adding the medically useful substances to the same.

Such substances include colagen and insoluble collagen derivatives, hydroxyapatite and soluble COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JLL-2007 14:31 A J PARK 64 9 3566990 P.16 12 0 o solids and/or liquids dissolved therein. Also included are antiviricides suchasthose effective against MV and hepatitis; antimicrobial and/or antibiotics such as erytbromycin, bacitracin, neomycin, penicillin, polymyxin B, tetracycline, viomyci, chloromycetin and streptomycin, cefazolin, o ampicillin, azactam, tobramycin, clindamycin, gentanmycin and silver salts. It is also envisioned that amino acids, peptides, vitamins, co-factors for protein synthesis; hormones; endocrine tissue or tisse fragments; synthesizers; enzymes such as collagenase, peptidases, oxidases; polymer ceilpl 00 scaffolds with parenchymal cells; angiogenic drugs and polymeric carriers containing such drugs; n collagenlattices; biocompatible surface active agents, antigenic agents; cytoskeletalagents; cartilage 0 fragments, living cells and cell elements such red blood cells, white blood cells, platelets, blood plasma, pluripotentialcells, chondrocytes, bone marrow cells, mesenchymal stem cells, osteoblasts, Sosteoclasts and fibroblasts, epithelial cells and endotbelial cells present as a concentration of I W and 106 per cc ofacarrier, natural extracts, tissue transplants, bioadhesives, transforming growth factor (TGF-beta), insulin-like growth factor (IGF- platlet derived growth factor (PDGF), fibroblast growth factor (FOF) (numbers 1-23), osteopontin, vascular endothelial growth factor (VEGF), growthhormones suchas somatotropin, cellular attractants and attachment agents, blood elements; natural extracts, tissue transplants, bioadhsives, bone digestors; antitamor agents; fibronectin; cellular attractants and attachment agents; immuno-suppressants; permeation enhancers, e.g. fatty acid esters such as laureate, myristate and stearate monoesters of polyethylene glycol, enamine derivatives, aipha-keto aldehydes can be added to the composition.

Whilethe present invention is described for use inthe cervicalspine, itis also suitable for use in the lumbar and/or thoracic spine. Th implant can be provided in avariety of sizes, each size configured to be inserted between a specific pair of adjacent vertebrae. For example, the implant can be provided in selected dimensions to maintain disc height, correct lordosis, kyphosis or other spinal deformities.

Theprinciples, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention should not be construed as limited to the particular embodiments which have been described above. Instead, the embodiments described here should beregarded asillustrative rather than restrictive. Variations and changes may be made by others without departing fromthe scope of the present invention as defined by the following claims: COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10

Claims (13)

10-JUL-20007 14:32 A J PARK 64 9 3566990 P.17 13 "What is claimed is: 3 1. A sterile composite graft comprising: a first cancellous bone component member and a second load bearing component member mounted to said first cancellous bone component, said load bearing component member presenting a smaller exposed area than the exposed area ofthe first cancellous member, said cancellous bone component Cl member defining an enlargement surface witha shaped recess cut into said engagement surface into 00 the interior ofthe cancelleous bone component member with at least aportion ofsaid shaped recess Ce Sbeing larger than the opening leading to the shaped recess, said load bearing component member derfiing an outer base portion wit an inner engagement surface and a locking member extending Soutward from said engagement surface, said locking member being configured with a distal portion being larger than its proximal portion to fit into said shaped recess holding said first and second component members together in a mated relationship. 2. A sterile composite graft as claimed in claim 1 wherein said first cancellous member is constructed ofallograft cancellous bone are taken from a group ofbones consisting ofa cancelous patela, femoral head, long bone condyles and talus. 3. A sterile composite graft as claimed in claim 1 wherein said load bearing component member is cortical bone- 4. A sterile composite graft as claimed in claim 1 wherein said caucellous bone component is constructed ofxenograftt cancellous bone. A sterile composite graft as claimed in claim 1 wherein said load bearing component is constructed of ceramic. 6. A sterile composite graft as claimed in claim 1 wherein said load bearing component is constructed ofbioabsorbable polymers. 7. A sterile composite graft as claimed in claim I wherein said locking member has a dove tail configuration and said shaped recess has a corresponding dove tail configuration. 8. A sterile composite graft as claimed in claim 1 wherein at least one of said graft component COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 1-JUL-2007 14:32! A J PARK 64 9 3566990 P.18 14 0 o members include a cellular material additive taken from a group consisting of living cells and cell elements such red blood cells, white blood cells, platelets, blood plasma, pluripotential cells, -cdaondrocytes, bone marrow cells, mesenchymal stemcells, osteoblasts, osteoclasts and fibroblasts, epithelial cells and endothelial cells present as a concentration of 10' and 10 6 per cc of a carrier. C' 9. A sterile composite graft as claimed claim 1 wherein at least one of said graft components 00 include an additive taken from a group of growth factors consisting oftransforming growth factor cn (TGF-beta), insulin-like growth factor platlet derived growth factor (PDGF), fibroblast CN growth factor (FGF) (numbers 1-23), osteopontin, vascular endothelial growth factor (VEGF), Sgrowth hormones such as somatotropin cellular attractants and attachment agents. A sterile composite graft as claimed claim I wherein at least one of said graft component members include an additive taken from a group of additives consisting of antimicrobials such as effective against IV and hepatitis; antimicrobialand/or antibiotics such as erythromycin bacitracin, neomycin, penicillin, polymyxin B, tetracycline, viomycin, chloromycetin and streptomycin, cefazolin, ampicillin, azactam, tobramycin, clindamycin, geatamycin and silver salts. 11 A sterile composite graft as claimed in claim 1 including pin means mounted in sid cancellous bone component member and said load bearing component member.

12. A sterile composite graft as claimed inclaim 11 wherein said pin means comprises a plurality of pins mounted through said load bearing member and seated in blind bores formed in said cancellous member.

13. A sterile composite graft as claimed in claim 11 wherein said pin means comprise a single pin mounted in a throughgoing bore cut through said cancellous bone component member and said load bearing component member.

14. A sterile composite graft as claimed in claim 1 wherein said locking member of said load bearing member is a truncated ellipsoid. 1 A sterile composite graft as claimed in claim 1 including a second load bearing member mounted to said cancellous member so that said graft has two load bearing members, one on each COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 1-JUL-2007 14:32 A J PARK 64 9 3566990 P.19 0 0 C, end of said cancellous member.

16. A sterile composite grat as claimed in can 1 wherein said load bearing member has at least two locking members of the same configuration which extend from the inner engagement surface of said load bearing member and are seated in corresponding formed recesses in said cancellous l member. 00 o 17. A sterile composite graft as claimed in claim 1 wherein said load bearing member has a r- ssubstantially T shaped configuration c 18. A sterile composite graft as claimed in claim I wherein said cancellous member has a substantially U shaped configuration.

19. A sterile composite graft comprising: acancellous bone component member and a load bearing component member, said cancellous bone component member having a planar outer surface and definig a shaped recess cut into said planar outer surface into the interior of the cancelleous bone component member, said load bearing component member having a T shaped configuration with a flat inner surface on the base of the crosspiece and a stem extending outward from said crosspieco flat surface, said stem being configured with a distal portion being larger than its proximal portion to fit into said shaped recess holding said component members together in a mated relationship. A sterile composite graft as claimed in claim 19 wherein said component members define bores which are axially aligned when the component members are mated together.

21. A sterile composite graft as claimed in claim 20 wherein a pin is mounted in said axially aligned bores, said pin extending across an intersection between said first cancellous bone component number and said second load bearing component member.

22. A sterile composite graft comprising: a cancellous bone component member and cortical bone component member, said cancellous bone component deining a U shaped configuration with the ends of the legs of the U defining a flat surface and the interior of the U forming a shaped recess, said cortical bone component member COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 10-JUL-2007 14:33 A J PARK 64 9 3566990 16 o defining a flat inner surface which seats on said cancellous bone component member legs flat surfaces and a mating member extending from said flat inner surface, said mating member being Z configured to fit into said shaped recess holding a first and second bone components together. 0

23. A sterile composite graft as claimed claim 22 wherein at least one of said graft components include an additive taken from a group of living cells and cell elements consisting of red blood cells, 00 white blood cells, platelets, blood plasma, pluripotential cells, chondrocytes, bone marrow cells, eC mesenchymal stem cells, osteoblasts, osteoclasts and fibroblasts, epithelial cells and endothelial cells 0, present on a concentration of 10 a and 10 per cc ofa carrier. O 24. A sterile composite graft as claimed in claim 22 wherein said component members each define bores which are axially aligned when the component members are mated together. A sterile composite graft as claimed in claim 24 wherein a pin is mounted in said axially aligned bores, said pin extending across an intersection between said first cancellous bone component nmber and said second load bearing component member.

26. A sterile composite graft as claimed in claim 22 wherein said mating member has a dove tail configuration and said shaped recess has a corresponding dove tail configuration.

27. A sterile composite graft as claimed in claim 22 wherein said mating member is a truncated ellipsoid and said shaped recess has a corresponding truncated ellipsoid configuration.

28. A sterile composite bone graft for use in implants comprising: a load bearing member constructed ofallograft cortical bone defining a planar surface and a dove tail mating shaped member extending from said planar surface, an allograft cancellous member defning tapered side walls, a flat proximal end surface and a flat distal end surface and a dove tail shaped recess cut into said flat proximalend surface with the narrowest portionofsaid recess exiting said flat proximal end surfce, said load bearing member and cancellous member being mated together and pin means extending into said load bearing member and said cancellous member.

29. A sterile composite graft comprising: a cancellous bone component member and two end cortical bone component members mounted to COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10 1-JUL-207 14:33 A J PARK 64 9 3566990 P.21 17 0 0 said cancellous bone component members, said cancellous bone component definig a flat surface Son each ed with at least one dovetail shaped recess formed in each end surface, each corticalbone component member defining a flat inner surface which seats on said cancellous bone component member end flat surface so that said cortical component uembers are opposite each other and at least one dove tail shaped mating member extending from said flat inner surface, each dove tail C mating member being configured to fit into a corresponding dove tail shaped recess holding said 00 Sbone components together. Ci, Asterile composite graft as claimed in claim29 wherein sid ancellous member has tapered Sside walls. cO COMS ID No: ARCS-152152 Received by IP Australia: Time 12:34 Date 2007-07-10