Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1999-08-03
2001-03-13
Hirsch, Paul J. (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S011110
Reexamination Certificate
active
06200347
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to bone grafts and more particularly, to bone grafts useful for spinal fusion. The invention provides a composite bone graft for implantation in a patient, and methods of making and using the composite bone graft. The composite bone graft contains two or more distinct bone portions where the bone portions are connected. The bone portions are preferably self-locking, interlocking, and/or connected by at least one mechanical connector, including for example, a bone pin. One or more of the bone portions may be demineralized, and may also be continuous or discontinuous. The composite bone graft may include one or more textured surfaces, preferably including a plurality of closely spaced protrusions. The composite bone graft is useful for repairing bone defects caused by congenital anomaly, disease, or trauma, and is particularly useful for spinal fusions. The composite bone graft can be appropriately sized for any application and can be used to replace traditional non-bone prosthetic implants. The composite bone graft promotes the growth of patient bone at an implantation site by promoting osteoinductivity and cellularization, provides added stability and mechanical strength, and does not shift, extrude or rotate, after implantation.
BACKGROUND OF THE INVENTION
In the field of prosthetic implants, materials often used include bone grafts and implants produced from non-bone materials, including for example stainless steel, titanium and plastics. The choice of whether to use a bone or a non-bone implant often depends on the clinical indication, implant site, whether the implant is load-bearing, and the size of the implant needed.
Prior to the present invention, the use of bone grafts versus non-bone prosthetic implants to for example, support and fuse together adjacent vertebrae, has been limited in part by the physical size of a cortical bone graft. Interbody bone grafting involves the problem of strength. Strong cortical bone (the outer layer) is required as a strut in the interbody position to prevent collapse of the disc space while healing occurs. For example, cortical bone obtained from a cadaver source fashioned into struts, is not wide enough for optimum load bearing. This natural limitation often excludes the use of a bone graft product.
The success or failure of a bone graft further depends on whether the bone graft remains at the implant site, is cellularized, and whether it can withstand the mechanical load. In spinal surgery, there are two primary indications for use of allograft bone: (1) when there is insufficient available autograft bone, and (2) in spinal fusion procedures when a structural element in needed. Typically, bone grafts are affixed at an implant site by fusion. Bone grafts for spinal applications often fail because they are extruded from the implantation site due to shifting, rotation, and slippage of the graft, are not cellularized, or fail mechanically.
The invention enables the use of bone grafts for applications normally suited for only non-bone prosthetic implants. The invention solves the problem of graft failure by providing a composite bone graft which can be appropriately sized for any application out of for example, strong cortical bone; promotes the ingrowth of patient bone at an implantation site by promoting osteoinductivity and cellularization; provides added stability and mechanical strength; and does not shift, extrude or rotate; after implantation.
SUMMARY OF THE INVENTION
The present invention is directed to a composite bone graft for repairing bone defects caused by congenital anomaly, disease, or trauma, including for example, for restoring vertical support of the posterior and/or anterior column. The present composite bone grafts can be used as structural grafts placed posteriorly in the spine as interbody grafts or as strut grafts spanning multiple segments. Posterior composite bone grafts can be used to supplement autologous bone for spinal fusions in patients who lack sufficient host bone and to avoid significant donor site morbidity. The present composite bone grafts can be used for applications normally suited for only non-bone prosthetic implants because the composite bone graft can be appropriately sized for any application and has adequate mechanical strength.
The invention provides a composite bone graft including a plurality of bone portions layered to form a graft unit, and one or more biocompatible connectors for holding together the graft unit.
The invention also provides a composite bone graft including two or more distinct bone portions, and one or more biocompatible connectors, where the biocompatible connectors hold together the two or more bone portions to form the composite bone graft.
The present invention provides a composite bone graft including two or more connected, distinct bone portions.
The present invention provides a composite bone graft including three or more connected, distinct bone portions.
The present invention provides a composite bone graft including three or more connected, distinct cortical bone portions.
The present invention provides a composite bone graft including one or more horizontally disposed channels provided through the composite bone graft perpendicular to the interfaces of the bone portions.
The present invention also provides a composite bone graft including one or more vertically disposed channels provided through the composite bone graft parallel to the interfaces of the bone portions.
The present invention further provides a composite bone graft including one or more horizontally disposed channels and vertically disposed channels where the one or more channels includes one or more therapeutically beneficial substances.
The invention further provides a composite bone graft including two or more connected bone portions, where the bone portions can include cortical bone and cancellous bone.
The invention also provides a composite bone graft, including a first bone portion, a second bone portion, a third bone portion, the first, second and third bone portions are disposed one on the other (ie. layered) to form a graft unit; and one or more biocompatible connectors for holding together the graft unit.
The invention provides a composite bone graft, including a first cortical bone portion, a second cortical bone portion, a cancellous bone portion disposed between the first cortical bone portion and the second cortical bone portion to form a graft unit, and one or more biocompatible connectors for holding together the graft unit.
The invention further provides a composite bone graft, including a first cortical bone portion, a second cortical bone portion provided on the first cortical bone portion to form a graft unit; and one or more biocompatible connectors for holding together the graft unit.
The invention provides a composite bone graft, including a plurality of layered cortical bone portions forming a graft unit, and one or more biocompatible connectors for holding together the graft unit.
The invention provides a composite bone graft, including a plurality of layered bone portions forming a graft unit, and one or more biocompatible connectors for holding together the graft unit.
The invention also provides a composite bone graft, including a first bone portion, a second bone portion provided on the first bone portion to form a graft unit, and one or more biocompatible connectors for holding together the graft unit.
The invention provides a composite bone graft including a plurality of distinct bone portions, where one or more of the bone portions are demineralized.
The invention provides a composite bone graft including a plurality of distinct bone portions, where one or more of the bone portions are continuous or discontinuous.
The invention further provides a composite bone graft including a plurality of distinct bone portions where one or more of the bone portions include a discontinuous bone portion, the discontinuous bone portion including one or more therapeutically beneficial substances including but not limited to, for example,
Anderson Billy G.
Wolfinbarger, Jr. Lloyd
Hirsch Paul J.
Hopkins Susanne M.
Lifenet
Priddy Michael B.
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