Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
2002-08-27
2004-02-24
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S423000, C424S443000, C424S484000, C424S623000, C623S016110
Reexamination Certificate
active
06696073
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to osteoimplants and their use in the repair of bone defects and injuries. More particularly, the invention relates to a load-bearing composite osteoimplant which can assume any of a wide variety of configurations, methods for their manufacture and the use of the osteoimplants for the repair of hard tissue.
BACKGROUND OF THE INVENTION
Shaped or cut bone segments have been used extensively to solve various medical problems in human and animal orthopedic surgical practice, and their application has also extended to the field of cosmetic and reconstructive surgery, dental reconstructive surgery, and other medical fields involving surgery of hard tissues. The use of autograft bone (where the patient provides the source), allograft bone (where another individual of the same species provides the source) or xenograft bone (where another individual of a different species provides the source) is well known in both human and veterinary medicine. In particular, transplanted bone is known to provide support, promote healing, fill bony cavities, separate bony elements (such as vertebral bodies), promote fusion (where bones are induced to grow together into a single, solid mass), or stabilize the sites of fractures. More recently, processed bone has been developed into shapes for use in new surgical applications, or as new materials for implants that were historically made of non-biologically derived materials.
Bone grafting applications are differentiated by the requirements of the skeletal site. Certain applications require a “structural graft” in which one role of the graft is to provide mechanical or structural support to the site. Such grafts contain a substantial portion of mineralized bone tissue to provide the strength needed for load-bearing. The graft may also have beneficial biological properties, such as incorporation into the skeleton, osteoinduction, osteoconduction, or angiogenesis.
Structural grafts are conventionally made by processing, and then cutting or otherwise shaping bones collected for transplant purposes. The range of bone grafts that might be thus prepared is limited by the size and shape limitations of the bone tissue from which the bone graft originated. Certain clinically desirable shapes and sizes of grafts may thus be unattainable by the cutting and shaping processes, due to the dimensional limitations of the bone. For some shapes they may also be available only in limited amounts, due to the large variations inherent in the human or animal donor source populations.
Many structural allografts are never fully incorporated by remodeling and replacement with host tissue due, in part, to the difficulty with which the host's blood supply may penetrate cortical bone, and partly to the poor osteoinductivity of nondemineralized bone. To the extent that the implant is incorporated and replaced by living host bone tissue, the body can then recognize and repair damage, thus eliminating failure by fatigue. In applications where the mechanical load-bearing requirements of the graft are challenging, lack of replacement by host bone tissue may compromise the graft by subjecting it to repeated loading and cumulative unrepaired damage (mechanical fatigue) within the implant material. Thus, it is highly desirable that the graft have the capacity to support load initially, and be capable of gradually transferring this load to the host bone tissue as it remodels the implant.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an osteoimplant possessing sufficient strength in a body fluid environment to enable the osteoimplant to bear loads.
It is a further object of the present invention to provide a load-bearing osteoimplant which contains pores or cavities which permit the osteoimplant to be revascularized and incorporated by the host.
It is yet a further object of the present invention to provide a load-bearing osteoimplant which is osteogenic and thereby promotes new host bone tissue formation within and around the osteoimplant.
It is yet another object of the invention to provide a load-bearing osteoimplant which supports load initially and is capable of gradually transferring this load to the host bone tissue as it remodels the osteoimplant.
It is yet another object of the invention to provide a load-bearing osteoimplant containing a reinforcing component.
It is yet an even further object of the present invention to provide methods for the manufacture of osteoimplants of any size and/or configuration ranging from the relatively simple to the relatively complex.
It is yet an even further object of the present invention to provide methods for the manufacture of bone-containing osteoimplants which are not limited by constraints imposed by the shape and/or size of the bone tissue from which the osteoimplants are manufactured.
It is still another object of the invention to provide tissue-engineered bone manufactured from one or more synthetic materials and tissue obtained from various sources such as transgenic animals, plants and microorganisms.
It is yet another object of the invention to provide an integral implant insertion instrument and implant possessing an implant portion in accordance with the invention which, following its implantation in the body, is separated from the insertion portion of the instrument.
These and further objects of the invention are obtained by a load-bearing osteoimplant which comprises a shaped, coherent aggregate of bone particles.
The load-bearing osteoimplant of this invention is fabricated by the method which comprises providing an aggregate of bone particles, optionally in combination with one or more additional components, and shaping the mass into a coherent unit of predetermined size and shape employing at least one or more processes such as extruding, molding, -solvent/gel casting, machining, computer aided design and computer aided manufacturing (CAD/CAM), and the like.
The bone particles utilized in the fabrication of the osteoimplant of this invention are selected from the group consisting of nondemineralized bone particles, demineralized bone particles and combinations thereof. The bone particles are remodeled and replaced by new host bone as incorporation of the osteoimplant progresses in vivo. As described more fully hereinbelow, the bone particles can be fully demineralized by removing substantially all of their inorganic mineral content, they can be partially demineralized by removing a significant amount, but less than all, of their inorganic mineral content or they can be superficially demineralized by confining the removal of inorganic mineral to just the surface of the bone particles.
The term “osteoimplant” as utilized herein contemplates any device or material for implantation that aids or augments bone or other hard tissue formation or healing for human or animal use. Osteoimplants are often applied at a bone defect or dental repair site, e.g., one resulting from injury, defect brought about during the course of surgery, infection, malignancy or developmental malformation. Therefore, osteoimplants are envisioned as being suitably sized and shaped as required for use in a wide variety of orthopedic, neurosurgical, oral and maxillofacial and dental surgical procedures such as the repair of simple and compound fractures and non-unions, external and internal fixations, joint reconstructions such as arthrodesis, general arthroplasty, deficit filling, discectomy, laminectomy, anterior cervical and thoracic operations, spinal fusions, dental restorations, etc. Therefore, the osteoimplants herein are intended for implantation at a bony site and, in addition to bone particles, can contain one or more other components, e.g., binder (adhesive), filler, biologically active component, reinforcing component or reinforcing structure, coupling agent, as described in U.S. Pat. No. 6,399,693, the contents of which are incorporates by reference herein, -and the like.
The term “shaping” refers to any of the various methods that can be used, individually or in combina
Boyce Todd M.
Manrique Albert
Shimp Lawrence
Winterbottom John M.
Dilworth & Barrese LLP
Ghali Isis
Osteotech Inc.
Page Thurman K.
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