Osseointegration (from Latin osseus "bony" and integrare "to make whole") is the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant ("load-bearing" as defined by Albrektsson et al. in 1981). A more recent definition (by Schroeder et al.) defines osseointegration as "functional ankylosis (bone adherence)", where new bone is laid down directly on the implant surface and the implant exhibits mechanical stability (i.e., resistance to destabilization by mechanical agitation or shear forces). Osseointegration has enhanced the science of medical bone and joint replacement techniques as well as dental implants and improving prosthetics for amputees.
Definitions Osseointegration is also defined as: "the formation of a direct interface between an implant and bone, without intervening soft tissue". An osseointegrated implant is a type of implant defined as "an endosteal implant containing pores into which osteoblasts and supporting connective tissue can migrate". Applied to oral implantology, this refers to bone grown right up to the implant surface without interposed soft tissue layer. No scar tissue, cartilage or ligament fibers are present between the bone and implant surface. The direct contact of bone and implant surface can be verified microscopically. Osseointegration may also be defined as:
Osseous integration, the apparent direct attachment or connection of osseous tissue to an inert alloplastic material without intervening connective tissue. The process and resultant apparent direct connection of the endogenous material surface and the host bone tissues without intervening connective tissue. The interface between alloplastic material and bone.
History
Osseointegration was first observed—albeit not explicitly stated—by Bothe, Beaton, and Davenport in 1940. Bothe et al. were the first researchers to implant titanium in an animal and remarked how it tended to fuse with bone. Bothe et al. reported that due to the elemental nature of the titanium, its strength, and its hardness, it had great potential to be used as future prosthesis material. Gottlieb Leventhal later described osseointegration in 1951. Leventhal placed titanium screws in rat femurs and said, "At the end of 6 weeks, the screws were slightly tighter than when originally put in; at 12 weeks, the screws were more difficult to remove; and at the end of 16 weeks, the screws were so tight that in one specimen the femur was fractured when an attempt was made to remove the screw. Microscopic examinations of the bone structure revealed no reaction to the implants, the trabeculation appeared to be perfectly normal." The reactions described by Leventhal and Bothe et al. would later be coined into the term "osseointegration" by Per-Ingvar Brånemark of Sweden. In 1952, Brånemark did an experiment where he used a titanium implant chamber to study blood flow in rabbit bone. At the end of the experiment, he discovered that the bone had integrated so completely with the implant that the chamber could not be removed. Brånemark called this "osseointegration", and, like Bothe et al. and Leventhal before him, saw the possibilities for human use. In dentistry, the implementation of osseointegration started in the mid-1960s as a result of Brånemark's work. In 1965 Brånemark, who was at the time Professor of Anatomy at University of Gothenburg, placed dental implants into the first human patient—Gösta Larsson. This patient had a cleft palate defect and needed implants to support a palatal obturator. Gösta Larsson died in 2005, with the original implants still intact after 40 years of function. In the mid-1970s, Brånemark entered into a commercial partnership with the Swedish defense company Bofors to manufacture dental implants and the instrumentation required for their placement. Eventually an offshoot of Bofors, Nobel Pharma, was created to concentrate on this product line. Nobel Pharma subsequently became Nobel Biocare. Brånemark spent almost 30 years fighting the scientific community for acceptance of osseointegration as a viable treatment. In Sweden, he was often openly ridiculed at science conferences. His university ceased funding for his research, forcing him to open a private clinic to continue treating patients. Eventually, an emerging breed of young academics started to notice the work being done in Sweden. Toronto's George Zarb, a Maltese-born Canadian prosthodontist, was instrumental in bringing the concept of osseointegration to the wider world. The 1983 Toronto Conference is generally considered to be the turning point when finally the worldwide scientific community accepted Brånemark's work. Osseointegration is now a highly predictable and common treatment modality. Since 2010, Professor Munjed Al Muderis in Sydney, Australia, used a high tensile strength titanium implant with plasma sprayed surface as an intramedullary prosthesis that is inserted into the bone residuum of amputees and then connect through an opening in the skin to a robotic limb prosthesis. This lets amputees mobilize with more comfort and less energy consumption. Al Muderis also published the first series of combining osseointegration prosthesis with Joint replacement enabling below knee amputees with knee arthritis or short residual bone to walk without needing a socket prosthesis. On December 7, 2015, Bryant Jacobs and Ed Salau, two military veterans who fought in Operation Iraqi Freedom/Operation Enduring Freedom, became the first persons in the USA to get a percutaneous osseointegrated prosthesis. In the first stage, doctors at Salt Lake Veterans Affairs Hospital embedded a titanium stud in the femur of each patient. About six weeks later, they went back and attached the docking mechanism for the prosthesis.
Mechanism
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