Tornier Inc. (Edina, MN) has just announced that the first implant of a shoulder arthroplasty comprised of pyrocarbon occured in France. This is not the first time we have covered the use of pyrocarbon, or pyrolytic carbon as it is commonly referred to, in medical devices, but it is a new application.
Pyrocarbon, developed as nuclear fuel cladding by General Atomics, has a structure similar to graphite, but with slightly different atomic bonding such that it gives it better durability in comparison to graphite. It has the advantage as an implantable biomaterial because it does not provoke blood clotting and can easily be made into geometries that mimic the natural elements that are being replacing. In terms of support and wear, the advantage of pyrocarbon is the elastic modulus, or its ability to deform when force is applied. Too hard, like in the case of ceramics, and this will cause an undue stress load on the natural bone, which can lead to premature aging and fracturing. Too soft, like in the case of polyethylene, and this can lead to deformation of the implant, excessive wear, the need for multiple replacements, and inflammation if wear particle break off from the implant. Pyrocarbon has an elastic modulus within the same region as that of bone which provides for a more natural fit. This is illustrated in the following force load diagram.
Tornier has a ten year history of pyrocarbon carpometacarpal implants for the base of the thumb, various interpositional implants for the wrist, and radial head implants for the elbow. The arthroplasty shoulder implant is a natural progression of pyrocarbon’s orthopedic device development.
Press release: Tornier Announces First Human Implant of Pyrocarbon Shoulder Arthroplasty Prosthesis…
Company site: Tournier
Flashback: Pyrolytic Carbon: Now and Then…
