This material has extremely attractive mechanical properties for an orthopedic implant. Its elasticity modulus is similar to cortical bone, making it attractive for implant-bone stress transfer. One preliminary study of articulating pyrocarbon on pyrocarbon finger joint implants in primates showed no evidence of wear or wear-related debris, no signs of inflammatory reaction and superior bone-implant incorporation. Results (Short, mid, and long-term) included increased range of motion, pain relief, acceptable biological fixation and limited complications. (Source: Journal of Bone and Joint Surgery, Volume 81-A, Number 5, May 1999: Long-Term Follow-up of Pyrolytic Carbon Metacarpophalangeal Implants Author S. Cook Ph.D.(et al.))
The biocompatibility of pyrocarbon has been well established through its successful use in heart valves, and has been extrapolated to orthopedic applications. The elastic modulus eliminates stress shielding and bone necrosis seen with metal implants. Its interface strength in bone, as measured by the push-out test, is on the order of 1 to 2 MPa (vacuum pressure measurement), one order of magnitude lower than metal implants. Bone growth onto pyrocarbon is termed appositional rather than in-growth. (Source: Journal of Applied Biomaterials, Volume 6, 243-248 (1995): Mechanical and Histological Fixation of the Hydroxylapatite – Coated Pyrolytic Carbon and Titanium Alloy Implants: A Report of Short-Term Results. Author V. Hetherington (et al.).)
