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On-X Carbon and Orthopedic Applications


On-X carbon has physical and mechanical properties that make it particularly well-suited for use in a number of orthopedic medical implant device applications. Some properties that may be of interest include:

Stiffness Similar to Bone

The modulus of elasticity of On-X carbon is similar to cortical bone. It can eliminate bone resorption caused by “stress shielding” often encountered when stiffer metallic or ceramic implants are inserted in bone.1-4

Cartilage Friendly

On-X carbon is well suited for interfacing with cartilage. It produces less cartilage wear than other commonly used orthopedic implant materials.5

Wear Resistant

The articulation of On-X carbon on itself has proven to be durable without the debris related problems that can occur between metals and polymers.6

Fatigue Resistant

Unlike other commonly used implant materials, On-X carbon does not fail in fatigue.6

On-X carbon is a structural pyrolytic carbon coating that is most often deposited on a graphite substrate pre-form. Alternatively for some geometries, deposition techniques can be employed to produce components of solid On-X carbon. Pyrolytic carbon or pyrocarbon as it is sometimes called is produced by the pyrolysis of a gaseous hydrocarbon in a fluidized bed using sophisticated computerized process controls. Required thickness of the deposited carbon depends on the design requirements of the product.

The surface can be polished to a high gloss where articulation or thromboresistance is required. The surface can also be left in an as deposited state providing some surface topography for bone or tissue in-growth.

On-X carbon will play an important role in the restoration of lost body functionality, particularly with the expanding needs of an aging population for prosthetic devices.


  1. Reilly DT and Burstein AH. J. Bone Joint Surg., 56-A, 1001 (1974)
  2. Walker PS. “Human Joints and Their Artificial Replacements, Springfield, Charles C. Thomas, 1977
  3. Piekarski K. J. Appl. Physics, 41, 215 (1970)
  4. Bokros, JC. New Material Concept in Orthopedics, Sampe Journal, July/August 1984
  5. Cook SD, Thomas KA, Kester MA. Wear Characteristics of the Canine Acetabulum Against Different Femoral Prostheses. Journal of Bone and Joint Surgery. Vol 71-B, No. 2. March 1989
  6. Bokros JC, Haubold AD, Akins RJ, Capbell LA, Griffin CD, Lame E. The durability of mechanical heart valve replacements in Replacement Cardiac Valves, Bodner Frater RWM editors 1991 Pregamon Press Inc. (New York pp21-48)