REFERENCE BIOMATERIAL FOR ORTHOPEDIC RESEARCH.

Reference Material (RM) 8456, an orthopedic grade Ultra High Molecular Weight Polyethylene (UHMWPE), became available in October 2000. RM 8456 is intended primarily for use in mechanical characterization of material properties and laboratory-simulated performance of orthopedic joint replacement implants. The availability of this reference polyethylene is expected to aid in development of improved test methods and materials by providing a benchmark for comparisons. The need for this reference biomaterial was identified at a workshop on reference biomaterials held at NIST and its development was the result of collaboration among a materials supplier, the orthopedic research community, and NIST.

The material used to prepare RM 8456 was donated by a private company in a form similar to that from which many orthopedic components are machined: a cylindrical bar with nominal dimensions of 7.62 cm in diameter. Reference properties, reported as mean values with their expanded uncertainties, are Young's modulus, tensile yield strength, tensile ultimate strength, and tensile elongation-to-failure. These properties characterize the bar across the center 5.62 cm of its diameter and down the entire bar length. Material beyond the central 5.62 cm was found to differ significantly from that within.