Topographical distribution of trabecular bone strength in the human os calcanei

Mechanical properties of twenty human os calcanei were determined by uniaxial compression testing of bone specimens from facies articularis talaris posterior, facies articularis cuboidea, and tuber calcanei. Specimens were taken oriented perpendicular to the planes of the facies articularis, and in tuber along the presumed loading axis throughout the gait cycle. Young's modulus and strength at facies articularis cuboidea and facies articularis talaris posterior were about three times those at the tuber calcanei. The variation of the relationship between Young's modulus and apparent density indicated differences in the orientation of the trabecula, in relation to the direction of evaluation between these locations. A more detailed analysis of the topographical variation of strength within each location was made using penetration testing of a further nineteen specimens. The results of both types of measurements indicated that the major part of the load during walking is carried by facies articularis talaris posterior and facies articularis cuboidea.