An experiment was performed to determine the relative contribution of the cortical shell and of the central trabecular bone to the peak, non-destructive compressive strength of excised human lumbar vertebrae. The vertebral “units” tested utilized the adjacent intervertebral discs to distribute the loads. Among other results the study indicated that (1) the cortex generally contributes 45–75% of the peak strength, regardless of percent ash or physical density of the trabecular bone; (2) when the ash content of a vertebral trabecular bone is <59%, only 40% or less of the forces are transmitted directly by the central trabecular bone. When the ash content exceeds 59, >40% of the forces are transmitted via the central trabeculae and, as would be expected, (3) less force is transmitted by way of the central trabeculae in older subjects than in those ≦40 years of age.
Keywords: Bone strength; Vertebral strength; Vertebral cortex; Vertebral; Trabecular bone