Mechanical rib testing and geometric analysis were explored as means of evaluating metabolic bone disease. Seventy-nine male patients were examined postmortem. Displacement rate at the loading point and patient age were important variables for which results had to be corrected. Like long bones, ribs apparently undergo progressive circumendosteal resorption with advancing age but unlike long bones, they show no evidence of continued subperiosteal apposition. Effects of selected individual diseases and of all diseases grouped by major organ system were analyzed. Most produced no discernible modification of rib volume, geometry or bending strength as quantified by modulus of rupture. Exceptions were myeloma and arthritis, where the bony material was weakened without remodeling or loss in volume.

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Radiographically normal vertebral bone cylinders from 80 male subjects were tested mechanicallly by static compression and analyzed for porosity, fluoride and ash content. As a group, they had low fluoride content, suggesting little prior intake, consonent with this geographic area. Nevertheless, increasing levels of fluoride were associated with bulkier bone, less porosity, and less mineral per unit of bone, which in direction though not degree suggested changes similar to those of osteomalacia and opposite from those of osteoporosis without apparent threshold. The higher fluoride hard tissue was weaker in static tests than that with less fluoride, but the increased bulk apparently offset this, resulting in bones of unchanged static strength. Hence, water fluoridation should not alter static bone strength. There has, however, been a recent report suggesting that increased mineralization of bone renders it more brittle and thus more likely to fracture on impact. Therefore, the possibility that fluoridation may increase impact resistance by lessening mineralization can be entertained.

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