PubMed · 15553277
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Bernadine Healy. 2004-11-01. Bones, beautiful bones.. https://pubmed.ncbi.nlm.nih.gov/15553277/
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Recent investigations of human skeletal material from the historic St. Martin's cemetery, England, found a range of abnormal lesions in six infants that are almost certainly related to scurvy. Porous and proliferative bone lesions affecting the cranial bones and scapulae were found, and this paper presents images obtained using both macroscopic and scanning electron microscope examination of the lesions. Previous work on infantile scurvy (Ortner et al., 1997-2001) relied heavily on changes at the sphenoid, which is often missing in archaeological bone, so the identification of changes attributable to scurvy on other cranial bones and the scapulae is encouraging. The ability to recognize changes related to scurvy on a range of bones will ensure an enhanced potential for recognition of this disease in future research involving archaeological bone. Research on historical documents from Birmingham dating to the eighteenth and nineteenth centuries, combined with the probable cases of scurvy identified, supports the view that the paucity of cases of infantile scurvy from the archaeological record reflects a lack of understanding and recognition of bone manifestations, rather than a lack of occurrence in this period. Changes linked to scurvy were only found in infants from the poorer sections of the community from St. Martin's, and this is almost certainly linked to patterns of food consumption and may be related to shortages of potatoes, due to blight, experienced during this period.
Gross and radiographic changes characteristic of inadequate bone mineralization due to rickets are described in 21 immature skeletons from a 19th century urban population from Birmingham, England. The aims of the study are as follows: to evaluate and if possible augment existing dry-bone criteria for the recognition of rickets in immature skeletal remains; to investigate the value of radiography for the paleopathological diagnosis of rickets; and to compare and contrast the expression of rickets in this group with that previously documented for a rural agrarian population from Wharram Percy, England. Some gross skeletal signs of rickets which were not previously well-documented in paleopathological studies are noted. The worth of radiography for evaluating structural changes to both cortical and trabecular bone in the disease is demonstrated, and features useful for the interpretation of vitamin D deficiency are discussed. The pattern of skeletal elements affected and the severity of changes differs in the Birmingham group from that seen in the comparative rural population. It is emphasized that a variety of factors may influence the expression of rickets in paleopathological material, including rate of skeletal growth, age cohort affected, and intensity of vitamin D deficiency. Nevertheless, careful analysis, not only of the frequency of rickets but also of the degree of severity of lesions and the patterning with respect to skeletal elements affected, may enable more nuanced understanding of the biocultural context of the disease in earlier populations.
Data for fracture in human humeral cortical bone are re-analyzed to assess the validity for this material of linear-elastic fracture mechanics (LEFM), which is the standard method of analyzing toughness and one basis for analyzing clinical data relating to bone quality. A nonlinear fracture model, which is based on representing the damage zone in the bone by a cohesive model, is calibrated against a number of sets of test data for normal (not diseased or aged) human cortical bone taken from cadavers. The data consist of load vs. load-point displacement measurements from standard compact-tension fracture tests. Conventional LEFM is unable to account for the shape of the load-displacement curves, but the nonlinear model overcomes this deficiency. Calibration of the nonlinear model against one data curve leads to predictions of the peak load and the displacement to peak load for two other data curves that are, for this limited test set, more accurate than those made using LEFM. Furthermore, prior observations of damage mechanisms in bone are incompatible with the modeling assumption of LEFM that all nonlinearity is confined to a zone much smaller than the specimen and the crack length. The predictions of the cohesive model and the prior observations concur that the length of the nonlinear zone in human cortical bone varies in the range 3-10 mm, which is comparable to or larger than naturally-occurring bones and the specimens used to test them. We infer that LEFM is not an accurate model for cortical bone. The fracture toughness of bone deduced via LEFM from test data will not generally be a material constant, but will take different values for different crack lengths and test configurations. The accuracy of using LEFM or single-parameter fracture toughness for analyzing the significance of data from clinical studies is called into question. The nonlinear cohesive zone model is proposed to be a more accurate model of bone and the traction-displacement or cohesive law is hypothesized to be a material property. The cohesive law contains a more complete representation of the mechanics of material failure than the single-parameter fracture toughness and may therefore provide a superior measure of bone quality, e.g., for assessing the efficacy of therapy for osteoporosis.