Noninvasive estimation of bone mass in ancient vertebrae

Abstract

Histomorphometry is useful in the assessment of trabecular bone mass (TBM), and thus, in the estimation of the prevalence and intensity of osteopenia in ancient population groups. However, it is a destructive method. It is therefore necessary to explore the accuracy of nondestructive approaches, such as radiography, bone mineral density (BMD) assessed by double-energy X-ray absorptiometry (DEXA), bone density (BD), or optical density (OD) in the diagnosis of osteopenia. We selected 51 vertebrae out of a total sample composed of 333 T12, L1, and L2 vertebrae belonging to adult pre-Hispanic inhabitants from El Hierro. These vertebrae underwent histomorphometrical analysis, a fine-grained film radiography with assessment of trabecular pattern following standard methods, OD, DEXA-assessed BMD, and BD. The presence of biconcave vertebrae and wedge-shaped vertebrae was also assessed by measuring anterior height (a), posterior height (p), and height at the middle point of the vertebral body (m), and further calculating the indices 2m/(a + p) ("spine score") and a/p. Significant correlations were observed between TBM and BMD (r=0.43), TBM and BD (r=0.49), TBM and OD (r=0.52), BMD and OD (r=0.51), and BMD and BD (r=0.36), but not between TBM and the indices 2m/(a + p) and a/p. In the stepwise multiple correlation analysis between TBM and BMD, BD, and OD, OD entered into first place and BD into second place, whereas BMD became displaced; the multiple correlation coefficient was 0.63, with a standard error of 3.78. A BMD greater than 0.60 g/cm2, or a bone density greater than 0.60 g/cm3, excluded osteopenia (TBM <15%) with a specificity greater than 90%, whereas a BMD value less than 0.35 g/cm2, a BD less than 0.35 g/cm3, or optical density >1.6 excluded a normal bone mass (TBM >20%) with a specificity greater than 90%. Based on radiographic criteria on the total sample, we also conclude that the overall prevalence of vertebral fractures in the adult pre-Hispanic population of El Hierro of any age is 7.5%.

Quantitative computerized tomography for the diagnosis of osteopenia in prehistoric skeletal remains

“…Moreover, the relative contents of both kinds of tissue (i.e., red marrow and marrow fat) varies with age, so that the standard error of QCT increases with advancing age, 6e9 to 10e15% in older patients with single energy CT and 3e6 and 6e10%, respectively, with double energy devices, [10]). However, our results on prehispanic samples are worse, but are consistent with those reported by others who have applied X-ray densitometry to the analysis of bare bones or bones from cadavers [16,28,45] and with our own results using DEXA [20] or X-ray density [21]. It is likely that attenuation differences caused by entrapped air bubbles may explain the relatively poor accuracy observed.…”

“…All these procedures have shown a good relationship both with bone calcium content and histomorphometrically assessed trabecular bone mass (TBM) in clinical studies [10]. However, their validity in ancient samples has been scarcely tested [5,16,19,21,23,28,31]. QCT is based on the principle that the attenuation suffered by the X-ray photons is related to the thickness and composition of the tissues at the attenuation path [32].…”

Dietary patterns during the early prehispanic settlement in La Gomera (Canary Islands)

“…In contrast, only 300 men should have survived in El Hierro, an island in which shellfishing surely was a major economic activity. Consequently, in contrast with the high prevalence of osteoporosis found in Gran Canaria, individuals from El Hierro showed a well preserved bone mass (Gonzá lez-Reimers et al, 2004), perhaps due to a better nutritional status, and a more favourable relationship between available food and population needs. Indeed, the subdesertic climate of the Islands leads to irregular and scarce rainfall, and vicinity to the Sahara desert and Sahel facilitated the arrival from locust plagues which almost certainly devastated the fields (repeatedly documented since short after Spanish conquest, Cola Benítez, 1996) and provoked widespread malnutrition, especially if food supply strongly relied on agriculture.…”

Paleonutritional and paleodietary survey on prehistoric humans from Las Cañadas del Teide (Tenerife, Canary Islands) based on chemical and histological analysis of bone

“…An unusually high prevalence of osteoporosis in a given, nonselected, population may indicate deranged nutritional status (González-Reimers et al, 2004), since bone mass depends on an equilibrium between bone synthesis and bone resorption, which may be disrupted in situations of starvation or poor protein intake. In this regard, it is important to note that stable isotopes may also be altered in starvation (Williams et al, 2007).…”