Orthotopic microCT images of the proximal femurs of A) a young adult B) an old adult, showing differences in trabecular patterns and density.
Analysis of 4000 year old human bone using microCT scans: Analytic implications for forensic and archaeological sciences
Microstructurally, bone loss occurs with increasing age in the trabeculae. Using radiography, other researchers have studied the applicability of using trabecular architecture as an indicator of age at death. However, primary and secondary groups of the trabeculae are impossible to distinguish using radiography and fine trabeculae that are resorbed first are not visually apparent radiographically until at least 30% of the bone has been lost. A unique collection of human skeletal remains (dating to 2200-2000 B.C.) was recovered from Tell Abraq, an archaeological site in United Arab Emirates. These remains were analyzed using Micro-CT scanning in order to obtain an accurate age of death and for understanding disease patterns for individuals buried in an undisturbed Bronze Age tomb. Methods: Due to the somewhat fragmentary nature of the collection and to deal with the loss of vital information, micro-CT scanning was applied to all available and intact proximal femora (n=70) to produce a three dimensional image of the microstructure of the trabecular architecture. The samples were scanned at 93 μm isometric resolution using an eXplore Locus RS Small Animal MicroCT Scanner (GE Healthcare, London, Ontario). The data was reconstructed with the manufacturer’s proprietary EVSBeamTM software. Image analysis was performed using visualization tool MicroView 2.1.2. Results: Micro-CT scans which produced far superior images (Fig. 1A, B) as compared to radiography allowed a better estimation of age at death. Using standard forensic sexing techniques, it was found that of the 70 adults buried in the tomb, 60% were males, and 40% were females. The majority of the population fell under the 30-40 year (n=23) and 40-50 (n=21) year bracket. While most of the individuals were free of pathology, there were a few cases (approx. 8%) of osteoarthritis, osteopororsis and one case of extreme femoral head fracture - probably due to hip dislocation. Conclusion: To our knowledge, this is the first application of this technology to ancient human remains of this antiquity. The data provides a clear picture of life and death in a Bronze Age community and suggests by this newly established age profile, a healthy and robust population. These individuals, even in their old age, were relatively free from debilitating degenerative diseases so prevalent today. Skeletal remains of this antiquity are often fragmentary and difficult to analyze using traditional gross anatomical, histological or radiographic techniques. The digital 3D imaging has the potential to provide information currently not available using more traditional techniques involving histology or radiography. While this project focuses on the analysis of intact trabeculae patterns, assessment of chronological age and diseases, the research has the potential to be expanded to examine the underlying structures in identification of biomechanics, and for correlating diagnostic anatomical features of bone with the underlying microstructure. The application has significant implications for the field of forensic and archaeological sciences particularly in the areas of paleodemography and paleopathology.