Estimation of age at death: examination of variation in cortical bone histology within the human clavicle.

Abstract

Continuously, numerous human remains of unknown identity are revealed all over the world. One of the elements of the identification process may be a proper assessment of a histological section of bone fragments in order to answer questions related to the age of the subject. The aim of the study was to define an optimum bone fragment to obtain samples for histological examination. The study material consisted of fragments of shafts of left clavicles taken from 39 males and 25 females (aged 22-86). The clavicles came from autopsies conducted between 2005 and 2011 at the Department of Forensic Medicine of Poznan and the Bialystok Medical University. The following were taken into account while estimating the age of the bone remains: clavicle length (CL), clavicle width (CW), clavicle thickness (CT), number of osteons in the field of vision (ON), number of osteons with the Haversian canal of more than 70 μm (HC > 70 μm), average diameter of the Haversian canals (avg. ØHC), area occupied by interstitial lamellae (ILA %), area occupied by osteons (OA %), area occupied by fragments-remnants of osteons remain as irregular arcs of lamellar fragments (OFA %), average thickness of outer circumferential lamellae (avg. OCL, μm), the relation of osteons with the Haversian canal of more than 70 μm in diameter to the total number of osteons (HC > 70 μm, %), at p < 0.00001. The age of the bone remains was estimated using univariate linear regression function. It was determined that the best place for sampling the osseous tissue for the analysis was the shaft of the clavicle. It was stated than the number of osteons with a large diameter increased with age. The relation of osteons with the Haversian canal of more than 70 μm in diameter to the total number of osteons (HC > 70 μm, %). The level of statistical significant was p < 0.00001. All analysed microscopic features of the osseous tissue showed significant statistical changes occurring with age. The exact method for preparing osseous tissue for a microscopic analysis to determine the age of the remains is the preparation of histological sections, as the structure of the osseous tissue does not change while processing the material and the time of preparations is relatively short (7-8 days). The best predictors of age with the use of the function of univariate linear regression were: the diameter of Haversian canal, the number of osteons with Haversian canal of more than 70 μm in diameter, the relation of osteons with Haversian canal bigger than 70 μm in diameter to the total number of osteons as well as fragments of secondary osteons.