Skeletal Age Estimation in Modern U.S. Adults: The Effects of Activity, Body Mass, and Osteoarthritis on Age-Related Changes in the Acetabulum

As submitted by the proposer: The identification of unknown decedents – often the victims of homicides, natural disasters, or armed conflicts – depends upon the accuracy of the scientific methods used to determine the biological profile: the age, sex, ancestry, and stature of skeletal remains. Accurate age-at-death estimation is essential to this process, but skeletal age estimates are difficult to achieve for adult individuals – particularly individuals of advanced age. Forensic anthropologists frequently examine joint surfaces to inform their adult age estimates. All joints change with age; but while some exhibit metamorphic change, others merely exhibit degenerative change. Metamorphic changes allow more accurate age estimates, as joint degeneration (osteoarthritis/OA) is influenced by many factors other than age (e.g., heredity, activity, obesity). While some anthropologists believe the acetabulum (the pelvic component of the hip) exhibits metamorphic changes, this remains unconfirmed. Before forensic scientists can responsibly use the acetabulum as an age indicator, research must ascertain whether the changes observed in the acetabulum are metamorphic or degenerative. If they are degenerative (OA), methods must be refined so that other influences can be identified and controlled for. The proposed research will examine the influences of age, activity, and obesity on the progressive changes of the acetabulum, the influences of these three factors on generalized OA, and the relationship between acetabular changes and OA. This study will utilize the skeletal remains of modern U.S. males and females of European ancestry (n=500) from the University of Tennessee’s W.M. Bass Donated Skeletal Collection, with documented age, sex, activity patterns, and body mass indices (BMI). All acetabula will be analyzed, scored, and aged; other major joints will be analyzed and scored for OA. This study will statistically test for correlations between acetabular changes and overall OA (whether acetabular changes are metamorphic or degenerative); then it will test whether age, activity, and BMI correlate with acetabular changes and overall OA, and which of the three factors exerts the most influence. Thus, the proposed study will: 1.) Clarify the nature of the changes observed in the acetabulum (metamorphic vs. degenerative); 2.) Identify which factors most influence these changes (age, activity, BMI); and 3.) Validate, reject, and/or refine current acetabular age estimation methods based on these findings. These outcomes will advance the science of adult age estimation, thus improving forensic science standards per recent NAS and Daubert recommendations, helping scientists to understand the biology underlying acetabular changes, and ultimately leading to the successful identification of unknown adult individuals. This project contains a research and/or development component, as defined in applicable law. ca/ncf