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

This project was supported by the NIJ Graduate Research Fellowship in STEM (FY 2015). The dissertation abstract appears below, and the dissertation is attached, along with the dataset utilized in a subsequent publication (see "Osteoarthritis and Age Estimation" folder). Datasets will be updated as publications based on these data progress.<br><br>ABSTRACT<br>This research investigated the nature of progressive changes in the acetabulum, with the aim of determining whether they are metamorphic or degenerative and ascertaining whether they are useful for the estimation of age at death. If degenerative, these changes could be linked with osteoarthritis, potentially affected by factors like physical activity and obesity, and deemed less useful for skeletal age estimation. In order to investigate these problems, the researcher analyzed a sample of 409 female and male European-American skeletal individuals from the W.M. Bass Donated Skeletal Collection (University of Tennessee, Knoxville). Acetabular changes and osteoarthritis were observed and scored, and these data were compared with documented demographic data (age, sex, body mass index, and habitual/occupational activities) for the 409 individuals. Statistical tests compared acetabular changes with age, osteoarthritis, activity, and obesity data.<br><br>Acetabular changes were found to correlate strongly positively with osteoarthritis and age. This indicates that the changes occurring in the joint are degenerative rather than metamorphic, but they are still useful for age estimation. Acetabular changes were relatively resistant to the effects of obesity and physical activity, also arguing for their relevance to studies of age. In other joints, osteoarthritis also showed strong positive correlations with age, further undermining the metamorphic vs. degenerative dichotomy of age-relevant skeletal change. Osteoarthritis exhibited limited positive correlations with obesity, but no relationship with activity. The disease likely has both biomechanical and systemic components.<br><br>In summary, the degenerative changes of the acetabulum are valid skeletal indicators of age. The etiology of osteoarthritis is multifactorial, but age is a major contributing factor. The impact of physical activity is less straightforward than once thought, and it may in some cases improve joint health. Thus, weight loss and exercise should be considered palliative for both osteoarthritis and obesity. These findings have implications not only for the study and identification of the dead, but also for the improvement of health outcomes and interventions for the living.