Use of backscattered scanning electron microscopy to quantify the bone tissues of midthoracic human ribs

Objectives Novel information on apartheid health conditions may be obtained through the study of recent skeletal collections. Using a backscattered scanning electron microscopy (BSE-SEM) approach, this study aims to produce bone quality and tissue mineralization data for an understudied South African population from the Western Cape province. Methods Using BSE-SEM imaging, cortical porosity (Ct.Po), osteocyte lacunar density (Ot.Lc.Dn), and the degree of tissue mineralization were quantified in midthoracic ribs from the Kirsten Skeletal Collection. Individuals ((n)female = 75, (n)male = 68, and mean age = 46.3 years) were predominantly from the South Africa Colored (SAC) population group ((n)SAC = 103, 72%). Full cross-sectional images of each rib were manually stitched together in Adobe Photoshop. Photomontages were imported into MATALB (Mathworks, Natick, MA) for image processing and analysis. Age-related changes in histomorphometric parameters and sex differences were examined using correlation analysis, as well as linear and nonlinear regressions. Results Young adult men have significantly less mineralized bone and fewer osteocyte lacunae, compared to women. Only men demonstrate a significant negative relationship between Ot.Lc.Dn and age. Average tissue mineralization decreases with age in women, while Ct.Po increases. Pore area (Po.Ar) does not vary with age, but pore density (Po.Dn) is highest in the perimenopause, when accelerated rates of bone turnover are first anticipated. Ct.Po is highest in the years following the predicted age of menopause, but levels off in the final decades of life. Conclusions Men and women display disparate patterns of bone aging. Systemic disenfranchisement of non-white population groups affected bone health in South Africa, and may continue to do so today. Indicators of poor bone quality are evident in the full study sample, indicating that osteoporosis and fracture risk are not just of concern to the aged white female population.