Metacarpal radiogrammetry: a useful indicator of bone loss throughout the skeleton?

Metacarpal radiogrammetry has received increasing interest in recent studies of archaeological human bone in facilitating the identification of age-related cortical bone loss and osteoporosis risk in the past. The technique is relatively simple and non-destructive, and existing comparative clinical data is an advantage in its application to archaeological samples. In order for metacarpal radiogrammetry to be useful in identifying individuals that could have been at risk of fracture in the past, cortical bone loss as measured at the second metacarpal is assumed to be reflective of bone loss occurring throughout the skeleton and across the metabolically different cortical and trabecular bone. Archaeological studies have frequently relied on literature reviews of clinical data to justify the technique as valid and useful. However, the present study has examined whether cortical bone loss measured in the second metacarpal is similar to bone loss measured at specific skeletal sites that are more frequently affected by osteoporosis-related fracture. Skeletons from two post-medieval collections from London, UK, Redcross Way and Farringdon Street (lower burial ground of St. Bride's Church) were studied. The results of the present study demonstrate that the second metacarpal is useful in identifying age-related bone loss at sites that are predilected to osteoporotic fracture, most notably the distal radius, which is prone to Colles' fractures. Metacarpal radiogrammetry also correlates well with bone loss in skeletal sites that are primarily composed of trabecular bone, including the fourth lumbar vertebra (a site of compression fractures) and the iliac crest (the location for clinical biopsies). The present study also confirms previous findings of significant differences between the pattern of cortical bone loss between the metacarpal and the femur. The poor relationship between these two areas is most likely attributable to mechanical loading.