Quantifying cortical bone in fragmentary archeological second metacarpals

Perspectives on anemia: Factors confounding understanding of past occurrence

OBJECTIVE

This paper reviews factors confounding the understanding of the past occurrence of anemia. Using the evidence gathered, a framework is presented of ways forward to enable greater confidence in diagnosing acquired anemia in paleopathology, facilitating insights into longer-term perspectives on this globally relevant condition.

RESULTS

To date, porotic lesions have been central to paleopathological investigations of anemia. The fact that porotic bone lesions are omnipresent and have multiple causes but are likely to have a relatively low, age-related frequency in individuals with anemia, a condition that will have been common in past communities, is confounding.

METHODS

Establishing frameworks that move away from porotic lesions is proposed to facilitate higher levels of more accurate anemia diagnoses in paleopathology.

SIGNIFICANCE

Acceptance of the fundamental principle that anemia may be better considered as a condition requiring metric evaluation of bone structures, supplemented by careful consideration of lesions, will advance understanding of acquired anemia in past communities. Such an approach would provide a clear basis for further consideration of congenital conditions causing anemia, such as sickle-cell disease and thalassemia.

LIMITATIONS

This paper simply opens the conversation on the better diagnosis of anemia in paleopathology; it starts the iterative process of achieving some consensus and progress on diagnosing anemia in paleopathology.

SUGGESTIONS FOR FURTHER RESEARCH

Engagement with ideas presented, sharing data and development of metric parameters will assist in identifying the effects of marrow hyperplasia on bone, enabling more robust work on the important topic of anemia.

Evolution of gliding in squirrel-related rodents (Mammalia: Sciuromorpha) did not induce a new optimum on the cortical thickness of the scapular glenoid fossa

Many of the squirrel-related rodents (i.e., Sciuromorpha) are tree-dwelling species known to be very agile climbers. This taxon also includes the most diverse clade of gliding (aerial) mammals that likely descended from a non-gliding arboreal ancestor and evolved a patagium (i.e., a gliding membrane) to increase gliding performance. Glides can cover distances of up to 150 m and landing is typically accomplished by stalling the patagium to reduce impact velocity. It remains unclear if this behavior suffices to keep stresses on the locomotor apparatus similar to those experienced by their arboreal relatives or whether gliding behavior increases landing forces and stresses. The sparsely available support reaction force data are ambiguous, but bone microstructure is highly adaptable to changes in loading regime and likely provides insights into this question. Using μCT scans, we compared the cortical thickness of the glenoid fossa of the shoulder joint between arboreal and aerial Sciuromorpha using evolutionary model comparison, while also accounting for regional differences of the glenoid fossa. We did not find any differences between these locomotor behaviors, irrespective of the glenoid region. These findings agree with previous analyses of the microstructure of the femur in Sciuromorpha. We discuss different aspects that could explain the similarity in cortical thickness. According to our analysis of glenoid cortical thickness the loading regime appears not to have changed after the evolution of gliding locomotion, likely due to adjustments in landing performance.

Exploring radiogrammetry beyond the second metacarpal: Using the third, fourth, and fifth metacarpals to quantify cortical bone

OBJECTIVE

Traditional metacarpal radiogrammetry, a method for quantifying cortical bone in metacarpals to identify bone loss, typically relies on the presence of an unaltered or undamaged second metacarpal. This study compares the cortical indices of the second to the third, fourth, and fifth metacarpals to test if an additional metacarpal can be used as substitute when the second metacarpal is not available for study.

METHODS

Hand and wrist radiographs from the Burlington Growth Study, belonging to 56 individuals (28 females; 28 males) between 18 and 20 years old, were included in this study. Cortical indices were calculated for metacarpals two through five. Cortical index differences were statistically compared by sex, and the second metacarpal cortical indices were correlated with those of the third, fourth, and fifth metacarpals.

RESULTS

The third, fourth, and fifth metacarpal cortical indices were all significantly correlated with the second metacarpal cortical indices for both females and males (p < .05). Cortical indices of the second metacarpal were most strongly correlated with those of the third metacarpal (females r = .644, p < .001; males r = .643, p < .001).

CONCLUSION

The results of this study indicate that the third, fourth, or fifth metacarpal may serve as substitutes for cortical index analyses when the second metacarpal is unavailable or unsuitable for analysis. While the second metacarpal should remain the primary choice in radiogrammetry analyses, the third metacarpal is the most suitable alternative for quantitative analyses of cortical bone.