Micro-computed tomographic analyses of trabecular bone architecture have been used to clarify the link between positional behavior and skeletal anatomy in primates. However, there are methodological decisions associated with quantifying and comparing trabecular anatomy across taxa that vary greatly in body size and morphology that can affect characterizations of trabecular architecture, such as choice of the volume of interest (VOI) size and location. The potential effects of these decisions may be amplified in small, irregular-shaped bones of the hands and feet that have more complex external morphology and more heterogeneous trabecular structure compared to, for example, the spherical epiphysis of the femoral head. In this study we investigate the effects of changes in VOI size and location on standard trabecular parameters in two bones of the hand, the capitate and third metacarpal, in a diverse sample of nonhuman primates that vary greatly in morphology, body mass and positional behavior. Results demonstrate that changes in VOI location and, to a lesser extent, changes in VOI size had a dramatic affect on many trabecular parameters, especially trabecular connectivity and structure (rods vs. plates), degree of anisotropy, and the primary orientation of the trabeculae. Although previous research has shown that some trabecular parameters are susceptible to slight variations in methodology (e.g. VOI location, scan resolution), this study provides a quantification of these effects in hand bones of a diverse sample of primates. An a priori understanding of the inherent biases created by the choice of VOI size and particularly location is critical to robust trabecular analysis and functional interpretation, especially in small bones with complex arthroses.

This study tests the effect of bilateral asymmetry on the success rate of correct prediction of sex based on osteometric dimensions of the second metacarpal, using a method proposed by Scheuer and Elkington. A total of 351 bones from 179 individuals (47 documented as to age and sex), including 172 pairs, obtained from a 19th century cemetery were used to test the null hypothesis of no effect. A high success rate (>90%) for correct identification was found for males irrespective of side, although the larger right second metacarpal was a significantly better predictor. Conversely, there was a much lower success rate for females irrespective of side (<65%), although the smaller left metacarpal tended to give better results. The high success rate for males and low rate for females likely reflects the greater skeletal robustness of this historic sample relative to modern individuals. It is concluded that side asymmetry can have a significant effect on predictive efficiency for the Scheuer and Elkington model. As well, it is questionable whether the technique should be applied to non-industrial, that is, more skeletally robust, populations.

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Continuing periosteal apposition (CPA) of small amounts of new lamellar bone, leading to absolutely larger size, has been identified in a number of adult cranial and postcranial bones. This paper reviews 42 studies published since 1964 that have found both significant and nonsignificant age-related change in various skeletal size dimensions, e.g., length, diameter, width, and area. Also considered are four hypotheses that have, or may be, postulated for the occurrence of CPA. To date, however, these hypotheses (cohort effect, mechanical compensation, bone repair and/or mechanical response potential, and heterochrony) have not been rigorously tested, hence remain speculative. An important interpretive problem that befalls the investigation of CPA is its small effect size (i.e., the magnitude of change between observations), since most studies have restricted sample sizes. This problem is illustrated by power analysis of three reviewed studies that reported nonsignificant age-related change. The analysis indicates that these studies had very little likelihood of finding a statistically significant result, i.e., a low probability of rejecting the null hypothesis stipulating no size change with age. This finding has implications for interpreting CPA and for distinguishing between the statistical and biological significance of this phenomenon.