Technical note: The effect of midshaft location on the error ranges of femoral and tibial cross‐sectional parameters

Abstract

In comparing long-bone cross-sectional geometric properties between individuals, percentages of bone length are often used to identify equivalent locations along the diaphysis. In fragmentary specimens where bone lengths cannot be measured, however, these locations must be estimated more indirectly. In this study, we examine the effect of inaccurately located femoral and tibial midshafts on estimation of geometric properties. The error ranges were compared on 30 femora and tibiae from the Eneolithic and Bronze Age. Cross-sections were obtained at each 1% interval from 60 to 40% of length using CT scans. Five percent of deviation from midshaft properties was used as the maximum acceptable error. Reliability was expressed by mean percentage differences, standard deviation of percentage differences, mean percentage absolute differences, limits of agreement, and mean accuracy range (MAR) (range within which mean deviation from true midshaft values was less than 5%). On average, tibial cortical area and femoral second moments of area are the least sensitive to positioning error, with mean accuracy ranges wide enough for practical application in fragmentary specimens (MAR 5 40-130 mm). In contrast, tibial second moments of area are the most sensitive to error in midshaft location (MAR 5 14-20 mm). Individuals present significant variation in morphology and thus in error ranges for different properties. For highly damaged fossil femora and tibiae we recommend carrying out additional tests to better establish specific errors associated with uncertain length estimates. Am J Phys Anthropol 141:325-332, 2010. V V C 2009 Wiley-Liss, Inc.

X-ray, CT and DXA study of bone loss on medieval remains from North-West Italy

“…These differences may be related to the different lifestyle led by the more privileged subjects compared to the less privileged classes who had a higher dietary calcium intake (milk and dairy products), more sun exposure and vigorous physical activity. Our findings support the results obtained from an earlier study on intrapopulation variation in stature and body proportions in relation to social status and gender differences, performed by other authors on the same samples of population from Trino Vercellese [32]. As the findings on the cortical index did not differ greatly among the groups, the differences in the BMD between burial sites seem to be of greater significance as it is a direct effect of changes in the mineral content of cancellous bone, which is more sensitive than is compact bone to osteopoenic modifications.…”

“…Moreover, a careful selection was made to ensure the use of bones that were as intact as possible on gross examination so as to rule out, as far as possible, the possibility that diagenetic changes had altered bone composition and accordingly density. CT was also used to evaluate the cortical index so as to identify the limit between the cortical bone and the endosteal trabecular component, using the correct visualisation parameters and an accurate measurement technique [28,31,32]. CT images make for an easy identification of the linea aspera, which is the posterior point of the diaphysis, allowing for precise geometrical measurements of both the medial and lateral cortical thickness [33].…”

Associated ilium and femur from Koobi Fora, Kenya, and postcranial diversity in early Homo

“…The exact location of midshaft cannot be determined accurately, so a reasonable estimate of original bone length cannot be made. However, midshaft diaphyseal geometry can be estimated using the distal end of this fragment and compared with femora of other individuals, as femoral midshaft contours do not change appreciably from about 40% to 60% of bone length (see Ruff and Hayes, 1983;Sladek et al, 2010).…”

The impact of subsistence changes on humeral bilateral asymmetry in Terminal Pleistocene and Holocene Europe

“…Cross-sectional properties-humeral cross-sectional 9 area (HCA) and polar section modulus (HZp)-were measured according to the standard protocol described in Ruff (2002) and Trinkaus (1997). Bones were oriented relative to anatomical antero-posterior (A-P) and medio-lateral (M-L) axes, and humeral cross-sectional contours were obtained at 35% of humeral biomechanical length (see Table 2) from the distal end, either by computed tomography (Sládek et al, 2006(Sládek et al, , 2010 or external molding combined with biplanar radiography to determine approximate endosteal contours (i.e., "Latex Cast Technique;" Trinkaus and Ruff, 1989;Stock, 2002;O'Neill and Ruff, 2004;Sylvester et al, 2010). Structural properties were derived from CT scans using either manually digitized periosteal and endosteal contours by CTi software (Sailer et al, 2003;Sládek et al, 2006Sládek et al, , 2010 or by the semi-automated MomentMacro procedure (http://www.hopkinsmedicine.org/fae/mmacro.htm).…”