Technical note: Shape variability induced by reassembly of human pelvic bones

Abstract

In traditional as well as in geometric morphometric studies, the shape of the pelvis is often quantified after the reassembly of the two hip bones and the sacrum. However, on dry bones, the morphology of the cartilaginous tissues that form the two sacroiliac joints and the pubic symphysis before death remains unknown, leading to potential inaccuracies and errors during the reassembly process. A protocol was established to investigate the effects of reassembly on the quantification of pelvis shape. The shape of fresh pelves obtained after dissection, in which the three bones are in an anatomically relevant position, was compared with the shape of different reassemblies based on the individual dry bones of the same individuals. Our results demonstrated a significant effect of the reassembly. Variation in the reassembly process is likely related, first, to the complete absence of cartilaginous tissues on dry bones and, second, to the morphology of the sacroiliac joint which, in vivo, allows physiological movements, resulting in different potential positions of the two sacroiliac surfaces relative to one another. However, the artificial variation introduced by the reassembly process appears small compared with the biological variation between the different individuals.

Shape variation in the human pelvis and limb skeleton: Implications for obstetric adaptation

“…For the measurements of the articulated pelvis, no accommodations were made for the soft tissue at the pubic symphysis and sacroiliac joints that would be present in life. Variation in the amount of soft tissue among individuals has minimal effect on measurements of the pelvis (Bonneau et al, ). Measurements of the articulated pelvis were selected based on their representation of different planes (inlet, midplane, and outlet) of the pelvic canal, while noncanal pelvic measurements were selected based on their representation of height and breadth of different parts of the bony pelvis as a unit.…”

Measurement error in μCT‐based three‐dimensional geometric morphometrics introduced by surface generation and landmark data acquisition

“…Several factors have been shown to cause measurement error in landmark data (see also review in Fruciano, 2016). The preservation and preparation of specimens can induce artefactual variance by altering the natural form of the structures of interest (Lee, 1982 [linear measurements]; Bonneau et al 2012). The variability within repeated measurements performed by the same observer and the variability between different observers can also contribute significantly to measurement error (Ross & Williams, 2008;Robinson & Terhune, 2017; reports of relatively large observer error without tests for statistical significance: Curth et al 2017;Fruciano et al 2017;Daboul et al 2018).…”

Accuracy and Reliability of Total Body Mass Estimation Techniques from Stature and Bi‐iliac Breadth in Non‐Hispanic U.S. Whites from the Bass Donated Skeletal Collection

“…Bonneau et al. have discussed the various reconstructions of the skeletal pelvic girdle, including high resolution models, and their potential to misrepresent the true pelvic anatomical orientation, which can affect SBIB measurement acquisition. Biological anthropologists still use a soft tissue adjustment equation published by Ruff to convert the SBIB into the LBIB.…”

“…When solitary, the SBIB measurement can be very challenging without the aid of someone to hold the girdle and rubber bands can be placed strategically to maintain stability without compromising the biomechanical properties of the pelvic girdle (see ref. ). Here Dunn used three rubber bands: (i) from the edge of the right ilium to the left sciatic notch; (ii) from the edge of the left ilium to the right sciatic notch; and (iii) around the base of the sacrum and both ischia (Fig.…”

“…To test the accuracy and reliability of recent body mass estimation techniques using the ST‐BIB method for modern individuals, skeletal BIB (SBIB) was measured by author Dunn in pelves housed at the William M. Bass Donated Skeletal Collection curated by the Forensic Anthropology Center at the University of Tennessee—Knoxville. Skeletal bi‐iliac breadth is a relatively standard osteometric measurement . Reconstructing the pelvic girdle with two practitioners is straightforward, but not trivial: One holds the girdle in place, while the other records the breadth from the two iliac blades with an anthropometer.…”