Growth of the Human Ilium: The Anomalous Sacroiliac Junction

Abstract

Despite the major anatomical importance of the human ilium in medicine and forensic investigations, little is understood about its pattern of growth. This study was conducted to investigate the changes in the surface area of the human ilium from birth through to adolescence in 80 human ilia. A photographic image of the pelvic surface of each bone was taken and examined using an image quantification package. The surface areas of four regions of interest were quantified: the auricular, post-auricular (PA), iliac fossa, and whole pelvic surface of the ilium. The results highlight a rapid increase in surface area for all regions in the first few years after birth which continues, albeit at a slower rate, until 4 years of age when the rate of growth is further reduced. Although the ilium and its various components continue to grow between 5 years and puberty, the rate of growth is markedly reduced until puberty when growth of the pelvis again increases. Interestingly, analysis of the differential growth of the auricular region compared with the PA region throughout development suggests that the PA region exhibits more advanced growth. This may indicate that its role in structural development for the purposes of preparation and maintenance of bipedal stance and locomotion may have been previously poorly understood. Anat Rec, 296:1688Rec, 296: -1694Rec, 296: , 2013. V C 2013 Wiley Periodicals, Inc.Key words: ilium; auricular; post-auricular; growth; developmental milestone; juvenile; ageThe human ilium is a flat, irregularly shaped bone with three surfaces: gluteal, pelvic, and acetabular. The pelvic surface can be divided functionally into two regions: a large ventral iliac fossa to accommodate the attachment of the large iliacus muscle, and a smaller thickened dorsal part for the articulation with the sacrum. This posterior region can be further subdivided into a ventral articular (auricular) surface and a dorsal nonarticular (post-auricular (PA)) surface which is primarily for ligamentous attachment. The gluteal surface is a relatively unremarkable expansive area well suited to accommodate large muscle attachments and it is this functional, even antagonistic, muscular interaction on both sides of the iliac blade that is reported to be the principal driver of bone formation during the early developmental period (Gardner et al., 1969;Last, 1984;Delaere and Dhem, 1999).The primary ossification center for the ilium appears superior to the greater sciatic notch, around two to three intrauterine months (Laurenson, 1964). Ossification then expands via periosteal apposition of cortical bone toward the metaphyseal growing surfaces of the cartilaginous anlage (Delaere et al., 1992;Cunningham and Black, 2009a). In contrast to the intramembranous origin of the external cortex, the internal cancellous structure of the ilium is formed via endochondral ossification.

Morphometric anatomical and CT study of the human adult sacroiliac region

“…This role is mainly played by the iliac tuberosity and the proximal bone prominence of sacrum which in vivo are in close contact with each other. This interpretation is consistent with the results of a study on the growth of human ilium showing that the extra-articular portion is considerably larger than the articular surface, a disparity that might be a response to the load placed on the extra-articular portion by the posterior sacroiliac ligaments [33].…”

“…The mechanical function of the SIJ is to allow the movements between the auricular surfaces of the sacrum and ilium, that have been named nutation (forward nodding) and counternutation (backward nodding), to be accomplished. A further function, however questioned [33], is a direct weight transfer from the axial to appendicular skeleton. This role is mainly played by the iliac tuberosity and the proximal bone prominence of sacrum which in vivo are in close contact with each other.…”

Three‐dimensional morphological analysis of the human sacroiliac joint: influences on the degenerative changes of the auricular surfaces

“…In a study of the changes in the surface of the human ilium from birth to adolescence, Yusof et al. () found that the surface area of the ASI increased rapidly from soon after birth until around 4 years of age. This period overlaps with the stage of human development in which children progress from a supine, non‐weight‐bearing environment to becoming capable of bipedal walking, and Yusof et al.…”

“…We found that it can be characterized in terms of (i) size, (ii) concavity of the posterior border and (iii) amount of undulation. In a study of the changes in the surface of the human ilium from birth to adolescence, Yusof et al (2013) found that the surface area of the ASI increased rapidly from soon after birth until around 4 years of age. This period overlaps with the stage of human development in which children progress from a supine, non-weight-bearing environment to becoming capable of bipedal walking, and Yusof et al (2013) suggest that the structure of the ASI may thus change in preparation for bipedalism and to maintain it.…”

“…In a study of the changes in the surface of the human ilium from birth to adolescence, Yusof et al (2013) found that the surface area of the ASI increased rapidly from soon after birth until around 4 years of age. This period overlaps with the stage of human development in which children progress from a supine, non-weight-bearing environment to becoming capable of bipedal walking, and Yusof et al (2013) suggest that the structure of the ASI may thus change in preparation for bipedalism and to maintain it. The fact that in this study the parameters indicating the size of the ASI and the amount of the concavity of the posterior border were not correlated with age may have been because the samples were from subjects older than adolescence at the time of death.…”