Sacroiliac joint morphologic changes from infancy to adulthood.

BACKGROUND CONTEXT: Report of sacroiliac morphology changes during growth is limited in the literature and the interest of such morphology and its consequence for surgery is increasing. PURPOSE: Aims of this work are (1) to anatomically define the sacroiliac joint (SIJ), and (2) to assess the influence of growth on the sacroiliac morphology and the pelvic parameters. STUDY DESIGN: Forty-nine young subjects from 6 months to 18 years old (y/o) and 20 adults aged from 18 to 50 y/o were selected from our institutional patient database. METHODS: They underwent a computed tomography (CT) examination on a 128-MDCT (GE Healthcare Optima CT660). Transverse CT image datasets were reconstructed, anonymized, and segmented with ITK-SNAP. Landmarks and surfaces were selected and a SIJ orientation analysis was performed using costumed Python scripts. RESULTS: The subjects were divided into four groups: infants (1.9±1 y/o), children (6.9±1.7 y/o), adolescents (13.7±1.8 y/o), and adults (27.3±5.6 y/o). Differences between SIJ orientation were found significant between young subject groups for synovial sacrum SIJ orientation (p<.001) and iliac total SIJ orientation (p=.036). Both orientations of younger subjects were found significantly different from the adult group (p<.035). SIJ synovial sacrum and iliac total orientations correlated significantly with age (p<.03). All orientations correlated with pelvic incidence (p<.04) except for synovial sacrum SIJ orientation (p=.2). No gender or symmetrical differences were found significant in any group. CONCLUSIONS: Morphologic definition of the SIJ confirmed the independency of the gender during growth. Such results will be beneficial for the analysis and management of vertebral pathology.

Growth of the human ilium: the anomalous sacroiliac junction.

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.

Improved accuracy in Risser sign grading with lateral spinal radiography.

Development of the ossification of the iliac crest is used to assess the remaining spinal growth. The clinical value of the Risser sign has been questioned because of its inaccuracy in grades 3 and 4. Estimation of the Risser sign based on the lateral spinal radiograph has not been reported. The aim of the study was to evaluate the course of ossification of the iliac apophysis along its full extension and to investigate relevance of the lateral spinal radiograph for more accurate Risser sign grading. Cross sectional analysis of spinal frontal and lateral long cassette standing spinal radiographs of 201 girls aged from 10.2 to 20.0 years were done. On the lateral spinal view, the ossification of the posterior part of the iliac apophysis was quantified at four grades: absent (A), partial (B), complete (C) or fused (D). The position of the posterior superior iliac spine was studied on both views as well as in pelvic specimens. The results showed that the posterior one-third portion of the iliac apophysis was sagittally oriented and obscured on the frontal radiograph by the sacroiliac junction. It could be studied on the lateral radiograph and revealed a different grading of the apophysis excursion in 58 of 201 (29%) patients, comparing to the frontal view. Both advanced or delayed ossification was observed and assessed with Lateral Risser Modifiers. Twenty-five percent of the patients at Risser 0 or 1 or 2 demonstrated a simultaneous ossification of the most anterior and the most posterior part of the iliac crest. The Risser grades of capping or fusion could be more precisely diagnosed using lateral radiograph in complement to the frontal one. The conclusions drawn from this study were: (1) Currently used Risser sign grading does not consider the actual excursion of the iliac apophysis, because one-third of the apophysis cannot be observed on the frontal radiograph. (2) Iliac apophysis full excursion or fusion can be more accurately estimated when the lateral spinal radiograph is analyzed with Lateral Risser Modifiers.

Pelvic age estimation using actual specimens and remote images.

Age estimates of the auricular surface (sacro-iliac joint) of the ilium taken from bony specimens, 35 mm slides, and digital images were compared for 29 intact specimens from archaeological contexts. Results demonstrate that age estimates from all photographic and digital images may result in significantly differing estimates of age than those from bony specimens. Of the imaging techniques, 35 mm slides provided estimates most similar to those from bony specimens. Digital images provided age estimates that varied more from bony specimens. In general, photographic and digital images may offer researchers a way of documenting age information that would otherwise be unavailable or delayed. Yet, caution should be used when age estimates are derived solely from images rather than from bony specimens.

On biomechanical properties of the sacroiliac joint in purebred dogs.

Relative to the Yorkshire Terriers and Maltese dogs the mean expected sacroiliac joint load was calculated to be 1.4-1.6 times higher in other small breeds and 1.7-2.7 times higher in large breeds. The statistically significantly different (p < 0.01, p < 0.001) and mechanically less efficient inclination angles of the wings of the sacrum in adult large breeds (especially German Shepherd Dogs) suggest even higher forces acting on their sacroiliac ligaments. Unlike the case in small breeds, the sacral auricular surface was concave in large dogs to improve interlocking between sacrum and ilium and to reduce craniocaudal translation. An additional ossification center forming the ventral aspect of the transverse process of the second sacral vertebra was present in large breeds, occasionally in midsized and small, but never in toy breeds. This and the relationship between age and inclination angles of the wings of the sacrum in juvenile specimens indicate an affection of the three-dimensional modeling of the wings of the sacrum by formative stimuli such as body weight and locomotion.

Macroscopic and microscopic anatomy of the sacroiliac joint from embryonic life until the eighth decade.

The macroscopic and microscopic anatomy of the sacroiliac joint from embryonic life until the eighth decade is presented to establish a baseline of normal anatomy for this joint. The literature concerning the anatomy of the joint was reviewed and found to be fragmentary and conflicting, particularly concerning the diarthroidial characteristics of the joint. From fetal life onward, the iliac cartilage surface is fibrocartilaginous, while the sacral surface is hyaline cartilage. Degenerative arthrosis of the joint commences at an early age, affecting the iliac cartilage to a greater extent than its sacral counterpart. These early degenerative changes in the sacroiliac joint may very well be a more common cause of low-back pain than previously thought.