Chapter 51Diagnosis and Management of Sacroiliac Joint Injuries
Anatomical and Functional Features
The pelvis is firmly attached to the axial skeleton by sacroiliac and sacrosciatic ligaments, which form a strong ligamentous sling (see Figure 51-1). The weight of the caudal aspect of the vertebral column is suspended from the sacroiliac ligaments, which function similarly to the fibromuscular sling found between the proximal aspect of the forelimb and the lateral thoracic body wall. Subsequently the sacroiliac articular cartilage may never be fully weight bearing, unlike most articular cartilage. The sacroiliac joint is supported by three pairs of strong ligaments: the dorsal, interosseous, and ventral sacroiliac ligaments. The dorsal sacroiliac ligament consists of dorsal and lateral portions (Figure 51-2). The dorsal portions form two round cords that span from the dorsal aspects of the tubera sacrale to the dorsal apices of the sacral spinous processes. The lateral portion forms a sheet of connective tissue that spans from the caudal margin of each tuber sacrale and iliac wing to the lateral border of the sacrum. The lateral portion of the sacroiliac ligament is continuous ventrally with the sacrosciatic ligament. The interosseous ligament of the sacroiliac joint is robust and consists of a series of vertical fibers that connect the ventral aspect of the wing of the ilium to the dorsal aspect of the wing of the sacrum (see Figure 51-1). The interosseous sacroiliac ligament provides the major resistance to vertically oriented weight-bearing forces acting on the sacrum. The ventral sacroiliac ligament interconnects the ventral aspects of the wings of the ilium and sacrum. The ventral sacroiliac ligament is thin and closely applied to the ventral margins of the sacroiliac joint capsule.