Biomechanics of sacral fixation

The wedge-shaped Sacrum not only gives support to the vertebral column, it also provides strength and stability to the pelvis. Recent renewed interest in sacral screw fixations together with advancements in mechanical understanding has resulted in increased attention being paid to the surgical anatomy of the sacrum^. Awareness of the anatomical structure, and the adjacent neurovascular and visceral structures and their configurations will minimize complications and contribute to a successful surgical outcome.In the adult, the sacrum is composed of five vertebral bodies fused together by four ossified intervertebral disks. The sacrum articulates above with the fifth lumbar (L5) vertebra, below with the coccyx, and laterally from the auricular surfaces with the two iliac bones of the hip to form the sacroiliac joints. The projecting anterior edge of the first sacral vertebra is called the sacral promontory and the two sides are the sacrum alas. The sacral promontory is used as a landmark for making pelvic measurements.