The sacrum is a large, triangular bone located between the lumbar and coccygeal portions of the caudal spinal axis.
A healthy sacral region is rarely fractured except in instances of serious injury, such as a fall or trauma to the area. However, patients with osteoporosis are inclined to develop stress fractures and fatigue fractures in the sacrum.
Sacroiliac Joint Pain
Inflammation of the SI joint (sacroiliitis) can be the source of
buttock and upper thigh pain. This is seen classically as ankylosing
spondylitis and the other SpA. The classic feature of sacroiliitis on history is that
the back pain is improved with activity and exacerbated by rest.