Presentation
Persistent back pain
Patient Data
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There is an irregular fracture line with sclerotic bands and trabecular disorganization in the right sacral ala, lateral to the sacral foramina, paralleling the sacroiliac joint with ventral cortical disruption. A small adjacent bone fragment is seen anteriorly. Similar, but more subtle findings are seen in the left sacral ala at the S2 level, with buckling of the anterior cortex of the S2 vertebral body. The appearances are suggestive of sacral insufficiency fractures, likely healing/subacute given the sclerosis.
See key images below.
Key images demeonstarting the findings described above.
Case Discussion
Insufficiency fractures occur when normal physiological stress is placed on abnormally weakened (e.g. osteoporotic) bone. Sacral insufficiency fractures typically involve the sacral ala, lateral to the sacral foramina and are vertically oriented, paralleling the sacroiliac joint. Associated abnormalities include vertebral compression fractures and other pelvic insufficiency fractures.
These fractures may be overlooked on imaging of the lumbar spine obtained for generalized back pain.
Case co-author: Rehana Jaffer, MD, FRCP