Pelvic insufficiency fractures
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Pelvic insufficiency fractures are a relatively common subtype of insufficiency fracture, and are recognized as a major cause of low back, buttock and groin pain in susceptible populations.
Senile/postmenopausal osteoporosis is the most common predisposing factor. Other important risk factors include:
- renal failure
- rheumatoid arthritis
- extended corticosteroid use
- history of radiation therapy
- mechanical changes after hip arthroplasty
Patients most frequently present with a history of minor trauma or an insidious onset of pain in the above noted locations.
Plain film, MRI and scintigraphic appearance at the site of fracture are the same as with all insufficiency fractures. They often occur in characteristic locations and patterns within the pelvis, and are best detected and evaluated using bone scintigraphy and/or MRI. CT is a relatively insensitive method of detection. Pelvic insufficiency fractures are typically occult on plain film unless secondary remodeling has begun.
Common locations include the following:
- sacrum: (sacral insufficiency fracture) usually vertically through the sacral ala, paralleling the sacroiliac joint, often with a transverse component - this pattern resembles the capital letter H, leading to the designation H sign (or Honda sign)
- medial iliac: vertical fracture paralleling the sacroiliac joint
- supra-acetabular region: about 1/3 are associated with sacral insufficiency fractures
- iliac wing: oblique fracture through the iliac wing, oriented somewhat parallel to the iliac crest
- pubic rami: nearly 90% of fractures at this site occur in conjunction with insufficiency fractures elsewhere within the pelvis
- parasymphyseal: (parasymphyseal insufficiency fracture 4,5) also frequently associated with other pelvic insufficiency fractures
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