Osteitis Condensans Ilii

Osteitis condensans ilii is a benign sclerosis of the ilium that is commonly seen in young women and has an estimated prevalence of between 1.0% to 3%. The condition is thought to be related to pregnancy, althout it can be seen in men and nulliparous women. When related to pregnancy, it is hypothesized that ligamentous laxity at the sacroiliac joints leads to instability and subsequent sclerosis.

While usually an incidental finding, patients with osteitis condensans ilii are more likely to have sacroiliac joint tenderness compared to controls. A high prevalence of back pain has been reported in patients with osteitis condensans ilii, but controlled studies have not been performed, and the association may be coincidental. In other words, a finding of osteitis condensans ilii should not be taken as an explanation of back pain witout excluding other etiologies.

On imaging, osteitis condensans ilii is characterized by sclerosis, predominantly involving the iliac bone, although the sacrum may also be involved. The sclerosis is usually bilateral (but can be unilateral) and triangular in shape and abuts an otherwise normal sacroiliac joint. Irregularity or narrowing at the sacroiliac joint should raise concern for an inflammtory or infectious cause for sacroiliitis. Bone scintigraphy may or may not show focal uptake at the site of sclerosis.

If patients are followed long enough, the majority show improvement or resolution of radiographic findings, which may explain the rarity of this condition in older patients.

References

• Anonymous. Osteitis condensans ilii. Radiology. 1953 Jun;60(6):895-6.
• Cidem M, Capkin E, Karkucak M, Karaca A. Osteitis condensans ilii in differential diagnosis of patients with chronic low back pain: a review of the literature. Mod Rheumatol. 2011 Sep 23.
• Isley JK Jr, Baylin GJ. Prognosis in osteitis condensans ilii. Radiology. 1959 Feb;72(2):234-7.
• Jenks K, Meikle G, Gray A, Stebbings S. Osteitis condensans ilii: a significant association with sacroiliac joint tenderness in women. Int J Rheum Dis. 2009 Apr;12(1):39-43.
• Gemmel F, de Coningh AV, Collins J, Rijk P. SPECT/CT of osteitis condensans ilii: one-stop shop imaging. Clin Nucl Med. 2011 Jan;36(1):59-61.
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