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Iliac tuberosity

The iliac tuberosity is a large, roughened bony prominence on the posterior aspect of the iliac crest, situated just superior to the auricular surface of the ilium. It forms part of the articular and ligamentous interface of the sacroiliac joint. The tuberosity serves as a major anchoring point for strong sacroiliac ligaments that stabilize the pelvis. Because of its deep location, it is clinically significant in pelvic stability, trauma, and in imaging evaluation of sacroiliac joint pathology.

Synonyms

  • Tuberositas iliaca

  • Posterior iliac roughened area

  • Iliac crest tuberosity

Location and Attachments

  • Location:

    • Found on the medial surface of the ilium, posterior to the auricular surface and beneath the posterior iliac crest

  • Attachments:

    • Serves as the attachment site for the interosseous sacroiliac ligament, one of the strongest ligaments in the body

    • Also gives attachment to parts of the posterior sacroiliac ligaments

    • These ligaments connect the ilium to the sacrum and stabilize the sacroiliac joint

Relations

  • Anteriorly: Auricular surface of ilium (articulates with sacrum)

  • Posteriorly: Posterior iliac crest and gluteal muscles

  • Superiorly: Iliac crest proper

  • Inferiorly: Greater sciatic notch and posterior inferior iliac spine

  • Medially: Sacrum and sacroiliac joint capsule

  • Laterally: Posterior gluteal surface of ilium

Function

  • Provides a major stabilizing attachment for sacroiliac ligaments

  • Helps transfer body weight from vertebral column to the pelvic girdle

  • Contributes to pelvic ring stability during locomotion and load-bearing

  • Serves as a bony landmark in surgical approaches to the sacroiliac region

Clinical Significance

  • Pelvic fractures: Iliac tuberosity may be involved in high-energy trauma, destabilizing sacroiliac joint

  • Sacroiliitis: Inflammatory or degenerative processes may affect the adjacent sacroiliac ligaments, with signal changes visible at the iliac tuberosity

  • Surgical relevance: Important landmark in sacroiliac joint fusion or fixation procedures

  • Radiology: Appears in sacroiliac joint imaging; subtle erosions, sclerosis, or irregularities may indicate inflammatory disease such as ankylosing spondylitis

MRI Appearance

T1-weighted images:

  • Iliac tuberosity shows low signal intensity (cortical bone)

  • Adjacent marrow may show intermediate signal intensity

  • Fat around the region is bright, highlighting bony margins

T2-weighted images:

  • Cortical bone remains dark (low signal intensity)

  • Bone marrow signal depends on age (fatty marrow = higher signal, red marrow = lower signal)

  • Inflammatory or edematous changes appear as bright areas near the tuberosity

STIR (Short Tau Inversion Recovery):

  • Cortical bone remains dark

  • Marrow edema, inflammation, or stress reaction in the iliac tuberosity appears as bright hyperintense signal

  • Surrounding fat is suppressed, improving visualization of pathology

T1 Fat-Sat Post-Contrast:

  • Normal cortical bone does not enhance

  • Pathological marrow or adjacent soft tissue (infection, inflammation, tumor) may show focal or diffuse enhancement

3D T2 SPACE / CISS:

  • Iliac tuberosity cortex appears dark

  • Adjacent fat and marrow signal appears brighter, improving contrast

  • Useful in detecting subtle cortical irregularities or erosions near sacroiliac joint

CT Appearance

Non-Contrast CT:

  • Iliac tuberosity seen as a dense, irregular bony prominence posterior to the auricular surface

  • Cortical bone appears hyperdense

  • Sclerosis, erosions, or fractures may be detected clearly

Post-Contrast CT:

  • Bone itself does not enhance

  • Adjacent soft tissue or marrow lesions may enhance (inflammatory or neoplastic processes)

  • Useful for evaluating sacroiliac joint disorders, tumors, or trauma around the tuberosity

MRI image

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MRI image

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CT image

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CT image

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