J Korean Orthop Assoc.  2010 Apr;45(2):160-163. 10.4055/jkoa.2010.45.2.160.

Pathologic Fracture in a Subchondral Cystic Lesion at the Superior Acetabulum

• Seo KB
• Nam KW
• Yoo JJ
• Kim HJ
• Kim SR

• KMID: 2185586
• DOI: http://doi.org/10.4055/jkoa.2010.45.2.160

Abstract

Subchondral cyst is a benign cystic lesion, and it is often found in patients with rheumatoid arthritis or osteoarthritis. However, its occurrence in those joints without preexisted disease is rare. Furthermore, there has been no report in the medical literature regarding pathologic fracture in the bony plate of a subchondral cyst at the superior acetabulum. We report here on a case of the 44-year-old woman for whom a pathologic fracture was found in the bony plate of a subchondral cyst at the superior acetabulum.

Keyword

acetabulum; subchondral cyst; bony plate fracture; pathologic fracture

MeSH Terms

Acetabulum
Adult
Arthritis, Rheumatoid
Bone Cysts
Female
Fractures, Spontaneous
Humans
Joints
Osteoarthritis

Figure

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  Figure 1 Both hip anteroposterior and frog leg radiographs obtained two months after the onset of pain in the right hip show ill-defined osteolytic lesion with focal poorly delineated right acetabular cortex.

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  Figure 2 Coronal T1 and T2-weighted magnetic resonance images obtained at about two weeks later show that subchondral bone plate of right superior acetabulum is destructed and heterogeneous low signal intensity on T1-weighted image, which converted to heterogeneous high signal intensity at T2-weighted image. There are diffuse bone marrow signal change and enhancement at superior acetabulum and ilium.

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  Figure 3 Axial T2-weighted enhanced magnetic resonance image obtained at about two weeks later shows diffuse bone marrow signal change at ilium and ill-defined round enhancement of the anterolateral aspect at right superior acetabulum.

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  Figure 4 Pelvis anteroposterior and oblique radiographs obtained twenty seven months after the onset of pain in the right hip show residual cortical irregularity of right acetabulum.

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  Figure 5 Coronal T2-weighted fat suppression magnetic resonance image obtained twenty seven months after onset of pain in the right hip does not show reactive change such as bone marrow edema and synovial enhancement. Also T2-weighted magnetic resonance image shows that destructed bony plate of superior acetabulum is migrated.

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  Figure 6 Axial computed tomographic image obtained twenty seven months after onset of pain in the right hip shows a subchondral cyst with subchondral bone plate fracture at right superior acetabulum and shows medullary sclerosis around subchondral cystic lesion.

Reference

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