Avascular Necrosis of the Hip in Systemic Lupus Erythematosus: The Role of Magnetic Resonance Imaging

Abstract

The value of magnetic resonance imaging (MRI) in the early diagnosis of avascular necrosis (AVN) of the hip in SLE was investigated. Twenty females with severe SLE were studied prospectively. Each underwent 6-monthly X-rays, technetium -99m (Tc-99m) pyrophosphate bone scans and MRI of the hips over a 3-yr period. AVN was diagnosed in five hips of three patients (15%) during the study period. It was confirmed histologically in three hips of two patients who underwent core decompression. Radiological evidence of AVN was present in two patients at diagnosis. One patient developed progressive radiological changes despite core decompression. Bone scintigraphy was abnormal at some stage in all three patients with AVN however failed to detect the early ischaemic stage of AVN. MRI was the most reliable investigation and was able to detect asymptomatic AVN prior to the appearance of radiological or scintigraphic abnormalities.

Imaging Findings in Systemic Lupus Erythematosus

“…This situation is confounding because almost all SLE patients are treated with corticosteroids at some point, although they may be receiving cyclophosphamide, azathioprine, or nonsteroidal anti-inflammatory drugs at the time of presentation. The femoral head is most commonly affected, followed by the humeral head, femoral condyle, and tibial plateau (2,(35)(36)(37). Radiographs are usually normal in early AVN, and late changes of bone sclerosis indicate the presence of irreversible articular damage.…”

“…Prospective studies have demonstrated that MR imaging is superior to and more sensitive than radiography and scintigraphy for documenting early AVN, and MR imaging has been used to document osteonecrosis in asymptomatic SLE patients receiving high-dose corticosteroids (36,37). The MR imaging appearance of AVN correlates with the pathophysiologic features of the process.…”

“…Collapse of the articular surface results in loss of the normal spheric contour of bone and incongruity of the articular surfaces. Such collapse usually has low signal intensity on T2-weighted images, a finding that is compatible with fibrotic changes in the infarcted bone marrow (35)(36)(37).…”

“…MR imaging may depict early or subtle insufficiency fractures, which may be occult on radiographs due to severe osteoporosis. At T2-weighted MR imaging, insufficiency fractures appear as areas of high signal intensity due to bone marrow edema in characteristic stress locations (35)(36)(37).…”

The use of joint-specific and whole-body MRI in osteonecrosis: a study in patients with juvenile systemic lupus erythematosus

“…Only a few reports in the literature have described the assessment of ON in juvenile SLE by MRI, and these studies combined paediatric and adult patients [14,15]. MRI appears to be a useful modality particularly in identifying pre-symptomatic ON lesions.…”