Objective: To evaluate the prevalence of avascular necrosis (AVN), using magnetic resonance imaging (MRI), in patients with primary antiphospholipid syndrome (APS) and in patients with systemic lupus erythematosus (SLE), with or without anticardiolipin antibodies (aCL), who are asymptomatic for AVN and have not taken corticosteroids.
Methods: Seventy-nine subjects who were asymptomatic for AVN were evaluated by MRI of the femoral heads: 30 patients with primary APS who had never received corticosteroids, 19 SLE patients who had never received steroids (divided into 2 groups, aCL positive and aCL negative, in order to examine any association between AVN and aCL), and 30 healthy subjects who were age- and sex-matched with patients with primary APS. Established MRI criteria were used for a diagnosis of AVN.
Results: Asymptomatic AVN was evident in 6 (20%) of 30 patients with primary APS: 3 of them (1 man, 2 women) had intermediate bilateral AVN, and 3 (all women) had early AVN (bilateral in 1 patient). Results of hip and pelvis radiography and dynamic scintigraphy were negative. Followup MRI 6 months later revealed no changes. At the time of the initial MRI examination, the mean (+/-SD) age of patients in whom AVN was identified was 31.2 +/- 7.3 years, and that of patients without AVN was 42.4 +/- 11.9 years (P = 0.036). Livedo reticularis occurred significantly more commonly in the group with AVN (P = 0.041). None of the healthy subjects and none of the patients with SLE demonstrated AVN on MRI.
Conclusion: AVN can be detected by MRI in 20% of patients with primary APS. Younger patients tend to develop AVN more frequently than do older patients, and the presence of livedo reticularis may identify individuals at risk for AVN. Clinicians should be aware of this possible clinical manifestation of primary APS, because early diagnosis can lead to early intervention.