Osteonecrosis in Primary Antiphospholipid Syndrome is Associated with Previous Glucocorticoid Use and Thrombocytopenia

INTRODUCTION: The aim of this study was to investigate the frequency of avascular necrosis (AVN) and its associations with clinical and laboratory parameters in patients with primary antiphospholipid antibody syndrome (pAPS). METHODS: This was a cross-sectional study of 66 patients with pAPS who fulfilled the Sidney criteria for APS. Epidemiological and clinical data, and data on antiphospholipid antibodies were collected. Diagnosis of AVN was based on studies of magnetic resonance (MRI) images of affected bones. RESULTS: AVN was found in three of the 66 (4.5%) enrolled patients. Comparison of patients with pAPS with and without AVN showed that demographic data, comorbidities, and antiphospholipid antibodies profile were similar in both groups. Compared to patients without AVN, those with AVN had thrombocytopenia more frequently (66.7 vs. 7.9%) and used more glucocorticoids (100 vs. 35%). CONCLUSION: AVN is rare in patients with pAPS and may be associated with thrombocytopenia and previous glucocorticoid use.