Isolated osteonecrosis revealing primary antiphospholipid syndrome

First described in 1983 by Graham RV Hughes,1 antiphospholipid syndrome (APS) is a clinical-biological entity characterized by the association of thromboembolic events, classically recurrent, with obstetrical complications, and the permanent and significant presence of autoantibodies against the phospholipids of cell membranes.2,3 It is a rare entity that may be primitive or secondary to other autoimmune diseases, in particular systemic lupus erythematosus. Its incidence is estimated at 5/100,000 person-years and its prevalence at 4050/100,000 people.2,3 The clinical manifestations of this syndrome are highly polymorphic and all tissues and organs can be affected2–4 making its diagnosis a real challenge for clinicians.5 The orthopedic complications associated with primary APS are very rare and little known.5,6 Among these manifestations, bone necrosis remains exceptional and unusual.5,7,8 We report an original observation of isolated osteonecrosis of the upper end of the humerus revealing a primary APS.