Recurrent spontaneous hemarthrosis associated with reflex sympathetic dystrophy.

Reflex sympathetic dystrophy is a mysterious entity with unclear pathogenesis. The diagnosis is largely clinical and based on signs and symptoms of pain and vasomotor dysfunction. Treatment is a challenge because the underlying mechanism remains unknown. Our patient is a 75-year-old woman 2 years after left total knee replacement who presented with her second spontaneous hemarthrosis in 3 months. After arthrocentesis, dusky discoloration, edema, hyperesthesia, and decreased range of motion of the left knee and entire distal extremity were noted. Despite analgesia and physical therapy her symptoms worsened. Radiographs of her left knee showed severe periprosthetic osteopenia and a triple phase bone scan was negative. Clinically, reflex sympathetic dystrophy was considered likely and a lumbar sympathetic block was performed. The patient improved and continued to do well after a series of blocks. This is the first reported case of recurrent atraumatic hemarthrosis associated with reflex sympathetic dystrophy.