Idiopathic osteonecrosis in an adult with familial protein S deficiency and hyperhomocysteinemia.

We describe a 36-year-old man with familial protein S deficiency and homozygosity to the methylene tetrahydrofolate reductase (MTHFR) thermolabile variant who had a stroke followed by an episode of idiopathic osteonecrosis that was successfully managed by surgical core decompression. The patient's symptomatic thrombophilia, as well as that of several of his first-degree relatives who also had thrombotic events, raises the possibility that the thrombophilia was a contributing factor to the development of his osteonecrosis.