[Epiphysis-metaphysis bone ischemia in hemorrhagic rectocolitis and Crohn's disease].

Aseptic osteonecrosis is a rare extraintestinal manifestation in patients with inflammatory bowel disease; its true prevalence is not precisely known. Steroid treatment undoubtedly participates in the pathophysiology of avascular osteonecrosis, however, other factors like hypercoagulability may be involved. Two cases of bilateral osteonecrosis of the knees--the first occurring during the course of ulcerative colitis, the second in a patient presenting with Crohn's disease--are described. Specific location of the lesions and regression of symptoms, as well as the importance of magnetic resonance imaging for early recognition of osteonecrosis, are noteworthy.