Spontaneous osteonecrosis.
D000293:Adolescent; D000368:Aged; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000000981:diagnostic imaging*; D011859:Radiography