[Spontaneous Ahlbäck's knee joint osteonecrosis].

Among the group of genuine osteonecroses there ranks the spontaneous osteonecrosis of the knee described for the first time by Ahlbäck, Bauer and Bohne in 1968. Characteristic of it is a subchondral defect on the medial condylus of the femur, which may occur in old persons, chiefly women. Supported by six illustrative cases in own patients clinical experience, radiology, diagnosis and differential diagnosis are presented and discussed.