[Herniation pits].
"Herniation pit" is a benign bone affection described first in 1982 by Michael J. Pitt et al. It is located typically in the proximal anterior and upper quadrant of the neck of the femur and develops as a result of the mechanical action of pressure of the adjacent articular capsule and synovialis. On the X-ray picture it is seen as a lighter spot which is relatively well defined, surrounded by a narrow margin of sclerotic bone; it is either round or oval and usually not more than 1 cm in diameter. In the authors' group of 100 patients selected at random from patients who had an X-ray picture of the hip joint taken during the last three years for different indications a herniation pit was found in six patients--4 women and 2 men. In one patient the finding was bilateral. This result is practically consistent with the 5% in the normal adult population, as reported in the world literature. In clinical practice the herniation pit is in the majority asymptomatic and is only an incidental finding during X-ray examination of patients with unexplained pain in the hip joint. Its importance is thus above all that it may be mistaken for other usually oncological bone affections such as osteoid, osteoma, Brodie's abscess, intraosseous ganglion or skeletal metastases of carcinoma.