الفهرس 
coverOnly 14 pages are availabe for public view
 |  | from | 74 |  |  |
| | | from | 74 | | |
Abstract
Osteonecrosis is defined as the death of a non-focal segment of bone. This has historically been called avascular or aseptic necrosis and results from a variety of factors leading to a diminished blood supply to the cellular structure of the bone. When this process occurs in the foot and ankle, it most commonly affects the second metatarsal head, navicular and talus.(3)
Kohler’s disease or idiopathic ‘osteonecrosis’ of the navicular in children is a self-limiting osteochondrosis and is different from the often debilitating version seen in adults that is called Muller Weiss disease. Current thought to the cause of Muller Weiss disease is that it is due to a delay in the ossification of the navicular, which can result from generalized or localized developmental disturbances. Abnormal navicular ossification can produce an abnormal shape to the bone during adulthood. This can result in both abnormal force distributions at the bone and a decreased ability of it to resist stresses. This can in turn affect the bone’s blood supply and result in osteonecrosis.(9,12)
Kohler’s disease is diagnosed on the basis of both clinical and radiographic findings. The patient walks with a limp, and tenderness, warmth, and swelling over the navicular are evident. It is more common in boys than girl.