Introduction
Acetabular necrosis (also known as aseptic femoral head necrosis) is a bone disease in which bone tissue dies due to reduced blood flow to the femoral head. This results in arthrosis and deformities, which lead to pain and restricted mobility. The femoral head is the upper end of the thigh bone, which is part of the hip joint in addition to the acetabulum, which is formed by the hip bone.
Necrosis is mainly felt through load-dependent pain in the groin, which can also radiate to the knees. In addition, there is often a rotation restriction in the hip joint. Necrosis of the femoral head can occur in adults and children. The form occurring in adolescence is also known as Perthes disease. Acetabular necrosis can be triggered by a specific cause such as femoral neck fracture, but it can also occur without a known cause (idiopathic hip joint arthrosis).
Causes
The causes of femoral head necrosis are manifold and often still unexplained. Idiopathic femoral head necrosis can be promoted by certain risk factors such as alcoholism or metabolic disorders. However, femoral head necrosis of traumatic origin (fracture of the femoral neck) is usually caused by injuries to the surrounding vessels.
The reason for femoral head necrosis can be, for example, a lateral or central fracture of the femoral neck. This is a fracture of the neck of the femur, which is located close to the joint. This usually affects older people and patients with osteoporosis.
The femoral neck fracture can be caused by falling onto the upper outer side of the femur or stumbling with forced external rotation. Chronic overloading of the femur can also lead to a femoral neck fracture. In this case, femoral head necrosis is a complication of the injury, since the vessels running along the neck of the femur (especially A. circumflexa femoris medialis) can be damaged.
The result is an undersupply of the femoral head, which leads to destruction of the bone at the femoral head. A direct femoral head fracture can also be the cause of femoral head necrosis, which can also injure vessels that result in an undersupply of the femoral head. This form of femoral head necrosis is not caused by an accident (trauma).
Idiopathic means that the cause is not known. However, there are known risk factors that promote idiopathic femoral head necrosis. However, the exact relationship between the risk factors and femoral head necrosis is not always clear.
Metabolic disorders are sometimes a risk factor for the development of femoral head necrosis. These include, for example, diabetes mellitus, hyperuricemia (too high uric acid levels in the blood) or hyperlipoproteinemia (too high fat levels in the blood), which can lead to vascular disease and thus also to an undersupply in the region of the femoral head. Long treatment with glucocorticoids such as cortisone can also cause femoral head necrosis.
Furthermore, alcoholism, smoking and overweight are possible risk factors. Sickle cell anemia, lupus erythematosus and Gaucher’s disease (lipid storage disease) also contribute to femoral head necrosis. Radiation and chemotherapy (especially for lymphomas and leukemias) can also promote femoral head necrosis.
Perthes disease describes an idiopathic, aseptic femoral head necrosis that occurs in children, especially between the ages of 4 and 8. Various causes are discussed. One of the causes of juvenile femoral head necrosis (occurring in adolescence) is the occlusion or adhesion of vessels, which leads to an undersupply and thus to bone resorption.
On the other hand, repetitive microtraumas caused by increased strain on the hip during running and jumping are counted among the possible causes. Blood clotting disorders can also cause occlusion of vessels and thus an undersupply of the femoral head. Hip joint dysplasia is an inherited disorder in which maturation disorders of the acetabulum occur already in the uterus.
As a result, the femoral head is not sufficiently secured in the acetabulum, thus increasing the risk of dislocation of the hip joint. Since a dislocation can often occur without treatment, the hip joint must be repositioned again and again.Necrosis of the femoral head is again a complication and is favored by frequent repositioning of the hip joint, since vessels supplying the femoral head can easily be damaged.