Definition – What is aseptic bone necrosis?
Bone necrosis refers to the loss of tissue from a bone. The bone cells die and leave behind a weakened tissue structure. This dying off is called necrosis. The term aseptic serves to distinguish it from infectious bone necrosis, which is caused by pathogens such as bacteria. In contrast, infections do not play a role in aseptic bone necrosis.
The causes of aseptic bone necrosis can be manifold. In most cases, there are various reasons that trigger a deficiency in the supply of oxygen and other nutrients to the bone cells. – This can occur, for example, after an injury to the bone.
In this case, small blood vessels are injured or parts of the bone are squeezed so that sufficient blood flow is no longer possible. The bone cells are no longer supplied with nutrients and the waste products of their metabolism cannot be removed. The combination of these factors leads to bone necrosis.
- Certain vascular diseases or a lack of vascular formation can also lead to a reduced supply of a bone area and thus to necrosis. – A similar effect can occur with blood diseases or those that change the viscosity of the blood (i.e. how liquid or viscous the blood is). – Other triggers can be environmental factors such as particularly high pressures (when diving or working with compressed air).
The blood must be pumped through the body against this increased pressure from outside. In doing so, areas far away from the heart, such as the feet, are often not sufficiently supplied. Excessive use of various drugs such as chemotherapeutic agents and steroids, as well as radiation, can change the metabolic position of the bone and thus cause bone necrosis despite normal blood circulation.
Puberty and growth
Some aseptic bone necroses occur preferentially during puberty. During this time, strong bone growth takes place, which changes the structure of the bones. This can lead to a temporary lack of blood supply to certain bone areas. If this reduced blood supply lasts longer, bone necrosis can develop. Since growth pains often occur during puberty, symptoms such as bone and joint pain are not always followed up, so that aseptic bone necrosis can also be overlooked
Drugs used in aseptic bone necrosis
Drugs can intervene directly in bone metabolism through their active ingredients and thus influence the nutritional requirements of a bone. Bisphosphonates, for example, are drugs that are intended to inhibit bone resorption and thus contribute to a stronger bone structure. Due to this increased mass of bone tissue, however, increased blood flow is necessary to supply all bone cells. If this is not ensured, bone necrosis occurs. Cortisone, on the other hand, tends to inhibit bone metabolism, resulting in increased bone breakdown.