The terms osteomyelitis, periostitis and ostitis are usually used as synonyms for inflammation of the bone.

As a bone cannot become inflamed all by itself (because of calcium), osteomyelitis (meaning inflammation of the bone marrow) or periostitis (meaning inflammation of the periosteum) would be better terms, but ostitis is used most frequently.

There are many different causes of inflammation: exogenic, meaning external factors or endogenic, meaning internal factors. There are also combinations of these. Yet another form is the idiopathic factors, which cannot be explained medically.

The exogenic factors are for example bacteria, viruses and fungus infections. These are all potential pathogens. If they get into the body, they can cause inflammation. If this happens inside the bone, then this is called inflammation of the bone.

The endogenic factors are caused by our bodies themselves. In the case of diabetics, for example, the higher blood sugar level makes the walls of the blood vessels get thicker, which makes blood circulation worse. Circulation can in fact become so poor that certain areas of the body are no longer supplied with blood, and the tissue in those areas dies due to lack of oxygen and recedes as a result of inflammation – which, as shown in the animation, can also occur in the bones.

Idiopathic osteomyelitis means that a doctor cannot find a reasonable explanation for the inflammation.

The most common causes of inflammation of the bone in the area of the jaw are exogenic and iatrogenic factors (iatrogenic means caused by the doctor). Extraction of teeth or faulty root treatment often leads to infections in the bone. In the picture you can see an x-ray of a wound (outlined in blue) left by extraction, the bone in this area is inflamed (outlined in red) – this is osteomyelitis.

An x-ray is usually enough to diagnose osteomyelitis – the same picture also shows a tooth (outlined in green), with an inflammation around the root (outlined in red), which appears as a dark spot. An x-ray can provide a lot of information about a bone, and a CT or MRT can help to find more details. These diagnostic methods are very reliable in the case of chronic osteomyelitis, but only of limited use in the early stages.

Medical examinations at the nuclear level such as skeletal scintigraphy (Tc-99m) are often used in cases of osteomyelitis. The radioactive element technetium is injected into the vein and augmented in areas with higher bone metabolism.

This augmentation can be detected from the outside using a special camera (these are the dark spots in the picture). But this does not provide the reason for the increase in metabolism. Is it an inflammation or merely a re-construction process in the bone? Adding marked anti-granulocyte antibodies can make the examination more precise.

Blood tests are also not very exact and the inflammation levels in the blood do not always correlate with those of the osteomyelitis – especially in the area of the jaw. A biopsy is usually the best diagnostic method, as the bone can be viewed under a microscope (histology), and the pathogen can be isolated in a test tube (bacteriology). Once this is done, then an antibiogram can be performed, which means finding the antibiotic which can destroy this pathogen.

There are some drawbacks to performing a bone biopsy, however. This is an invasive procedure (which leaves behind a wound) and it is not easy to perform a biopsy on all types of bones. It is also not always possible to identify bacteria, and sometimes the sample can be contaminated by germs in the mouth.

There are many types of treatment available – removal of the bone in the worst case, but this is hardly ever necessary. The most common and simplest treatment is administering antibiotics. The medication can take the form of a pill or an injection – which leads to a higher concentration in the blood. Oxygen therapy means adding more oxygen to the blood, because if a bone is inflamed then it gets less blood and therefore less oxygen. This is the perfect breeding ground for bacteria which avoid oxygen – called anaerobes. Oxygenated blood is used to fight this type of bacteria, using a smaller quantity of blood but with a larger amount of oxygen.

Another very promising type of therapy is removing the affected bone and replacing it with bone from a donor which has been augmented with antibiotics. The animation shows the bone being augmented with antibiotics (highlighted in green). The inflamed bone (highlighted in red) is removed and the bone from the donor inserted in its place. The antibiotic is slowly released into the body over a period of several months, while the wound is allowed to heal. The advantage to this type of therapy is that the affected area is exposed to higher concentrations of the medication than if this is taken the usual way (orally, or intravenously). But long-term studies still need to be completed, so that it will not be possible to rate the success of this therapy for another few years.