Definition
In medicine, a bone contusion is an injury to the bone that cannot be described as a fracture. This causes oedema, i.e. fluid accumulation in the bone itself or between bone and periosteum, as well as so-called microfractures. Microfractures are the smallest fractures of the bone building blocks. Bone contusions are also called bone bruises.
Difference between bone fracture and bone contusion
Bone contusions have in common with fractures that they do not necessarily involve externally visible skin injuries. However, the tiny fractures and the accumulation of fluid in the bone and surrounding tissue often damage the small blood vessels that run through them, causing blood to leak out and cause an externally visible bruise.
Causes
A bone contusion is always caused by an injury. It is usually a clearly identifiable event, typically a fall or the impact of a bone (e.g. shin or hip) against a hard object (e.g. table).
On the other hand, however, a bone contusion can also be caused by recurring micro injuries to the bone. These are usually not noticed acutely at all, but only late, when these smallest injuries add up and finally lead to a bone contusion. Such a chronic bone contusion is often caused by overstrain in the context of sports or by incorrect posture or position of joints, which lead to an inappropriately high load in individual bone areas and in this way promote the development of the micro injuries. The acute or chronic injury can lead to the tearing of small blood and lymph vessels within the bone and surrounding tissue. The resulting fluid accumulations irritate the periosteum surrounding the bone, which is very sensitive to pain.
Symptoms
The main symptom of a bone contusion is pain in the affected area. This can lead to pressure and movement pain, but also to pain at rest. The latter typically occur at night.
In addition to the pain, swelling and bruising can often be observed. The latter is caused by injury to small blood vessels in the area of the bone and surrounding tissue. However, since other injuries such as bone fractures, joint or muscle injuries can also cause pain and swelling, and since the pain localization cannot normally be narrowed down to the bone with one hundred percent certainty, bone contusion is an exclusion diagnosis.
This means that other injuries that could be the cause of pain must first be excluded by means of imaging diagnostics (e.g. X-ray or ultrasound) in order to be able to diagnose bone contusion. However, experienced examiners are also able to determine relatively well on the basis of the intensity and type of pain indicated by the patient and the injury mechanism described, whether it is merely a bone contusion or a more serious injury. In this way, potentially superfluous imaging examinations and their disadvantages (e.g. X-ray: radiation exposure) can be avoided.
The pain caused by the bone contusion can last from days to weeks. If the pain persists for another 4-6 weeks after consultation with a specialist, the possibility of an MRI examination should be considered. On the one hand, this is suitable for excluding other possible causes of pain, especially joint and soft tissue injuries, and on the other hand, it is the only way to actually see a bone contusion. However, this option should be used sparingly due to the high time and financial expenditure involved. Therefore, if the examiner suspects a bone contusion as the most likely cause of pain, a wait-and-see approach and possibly an X-ray is preferable to an MRI examination.
