Osteomyelitis is a medical term that describes an infection of bone. The infection is usually bacterial. Symptoms of osteomyelitis may include:
- high temperature (fever) of 38°C (100.4°F) or above
- pain in the affected area, which can often be intense
- swelling in the affected area
- a passageway that opens in the skin through which pus or fluid leaks (this is known as a discharging sinus)
For more information, see Osteomyelitis - symptoms.
Types of osteomyelitis
There are two main types of osteomyelitis:
- Acute osteomyelitis is where the bone infection develops within two weeks of an initial infection, injury or underlying disease and may respond to antibiotic treatment.
- Chronic osteomyelitis is where the bone infection has produced irreversible bony changes that cannot be treated by antibiotics alone.
Acute osteomyelitis
There are two ways that acute osteomyelitis can occur:
- Contiguous osteomyelitis is where an infection spreads directly into the bone as a result of an injury, such as a fractured bone or animal bite, during surgery, or as a result of another condition such as diabetes or vascular disease.
- Haematogenous osteomyelitis is where an infection spreads into a bone from the bloodstream.
Contiguous osteomyelitis is the most common type of acute osteomyelitis, accounting for four out of five cases. It mainly affects adults.
People who have a condition that affects the blood supply to certain parts of their body, such as type 2 diabetes, have an increased risk of developing contiguous osteomyelitis. Any surgical procedure on the skeleton may introduce infection into bone.
Haematogenous osteomyelitis mostly affects younger children, although adult cases may occur in anyone with a weakened immune system, such as those with rheumatoid arthritis or HIV.
People who regularly inject drugs, such as heroin, also have an increased risk of developing haematogenous osteomyelitis.
Chronic osteomyelitis
Chronic osteomyelitis can sometimes start as acute osteomyelitis. If acute osteomyelitis is not treated properly it can become established and produce permanent, destructive changes to bone, resulting in pain, discharge and loss of function.
As with acute osteomyelitis, the infection can be spread through the blood or directly into the bone as a result of injury or other trauma.
Chronic osteomyelitis can also develop as a complication of a pre-existing infection such as tuberculosis (a bacterial infection) or syphilis (a sexually transmitted infection), although this is uncommon in the UK today.
How common is osteomyelitis?
At present, there are limited data on how widespread osteomyelitis is in adults. However, in England, an average of 7,000 adults are treated in hospital for osteomyelitis each year.
Acute osteomyelitis is rare in children. It is estimated that one child in every 1,000 children under the age of one, and one in every 5,000 over the age of one will develop acute osteomyelitis.
The condition is known to be a common complication of certain health conditions. For example:
- 30-40% of people with diabetes who experience a puncture injury to their foot will develop osteomyelitis
- one in every 200 people with sickle cell anaemia (a hereditary blood condition) will develop osteomyelitis in any given year
Outlook
The outlook for acute osteomyelitis is generally good because the condition usually responds well to antibiotics. However, for people with underlying risk factors for osteomyelitis, such as diabetes, there is a chance that the infection could come back.
The outlook for chronic osteomyelitis is mixed because the infection can be more challenging to treat, particularly if significant bone damage has occurred. Most cases will require a combination of antibiotics and surgery. See Osteomyelitis - treatment for more information.
