What is Osteomyelitis?
Osteomyelitis is an infection of the bone mainly due to bacteria. Usually infection spreads from already infected tissue nearby or from a distant site once the bacteria travel through blood stream. Infection may also start from the bone itself following injury which exposes the bone to the environment and allows bacteria to then enter. Osteomyelitis can be classified under different classes based on the infecting organism, route of infection, site of involvement and duration.
Osteomyelitis commonly occurs in long bones in case of children whereas in case of adults the vertebral bones forming the vertebral column is the most commonly affected bone. Sometimes in elderly diabetic patients osteomyelitis may affect the bones of foot which are already damaged by diabetic foot. Although in the past osteomyelitis was considered to be difficult to treat, these days newer and stronger antibiotic treatment of is effective. In most of the patients surgical removal of damaged bone is essential.
Symptoms of Bone Infection
The usual presenting symptoms of osteomyelitis include high degree of fever along with chill and rigor, increased tiredness, irritability, pain in the area involved along with swelling, increase of temperature and redness. However in patients of osteomyelitis there may not be any symptoms. Without treatment osteomyelitis may lead to number of serious complications like
- Bone death: Osteomyelitis may lead to obstruction of blood flow to the affected bone thereby depriving the bone of nutrition and eventually the affected bone dies (osteonecrosis). Surgery is required to remove these dead pieces of bone as following removal new bones may grow. Sometimes when large part of bone is affected partial removal of the affected limb is required.
- Septic arthritis: Infection of the bone affected may spread to the adjacent joint resulting in joint inflammation (septic arthritis). This should not be confused with more common types of arthritis like osteoarthritis and rheumatoid arthritis.
- Stunted growth: osteomyelitis if occurs at the end of the long bones (cartilages) especially in children in whom the ends of the bones are not are yet to be united. Thus in children there is a risk of short height following suffering from osteomyelitis
In some patient the lesion of osteomyelitis may open on the skin with pus drainage.
Causes of Osteomyelitis
In most of the patients of osteomyelitis occurs following infection by staphylococcus, a commonly found bacteria. The infective organism usually enter into the bone via the following routes:
- Bloodstream: Bacteria from distant organs especially those causing pneumonia or urinary tract infection usually reach a susceptible part in the bone, in case of children cartilages are commonly affected.
- Puncture wounds: offending bacteria may enter the bones through puncture wounds.
- Direct injury: fracture of bones opening directly to the skin or contamination during surgery may lead to bone infection followed by osteomyelitis.
Common risk factors for osteomyelitis include injury to bone or undergoing bone surgery recently, circulation problems like chronic diabetes, sickle cell anemia, peripheral arterial diseases etc which lead to inadequate clearing of infecting organisms by white blood cells, putting intravenous or intra-arterial catheters like dialysis and intravenous tubing especially when inserting a central line, taking illicit intravenous (IV) drugs with non-sterile needles.
Treatment of Osteomyelitis
Antibiotics are administered as intravenous injections usually for 6 weeks. Choice of antibiotics depends upon the infecting bacteria as identified by bone biopsy. Surgical options include drainage of pus, removal of diseased bones and tissue, removal of foreign substances, if any like catheters, restoration of blood flow and finally in some cases amputation of the affected limb. Sometimes in difficult cases hyperbaric oxygen therapy may help.