What Is Osteomyelitis?

When bacteria or fungus invade a bone, a bone infection called osteomyelitis can result. Bone infections occur most commonly in the long bones of the arms and legs. They can happen over a period of time or all of a sudden. These infections can leave a bone permanently damaged if they are not treated properly.

In almost 80 percent of people, an infection develops due to an open wound. The person experiences muscle spasms in the area that is inflamed, along with deep pain and a fever. Commonly, the long bones in the leg, pelvis, upper arm, and spine are affected. Treatment of osteomyelitis was difficult in the past, but now the infected bone can be saved by aggressive treatment. 2 out of every 10,000 people are affected by osteomyelitis in the United States.

Osteomyelitis in Children and Adults

Osteomyelitis in children can be acute. Usually within two weeks of a pre-existing blood infection, osteomyelitis may occur. Methicillin-resistant staphylococcus aureus normally causes it. This is also known as hematogenous osteomyelitis.

It is important to get the condition diagnosed as soon as possible since growth disturbances or deformities can be caused by a delayed diagnosis. Diagnosis can be difficult, however. Also, this condition can be fatal. In adults, osteomyelitis is usually sub-acute, or chronic. This can occur particularly after a trauma or injury. This usually affects people above the age of 50. It is also known as contiguous osteomyelitis.

Types of Osteomyelitis 

The three main types of osteomyelitis are:

• Acute osteomyelitis: Within two weeks of an injury, the infection may develop. It can also develop at the start of an underlying disease. This condition can be life-threatening and the pain can be intense.
• Sub-acute osteomyelitis: Within one to two months of an injury, the infection develops. It may also develop at the start of an underlying disease.
• Chronic osteomyelitis: At least two months after an injury, this infection may start, or it may develop at the start of an underlying disease.

Causes

Staphylococcus aureus travels most commonly through the bloodstream, thus a bone infection can develop. The infection may begin in one part of the body and then can spread through the bloodstream. In nearby bones, infections can be caused by organisms that invade a deep cut, severe injury, or wound. Bacteria can enter one’s system at a surgical site, such as the site of a bone fracture repair or hip replacement. Osteomyelitis can be caused when the bone breaks and is then invaded by bacteria. Staphylococcus aureus bacteria are the most common cause of toxic infections. These bacteria commonly occur on the skin, however, these may not always cause health problems. But, if the immune system is weakened by any illness or disease, then it can be overpowered by the bacteria. Also, these bacteria can cause infections in injured areas.

Osteomyelitis occurs when a bacterial or fungal infection develops within a bone, or the infection may be carried from another part of the body through the blood. 

When the infection develops inside the bone, the immune system tries to kill it. For this, neutrophil is sent to the source of infection. However, dead neutrophils will accumulate inside the bone if the infection takes hold and is not treated. Thus, an abscess or pocket of pus is formed.

The vital blood supply to the affected area is blocked by the abscess, and so the bone may eventually die from chronic osteomyelitis. Normally, the bones are resistant to infection, but under certain conditions, the infection may enter the bones. The person’s ability to resist infection is reduced by an infection in the bloodstream, surgery, complications due to trauma, or pre-existing conditions such as diabetes.

How the Infection Starts

The bone infection can occur in different ways:

• Hematogenous osteomyelitis: The infection may start as a urinary tract infection or a mild respiratory tract infection. This may then spread through the blood. This type is more common in children.
• Post-traumatic osteomyelitis: This may occur after an open wound to the surrounding skin and muscle, a compound fracture, skin is broken by a broken bone, or after surgery, if screws or plates are used to secure the broken bones.
• Vascular deficiency: An infection may develop on the feet from a minor scrape or cut. The white blood cells are prevented from reaching the site, and this causes deep ulcers. Thus, deep tissue and bone are exposed to infection.
• Vertebral osteomyelitis: This occurs in the spine. Usually, it starts with endocarditic infection in the mouth, infection in the bloodstream, infection at the injection site, or a urinary or respiratory tract infection.

Symptoms at the Infection Site

Pain is the first symptom of an infection. Other symptoms are:

• Chills and fever
• The infected area becomes red
• General feeling of being unwell or irritable
• The affected area may become swollen
• The person finds it difficult to use an affected limb, or the limbs become stiff
• The ankles, feet, and legs may swell
• Walking pattern may change, such as limping

The symptoms of osteomyelitis could resemble the symptoms of an injury or sometimes they are not obvious. Accurate diagnosis becomes difficult, though, especially in the pelvis, hip, or spine. 

Diagnosis

If there are any symptoms of a bone infection, then, to diagnose the condition, several methods are used. To check for swelling, discoloration, and pain, a physical exam is performed. To determine the exact location and extent of the infection, lab and diagnostic tests may be ordered by the doctor. To check for the organism causing the infection, it’s likely that the doctor will order blood tests. Throat swabs, stool analyses, and urine cultures are other tests used to check for bacteria. An example of stool analyses is a stool culture. The cellular and metabolic activity in the bones can be revealed through another test, called a bone test: to highlight the bone tissue, a type of radioactive substance is used. If enough information is not provided by the bone scan, the doctor may order an MRI scan. If necessary, a bone biopsy may be needed. However, for the doctor to determine the right treatment for the person, a simple bone X-ray may be enough.

Treatments

To treat a bone infection, several options are provided by the doctor:

Antibiotics may be necessary for the infection. This antibiotic can be administered directly into the veins or intravenously. Antibiotics may be necessary for up to six weeks if the infection is severe. Sometimes, surgery may be required for a bone infection. Any infected bone and dead tissues are removed, and any abscesses or pockets of pus are drained. If the infection is caused by prosthesis, then it is removed and replaced with a new one by the doctor. Any dead tissue near or around the infected area will be removed by the doctor.

Risks Factors

The chances of developing osteomyelitis can be increased by a few conditions and circumstances, such as:

• Blood supply to the bones is affected by diabetic disorders
• Drug used intravenously
• Treatment used for kidney conditions (hemodialysis)
• Sickle cell disease
• Smoking
• Infected artificial joints

People in whom the risks are higher include:

• A person with a weakened immune system due to conditions such as malnutrition, chemotherapy, radiation, having a urinary catheter, dialysis, or injecting illegal drugs
• Having circulatory problems, such as peripheral disease or diabetes
• A fracture or deep puncture wound that can break the skin
• Surgery to repair or replace bone

In children, acute osteomyelitis is very common. In patients over the age of 50, the spinal form is seen more often, and it is also more common in males.

Prevention

In the skin if there are any cuts or open wounds then wash it clean thoroughly. If by home treatment the wound or cut does not heal then get it examined by the doctor. Before placing the prosthesis clean and dry amputation. To avoid injuries when running, jumping or participating in sports use the proper footwear and protective equipment.

Long-term Outlook

In the majority of cases, it is possible to treat osteomyelitis. However, healing may take longer if the bone infection is chronic, and surgery may even be required. Sometimes, amputation can become necessary, too, hence, treatment should be aggressive. If the condition is treated early, then the outlook for this condition is good.