What is Osteomyelitis?

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Osteomyelitis is an infection of the bone. It is rare, but chronic cases are increasing, as Diabetes and other risk factors, increase.

How does it happen?

The infection occurs when bacteria (or less commonly fungus) enters the bone and creates an infection. This can occur in anyone who has 

  • an infection in the blood stream
  • penetrating trauma (such as a cut or bone break exposing bone at the surface)
  • another infection near the bone (such as cellulitis or poor dental hygiene)
  • orthopedic surgery, such as for joint replacement or a rod or plate placement

This means if someone breaks a bone and the bone is visible this is a risk factor. Anyone with bacteria in their bloodstream is at risk. Likewise, anyone who has surgery with metal plates or artificial joints placed may be at risk. A rotted tooth can lead to an infection.

Who is at risk?

Osteomyelitis is more common in children (especially infants and younger children) and the elderly.

There are particular persons who are at more risk:

Those with Diabetes may have nerve damage in their feet, leading to injuries and hence infections in their feet. Those with diabetes may not have the immune system control to fight the infection and may develop persistent bone infections in their feet. 

Those who do not have good blood flow (circulation) in their feet and legs, such as those with Peripheral Vascular Disease, may be prone to bone infections.

Others who are immunocompromised may also have bone infections, such as those with HIV and on immunosuppressive medication, such as those with Rheumatoid Arthritis, Crohn's Disease, or on chemotherapy for cancer.

Those with Sickle Cell Disease are particularly at risk, as the disease can damage the spleen affecting immune response, and crises may limit blood flow to bones, allowing infections to build up.

(Bone Infections with Salmonella are known to be particularly associated with Sickle Cell Disease, but Staph Aureus is more common).

Those who are Intravenous Drug Use can increase risk, as the practice may introduce bacteria into the blood stream and seed bones.

Likewise, those with artificial hardware (such as rods or plates to fix broken bones or damaged vertebrae) or artificial joints (hips, knees) are also at increased risk.

What are the symptoms?

Infections may involve fever, pain in the affected area as well as difficulty moving the affected area or bearing weight on it. There may be swelling, redness, and warmth. A young child may simply irritable. A child who is walking may simply have a new limp. Some presentations may begin simply with back pain or a stiff back.

Some infections are acute (less than 2 weeks), subacute, or chronic. Infections can even persist after treatment with antibiotics. Some may even create drainage tracks with pus draining for years in some cases. 

Which bones are at risk?

Children are often risk and usually because of hematogenous spread (infection spreads through the blood). Some cases are related however to trauma (especially as children are quite active) or surgery or spread from a nearby infection. Children are still growing and have more blood flow through their bones. The bones usually affected are the long bones of their limbs, such as the femur, tibia or humerus. It is important these infections are caught as it can affect growth of these limbs - and may simply present with irritability in a very young child or a limp in a pre-school age child.

In adults, however, infection may seed where blood flow is limited and cannot clear an infection. 

In general, the bones most affected are still the tibia, femur, humerus, as well as the vertebrae of the spine and the maxilla and mandibular bones of the jaw and face. Diabetics usually have infections in their feet.

What cause osteomyelitis?

Usually bacteria causes osteomyelitis, but in rare case fungal infections do. By far, the most common bacteria involved are Staph Aureus, including the drug resistant form - MRSA. There are other bacteria that can be involved, depending on the age and risk factors, including: Enterobacter bacteria (Salmonella, E coli, Serrate marcescens), Streptococcus, Tuberculosis, Pseudomonas aeruginosa, and others.

How is osteomyelitis diagnosed?

It can be difficult to diagnose osteomyelitis. 

A history and examination by a clinician may be the key component to diagnosis. A chronic history of pain in the region, especially associated with a history that could leading to seeding infection in the affected area as well as other risk factors, may point to a diagnosis.

Blood tests, such as a blood culture, that show an microorganism, like Staph Aureus, in the blood may point to an infection.A bone biopsy showing a microorganism present in bone will diagnose more definitively, if possible.

Diagnosis can be supported by White Blood Cell count elevations, as well as elevations in ESR (Erythrocyte Sedimentation Rate) and CRP (C-Reactive Protein) which point to inflammation.

Simple imaging sometimes does not easily show infection. An X-Ray may show advanced, but not early, infection. An MRI can show infections earlier. CTs and Bone Scans can also be used. Ultrasound may be particularly useful in diagnosis in children.

What is treatment like?

Antibiotic courses can be long. It is hard for antibiotics to get into some bones and stop the infection. Antibiotics will sometimes need to be IV (depending on what bacteria are involved, what the bacterial drug resistance is, which bones are infected and for how long).

If there are prosthetic joints, plates, or rods involved, these will often need to be removed. If the infection has progressed to a substantial degree and blood flow is not sufficient, there are times when amputation of the infected bone is required.

What are the long term effects?

Children may have stunted growth if the infection is not caught and treated. They may also have arthritis - or joint pain and swelling - in nearby joints. Others may more easily break an affected bone. Some may require surgery, such as amputation, if the infection has progressed and blood flow is limited (especially if gangrene develops).

Who has had osteomyelitis?

The career of Mickey Mantle, a baseball player for the Yankees, is owed to the distribution of penicillin. He had osteomyelitis in his leg (around his ankle) before his career began and without treatment with newly available antibiotics he would likely have required surgery, even amputation, that would have never allowed him to play baseball as he did.

Where did the word Osteomyelitis come from?

The word derived from Greek, where Osteo- refers to bone, -myelos to bone marrow, and -itis to inflammation. As such, it means inflammation of the bone (and marrow) - which is generally caused by infection

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