Osteomyelitis

Definition

Osteomyelitis refers to a bone infection, almost always caused by a bacteria. Over time, the result can be destruction of the bone itself.

Description

Bone infections may occur at any age. Certain conditions increase the risk of developing such an infection, including sickle cell anemia, injury, the presence of a foreign body (such as a bullet or a screw placed to hold together a broken bone), intravenous drug use (such as heroin), diabetes, kidney dialysis, surgical procedures to bony areas, untreated infections of tissue near a bone (for example, extreme cases of untreated sinus infections have led to osteomyelitis of the bones of the skull).

Causes and symptoms

Staphylococcus aureus, a bacterium, is the most common organism involved in osteomyelitis. Other types of organisms include the mycobacterium which causes tuberculosis, a type of Salmonella bacteria in patients with sickle cell anemia, Pseudomonas aeurginosa in drug addicts, and organisms which usually reside in the gastrointestinal tract in the elderly. Extremely rarely, the viruses which cause chickenpox and smallpox have been found to cause a viral osteomyelitis.

There are two main ways that infecting bacteria find their way to bone, resulting in the development of osteomyelitis. These include:

• Spread via the bloodstream; 95% of these types of infections are due to Staphylococcus aureus. In this situation, the bacteria travels through the bloodstream to reach the bone. In children, the most likely site of infection is within one of the long bones, particularly the thigh bone (femur), one of the bones of the lower leg (tibia), or the bone of the upper arm (humerus). This is because in children these bones have particularly extensive blood circulation, making them more susceptible to invasion by bacteria. Different patterns of blood circulation in adults make the long bones less well-served by the circulatory system. These bones are therefore unlikely to develop osteomyelitis in adult patients. Instead, the bones of the spine (vertebrae) receive a lot of blood flow. Therefore, osteomyelitis in adults is most likely to affect a vertebra. Drug addicts may have osteomyelitis in the pubic bone or clavicle.
• Spread from adjacent infected soft tissue; about 50% of all such cases are infected by Staphylococcus aureus. This often occurs in cases where recent surgery or injury has result in a soft tissue infection. The bacteria can then spread to nearby bone, resulting in osteomyelitis. Patients with diabetes are particularly susceptible to this source of osteomyelitis. The diabetes interferes with both nerve sensation and good blood flow to the feet. Diabetic patients are therefore prone to developing poorly healing wounds to their feet, which can then spread to bone, causing osteomyelitis.

Acute osteomyelitis refers to an infection which develops and peaks over a relatively short period of time. In children, acute osteomyelitis usually presents itself as pain in the affected bone, tenderness to pressure over the infected area, fever and chills. Patients who develop osteomyelitis, due to spread from a nearby area of soft tissue infection, may only note poor healing of the original wound or infection.

Adult patients with osteomyelitis of the spine usually have a longer period of dull, aching pain in the back, and no fever. Some patients note pain in the chest, abdomen, arm, or leg. This occurs when the inflammation in the spine causes pressure on a nerve root serving one of these other areas. The lower back is the most common location for osteomyelitis. When caused by tuberculosis, osteomyelitis usually affects the thoracic spine (that section of the spine running approximately from the base of the neck down to where the ribs stop).

When osteomyelitis is not properly treated, a chronic (long-term) type of infection may occur. In this case, the infection may wax and wane indefinitely, despite treatment during its active phases. An abnormal opening in the skin overlaying the area of bone infection (called a sinus tract) may occasionally drain pus. This type of smoldering infection may also result in areas of dead bone, called sequestra. These areas occur when the infection interferes with blood flow to a particular part of the bone. Such sequestra lack cells called osteocytes, which in normal bone are continuously involved in the process of producing bony material.

Diagnosis

Diagnosis of osteomyelitis involves several procedures. Blood is usually drawn and tested to demonstrate an increased number of the infection-fighting white blood cells (particularly elevated in children with acute osteomyelitis). Blood is also cultured in a laboratory, a process which allows any bacteria present to multiply. A specimen from the culture is then specially treated, and examined under a microscope to try to identify the causative bacteria.

Injection of certain radioactive elements into the bloodstream, followed by a series of x-ray pictures, called a scan (radionuclide scanning), will reveal areas of bone inflammation. Another type of scan used to diagnose osteomyelitis is called magnetic resonance imaging, or MRI

When pockets of pus are available, or overlaying soft tissue infection exists, these can serve as sources for samples which can be cultured to allow identification of bacteria present. A long, sharp needle can be used to obtain a specimen of bone (biopsy), which can then be tested to attempt to identify any bacteria present.

Treatment

Antibiotics are medications used to kill bacteria. These medications are usually given through a needle in a vein (intravenously) for at least part of the time. In children, these antibiotics can be given by mouth after initial treatment by vein. In adults, four to six weeks of intravenous antibiotic treatment is usually recommended, along with bed-rest for part or all of that time. Occasionally, a patient will have such extensive ostemyelitis that surgery will be required to drain any pockets of pus, and to clean the infected area.

Alternative treatment

General recommendations for the treatment of infections include increasing vitamin supplements, such as vitamins A and C. Liquid garlic extract is sometimes suggested. Guided imagery can help induce relaxation and improve pain, both of which are considered to improve healing. Herbs such as echinacea (Echinacea spp.), goldenseal (Hydrastis canadensis ), Siberian ginseng (Eleutherococcus senticosus ), and myrrh (Commiphora molmol ) are all suggested for infections. Juice therapists recommend drinking combinations of carrot, celery, beet, and cantaloupe juices. A variety of homeopathic remedies may be helpful, especially those used to counter inflammation.

Prognosis

Prognosis varies depending on how quickly an infection is identified, and what other underlying conditions exist to complicate the infection. With quick, appropriate treatment, only about 5% of all cases of acute osteomyelitis will eventually become chronic osteomyelitis. Patients with chronic osteomyelitis may require antibiotics periodically for the rest of their lives.

Prevention

About the only way to have any impact on the development of osteomyelitis involves excellent care of any wounds or injuries.

Resources

PERIODICALS

Calhoun, Jason H., et al. "Osteomyelitis: Diagnosis, Staging, Management." Patient Care 32 (January 30, 1998): 93+.

KEY TERMS

Abscess— A pus-filled pocket of infection.

Femur— The thighbone.

Humerus— The bone of the upper arm.

Thoracic— Pertaining to the area bounded by the rib cage.

Tibia— One of the two bones of the lower leg.

osteomyelitis , infection of the bone and bone marrow. Direct infection of bone usually occurs through open fractures, penetrating wounds, or surgical operations. Infecting microorganisms may also reach the bone via the bloodstream, the most common means of bone infection in children. Osteomyelitis is characterized by pain, high fever, and formation of an abscess at the site of infection. Infection may be caused by a variety of microorganisms, including staphylococci, streptococci, and other pathogenic bacteria. Unless treated vigorously with antibiotics and sometimes surgery, bone destruction may result.

Osteomyelitis

What Is Osteomyelitis?

How Common Is Osteomyelitis?

Is It Contagious?

What Are the Signs and Symptoms of Osteomyelitis?

How Is the Disease Diagnosed?

What Is the Treatment for Osteomyelitis?

How Long Does the Disease Last?

What Are the Complications?

How Can Osteomyelitis Be Prevented?

Resource

Osteomyelitis (ah-stee-o-my-uh-LYE-tis) is a bone infection that is usually caused by bacteria. It can involve any bone in the body, but it most commonly affects the long bones of the arms and legs.

KEYWORDS

for searching the Internet and other reference sources

Orthopedics

Staphylococcus aureus

Streptococcus bacteria

What Is Osteomyelitis?

Osteomyelitis usually is caused by infection with bacteria. Staphylococcus aureus (stah-fih-lo-KAH-kus ARE-ree-us), streptococcal (strep-tuh-KAHkul) species of bacteria, and Pseudomonas aeruginosa (su-doe-MO-nas airew-jih-NO-suh) are the major organisms associated with osteomyelitis. These bacterial intruders can travel from other parts of the body, such as the ear, throat, or intestines*, through the bloodstream and to a bone, where they can start an infection. Bones that have been weakened or damaged, such as one that has been injured recently, are more susceptible to bacterial invasion. When there is trauma* to the bone, like a puncture wound from stepping on a nail, bacteria can infect the bone directly. Rarely, fungi may cause osteomyelitis, and the spread of tuberculosis (too-ber-kyoo-LO-sis), a contagious disease that typically affects the lungs, through the body also can lead to bone infection, usually in the spine.

*intestines

are the muscular tubes that food passes through during digestion after it exits the stomach.

*trauma

is severe injury to the body.

In children, osteomyelitis occurs most often in the long bones of the leg, such as the femur (FEE‐mur) and tibia (TIH‐be‐uh). Adults tend to have the infection in the hipbones and vertebrae*, where it may occur following surgery on a bone or from an infection that has spread from the skin. People with diabetes* can have osteomyelitis in the foot bones from ulcerations* on their feet. Osteomyelitis that evolves rapidly is called acute* osteomyelitis. If a bone infection persists because it is not treated or it does not respond to treatment, it is known as chronic* osteomyelitis. Over time, the infection may interfere with the blood supply to the bone, causing the bone tissue to die.

*vertebrae

(VER-tuh-bray) are the bones that form a column surrounding the spinal cord; there are 39 vertebrae in the spine.

*diabetes

(dye-uh-BEE-teez) is a condition in which the body’s pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.

*ulcerations

are open sores on the skin or tissue lining a body part.

*acute

describes an infection or other illness that comes on suddenly and usually does not last very long.

*chronic

(KRAH-nik) means continuing for a long period of time.

How Common Is Osteomyelitis?

Chronic osteomyelitis occurs in about 2 in 10,000 adults. Children have the acute form of the disease more often than adults do, at a rate of about 1 in 5,000. People who have diabetes, who have had a traumatic injury recently, or who use intravenous* drugs are at greatest risk for chronic infection.

*intravenous

(in-tra-VEE-nus) means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin’s surface directly into a vein.

An Historic Infection

Some cases of osteomyelitis last for years, even a lifetime. Joshua Lawrence Chamberlain rose to the rank of general in the U.S. Civil War and was a hero in the Battle of Gettysburg. General Ulysses S. Grant selected Chamberlain to receive the official surrender of the Confederate Army’s weapons at Appomatox, Virginia, in 1865. He later served as governor of Maine and president of Bowdoin College. Before he reached that lofty standing, Confederate soldiers had shot him in the groin in a battle at Petersburg, Virginia, in 1864. The ball pierced both hipbones, but despite the crude battlefield surgery of the time he survived his injury. His wound never healed completely, though, and Chamberlain lived another 50 years with chronic osteomyelitis. He died in 1914, at the age of 85, from complications of that long-lasting wound.

Is It Contagious?

Bone infections are not contagious. However, some types of bacteria that cause the infections that can progress to osteomyelitis are passed from person to person.

What Are the Signs and Symptoms of Osteomyelitis?

The first sign of acute infection may be a fever that begins suddenly. The area over the infected bone may become warm, red, and swollen, and the joints next to the bone may swell as well. As the infection progresses, it can cause pain in the affected bone and may limit the person’s movement in that area. Some people with osteomyelitis feel irritable, nauseated, and generally sick. Patients with long-term bone infection may experience drainage of pus* through the skin covering the affected bone.

*pus

is a thick, creamy fluid, usually yellow or greenish in color, that forms at the site of an infection. Pus contains infection-fighting white blood cells and other substances.

How Is the Disease Diagnosed?

To help make the diagnosis, a doctor may order an X ray of the suspect area to look for signs of bone inflammation or damage, but changes in the bone may not show up for weeks after the infection begins. Magnetic resonance imaging* (MRI) or a computerized tomography* (CT) scan may show changes that reflect osteomyelitis sooner than X rays will. Radionuclide scans* may help pinpoint the location of the infection early in the course of the disease. Blood cultures* or, less commonly, a bone biopsy* may identify the infectious agent.

*magnetic resonance imaging

(MRI) uses magnetic waves, instead of X rays, to scan the body and produce detailed pictures of the body’s structures.

*computerized tomography

(kom-PYOO-ter-ized toe-MAH-gruh-fee) or CT, also called computerized axial tomography (CAT), is a technique in which a machine takes many X rays of the body to create a three-dimensional picture.

*radionuclide

(ray-dee-o-NU-klide) scans are tests that begin by giving a patient a small amount of a radioactive substance. The radioactive substance shows up on a scan, producing a view of the structure or function of the part of the body being studied.

*cultures

(KUL-churz) are tests in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

*biopsy

(BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.

What Is the Treatment for Osteomyelitis?

Patients with osteomyelitis usually need to be hospitalized. They typically receive antibiotics for 4 to 6 weeks to combat the infection. At first, the medication is given intravenously, but patients may be switched to oral (by mouth) medicine as the treatment continues and their condition improves. In more serious and chronic cases, patients may need an operation to remove bits of bone that have died. To help new bone grow, surgeons may perform a bone graft, in which bone from another part of the body is placed in the spot where dead bone has been removed; doctors may use packing material to fill in the open area temporarily.

How Long Does the Disease Last?

Patients with osteomyelitis often need several weeks or months of treatment before the infection clears up. Acute cases may resolve after as little as 1 month of antibiotic therapy, but chronic cases can linger much longer.

What Are the Complications?

In children, osteomyelitis can damage growing bones permanently, especially if it is not promptly and adequately treated. Infection may spread to the blood, overlying skin, or nearby joints. Bones may be weakened and break more easily. Movement of nearby joints or limbs may become limited. Occasionally in chronic cases, severe infection or damage to the bone may result in the need to amputate, or remove, part or all of a limb.

How Can Osteomyelitis Be Prevented?

Quick, thorough treatment of any infection, particularly those from deep wounds, can lower the risk of osteomyelitis. It is recommended that patients who are more susceptible to osteomyelitis, such as those with diabetes, contact a doctor promptly if they notice signs of infection.

See also

Arthritis, Infectious

Staphylococcal Infections

Streptococcal Infections

Tuberculosis

Resource

Website

KidsHealth.org. KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children’s health. It contains articles on a variety of health topics, including osteomyelitis.

http://www.KidsHealth.org

osteomyelitis (osti-oh-my-ĕ-ly-tis) n. inflammation of bone due to infection. It can cause fracture and deformity of the bone. acute o. osteomyelitis occurring when bacteria enter the bone via the bloodstream; it is more common in children. There is severe pain and redness over the involved bone, accompanied by general illness and high fever. chronic o. osteomyelitis that may develop from partially treated acute osteomyelitis or after open fractures or surgery during which the bone is contaminated.

osteomyelitis Infection of the bone, sometimes spreading along the marrow cavity. Rare except in diabetics, it can arise from a compound fracture, where the bone breaks through the skin, or from infection elsewhere in the body. It is accompanied by fever, swelling, and pain. The condition may be treated with immobilization, antibiotics, and surgical drainage.

os·te·o·my·e·li·tis / ˌästēōˌmīəˈlītis/ • n. Med. inflammation of bone or bone marrow, usually due to infection.