Knee Injury

Your bones and joints play an important role in your overall health. They give your body its shape, protect organs, produce blood cells, make it possible to move — and much, much more.

But germs from many different sources can cause your bones and joints to become infected. Bone and joint infections can have long-lasting health effects if left untreated.

Learn more about how these infections occur, how to recognize them, and how doctors treat them.

What Are Bone and Joint Infections?

Bone infections, also known as osteomyelitis, are infections of any bone within the body. Joint infections are infections of the joints, the areas where bones meet. If joint infections get worse over time, they can spread to the adjacent bone.

Bone infections are a broad term covering a variety of infections, including:

  • Blood infections that spread to the bone.
  • Diabetic foot infections.
  • Spinal infections.
  • Artificial joint infections.

“When you combine all of them, they are a fairly prevalent issue in the world of infectious disease,” says Neel Shah, MD, infectious disease specialist at UPMC. “About one-third to one-fourth of day-to-day infectious disease consults involve some sort of bone and joint infection. It’s becoming more and more commonplace.”

What Causes Bone and Joint Infections?

Most bone and joint infections come from bacteria, but fungal infections also can happen.

Many bone infections can begin with an injury to the skin over the bone. Your skin protects your body, but any wound can cause bacteria to enter your body and eventually work into the bone. Staph and strep bacteria that live on your skin are two common causes of bone infections.

“Anything that damages or injures the overlying skin increases the risk for an underlying bone infection,” Dr. Shah says. “The skin is the natural barrier that protects your body from getting infected. So any type of trauma can lead to infection.”

Infections also can occur in other parts of your body and work their way to your bone through the bloodstream. Another potential cause is surgery — complications with the bone, joint, or device installed during surgery can lead to an infection.

Risk factors for bone and joint infections

Many factors can increase your risk for bone and joint infections, including:

  • Trauma, puncture, or piercing injury.
  • Injectable drug use.
  • Smoking or alcohol use.
  • Medical conditions like diabetes or vascular disease that can cause chronic wounds.
  • Obesity.
  • Poor wound control.
  • Recent bone or joint surgery.
  • Compromised immune system.

Types of Bone and Joint Infections

There are two major types of bone infections: acute osteomyelitis and chronic osteomyelitis.

Acute osteomyelitis

Acute osteomyelitis is a bone infection that typically comes from the bloodstream. An infection enters the blood and makes its way to the bone.

“The bone is a vascular structure, so the infection is able to get from the bloodstream into the bone and work its way from the inside outward,” Dr. Shah says. “It involves the internal blood vessels of the bone, which are usually concentrated in the bone marrow, and it works its way out.”

Dr. Shah says patients with acute osteomyelitis tend to look sicker because the infection begins in their blood. They may have a fever, unstable vital signs like low blood pressure or a high heart rate, and an elevated white blood cell count.

Chronic osteomyelitis

Chronic osteomyelitis usually occurs in people who have chronic wounds or ulcers on the skin. Bacteria gather on the surface of the skin and work their way through an open wound to the bone.

“As the wound or ulcer gets deeper and deeper, the bacteria are able to progress down deeper into the tissue structures,” Dr. Shah says. “It eventually ends up involving the underlying bone.”

Because chronic osteomyelitis is a slower process than acute osteomyelitis, patients generally don’t appear as sick, Dr. Shah says. While a single organism typically causes acute osteomyelitis, multiple bacteria usually cause chronic osteomyelitis.

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Symptoms of Bone and Joint Infections

The most common symptom of bone and joint infections is pain at the site of the infection. If you feel a constant ache and/or shooting pains, it may be the sign of an infection.

Other possible symptoms of osteomyelitis include:

  • Worsening of existing wounds or ulcers (i.e., getting bigger, draining, or looking redder).
  • Wounds that don’t heal, even with proper wound care.
  • Redness or swelling of the skin over the infected bone.
  • Fever, chills, and/or sweating.
  • Fatigue or malaise.

Some symptoms depend on the site of the infection. For example, severe pain in your back with shooting pain down your legs and arms could indicate a spinal infection. Numbness in your arms, legs, and buttocks and a loss of bladder or bowel function suggest a spinal cord infection.

If you notice any or all of the above symptoms, call your doctor.

Bone and Joint Infection Diagnosis

Doctors can diagnose infections in several ways. They can see signs of bone infection, such as exposed bone, during a physical examination. They also may run tests to diagnose infections, including:

  • X-rays.
  • MRIs.
  • Blood work.
  • Biopsy of the involved bone.
  • Bone scan.

Treatment of Bone and Joint Infections

Once an infection is diagnosed, doctors can begin treatment. Treatment usually begins by removing the source of the infection — typically through surgery — and antibiotics.

Surgeons remove infected bone through a process called debridement. They clean out the infected bone and remove the source of the infection.

“In an ideal world, cleaning out the infected bone is always thought to be best,” Dr. Shah says. “You eliminate the source of the infection and get rid of a majority of the bacteria present within the body at that particular site.”

If hardware within your body is causing the infection, surgeons remove the hardware.

After surgery, doctors usually prescribe antibiotics to help your body overcome the infection. For some infections, antibiotics may be the only treatment needed.

Are bone infections curable?

When a bone infection is treated early, outcomes tend to be better. Factors that impact recovery include the location and extent of the infection and your overall health.

If left untreated, bone infections can cause complications like amputation, septic arthritis — infections that spread to nearby joints — and impaired growth.

“The overwhelming majority of cases are completely treatable,” Dr. Shah says. “The more it progresses, the harder it is to cure things without more drastic measures being undertaken, things like amputation and long courses of antibiotics. The earlier it’s diagnosed and discovered, the easier it is to treat.”

Preventing Bone Infections

The best way to prevent bone infections is to take good care of wounds. Proper wound care can help prevent infections.

If you have a condition that could cause chronic wounds, like diabetes, controlling your underlying disease can help prevent infections.

Avoiding alcohol, tobacco, and drug use and maintaining a healthy lifestyle also can help.

The UPMC Center for Care of Infectious Diseases can treat a wide range of conditions caused by bacteria, fungi, parasites, or viruses. For more information, or to schedule an appointment, call 412-647-7228 or 1-877-788-7228.

Sources

National Organization for Rare Disorders, Osteomyelitis. Link

U.S. National Library of Medicine, Osteomyelitis. Link

About Infectious Diseases

If you have a disease caused by bacteria, fungi, parasite, or virus, the UPMC Center for Care of Infectious Diseases can help. We have specialty units for prevention and treatment of HIV-AIDs, postsurgical and transplant infections, and illnesses caused by international travel. Our faculty research infectious diseases and participate in clinical trials to learn more and develop better treatment and prevention methods.