What are the types of infections?
The technical term for a bone infection is osteomyelitis. We also treat prosthetic joint infections as well as atypical joint and soft tissue infections.
Who gets bone or joint infections?
Certain types of bone and joint infections develop in patients with an underlying condition of autoimmune disease or immune suppression. This could originate from rheumatoid arthritis, cancer, or an organ transplant.
A history of trauma or injury to a bone, for example, can create a an infection. A fracture, deep bruise, or puncture of a foreign object can also add to your risk. If you're treated with hardware to fix the fracture or if the trauma occurred where the wound became contaminated with dirt or debris, you may be more susceptible to developing an infection.
People with total joint replacements that suffer an infection elsewhere in their body are at increased risk of infection in the joint that has been replaced. This requires an extensive amount of time and numerous surgeries to rectify.
Infections can develop anytime after a surgery, however, and often there is not a known cause of a bone infection or reason for infection to settle into a joint.
Signs and Symptoms
What are symptoms of bone infections?
Symptoms can vary widely between patients and types of infection. The most common symptoms of bone infections include:
- Pain (can occur with activity or while at rest)
- Swelling or presence of a palpable mass (bump)
- Redness or skin changes over a painful joint or bone
- Inability to bend the joint or use the affected extremity
- Pus or drainage from a wound or site of prior trauma
- Unexplained weight loss
- Poor appetite
Tests and Diagnosis
How are bone and joint infections diagnosed?
When you first meet with a clinician, he or she will discuss your detailed medial history and do a physical examination, in addition to imaging and/or blood tests. If an open biopsy is needed to determine the type of the infection, it will be performed by our orthopedic musculoskeletal physician (a doctor who specializes in bone infections).
The biopsy will help determine whether the infection is present in the bone and or soft tissue. If a biopsy was already performed before coming to our system, another biopsy may or may not be necessary.
If you have or are suspected to have a bone or joint infection, you cannot be on on any antibiotic medication prior to the biopsy. This will ensure that the biopsy provides accurate information regarding the type of infection that is present.
Once the type of infection is determined, a plan for definitive surgery and treatment with antibiotics can be initiated.
If a biopsy is needed to determine the type of the tumor, it will be performed by our orthopedic oncologist (a doctor who specializes in bone tumors). A biopsy is a small surgery during which a sample of tissue or bone is taken. For children and for many adults, this is done under general anesthesia in the operating room. For some adults with soft tissue tumors, a biopsy may be done in the office using numbing medicine so that the biopsy will not cause pain.
If a biopsy was already performed before coming to our system, another may or may not be necessary.
In addition to determining whether the infection is present in the bone or the joint, the musculoskeletal team may perform other tests. This series of tests is known as staging. The tests will determine the extent of the infection and help give your team the information they need to provide the most effective treatment. Some of these tests will be performed before the biopsy.
Bone scan: A bone scan is an imaging study done to detect abnormalities in bones. Sometimes the doctor will order a bone scan with "contrast," a dye injected into a vein two hours before the scan is done. It is important that you be well hydrated for this study. Your doctor will give you detailed instructions on how to prepare for this study and when to arrive at the radiology department.
Your doctor may also order a "tagged white blood cell" scan, which is a test that separates white blood cells from the rest of a blood sample and then mixes them with a small amount of radioactive material (radioisotope) called indium-111. These cells are considered "tagged." The tagged white blood cells are then returned to your body through an injection into the vein two to three hours later. The tagged cells gather in the areas of inflammation or infection.
CT scan: A CT (computed tomography) scan is an imaging study that uses a combination of x-ray and computer technology to produce cross-sectional images of the body, including bones, muscles, fat, and organs. CT scans are primarily used to check for a infection or abnormalities in the bone.
MRI scan: An MRI (magnetic resonance imaging) scan is a study that uses a combination of large magnets, radiofrequency, and a computer to produce detailed images of structures in the body. It is used to determine the extent of the infection within the bone and soft tissues. Your health care team will provide specific instructions about eating and drinking before the MRI.
How We Treat
How are bone or joint infections treated?
Treatment is based on the extent and location of the disease, although the infection will typically be removed by surgery. The kind of surgery depends on the location and the extent of the infection and whether or not it involves a joint that has been replaced.
Surgical options may include:
For infections of prior joint replacement or sites of known bone infections (osteomyelitis), you will need to undergo an explant (complete removal of all metal, plastic, and cement) from that surgery.
If involving the removal of a joint, a temporary spacer is placed in that joint so that proper antibiotic treatment can be administered. It is not uncommon to also have antibiotic beads placed at the site of infection inside the bone or the joint.
During this time you will not be able to fully use or weight bear on this extremity. Also, you will have a special catheter placed in your vein, typically in your arm, called a PICC line. You will receive a minimum of six weeks of antibiotics under the care of the infectious diseases physician.
Typically, once antibiotic therapy is complete, there is a minimum of two weeks where there are no antibiotics given and then a repeat open biopsy is performed to confirm that all the infection as been treated. If all results are negative, then a revision or another total joint replacement can occur.
This entire process usually takes anywhere from three to four months from the initial surgery of joint removal or extensive bone debridement after infection is diagnosed.
Limb-sparing surgery removes the infection from the bone or the joints—as well as the tissues surrounding it that contain infection—while leaving the surrounding muscles, nerves, and blood vessels. A bone graft or metal implant will replace the bone and soft tissues that have been removed, thereby preserving the patient's extremity.
Sometimes the infection will be so extensive or will have destroyed so much of the soft tissue and the bone that it will be necessary to amputate the affected extremity.
Patients are typically very good at using and adapting to an artificial limb (prosthetics). Patients who have amputations can live happy and normal lives. In fact, many patients with artificial limbs are quite active and participate in sports.