Osteomyelitis is an infection of the bone and its inner marrow. When a bone becomes infected, the soft interior marrow swells. This swelling presses against the bone’s hard outer wall, which can compress blood vessels and reduce blood flow. Without a proper blood supply, sections of the bone can die, making the infection more difficult to treat.
What Causes Inflammation of Bone and Bone Marrow?
The primary cause of osteomyelitis is a bacterial infection, with Staphylococcus aureus, a bacteria often found on the skin, being a frequent cause. Microorganisms can reach the bone through several pathways. One route is through the bloodstream, where an infection from another part of the body, like pneumonia, travels to a bone. This is referred to as hematogenous spread.
Infection can also occur through direct inoculation, where germs enter from a traumatic injury like a deep puncture wound or a severe fracture that breaks the skin. Surgical procedures involving bone or the placement of orthopedic hardware also create an entry point for bacteria. An infection can also spread from an adjacent area of infected tissue, a process called contiguous spread, often seen in individuals with diabetes-related foot ulcers.
Certain factors increase a person’s risk of developing osteomyelitis. Conditions that impair circulation, such as peripheral artery disease or poorly controlled diabetes, make it harder for the body to deliver infection-fighting cells to an affected area. A weakened immune system, recent orthopedic surgery, an open fracture, or the use of intravenous drugs also heightens susceptibility.
Recognizing Symptoms of Bone and Bone Marrow Inflammation
The signs of osteomyelitis differ depending on whether the condition is acute or chronic. Acute osteomyelitis develops rapidly over a few days. Individuals experience intense, localized bone pain, and the area over the infected bone can become swollen, warm, and red. Systemic symptoms like fever, chills, and fatigue are also common with acute cases.
Chronic osteomyelitis presents more subtly and develops over a longer period. The bone pain may be persistent but less severe than in an acute infection, and fever is less common. A distinct feature of long-term osteomyelitis can be the formation of a sinus tract, which is a passage from the infected bone to the skin’s surface that allows pus to drain.
In some individuals, like very young children, older adults, and those with compromised immune systems, symptoms might be less obvious. For example, vertebral osteomyelitis, affecting the spine, may cause continuous back pain that does not improve with rest. Any worsening bone pain accompanied by a fever warrants a consultation with a healthcare professional.
How Doctors Diagnose Bone and Bone Marrow Inflammation
A diagnosis of osteomyelitis involves a physical assessment, laboratory tests, and imaging. A physician will review the patient’s medical history for risk factors and ask about specific symptoms. The physical examination focuses on checking the affected area for tenderness, swelling, redness, and any drainage.
Blood tests are used to look for markers of infection and inflammation. Tests for C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) can show elevated levels, supporting a diagnosis. While these tests indicate inflammation, they do not confirm a bone infection on their own. Blood cultures may also be taken to identify bacteria in the bloodstream.
Imaging is used to visualize the bone and surrounding tissues. Plain X-rays are a first step but may not show evidence of infection in the early stages. Magnetic resonance imaging (MRI) is highly sensitive for detecting early bone infections and showing the extent of soft tissue involvement. Computed tomography (CT) scans offer detailed images of the bone structure.
The most definitive method for diagnosing osteomyelitis is a bone biopsy. In this procedure, a small sample of bone or fluid is taken from the infected area. The sample is then sent to a laboratory to be cultured, which can identify the specific microorganism causing the infection and help guide antibiotic choice.
Treatment for Inflammation of Bone and Bone Marrow
The management of osteomyelitis centers on eradicating the infection and preserving bone function. Treatment involves a long course of antibiotics, which are initially administered intravenously (IV) in a hospital to ensure high concentrations reach the infected bone. This IV treatment can last for several weeks, followed by oral antibiotics that may continue for weeks or months. It is important to complete the entire course to prevent the infection from returning.
In many cases, surgery is necessary in addition to antibiotics. A primary surgical procedure is debridement, where the surgeon removes dead or infected bone tissue and drains any abscesses. Removing this non-viable tissue is a prerequisite for antibiotics to work effectively, as medication cannot easily reach areas with poor blood supply. A surgeon may fill the space left by debridement with a bone graft to promote healing.
Supportive care is another aspect of treatment. The affected limb may need to be immobilized with a splint or cast to protect the bone as it heals, and pain medication is provided for comfort. For severe infections that do not respond to other treatments, amputation may be a last resort to prevent the spread of a life-threatening infection. Regular follow-up appointments are needed to monitor the healing process.