Osteomyelitis

Osteomyelitis is a serious bone infection that can affect anyone, but early diagnosis and treatment are crucial to prevent permanent damage and restore normal function.

Table of contents

• What is Osteomyelitis?
• Types of Osteomyelitis
• How Bones Become Infected
• Symptoms to Watch For
• Who is at Higher Risk?
• How Doctors Diagnose Osteomyelitis
• Treatment Options
• Possible Complications

What is Osteomyelitis?

Osteomyelitis is an infection that affects the bone. It happens when bacteria or fungi invade bone tissue and begin to multiply there^[1][2]. The infection causes painful swelling in the bone marrow (the spongy center of some bones where blood cells are made)^[2].

Healthy bone is normally resistant to infection. However, when large numbers of germs are introduced into the bone through trauma, surgery, or when foreign materials are present in the body, the bone can become vulnerable to infection^[3]. Some bacteria have special abilities that allow them to stick to bone surfaces and protect themselves from antibiotics and the body’s immune defenses^[3].

While osteomyelitis can affect any bone in the body, it most commonly occurs in different locations depending on age. Children typically develop it in the long bones of their legs or arms, while adults usually experience it in the vertebrae (the bones that make up the spine) or in the hip bones^[2][4].

Types of Osteomyelitis

There are several types of osteomyelitis based on how quickly the infection develops and how it reaches the bone^[2][5]:

Acute osteomyelitis is the most common type. It develops suddenly, usually within days to weeks after the infection begins. Symptoms appear rapidly, often including fever and severe pain. People with acute osteomyelitis typically do not yet have dead bone tissue^[2][5].

Chronic osteomyelitis is a long-lasting infection that develops after months or years of persistent infection. It can occur when the initial infection is not completely eliminated after treatment, allowing it to linger in the body and come back months or years later^[2][5]. This type may be characterized by the presence of dead bone tissue and abnormal passages (called fistulous tracts) that form from the skin down to the bone^[5]. Some people with chronic osteomyelitis may not have any symptoms at all^[2].

Hematogenous osteomyelitis occurs when bacteria spread to the bone through the bloodstream from an infection elsewhere in the body. This type is most common in children, older adults, and people with weakened immune systems^[5].

Nonhematogenous osteomyelitis develops from direct exposure of bone to bacteria. This can happen during surgery, after trauma that exposes the bone, or when infection spreads from nearby infected soft tissue or joints^[5].

Vertebral osteomyelitis specifically affects the bones of the spine. It is the most common type of hematogenous osteomyelitis and usually involves two adjacent vertebrae along with the disk between them^[6].

How Bones Become Infected

Osteomyelitis is most commonly caused by a type of bacteria called Staphylococcus aureus (often called “staph”), which normally lives on the skin^[4][5]. Other bacteria that can cause bone infections include Pseudomonas aeruginosa, Streptococcus species, and various other organisms^[5].

Infections can reach the bone in several ways^[1][2]:

• Through the bloodstream from another infection in the body, such as a urinary tract infection or pneumonia
• From nearby infected tissue that spreads to the bone
• Through an open wound, injury, or bone fracture that allows bacteria from the skin to enter the body
• After surgery, especially bone or joint surgery

Once bacteria enter the bone, a lack of blood flow to the infected area means less oxygen reaches that spot. This makes it harder for the body’s immune system to fight the infection, allowing the bacteria to multiply and potentially cause bone death^[7].

Symptoms to Watch For

The symptoms of osteomyelitis can vary depending on the type of infection and which bones are affected. Sometimes osteomyelitis causes no symptoms at all, which can make it particularly dangerous^[1][2].

The most common symptoms include^[1][2][4]:

• Fever, sometimes very high
• Pain in the affected bone
• Swelling, redness, and warmth over the infected area
• Tenderness when touching the area
• Tiredness and feeling generally unwell
• Chills and sweating
• Nausea and vomiting
• Difficulty moving joints near the affected area
• Pus or drainage if the infection is near a wound or surgery site

In children, additional symptoms may include irritability and a new limp. Young children may refuse to use an arm or leg even without showing a fever^[8][14]. When osteomyelitis affects the spine (vertebral osteomyelitis), it typically causes low back pain or a stiff back^[2][7].

You should see a doctor right away if you experience bone pain and fever that gets worse, especially if you have risk factors for infection such as a recent medical procedure, an injury, or a chronic health condition^[1][4].

Who is at Higher Risk?

Anyone can develop osteomyelitis, but certain groups of people are at higher risk^[1][2][4]:

• People younger than 20 or older than 50
• Those with open wounds after an injury or trauma
• People who have recently had surgery, especially joint replacement or procedures involving metal implants like pins and screws to repair broken bones
• Individuals with puncture injuries (something stabbing into the body)
• People with pressure injuries (bedsores)
• People who inject drugs intravenously

Certain health conditions also increase the risk of developing osteomyelitis^[1][2][4]:

• Diabetes, especially if you have foot ulcers (open sores on the feet)
• Kidney failure requiring dialysis
• Sickle cell anemia
• Weakened immune system from conditions like HIV or cancer, or from treatments like chemotherapy
• Poor blood circulation or vascular disease

People who smoke are also at higher risk, as smoking can slow the healing of infections^[1].

Researchers estimate that fewer than 25 per 100,000 people experience osteomyelitis each year in the general population. However, it is much more common among people who need to stay in the hospital, occurring in as many as 1 out of every 675 hospital admissions^[2][3].

How Doctors Diagnose Osteomyelitis

Diagnosing osteomyelitis involves a combination of physical examination, laboratory tests, and imaging studies^[4][5][9].

During the physical examination, your doctor will feel the area around the affected bone for tenderness, swelling, or warmth. If you have a foot sore, the doctor may use a dull probe to determine how close the sore is to the bone underneath^[9].

Blood tests can show high levels of white blood cells and other markers that indicate your body is fighting an infection. Blood tests can also sometimes identify which specific germ is causing the infection through a blood culture. However, blood tests alone cannot definitively diagnose osteomyelitis—they help doctors decide what additional tests may be needed^[4][9].

Imaging tests help identify the location and severity of the infection. Several types may be used^[4][9]:

• X-rays are usually performed first but have low sensitivity in the early stages of the disease. Damage may not show on X-rays until osteomyelitis has been present for several weeks^[5][9].
• MRI scans (magnetic resonance imaging) are the imaging method of choice for suspected osteomyelitis. They create detailed images of bones and surrounding soft tissues and have higher sensitivity for identifying areas of dead bone tissue in later stages of the disease^[5][9].
• CT scans (computed tomography) combine X-ray images from many angles to provide detailed views of internal structures. They may be used if you cannot have an MRI^[4][9].
• Bone scans use small amounts of radioactive substances that are absorbed by infected bone tissue, making the infection visible on the scan^[9].

A bone biopsy is the most definitive way to diagnose osteomyelitis. During this procedure, a small piece of bone is removed and tested to identify the exact type of germ causing the infection^[4][5][9]. Knowing which specific bacteria or fungi is present helps doctors choose the most effective antibiotic treatment.

Treatment Options

Treatment for osteomyelitis typically combines antibiotics with surgical intervention when necessary. The goal is to eliminate the infection and restore function while preventing permanent bone damage^[1][4].

Antibiotic treatment is the primary approach for treating osteomyelitis. Treatment should be tailored based on the results of cultures that identify the specific bacteria causing the infection^[5]. Initially, you will likely receive antibiotics intravenously (through a vein) in the hospital. As symptoms improve, you may be able to switch to oral antibiotic pills and continue treatment at home^[4][9].

Antibiotic treatment typically lasts at least four to six weeks for acute infections, and sometimes up to 12 weeks for severe infections^[4][5][14]. It is crucial to finish the entire course of antibiotics even if you start feeling better, as stopping too early can allow the infection to return and potentially become chronic^[1][14].

Research has shown that in adult patients with chronic osteomyelitis, switching from intravenous to oral antibiotics after initial treatment can be as effective as long-term intravenous therapy alone^[5].

Surgical treatment is often necessary in addition to antibiotics. Surgery may be needed to^[1][4][14]:

• Drain pus that has built up in the bone
• Remove dead or infected bone tissue (a procedure called debridement)
• Remove damaged parts of the bone when the infection has caused significant destruction
• Fill empty spaces left after removing diseased bone
• Stabilize the bone if needed

Surgical debridement is particularly important for chronic osteomyelitis and for infections that do not respond well to antibiotics alone^[5]. Sometimes more than one operation is needed to fully treat the infection. Muscle and skin from other parts of the body may be used to repair the area near the affected bone^[14].

Additional supportive measures can help with recovery^[9]:

• Pain medications to ease discomfort
• Splints, slings, or braces to prevent movement of the affected area during healing
• Bed rest or restricted movement
• Physical therapy to help restore normal range of motion

If the infection is treated quickly (within three to five days of starting), it often clears up completely^[14]. Most people with osteomyelitis need surgery to remove affected bone areas, and after surgery, most require strong antibiotics^[1].

Possible Complications

If osteomyelitis is not treated promptly and properly, it can lead to serious complications^[2][4]:

Permanent bone damage and necrosis (tissue death) can occur when the infection destroys bone tissue faster than the body can rebuild it. This can result in lasting disability or deformity^[1][2].

Chronic or recurrent infection is a major concern. Even after apparently successful treatment, osteomyelitis can come back months or years later. Taking the full course of prescribed antibiotics is the best way to prevent chronic osteomyelitis from developing^[2].

Sepsis (blood poisoning) can develop if bacteria from the bone infection spread through the bloodstream to other parts of the body, creating a life-threatening medical emergency^[4].

Abscess formation occurs when pus builds up in the bone, creating a pocket of infection that may need to be surgically drained^[4].

For people with diabetes, osteomyelitis in the feet can be particularly dangerous. If diabetes is poorly controlled, loss of sensation in the feet may prevent people from noticing small cuts that could develop into serious infections spreading to the bone. This can ultimately lead to amputation^[14].

Osteomyelitis has a major impact on quality of life and represents a substantial financial burden for healthcare systems. The condition requires long-term treatment, careful monitoring, and often multiple hospital stays^[1].