Bone infection

Osteomyelitis is the medical term for a bone infection, usually caused by bacteria.

Introduction

Osteomyelitis is the medical term for a bone infection, usually caused by bacteria.

Symptoms of osteomyelitis may include:

  • a high temperature (fever) of 38°C (100.4°F) or above
  • bone pain, which can often be intense
  • swelling, redness and a warm sensation in the affected area

Osteomyelitis most commonly affects the long bones in the legs, but other bones, such as those in the back or arms, can also be affected.

Read more about the symptoms of osteomyelitis.

The condition is often referred to as acute osteomyelitis when the infection develops following an injury, infection or underlying condition. It's referred to as chronic osteomyelitis when the condition regularly returns.

When to see your doctor

Osteomyelitis can affect people of any age, so you should visit your doctor if you or your child experiences persistent bone pain with a fever.

Very young children do not always develop a fever when they have osteomyelitis and they may not be able to communicate that they have bone pain. You should see your doctor if your child becomes irritable, has a reduced appetite and is reluctant to use a certain part of their body (most often an arm or leg).

Why does osteomyelitis happen?

Osteomyelitis develops when the bone becomes infected. In most cases, bacteria is responsible for the infection, although it can also be caused by fungi.

Blood tests and a biopsy may be used to determine whether you have an infection and what caused it. Read more about diagnosing osteomyelitis.

There are two ways the infection can occur:

  • following an injury (known as contiguous osteomyelitis) – such as a fractured bone, animal bite or during surgery
  • via the bloodstream (known as haematogenous osteomyelitis)

Contiguous osteomyelitis is more common in adults, whereas haematogenous osteomyelitis is more common in children.

Certain things can increase your chances of developing osteomyelitis. For example, if you have a condition that affects the blood supply to certain parts of your body, such as diabetes, or a condition that weakens the immune system, such as rheumatoid arthritis.

Osteomyelitis can become chronic osteomyelitis if not treated quickly, as the bones can become permanently damaged, resulting in persistent pain and loss of function.

Read more about the causes of osteomyelitis.

How is osteomyelitis treated?

Osteomyelitis is usually treated with antibiotics, used for at least four to six weeks. At first, you may have to receive this while staying in hospital, but you should be able to take them at home when you start to get better.

In severe or chronic cases of osteomyelitis, surgery may be used in combination with antibiotics. Surgery is most often used to remove damaged bone and drain pus from wounds.

Read more about treating osteomyelitis.

Complications

Osteomyelitis usually responds well to antibiotics. However, for people with underlying conditions which increase the risk of osteomyelitis, such as diabetes, there is a chance the infection could come back.

As a last resort, amputation is sometimes used if the blood supply to the bone is severely reduced. However, these days it is highly unlikely this will be necessary, as the condition can usually be treated before it reaches this stage.

Read more about the complications of osteomyelitis.

Preventing osteomyelitis

It is not always possible to avoid getting osteomyelitis, however, there are steps you can take to reduce your chances.

Cleaning wounds thoroughly with water and dressing them in a clean bandage will reduce your chances of getting an infection from an injury.

Improving your general health will help reduce the risk of developing osteomyelitis or another condition that causes high blood pressure or a weakened immune system.

Read more about preventing osteomyelitis.

Symptoms

The most common signs of osteomyelitis are bone pain and a high temperature.

Acute osteomyelitis

Most cases of acute osteomyelitis involve one of the long bones in the legs. However, sometimes the bones in the arm or the vertebrae (in the back) can be affected.

The symptoms of acute osteomyelitis include:

  • a sudden high temperature (fever) of 38°C (100.4°F) or above, although this symptom is often absent in children under one year old
  • bone pain, which can often be severe
  • swelling, redness and warmth at the site of the infection
  • a general sense of feeling unwell
  • the affected body part is tender to touch
  • the range of movement in the affected body part is restricted
  • lymph nodes (glands) near the affected body part may be swollen

In teenagers and adults, these symptoms tend to develop within a few weeks of an injury or accident, such as a broken bone.

Young children who cannot talk may be unable to report their painful symptoms to you. You should look out for the following signs and symptoms:

  • irritability
  • eating much less than usual
  • reluctance to use the affected body part

Chronic osteomyelitis

In cases of chronic osteomyelitis, symptoms are usually a recurrence of those that have been experienced during a previous infection.

Once chronic osteomyelitis is established, the person affected may have periods of almost no symptoms. However, symptoms can flare up at any time. For example, you may experience:

  • bone pain
  • feeling persistently tired
  • pus draining from the sinus tract (a passageway that develops near the infected bone)
  • local swelling
  • skin changes
  • excessive sweating
  • chills

When to seek medical advice

You should always visit your doctor if you or your child develops a high temperature (fever) and persistent bone pain, or if you are worried about symptoms in a very young child.

Causes

Osteomyelitis is an infection of the bone usually caused by bacteria.

Around 90% of cases are caused by bacteria called staphylococcus aureus, commonly found on the skin or in the nose.

Why the infection happens

Your bones are usually resistant to infection, but can become infected when:

  • a pre-existing infection in the blood spreads to a bone
  • there is an injury, such as a bone fracture
  • bacteria enters a wound during or after surgery, such as a joint replacement operation
  • there is a pre-existing health condition, such as diabetes, which means the bone does not get a steady blood supply, so infection-fighting white blood cells cannot reach the site of injury

Blood infections that spread to the bone are more common in children than adults. This may be because children’s bones are still developing, which makes them more vulnerable than adult bones. In addition, a child's immune system (the body’s natural defence against infection and illness) is still developing, so it is less effective at fighting off infection.

Infection after injury, particularly to the foot or ankle, is the most common cause of osteomyelitis in adults.

When a bone becomes infected

When an infection develops inside a bone, the immune system will attempt to stop it with infection-fighting white blood cells.

If the infection is not treated and the immune system is unable to deal with the bacteria, a collection of dead white blood cells will build up inside the bone, forming a pocket of pus known as an abscess.

In cases of chronic osteomyelitis, abscesses can block the blood supply to the bone, which will eventually cause the bone to die. Dead bone with no blood supply must be removed if infection is to be cleared.

Increased risk

There are several things that can make people more vulnerable to developing osteomyelitis:

Weakened immune system

If your immune system is weakened, an infection in your body is more likely to spread to your bone. Your immune system may become weakened if you:

  • are undergoing certain treatments, such as chemotherapy](yourmd:/condition/chemotherapy/definition), radiotherapy or a long-term dose of [steroid tablets
  • have malnutrition, which is when your diet does not contain all the nutrients needed for good health
  • have a health condition, such as HIV or AIDS (although this is an uncommon cause of osteomyelitis)

Poor circulation

People with health conditions that affect the blood flow are at greater risk of developing osteomyelitis. This is because their bones may not be getting a steady supply of infection-fighting white blood cells.

Conditions known to cause poor circulation include:

Diabetes and foot injury

People with diabetes are particularly vulnerable to osteomyelitis because they are at risk of developing foot injuries.

Increased levels of glucose in the blood can cause nerve damage, which means people with poorly controlled diabetes can lose sensation in their feet and small cuts to the feet go unnoticed. Due to poor circulation, a serious infection can quickly develop in the feet before spreading to the bone.

Injury and trauma

If you break a bone or have a serious puncture injury that exposes deep tissue to germs, there is a chance you will develop osteomyelitis. This risk is increased if you also have a weakened immune system and/or poor circulation. Any broken bone with a loss of skin cover needs emergency surgery to clean the wound, get rid of dead tissue and stabilise the fracture.

Orthopaedic surgery

If you have orthopaedic surgery (surgery that involves the bones or joints) or you have had metalwork implanted, there is a small chance you may develop osteomyelitis. However, there is less than a 1% chance of this happening.

Intravenous drug misuse

People who regularly inject themselves with illegal drugs such as heroin or methamphetamine (crystal meth) have an increased risk of developing osteomyelitis. This is because many people who misuse drugs do not use properly sterilised needles, which significantly increases the risk of introducing bacteria into their bloodstream.

Diagnosis

If you have a high temperature and bone pain, you should visit your doctor for a diagnosis.

Physical examination

To confirm a diagnosis of suspected osteomyelitis, your doctor will first carry out a physical examination of your affected body part to check for redness, swelling and tenderness.

They will want to know your recent medical history, such as whether you have recently had an injury, surgery or a previous infection.

If your doctor is unsure about a diagnosis, or suspects osteomyelitis, they may refer you to an orthopaedic surgeon (a specialist in bones and joints).

Blood test

You may be referred for a blood test. This cannot confirm osteomyelitis, but can indicate whether you have a high number of white blood cells in your blood, which may suggest you have an infection. Also, if the osteomyelitis was caused by bacteria spreading in your blood, a blood test may be useful for detecting the bacteria.

Imaging tests

If osteomyelitis is suspected, it is likely you will be referred for further imaging testing. There are several imaging tests that may be able to detect bone damage caused by osteomyelitis. They include:

  • X-rays, where low levels of radiation are used to create an image of the affected bone – this test is not usually useful for diagnosis if the condition is in the early stages.
  • magnetic resonance imaging (MRI) scan, where a strong magnetic field and radio waves are used to build up a picture of the inside of the affected bone
  • computerised tomography (CT) scan, where a series of X-rays of your affected bone are taken and a computer is used to assemble them into a more detailed three-dimensional image
  • ultrasound scan, where high-frequency sound waves are used to create an image of the affected bone to highlight any abnormalities

Biopsy

If earlier testing suggests osteomyelitis, it is usually necessary to remove a small sample of bone for further testing. This is known as a biopsy.

A biopsy is usually necessary to confirm a diagnosis of osteomyelitis and can help establish the exact type of bacteria or fungus causing your infection. This can be very useful when deciding on the most effective treatment.

A biopsy is usually combined with surgery in chronic cases.

If you have a wound producing pus, a sample of this may also be taken for further testing.

Treatment

Osteomyelitis is usually treated with antibiotics, although surgery may also be used in severe cases.

Treating acute osteomyelitis

Acute osteomyelitis can usually be successfully treated using a course of antibiotics for at least four to six weeks.

For part of the treatment you will need to take the medicine intravenously (directly into a vein), usually while in hospital. If you are well enough, you may be able to receive the injections as an outpatient, so you can go home the same day.

After your symptoms start to improve, a switch is usually made to antibiotic tablets you can take at home.

In cases of osteomyelitis, there is usually a choice of antibiotics available to treat the infection and often two antibiotics are used in combination. This is known as dual therapy.

Occasionally, the bacteria causing the infection are resistant to standard antibiotics and less frequently used antibiotics are needed.

All antibiotics have side effects, which you should discuss with your doctor or the doctor in charge of your care.

In the rarer cases where a fungal infection has caused osteomyelitis, antifungal medications are used.

Painkillers may also be used if the condition is causing you discomfort.

Read more about the medications used in the [medicines guide for osteomyelitis].

Treating chronic osteomyelitis

People with chronic osteomyelitis will usually require a combination of antibiotics and surgery. Surgery may be used to remove bone, to drain pus from a wound or abscess, or to remove and replace a joint replacement if it was the cause of infection.

If there is extensive bone damage, it will be necessary to surgically remove any diseased bone and tissue. This procedure is known as debridement.

Debridement can often leave an empty space in the bone, which is sometimes packed with antibiotic-loaded cement. If the surgeon does this, a second operation will be required to remove the cement within a few weeks of the first. Bone may also be taken from elsewhere in your body, often from around the hip, to replace the damaged bone.

In some cases, it may also be necessary to transfer muscle and skin from another part of the body to repair the tissue surrounding the affected bone.

Hyperbaric oxygen therapy

Some researchers have argued that a type of non-surgical treatment called hyperbaric oxygen therapy may be useful in treating cases of both acute and chronic osteomyelitis that do not respond to conventional treatment.

During hyperbaric oxygen therapy, you are placed in a specially designed chamber, similar to a decompression chamber used by divers.

The chamber is filled with oxygen, administered at a much higher pressure (hyperbaric) than the normal level of oxygen in the atmosphere. The high levels of oxygen are thought to speed up the healing process and slow the spread of infection.

There is currently only limited evidence supporting the effectiveness of hyperbaric oxygen therapy for treating osteomyelitis. From the evidence available, it would appear it is most effective in treating osteomyelitis associated with a diabetic foot ulcer.

Complications

Although osteomyelitis is usually treated successfully, chronic and severe cases can lead to other problems.

Recurring osteomyelitis

Underlying conditions that are often the cause of osteomyelitis, such as poor circulation or a weakened immune system, can be difficult to treat. Therefore, if you have had a previous episode of osteomyelitis, there is a chance of it returning.

Read more about preventing osteomyelitis.

Amputation

Amputation is used as a last resort for treating chronic osteomyelitis if the blood supply to bones is severely reduced.

With a reduced blood supply, the bones receive fewer infection-fighting blood cells. This means the infection may spread beyond the bone and into the surrounding soft tissue. The tissue will then begin to die, which is known as gangrene.

Once gangrene develops, it may be necessary to amputate the affected limb to prevent the spread of infection and prevent further damage to healthy tissue.

Prevention

It is not always possible to prevent osteomyelitis, but there are steps you can take to reduce your chances of developing the condition

Avoiding infection

You can reduce your chances of getting an infection from an injury by ensuring that wounds are cleaned thoroughly. Running them under a tap for a few minutes should help. Afterwards cover the wound with sterile gauze or a clean cloth.

If an injury is severe, you should visit your nearest hospital for treatment.

Checking any wounds regularly for signs of infection can help to get an early diagnosis if osteomyelitis does develop.

Improving your health

You may be at a particularly high risk of osteomyelitis if you have a weakened immune system or poor circulation.

Taking steps to improve your general health can reduce your risk of osteomyelitis.

Stop smoking

Smoking cigarettes can clog your arteries and increase your blood pressure, both of which are bad for your circulation. It can also weaken your immune system.

If you smoke, it is strongly recommended you quit as soon as possible. The NHS Smokefree website can provide support and advice. Your doctor will also be able to recommend and prescribe medication that can help you give up.

Read more about [stopping smoking].

Healthy diet

High fat foods can cause a build-up of fatty deposits in your arteries, and being overweight can lead to high blood pressure.

To improve your circulation, a low-fat high-fibre diet is recommended, including plenty of fresh fruit and vegetables (at least five portions a day) and wholegrains.

Eating a healthy diet can also help boost your immune system.

Read more about [healthy eating].

Managing your weight

If you are overweight or obese, try to lose weight and then maintain a healthy weight by using a combination of a calorie-controlled diet and regular exercise. Once you have achieved a healthy weight it will help keep your blood pressure at a normal level, which will help improve your circulation.

Alcohol

If you drink alcohol, don't exceed the recommended daily limits. These are:

  • three to four units a day for men
  • two to three units a day for women

A unit of alcohol is roughly half a pint of normal-strength beer, a small glass of wine or a single measure (25ml) of spirits. Regularly exceeding the recommended alcohol limits will raise both your blood pressure and cholesterol level, which will make your circulation worse.

Contact your doctor if you are finding it difficult to moderate your drinking. Counselling services and medication can help you reduce your alcohol intake.

Read more about [drinking and alcohol] and treatment for alcohol misuse.

Regular exercise

Regular exercise will lower your blood pressure, make your heart and blood circulatory system more efficient and can help boost a weak immune system.

For most people, 150 minutes of moderate to vigorous exercise a week is recommended. However, if your overall health is poor, it may be necessary for you to exercise using a programme tailored specifically to your current needs and fitness level. Your doctor will be able to advise you about the most suitable level of exercise for you.

If you find it difficult to achieve 150 minutes of exercise a week, start at a level you feel comfortable with. For example, you could do five to 10 minutes of light exercise a day before gradually increasing the duration and intensity of your activity as your fitness starts to improve.

Content supplied by NHS Choices