Saturday, April 13, 2024
DIABETES Diabetic Infections

Diabetic Foot Osteomyelitis (Bone Infection)- A Helpful Guide

Diabetes can cause many different foot problems. If you have a foot infection that progresses to the bone, it is called “Osteomyelitis”. Osteomyelitis means inflammation of the bone, secondary to infection. One-third of diabetics with foot infections will go on to develop osteomyelitis (1).

Osteomyelitis can be a devastating consequence of diabetes, and it’s important to be educated on how it develops and what you can do to prevent it. 

In this article, we’ll discuss in detail how osteomyelitis can impact the feet and everything you should know.  

Let’s dive in…

diabetes testing

What Causes Diabetics to Develop Osteomyelitis?

A large number of diabetics suffer from neuropathy. With elevated blood sugar levels, nerve damage can occur in the feet. This can cause numbness, tingling, and burning in the feet. This is called “neuropathy”. If you have neuropathy, you can develop wounds that become infected. When the infection spreads to the bone, there is osteomyelitis. 

Let’s discuss this in more detail. 

When you have numbness in your feet, you have a higher likelihood of stepping on something and not knowing it. Not only that, if you have neuropathy you may not even feel a blister develop in your foot from wearing the wrong shoes. Some diabetics can’t feel the difference between hot and cold water. This can result in burn injuries. These are the sensory effects of diabetes. 

Diabetes can also cause motor dysfunction. This means that due to weak muscles inside the feet, structural changes can occur, such as the development of hammertoes (bent toes). This can cause painful pressure points to develop when walking.

For instance, if you have severe hammertoes and wear constrictive shoes, you may develop corns on your toes that later turn into wounds.

To read more about hammertoes, check out 7 Things You Didn’t Know That May Have Caused Your Hammertoes. 

Foot deformities plus neuropathy place you at higher risk for developing wounds. Unlike someone who doesn’t have neuropathy, diabetics with neuropathy have difficulty changing the way they walk to prevent excess pressure. This causes the breakdown of the skin. 

Diabetics will also experience autonomic changes. These are changes that affect body functions. For instance, the skin on the feet of diabetics tends to be drier, thus placing them at higher risk for developing cracked heels and fissures. This can also increase the risk of infection. 

Staphylococcus aureus, a common bacteria seen in the feet, is seen more often in diabetics. 

When you develop an infected diabetic wound/ulcer, the infection can progress down to the bone, causing osteomyelitis. 

Fungal infections are also common in diabetic patients, and they too allow entry of bacteria through broken skin (2).

xray foot

How Is Osteomyelitis Diagnosed?

Osteomyelitis can be diagnosed clinically and with imaging. A foot examination is done to assess clinical symptoms of osteomyelitis, such as the presence of a deep infected wound. Imaging such as x-ray and MRI can confirm the presence of a bone infection. In addition, a bone biopsy is beneficial to identify infection in the bone. 

Let’s discuss this more in detail.

Your foot doctor will assess your foot ulcer. Your doctor will be checking the size/depth/and appearance of your foot ulcer. Your doctor will also be checking to see if there is pus in the wound.

For more information about diabetic foot ulcers, make sure to check A Simple Guide to Managing Diabetic Foot Ulcers.

Large, deep wounds that have exposed bone visible can indicate that there may be an underlying bone infection. Wounds greater than 2cm and deeper than 3mm indicate a higher suspicion of underlying bone infection (3).

Your doctor will use a cotton tip applicator to probe the wound. If the wound probes to the bone, there is a higher likelihood that there is osteomyelitis present. If there is exposed bone visible with a soft tissue defect, there is a high chance of osteomyelitis. 

Your doctor will order an x-ray to evaluate the foot. Osteomyelitis can take several weeks to show on x-ray. X-ray changes would show erosion of the bone with resorption. 

Your doctor may also choose to order an MRI to further evaluate the bone and the extent of infection. 

On MRI, inflammation of the bone marrow can be identified. Not only that, MRI can show the extent of infection, as well as identify any abscess (pus) that may need to be drained. Ordering an MRI can be useful for surgical planning. 

Sometimes ordering an MRI is not possible, like when someone has a pacemaker in place. If an MRI is contraindicated, your doctor may choose to order a bone scan or a labeled white blood cell scan as an alternative to confirm infection.  

Your doctor may also choose to obtain a bone biopsy to confirm there is a bone infection. This can be done under mild sedation in the operating room. A bone sample would be taken from the infected bone and sent to Pathology to confirm the presence of bone infection. It can also identify the organism growing in the bone. 

blood test

Does a Bone Infection Show Up on Blood Work?

Although blood tests can help confirm the presence of an infection, they should not be used alone to diagnose osteomyelitis, as they can be elevated in other conditions as well. Physical exam, imaging, and blood work should all be used to confirm a bone infection in the foot. 

There are certain blood tests that your doctor will want to order that reveal inflammatory markers that are usually present when you have an infection These blood tests include complete blood count (CBC), Erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). Abnormal values can indicate the presence of infection. 

What Are the Symptoms of Diabetic Foot Osteomyelitis?

Some people with complete numbness in their feet may not develop any symptoms from foot osteomyelitis. Others may feel pain and swelling in the foot, along with worsening redness and pus at the wound site. As the infection worsens, you may experience flu-like symptoms. You may feel nausea, chills, fatigue, and dizziness. You may also develop a fever. 

Where Is Osteomyelitis Most Commonly Seen in the Feet?

Osteomyelitis is most commonly seen in the calcaneus (heel bone), the first metatarsal bone, and the fifth metatarsal bone (4). These areas are high-pressure areas in the feet. The heel is also an area where pressure ulcers are commonly seen in the elderly. Infected pressure ulcers in the heel can cause bone infection in the calcaneus. However, osteomyelitis can occur in any foot bone. 

nurse checking iv drip

How Is Osteomyelitis From Diabetes Treated?

Osteomyelitis treatment can range from non-surgical to surgical. There are many factors to consider when treating osteomyelitis.

Some factors to consider are: 

  • Age of the patient: Is the patient young or older? Would the patient be a better candidate for antibiotics or surgery?
  • The activity level of the patient: Is the patient an athlete? Is the patient wheelchair bound?
  • Location of bone infection: Is the infection present in a toe? Is the infection in the heel?
  • Risk factors: Does the patient have risk factors that make healing difficult such as peripheral vascular disease? Does the patient smoke? Does the patient have uncontrolled diabetes?
  • Systemic involvement: Does the patient have sepsis or bacteremia due to the bone infection? Is the patient sick because of this infection? Is this a life-threatening infection that requires immediate surgery?
  • Patient preference: Is the patient willing to undergo amputation and obtain a prosthetic? Or is the patient wishing to try antibiotics?

These are all important factors for the physician to consider when determining whether antibiotic therapy alone is needed versus surgery. 

Antibiotic Therapy

If you have a bone infection, you will likely need to be admitted to the hospital for evaluation and treatment. Strong antibiotics that penetrate the bone will be administered. Depending on whether the infected bone is removed or not, antibiotic therapy may be needed for 6 weeks to 3 months or more to treat the bone infection (5).

Broad-spectrum antibiotics are initially given to cover the main organisms that are present in foot infection. If your doctor obtained a bone biopsy, the biopsy can identify the exact organisms growing in the bone, thus allowing for more targeted antibiotic therapy. The most common bacteria seen in foot osteomyelitis is Staphylococcus Aureus. 

Antibiotic therapy may be a good choice for someone who has a bone infection limited to a part of the foot that could be easily offloaded and treated with local wound care.

It would also be a good choice for someone who is not a surgical candidate due to other health problems. Younger, active patients may also respond well to antibiotic therapy.

Prolonged IV antibiotic therapy would not be a great option for someone who has kidney disease, extensive infection requiring debridement, or someone who is septic from a bone infection. In this case, surgery may be a better option. 

Surgical Treatment for Osteomyelitis

Surgery has been done for many years for foot osteomyelitis. Surgery involves the amputation of the infected bone. Your surgeon will remove infected tissue and bone, and obtain clean margins to ensure that the infection was removed. 

This can decrease the time you will need antibiotics and in most cases ensure clearance of infection. This is also a good option for people who suffer from poor blood flow, which can decrease the ability of the antibiotic to penetrate the bone. 

However, amputations can affect the way you walk. 

To read more about foot amputations, check out this supplemental post “Can You Walk Without Toes”.

Your surgeon will take care to preserve as much of the foot and ankle as possible, and carefully plan the amputation to hopefully allow for some ambulation in the future. 

Your surgeon may recommend a few surgeries to ensure clearance of the infection. Your surgeon may also use wound grafts to help the wound heal faster. 

Depending on the level of amputation, you will likely need to stay off of your foot for several weeks following surgery to allow the foot to heal. Once your incision heals, your doctor will suggest diabetic shoes and insoles prevent further wounds. If you have an extensive amputation, you may need a foot filler/prosthetic. 

You may need rehabilitation after surgery to help regain strength to help you walk. Healing can take anywhere from 6 weeks to 3 months. 

What Can Happen if Osteomyelitis Is Not Treated?

If there is a bone infection that is left untreated, the bone infection can continue to spread. This can place you at a higher risk for further amputation. This can impact your ability to walk and decrease the quality of your life. Not only that, you can develop bacteria in the blood and become very ill. Bone infections should be taken seriously and should be addressed quickly. 

podiatry foot exam

How Can You Prevent Foot Osteomyelitis?

  • Check your feet daily: Make sure you are regularly checking the bottoms of your feet for blisters, cuts, and wounds. Make sure to check between the toes for any sores. If you can’t reach down to check your feet, have a family member or friend help you. You can also rest a mirror against a wall and check your feet that way
  • Get regular foot exams: Make sure you schedule regular diabetic foot exams with your foot doctor. Your foot doctor will check the health of your feet and address any concerns they may find. Foot exams should be done on diabetics every 3 months. 
  • Practice proper hygiene: Wash your feet daily using soap and water. Make sure to dry the skin between your toes. Apply moisturizer daily onto your feet, but not in between your toes. Avoid using harsh chemicals like peroxide on your feet. 
  • Wear appropriate shoes: If you have diabetes with neuropathy, make sure to obtain diabetic shoes with diabetic insoles. These shoes and inserts are designed for people with sensitive skin to help prevent blisters and ulcers. 

Read more about how “Bad Shoes Can Cause Foot Pain” in this supplemental article. 

Conclusion

Diabetic bone infections should be taken seriously and addressed promptly. The earlier the bone infection is caught, the better antibiotics will work. Treating osteomyelitis requires a team approach by your family doctor, your foot doctor, an infectious disease physician, as well as a physical therapist. Appropriate post-op care is also needed to prevent future infections. 

Appropriate foot care is so important in preventing bone infections. Make sure to regularly get foot exams to ensure your feet are doing well. 

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Related articles:

The Ultimate Guide To Nerve Pain On The Foot

Actionable Solutions For Foot Problems From Diabetes

Diabetic Neuropathy in the feet- A Simple Treatment Guide

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References

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Vaishnavi Bawa
Dr. Vaishnavi Bawa is a Podiatrist who specializes in treating foot and ankle pathology. LifesLittleSteps mission is to educate the public about foot health in an easy-to-understand manner using evidence-based medicine.
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