Dr. Abhijit Joshi explains how people with Diabetes have a higher risk of bone infection.
Increased risk of bone infection
People with Diabetes are at high risk for developing infection of the soft tissue and bones of the feet as a consequence of
- various neurologic (nerve damage)
- vascular (blood vessel damage)
- metabolic (high blood sugar) changes
When infection sets in the bone it is called as osteomyelitis.
Managing daily activities
Complications of Diabetes include:
- Neuropathy (damage of the nerves, especially of the feet) This causes muscles of the feet to lose their ability to contract. This severely diminishes the sensation in the sole of the feet. This deforms the foot and causes high pressure areas on the sole of the feet. The skin eventually breakdowns and exposes the tissues around the bone. This open wound often gets infected with bacteria leading to collection of pus called an abscess. If left untreated, this infection can spread to the underlying bone causing acute (recent) osteomyelitis.
- Vasculopathy (have reduced blood supply to their legs) Some patients with long standing Diabetes have vasculopathy and very high blood sugar levels. This worsens the condition and makes healing of the wound more difficult. When the wound remains unhealed for a long time, the bone gets severely infected and this condition is then known as chronic (long standing) osteomyelitis.
- Infections transferred from other organs The bone also gets infected when germs from an infected tooth or an infection in the lung (pneumonia) travel through the bloodstream and infect the bone. Around 20 per cent of patients who have a diabetic foot ulcer have some form of osteomyelitis in the bone under the wound.
Note: A confirmed diagnosis of osteomyelitis in the bone increases the chance of treatment failure and also increases the possibility of amputation of the affected area.
Signs and symptoms of osteomyelitis
The symptoms of acute osteomyelitis, which is quick occurring, are
- severe pain or tenderness over the affected bone
- difficulty or inability to use the affected limb or to bear weight or walk
- redness at the site of infection
- the blood investigations show elevated white blood cells
In chronic osteomyelitis, symptoms often develop more gradually and include
- swelling or redness over the affected bone
In people with Diabetes, there are very few signs and symptoms to indicate the presence of chronic bone infection; one indication being a non-healing wound which heals and again breaks down.
Confirming a diagnosis of osteomyelitis is essential
To confirm a diagnosis of osteomyelitis the following steps are taken:
- The unhealed wound is examined to check if there is any continuous secretion coming from the wound.
- Tissue samples are analysed for germ identification and antibiotic sensitivity.
- Blood investigation is sought to confirm the presence of infection in the blood and bone.
- High resolution digital X-ray helps detect the presence of infection in bone at an early stage.
- Magnetic resonance imaging (MRI) helps detect infection in the bones.
- A nuclear scan is used when diagnosis is unclear. A safe radioactive substance is given to the patient and images are taken after a certain interval of the whole body or a localised area like the foot. The radioactive substance attaches itself to the infected part of the bone and this helps localise and identify bone infection.
- In some cases, a small surgery is performed to retrieve a small piece of bone from the wound. This is sent for analysis and germ identification and sensitivity to determine the best choice of antibiotics
Treatment of osteomyelitis
Depending on the stage of the infection and severity, the treatment can range from non surgical to surgical and often is a combination of the two.
- Foot Care
The wound is cleaned with antiseptic solutions. The foot is protected in a plaster and the patient is advised not to bear weight on the foot. A walker or crutches is recommended until the wound heals and infection is eradicated.
- Regulated blood sugar levels
High sugar levels act as food for the germs and they thrive happily in such an environment as they develop resistance to the antibiotics, which need to be administered for a long duration ranging from six weeks to one year.
After a positive confirmation of the diagnosis, laboratory test are done and the germ is identified and its susceptibility to antibiotic is determined. Usually a combination of antibiotics is given as often there is more than a single type of germs causing bone infection.
- Hyperbaric oxygen therapy
Hyperbaric oxygen therapy is sometimes given to help in the healing of the wound.
In severe cases, surgery is recommended and the infected bone and surrounding tissue has to be removed from the foot in order to treat the infection.
Dr Abhijit Joshi is Consultant Orthopaedic and Diabetic Foot Surgeon at Chellaram Diabetes Institute, Pune.