By: Norman Bauman for Wounds1
When do you amputate a diabetic foot, and how much do you remove? When you have osteomyelitis, or infection in the bone, you're in trouble. If you delay amputation too long in a hopeless case, the infection will spread and you'll finally have to amputate even more. Or you may be too late. If the infection spreads to the bloodstream, the patient can die.
|One of the most important treatments for non-healing diabetic foot ulcers is to stay off your feet, even around the house, but this is difficult for most patients.|
Another way to relieve pressure on the diabetic foot is a total-contact cast.
Ulcers form over the bony prominences, and this bone can be removed by surgery.
Diabetic patients can't tell whether they have osteomyelitis. They must see a doctor regularly.
Osteomyelitis requires amputation up to half the time.
The main treatment for osteomyelitis is debridement of dead tissue and bone.
Another important treatment for osteomyelitis is surgery to restore blood circulation around blocked arteries.
Antibiotics are necessary but won't do the job by themselves. Overuse creates antibiotic resistance and adverse effects.
Imagine surgeons in Zurich or Boston debating over whether a patient's foot must be amputated, or whether it can be saved. The VEITHsymposium™ set up a debate between Gary W. Gibbons, M.D., Professor of Surgery, Boston University School of Medicine, who argued for aggressively amputating, and Thomas Boeni, M.D., lecturer at the University of Zurich Medical School, who argued for aggressively trying alternatives before amputating. Actually, they didn't disagree that much. They each argued for aggressively using the best foot-saving treatments first, and for amputating as little as possible.
There are six evidence-based principles in treating a diabetic ulcer, said Dr. Gibbons: offloading weight from the foot, debridement, antibiotics, dressings, vascular reconstruction, reconstructive foot surgery, and finally, if that fails, amputation. "Evidence-based" means that someone actually compared each treatment with the alternative, found that it worked, and and published the results in a medical journal.
First, said Dr. Gibbons, make sure the leg really has osteomyelitis, which is difficult to diagnose, especially in diabetes. "There is an improper immune response and altered wound healing," especially when their blood sugar is poorly controlled. The classic signs of infection are redness, swelling, heat, and pain. But in one published study, only a few diabetics with osteomyelitis in the foot actually had a fever or elevated white blood count. And patients with diabetic neuropathy, or nerve damage, don't feel pain.
"Delay in diagnosis and treatment of osteomyelitis increases the risk of amputation," said Dr. Gibbons. The simple, old-fashioned techniques are as good as the latest technology. "Simply take a probe," and explore the ulcer, said Dr. Gibbons. "If you can hit the bone, tap, tap, that was as good as any of the radiological tests." This examination is not painful. That's the problem – the foot doesn't feel pain.
Dr. Boeni noted that the gold standard for diagnosing osteomyelitis is a bone biopsy, but that's invasive and not usually done. He uses an MRI exam. If the osteoporosis is not severe – perhaps in an early stage – "then you have a better chance to do more conservative treatment."
"Osteomyelitis is a surgical disease," said Dr. Gibbons. The treatment is extensive surgical debridement, especially dead or necrotic tissue and bone, and draining the wound. "The diabetic [ulcer] is a chronic wound," he said. "Debridement is the only way to change the chronic wound into an acute wound," which can heal, because it's uninfected and free of toxic tissue breakdown products.
In addition, during debridement of the bone you can shave off the bony prominence, the bump that is the source of the pressure that leads to the ulcer and infection, Dr. Gibbons said. Antibiotics are a helpful adjunct, but they won't cure osteomyelitis without debridement, and have well-known adverse effects such as kidney failure, said Dr. Gibbons. He's seen patients who have been on antibiotics for six months with osteomyelitis and sometimes sepsis. Dr. Gibbons only uses antibiotics for 14 days.
The next step, said Dr. Gibbons, is to revascularize the foot. A bony prominence leads to an ulcer because the diabetic foot has nerve damage and inadequate blood flow. The skin can't heal without adequate blood supply for the re-growing skin cells and for immune cells that fight infection. Diabetics often have blocked arteries, and vascular surgeons can treat that, sometimes by opening the arteries in the leg with high-pressure balloons and sometimes by bypassing an obstructed section with an artificial graft or blood vessel from elsewhere in the patient's body.
"By doing that we were able to get away with local reconstructive surgery instead of going on to amputation," said Dr. Gibbons. Dr. Boeni cited studies in which over half the patients with foot osteomyelitis were treated conservatively, with antibiotics, and avoided amputation, after follow-ups of 12 months or more. "In cases of proven osteomyelitis with severe infection, we still recommend meticulous surgical debridement of the entire infected bone," he said.