New book focuses on how to avoid leg amputation when diabetes-related foot wounds develop bone infection

Osteomyelitis, or bone infection, is a common enough condition to be seen daily in most hospitals around the world, yet there are limited resources to guide treatment of an individual patient’s unique situation. Evidence-based guidelines that help the surgeon determine what or when to amputate are lacking, and many hospitals do not have access to podiatric medical and surgical care. Meaningful evidence is challenging for this limb-threatening condition due to highly variable patient presentation including location and size of the wound, foot structure, peripheral circulation, and extent of bone involvement.

This book is designed to help medical providers decide who is better off with medical, surgical or combined medical and surgical treatment, and it provides surgeons with a step-by-step plan that can be customized based on the clinical situation.

Who is at risk of getting osteomyelitis?

Diabetics with neuropathy-related open foot wounds are highly prone to developing osteomyelitis. Of the roughly 350 million diabetics worldwide (9 percent of all adults), the risk of foot ulceration is around 25 percent. The likelihood of a diabetic foot wound becoming complicated by bone infection ranges from 20 to 68 percent, which brings a significant risk of partial foot or leg amputation reported to be as high as 66 percent. Osteomyelitis can also occur from open fractures, penetrating injuries like stepping on a nail, or hematogenous spread of infection in the blood, which mainly occurs in children.

How does bone infection lead to leg amputation?

Osteomyelitis pre-op
Pre-op: Widespread osteomyelitis is seen here on an MRI of the calcaneus. Note the broad soft tissue deficit associated with a decubitus heel ulcer. The surrounding soft tissues have developed a local abscess, and limb loss is highly likely for this condition

A chronic lower extremity wound can remain stable for months or even years without much more than topical treatment or occasional antibiotics for localized cellulitis. It is the onset of deep infection of the underlying bone and joint structures that frequently leads to hospitalization, emergency surgery and leg amputation. Bone infection is largely considered to be a permanent condition that can progressively destroy the bone and that causes recurring infection and abscess in the surrounding tissues. Life-threatening infection can develop when bacteria enters the bloodstream causing septic shock. Leg amputation may be needed on an emergency basis but is more commonly performed to remove dead tissue and bone associated with gangrene and tissue necrosis so the patient can heal and resume walking with a prosthetic leg.

What is new in the treatment of osteomyelitis?

There is a philosophical shift away from radical resection and toward biomechanically sound methods that make foot function a priority. These methods often employ minimal resection techniques combined with biopsy-directed antibiotic treatment in an effort to preserve the structures of the foot and ankle, which are important for gait. This conservative approach applies to ideal procedure selection, incision or flap design, extent of bone resection and level of amputation. There is also a shift toward isolated medical treatment, but this approach would ideally involve bone biopsy to confirm the diagnosis and direct selection of antibiotics.

What kinds of medical costs are incurred when treating osteomyelitis?

A diabetic who requires leg amputation to treat osteomyelitis associated with a foot wound can easily incur medical costs above $100,000 for the initial hospital encounter. Additional costs associated with long-term IV antibiotics, rehabilitation and a prosthetic leg can add up quickly, yet this only represents the first few months of care. The one- and five-year survival rate after loss of a leg is worse than most other medical conditions. Poor survival rate is primarily related to the underlying medical conditions that led to the amputation in the first place, including heart disease, kidney disease and uncontrolled diabetes.

When osteomyelitis is caught early, office-based podiatric procedures including bone biopsy and debridement can provide a surgical cure in some cases for as little as $1,000.

Can leg amputation be prevented?

Osteomyelitis post-op
Post-op: Limb preservation surgery allowed partial calcanectomy with a rotational flap closure of the soft tissue deficit. Combined medical and surgical treatment was successful to avoid limb loss and preserve a functional lower extremity. This lateral x-ray was taken with the patient standing while wearing an ankle-foot orthotic and shoe that were designed to restore limb length.

Treatment of osteomyelitis can be very effective, especially when infection is caught early. Some form of partial foot amputation or bone resection procedure is frequently necessary, which allows culture-directed antibiotic treatment, removal of the nidus of infection, wound excision and closure and removal of deformed or prominent bone. Common foot conditions like arthritic spurs, hammertoe contracture or bunion deformity predisposes to sores in diabetics with neuropathy, and these conditions may need to be addressed as part of the overall treatment plan. Foot surgery in this situation can actually make the foot less likely to suffer with recurrent sores.

Most patients require a combined medical and surgical approach, although surgical cure of infection is common allowing only a short course of oral antibiotics after surgery. A variety of rotational flaps and advanced wound closure techniques are commonly used to provide wound coverage.

How can providers help diabetic patients avoid osteomyelitis?

Prevention of ulceration is the key to avoiding diabetic foot osteomyelitis. Tight blood sugar control is the key to avoiding peripheral neuropathy, which is the initial pathway to problems. If neuropathy is already present, avoiding open sores is the best plan to avoid osteomyelitis. Avoiding minor cuts or injuries can be as simple as wearing properly fitting shoes and not going barefoot, even in the home.

Diabetics should be taught how to perform daily foot inspections and to seek prompt medical help for even minor foot problems. If an open sore or neuropathic ulcer is already present, get it healed before infection develops. Intact skin is the best way to avoid foot infection. Most diabetes-related foot problems are easy to avoid but also easy to ignore until it is too late.

Troy J. Boffeli, D.P.M.'90

Troy J. Boffeli, D.P.M.’90, FACFAS, is an adjunct clinical professor of podiatric medicine at DMU and the residency program director of foot and ankle surgery at HealthPartners/Regions Hospital in St. Paul, MN.

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