Point/Counterpoint

Should toe amputation be delayed in diabetic patients with osteomyelitis?

Publish date: November 29, 2018

Amputation: Often the best option

For many years there has been debate about the best management strategy for diabetic foot infection including osteomyelitis. The principles of appropriate antibiotics, surgical debridement, good wound care, and proper offloading will always remain. There are no randomized controlled trials of medical vs. surgical management of diabetic foot ulceration with osteomyelitis.

Dr. Mark P. Androes

We now have a number of widely accepted ways to define wounds including Wagner and the SVS-adopted WIFI score. Historical papers are somewhat plagued by heterogeneity in the wounds included. This is even more apparent with any attempted meta-analyses. I think everyone would agree that the superficial toe wound with minimal cellulitis is best managed medically. The issue at hand is the profoundly neuropathic diabetic often with underlying anatomic abnormality and osteomyelitis. My esteemed colleague would suggest that we are too quick to pull a trigger and amputate a toe with underlying osteomyelitis.

I think the initial item for debate is the technique of diagnosis of osteomyelitis. We have multiple ways this is reported. Plain x-ray, bone scan, MRI, and “clinical osteomyelitis” are among the alternative ways osteomyelitis is diagnosed. The reliability of the last is the most variable because clinical osteomyelitis ranges from “probes close to bone” to exposed bone visible protruding from the wound bed. Given the variability of diagnostic techniques, the literature is an amalgam of clinical scenarios and difficult to navigate in a way to affect treatment decisions.

In addition, the medical treatment for osteomyelitis is highly variable. This commonly involves tunneled catheter insertion and 6 weeks to 3 months of IV antibiotics. In some institutions antibiotics are tailored to “wound culture.” Several of our infectious disease specialists prefer bone culture and pathology of bone demonstrating an acute destructive process. Obviously, this often requires surgical debridement to obtain a specimen. Antibiotic duration recommendations may vary from 1 week (if all infected bone is resected) to 90 days if a standalone antibiotic management is selected. Chronic osteomyelitis has a reinfection rate of up to 30%.¹

Medical management is not without risk. These risks include recurring infection with resistant organisms, wound deterioration, gastrointestinal complications (Clostridium difficile), catheter-related complications, and acute kidney injury. A recent paper found over 30% of patients treated medically for osteomyelitis developed acute kidney injury. These patients had more frequent hospitalization, recurring ulceration, and infection.² We have all experienced the patient with multiple hospitalizations and episodic AKI that culminates in ESRD requiring hemodialysis.

If the argument is with good follow-up these patients will ultimately experience preservation of the toe, I would take the stance that in our patient population of diabetics presenting with foot ulcer and osteomyelitis the average hemoglobin A1c is over 9. Although this is not only related to patient compliance, in many instances this is a large piece of the puzzle. It is hard to infer that suddenly with biopsy-proven osteomyelitis the patient will become compliant with medical management of the disease process. Certainly, in some circumstances, this is the case. There are a number of studies with a wide range of findings on HbA^1c as it relates to predictive value of wound healing.

There are various studies comparing surgical to medical management for osteomyelitis. Limb salvage is contingent upon location (forefoot, midfoot, hindfoot), the extent of infection, and patient comorbidities. The conclusion of the majority of these studies is that a standalone antibiotic treatment algorithm results in greater limb loss. Patients with peripheral occlusive disease and preadmission antibiotic use have been shown to have decreased wound healing. Minor amputation has been shown to be protective from mortality, risk of major amputation, and unfavorable discharge in patients admitted with a diagnosis of osteomyelitis.³ The major limb amputation rate for antibiotics alone is 20%-30% according to two trials with duration of antibiotics of 3 months.^4,5 The available randomized trials tend to exclude patients with severe infection (poorly defined), those with PAD, or those with severe comorbid conditions.

Cost of treatment is even more poorly delineated. Obviously, surgical treatment is not without cost to the health care system. Toe amputation especially when including the metatarsal head shifts pressure points and in the neuropathic patient may lead to recurrent ulceration. The average outpatient cost per patient per ulcer is often over $30,000. The goal of surgical treatment can be defined as trying to maintain the greatest degree of function with the least risk. Removing infected bone (i.e., minor amputation) limits exposure to prolonged antibiotic treatment and hopefully lessens recurring ulceration and hospitalization. This is only one piece of the puzzle, however. A multidisciplinary approach with endocrinology, infectious disease, and orthotics for offloading are keys to decrease future ulceration.

Although I do not advocate for widespread toe carnage as suggested by Dr. Koleilat, I do think liberal application of minor amputation to limit hospital stay, limit antibiotic duration and its inherent risk, and possibly affect readmission is often in the best interest of the patient and the system as a whole. Obviously, based on the variable reports in the literature there cannot be a single approach to these patients and the treatment must be individualized based on extent of infection, compliance of the patient, access to multidisciplinary care, and comorbid conditions.