Foot Osteomyelitis in Patients Without Diabetes—Editorial Comment

Abstract

Relatively few articles have been written on the subject of foot osteomyelitis in patients without diabetes. Even a PubMed search using the terms “osteomyelitis, foot” yields a majority of articles on diabetic foot osteomyelitis. But is there a difference between the two? In this article, Mitbander et al1 conclude that foot osteomyelitis is not clinically distinct in patients with diabetes versus those without, and the approach to management need not differ. We commend the authors for their important and interesting article. It is the first study to our knowledge that seeks to directly compare the two. There are pitfalls for any investigator trying to study osteomyelitis, whether in patients with or without diabetes. The answers to the most basic questions such as definition of the condition, appropriate diagnosis, length and course of treatment, surgical versus medical therapies, and even the definition of a “cure” remain elusive. Various clinical practice guidelines have attempted to answer some of these questions, but most recommendations are based on relatively low levels of evidence and tend to comprise mostly consensus opinion. For the case definitions used to include patients into this study, the authors reference the International Working Group on the Diabetic Foot 2008 consensus statement. That this work was specifically looking at diabetic foot osteomyelitis is, in and of itself, demonstrative of the central premise of this work. Are criteria used to define osteomyelitis in the diabetic foot different from those in patients without diabetes? Should clear diagnostic criteria (was osteomyelitis diagnosed via positive bone culture, histopathology, changes on plain x-ray or magnetic resonance imaging, elevated erythrocyte sedimentation rate?) be required to define a case? The authors state that the frequency of peripheral arterial disease (PAD) was similar in both groups, yet the nondiabetes cohort was more frequently found to be smokers. The authors reference the relatively recent Society for Vascular Surgery “WIFI” consensus document to define PAD. These guidelines utilize not only ankle-brachial index but also ankle systolic pressure, toe pressures, and transcutaneous oximetry to stratify patients into 1 of 4 risk grades. Were any, or all, of these techniques used to diagnose PAD in this population? Is it possible that the cigarette smoking in the nondiabetic group led to microvascular disease of the toes that may not have been appreciated if only ankle-brachial index or ankle pressures were utilized? How is a cure defined other than “no further surgery being necessary”? This singular point is one of the reasons there are so few outcome studies on the treatment of osteomyelitis. No one can agree upon an end point! Is there a better definition of treatment failure, which the authors define as “unanticipated resection of additional bone from the initial area of infection or an above-ankle amputation because of ongoing infection”? It's not at all uncommon for patients with osteomyelitis, either with or without diabetes, to have to undergo serial bone debridements. This does not mean that the treatment is a “failure” but rather is part of the standard treatment. Likewise, it would be important to mention the length of treatment for each group. Do patients without diabetes require a longer or shorter course of therapy? The question of “how long to treat” is an important one and is usually based on radiographic studies, biomarkers, and clinical signs. Finally, given that the patient population was skewed toward older males because the study took place on the vascular service at a Veterans Administration Hospital (all but 2 patients were male, and only 20 subjects did not have diabetes), are these results generalizable across a broader population? It would be interesting to see if there were similar outcomes in future studies that included a more diverse demographics and a larger patient base. It was heartening to see the authors use oral antibiotics as their primary treatment regimen. Over the years, intravenous antibiotics have remained for many the perceived criterion standard for treating osteomyelitis. Many clinicians still doggedly cling to the notion that intravenous is superior to oral despite mounting evidence to the contrary. It is nice to see this timeworn dogma give way to an evidence-based approach. We look forward to more studies of this type and applaud the authors for taking the first step in answering the question: Are diabetic and nondiabetic foot osteomyelitis clinically distinct entities?