Diabetic foot osteomyelitis: a progress report on diagnosis and a systematic review of treatment

Surgical complications associated with primary closure in patients with diabetic foot osteomyelitis

Background

The aim of this study was to determine the incidence of complications associated with primary closure in surgical procedures performed for diabetic foot osteomyelitis compared to those healed by secondary intention. In addition, further evaluation of the surgical digital debridement for osteomyelitis with primary closure as an alternative to patients with digital amputation was also examined in our study.

Methods

Comparative study that included 46 patients with diabetic foot ulcerations. Surgical debridement of the infected bone was performed on all patients. Depending on the surgical technique used, primary surgical closure was performed on 34 patients (73.9%, Group 1) while the rest of the 12 patients were allowed to heal by secondary intention (26.1%, Group 2). During surgical intervention, bone samples were collected for both microbiological and histopathological analyses. Post-surgical complications were recorded in both groups during the recovery period.

Results

The average healing time was 9.9±SD 8.4 weeks in Group 1 and 19.1±SD 16.9 weeks in Group 2 (p=0.008). The percentage of complications was 61.8% in Group 1 and 58.3% in Group 2 (p=0.834). In all patients with digital ulcerations that were necessary for an amputation, a primary surgical closure was performed with successful outcomes.

Discussion

Primary surgical closure was not associated with a greater number of complications. Patients who received primary surgical closure had faster healing rates and experienced a lower percentage of exudation (p=0.05), edema (p<0.001) and reinfection, factors that determine the delay in wound healing and affect the prognosis of the surgical outcome. Further research with a greater number of patients is required to better define the cases for which primary surgical closure may be indicated at different levels of the diabetic foot.

2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections

Foot infections are a common and serious problem in persons with diabetes. Diabetic foot infections (DFIs) typically begin in a wound, most often a neuropathic ulceration. While all wounds are colonized with microorganisms, the presence of infection is defined by ≥2 classic findings of inflammation or purulence. Infections are then classified into mild (superficial and limited in size and depth), moderate (deeper or more extensive), or severe (accompanied by systemic signs or metabolic perturbations). This classification system, along with a vascular assessment, helps determine which patients should be hospitalized, which may require special imaging procedures or surgical interventions, and which will require amputation. Most DFIs are polymicrobial, with aerobic gram-positive cocci (GPC), and especially staphylococci, the most common causative organisms. Aerobic gram-negative bacilli are frequently copathogens in infections that are chronic or follow antibiotic treatment, and obligate anaerobes may be copathogens in ischemic or necrotic wounds. Wounds without evidence of soft tissue or bone infection do not require antibiotic therapy. For infected wounds, obtain a post-debridement specimen (preferably of tissue) for aerobic and anaerobic culture. Empiric antibiotic therapy can be narrowly targeted at GPC in many acutely infected patients, but those at risk for infection with antibiotic-resistant organisms or with chronic, previously treated, or severe infections usually require broader spectrum regimens. Imaging is helpful in most DFIs; plain radiographs may be sufficient, but magnetic resonance imaging is far more sensitive and specific. Osteomyelitis occurs in many diabetic patients with a foot wound and can be difficult to diagnose (optimally defined by bone culture and histology) and treat (often requiring surgical debridement or resection, and/or prolonged antibiotic therapy). Most DFIs require some surgical intervention, ranging from minor (debridement) to major (resection, amputation). Wounds must also be properly dressed and off-loaded of pressure, and patients need regular follow-up. An ischemic foot may require revascularization, and some nonresponding patients may benefit from selected adjunctive measures. Employing multidisciplinary foot teams improves outcomes. Clinicians and healthcare organizations should attempt to monitor, and thereby improve, their outcomes and processes in caring for DFIs.

Medical management of diabetic foot infections

Diabetic foot infections (DFIs) are a commonly encountered medical problem. They are associated with an increased frequency and length of hospitalization and risk for lower-extremity amputation. Furthermore, they have substantial economic consequences. Patients with diabetes mellitus are particularly susceptible to foot infections because of neuropathy, vascular insufficiency, and diminished neutrophil function. The approach to managing DFIs starts with determining if an infection exists. If an infection exists, then the type, severity, extent of infection, and risk factors for resistant organisms should be determined through history, physical examination, and additional laboratory and radiological testing. Optimal management requires surgical debridement, pressure offloading, effective antibiotic therapy, wound care and moisture, maintaining good vascular supply, and correction of metabolic abnormalities, such as hyperglycemia, through a multidisciplinary team. Empiric antibiotics for DFIs vary based on the severity of the infection, but must include anti-staphylococcal coverage.

Diagnostics and treatment of the diabetic foot

Every 30 s, a lower limb is amputated due to diabetes. Of all amputations in diabetic patients 85% are preceded by a foot ulcer which subsequently deteriorates to a severe infection or gangrene. There is a complexity of factors related to healing of foot ulcers including strategies for treatment of decreased perfusion, oedema, pain, infection, metabolic disturbances, malnutrition, non-weight bearing, wound treatment, foot surgery, and management of intercurrent disease. Patients with diabetic foot ulcer and decreased perfusion do often not have rest pain or claudication and as a consequence non-invasive vascular testing is recommended for early recognition of ulcers in need of revascularisation to achieve healing. A diabetic foot infection is a potentially limb-threatening condition. Infection is diagnosed by the presence or increased rate of signs inflammation. Often these signs are less marked than expected. Imaging studies can diagnose or better define deep, soft tissue purulent collections and are frequently needed to detect pathological findings in bone. The initial antimicrobial treatment as well as duration of treatment is empiric. There is a substantial delay in wound healing in diabetic foot ulcer which has been related to various abnormalities. Several new treatments related to these abnormalities have been explored in wound healing with various successes. An essential part of the strategy to achieve healing is an effective offloading. Many interventions with advanced wound management have failed due to not recognizing the need for effective offloading. A multidisciplinary approach to wounds and foot ulcer has been successfully implemented in different centres with a substantial decrease in amputation rate.

Does osteomyelitis in the feet of patients with diabetes really recur after surgical treatment? Natural history of a surgical series

AIMS/HYPOTHESIS

The aim of this study was to determine the rate of recurrence, reulceration and new episodes of osteomyelitis and the duration of postoperative antibiotic treatment in a prospective cohort of patients with diabetes who underwent conservative surgery for osteomyelitis.

METHODS

The prospective cohort included patients with diabetes and a definitive diagnosis of osteomyelitis who were admitted to the Diabetic Foot Unit (Surgery Department, La Paloma Hospital, Las Palmas de Gran Canaria, Spain) and underwent surgical treatment from 1 November 2007 to 30 May 2010.

RESULTS

Eighty-one patients were operated on for osteomyelitis during the study period. Seven patients were lost to follow-up at different stages of the study. The median duration of follow-up was 101.8 weeks (quartile 1 = 56.6, quartile 3 = 126.7). Forty-eight patients (59.3%) underwent conservative surgery, 32 (39.5%) had minor amputations and there was one (1.2%) major amputation. Twenty patients (24.7%) required reoperation because of persistent infection. Postoperative antibiotic treatment over a median period of 36 days was provided. Wound healing was achieved by secondary intention for a median of 8 weeks. Sixty-five patients were available for follow-up after healing. The percentage of recurrence, reulceration, and new episodes of osteomyelitis was 4.6% (3/65), 43% (28/65) and 16.9% (11/65), respectively. Mortality during follow-up (excluding in-hospital deaths and patients lost to follow-up) was 13% (9/69).

CONCLUSION

A low rate of recurrence of osteomyelitis after surgical treatment for osteomyelitis was achieved. Despite new episodes, our approach to managing this cohort of patients with diabetes and foot osteomyelitis achieved 98.8% limb salvage.

Primary Closure With a Filleted Hallux Flap After Transmetatarsal Amputation of the Big Toe for Osteomyelitis in the Diabetic Foot

In the diabetic foot, osteomyelitis of the first metatarsal head adjacent to a malum perforans may require resection of the metatarsophalangeal joint. This results in a dysfunctional great toe and large tissue defects that take a long time to heal. The authors postulated that transmetatarsal amputation followed by primary closure with a filleted hallux flap would be feasible in selected cases. Patients that required surgery for diffuse bone destruction of the first metatarsal head were included in the study. Transmetatarsal amputation was performed only if tissue removal rendered the hallux functionless. Primary closure with a filleted hallux flap was attempted in four out of sixteen patients. The developed skin flaps invariably were long enough to cover the plantar tissue defect; no flap necrosis or recurrent infection was noted. Mean healing time was 44 days (range 9-69). Long-term results were disappointing due to ulcer recurrences under the remaining metatarsal heads.

Evidences and Controversies About Recurrence of Diabetic Foot Osteomyelitis

Recurrence is one of the most worrying issues when dealing with diabetic foot osteomyelitis (DFO). In accordance with expert opinion in other areas of bone infection, it is accepted that very late relapse of apparently successfully treated osteomyelitis is not uncommon. However, the physiopathology of infections in large bones secondary to hematogenous osteomyelitis, infected prostheses, and open fractures is quite different from what is seen in the feet of patients with diabetes. The anatomy of the bones, the mechanism of infection and alterations in host defenses that are frequently seen in patients with diabetes may condition the onset, clinical course, and outcomes. Apparent eradication, disappearance of inflammatory signs, wound healing, bone healing based on image studies, and no recurrences during follow-up are common terms used for defining the success of therapy for DFO. Failure of initial surgical treatment, readmission to hospital, and new episodes of infection at the same or a contiguous site are considered as recurrence of osteomyelitis. Theoretically, bacteria living in the bone could be the source of clinical recurrence, but is it possible to obtain complete healing while bacteria remain alive in the bone in the feet of patients with diabetes? Can these bacteria grow and spread from the bone to the skin after years of healing? In the author’s opinion, this type of long-term recurrence of DFO has not been well documented in the medical literature. It is the aim of this illustrated guide to review the evidence and controversies regarding the recurrence of DFO.

Treatment algorithms for chronic osteomyelitis

BACKGROUND

Osteomyelitis was described many years ago but is still incompletely understood. Its exogenously acquired form is likely to become more common as the population ages. We discuss biofilm formation as a clinically relevant pathophysiological model and present current recommendations for the treatment of osteomyelitis.

METHODS

We selectively searched the PubMed and Cochrane databases for articles on the treatment of chronic osteomyelitis with local and systemic antibiotics and with surgery. The biofilm hypothesis is discussed in the light of the current literature.

RESULTS

There is still no consensus on either the definition of osteomyelitis or the criteria for its diagnosis. Most of the published studies cannot be compared with one another, and there is a lack of scientific evidence to guide treatment. The therapeutic recommendations are, therefore, based on the findings of individual studies and on current textbooks. There are two approaches to treatment, with either curative or palliative intent; surgery is now the most important treatment modality in both. In addition to surgery, antibiotics must also be given, with the choice of agent determined by the sensitivity spectrum of the pathogen.

CONCLUSION

Surgery combined with anti-infective chemotherapy leads to long-lasting containment of infection in 70% to 90% of cases. Suitable drugs are not yet available for the eradication of biofilm-producing bacteria.

Chapter V: Diabetic foot

Ulcerated diabetic foot is a complex problem. Ischaemia, neuropathy and infection are the three pathological components that lead to diabetic foot complications, and they frequently occur together as an aetiologic triad. Neuropathy and ischaemia are the initiating factors, most often together as neuroischaemia, whereas infection is mostly a consequence. The role of peripheral arterial disease in diabetic foot has long been underestimated as typical ischaemic symptoms are less frequent in diabetics with ischaemia than in non-diabetics. Furthermore, the healing of a neuroischaemic ulcer is hampered by microvascular dysfunction. Therefore, the threshold for revascularising neuroischaemic ulcers should be lower than that for purely ischaemic ulcers. Previous guidelines have largely ignored these specific demands related to ulcerated neuroischaemic diabetic feet. Any diabetic foot ulcer should always be considered to have vascular impairment unless otherwise proven. Early referral, non-invasive vascular testing, imaging and intervention are crucial to improve diabetic foot ulcer healing and to prevent amputation. Timing is essential, as the window of opportunity to heal the ulcer and save the leg is easily missed. This chapter underlines the paucity of data on the best way to diagnose and treat these diabetic patients. Most of the studies dealing with neuroischaemic diabetic feet are not comparable in terms of patient populations, interventions or outcome. Therefore, there is an urgent need for a paradigm shift in diabetic foot care; that is, a new approach and classification of diabetics with vascular impairment in regard to clinical practice and research. A multidisciplinary approach needs to implemented systematically with a vascular surgeon as an integrated member. New strategies must be developed and implemented for diabetic foot patients with vascular impairment, to improve healing, to speed up healing rate and to avoid amputation, irrespective of the intervention technology chosen. Focused studies on the value of predictive tests, new treatment modalities as well as selective and targeted strategies are needed. As specific data on ulcerated neuroischaemic diabetic feet are scarce, recommendations are often of low grade.

What the radiologist needs to know about the diabetic patient

Diabetes mellitus (DM) is recognised as a major health problem. Ninety-nine percent of diabetics suffer from type 2 DM and 10% from type 1 and other types of DM. The number of diabetic patients worldwide is expected to reach 380 millions over the next 15 years. The duration of diabetes is an important factor in the pathogenesis of complications, but other factors frequently coexisting with type 2 DM, such as hypertension, obesity and dyslipidaemia, also contribute to the development of diabetic angiopathy. Microvascular complications include retinopathy, nephropathy and neuropathy. Macroangiopathy mainly affects coronary arteries, carotid arteries and arteries of the lower extremities. Eighty percent of deaths in the diabetic population result from cardiovascular incidents. DM is considered an equivalent of coronary heart disease (CHD). Stroke and peripheral artery disease (PAD) are other main manifestations of diabetic macroangiopathy. Diabetic cardiomyopathy (DC) represents another chronic complication that occurs independently of CHD and hypertension. The greater susceptibility of diabetic patients to infections completes the spectrum of the main consequences of DM. The serious complications of DM make it essential for physicians to be aware of the screening guidelines, allowing for earlier patient diagnosis and treatment.

A systematic review of the effectiveness of interventions in the management of infection in the diabetic foot

The International Working Group on the Diabetic Foot expert panel on infection conducted a systematic review of the published evidence relating to treatment of foot infection in diabetes. Our search of the literature published prior to August 2010 identified 7517 articles, 29 of which fulfilled predefined criteria for detailed data extraction. Four additional eligible papers were identified from other sources. Of the total of 33 studies, 29 were randomized controlled trials, and four were cohort studies. Among 12 studies comparing different antibiotic regimens in the management of skin and soft-tissue infection, none reported a better response with any particular regimen. Of seven studies that compared antibiotic regimens in patients with infection involving both soft tissue and bone, one reported a better clinical outcome in those treated with cefoxitin compared with ampicillin/sulbactam, but the others reported no differences between treatment regimens. In two health economic analyses, there was a small saving using one regimen versus another. No published data support the superiority of any particular route of delivery of systemic antibiotics or clarify the optimal duration of antibiotic therapy in either soft-tissue infection or osteomyelitis. In one non-randomized cohort study, the outcome of treatment of osteomyelitis was better when the antibiotic choice was based on culture of bone specimens as opposed to wound swabs, but this study was not randomized, and the results may have been affected by confounding factors. Results from two studies suggested that early surgical intervention was associated with a significant reduction in major amputation, but the methodological quality of both was low. In two studies, the use of superoxidized water was associated with a better outcome than soap or povidone iodine, but both had a high risk of bias. Studies using granulocyte-colony stimulating factor reported mixed results. There was no improvement in infection outcomes associated with hyperbaric oxygen therapy. No benefit has been reported with any other intervention, and, overall, there are currently no trial data to justify the adoption of any particular therapeutic approach in diabetic patients with infection of either soft tissue or bone of the foot.

Expert opinion on the management of infections in the diabetic foot

This update of the International Working Group on the Diabetic Foot incorporates some information from a related review of diabetic foot osteomyelitis (DFO) and a systematic review of the management of infection of the diabetic foot. The pathophysiology of these infections is now well understood, and there is a validated system for classifying the severity of infections based on their clinical findings. Diagnosing osteomyelitis remains difficult, but several recent publications have clarified the role of clinical, laboratory and imaging tests. Magnetic resonance imaging has emerged as the most accurate means of diagnosing bone infection, but bone biopsy for culture and histopathology remains the criterion standard. Determining the organisms responsible for a diabetic foot infection via culture of appropriately collected tissue specimens enables clinicians to make optimal antibiotic choices based on culture and sensitivity results. In addition to culture-directed antibiotic therapy, most infections require some surgical intervention, ranging from minor debridement to major resection, amputation or revascularization. Clinicians must also provide proper wound care to ensure healing of the wound. Various adjunctive therapies may benefit some patients, but the data supporting them are weak. If properly treated, most diabetic foot infections can be cured. Providers practising in developing countries, and their patients, face especially challenging situations.

Assessment and management of diabetic foot ulcers

Diabetic foot ulcers can cause considerable disability and morbidity. The complex pathology requires expert and in-depth assessment and management to achieve the best outcomes. Assessment is underpinned by attention to four key points: vascular sufficiency, neurological/sensory status, appropriateness of footwear, and presence of foot deformity. The 'shopping list' for management is derived from the assessment and requires careful planning and a multidisciplinary approach. This article outlines key first line principles and practices in assessment and management of diabetic foot ulcers, including the importance of offloading pressure and mechanical trauma to aid healing and prevent recurrence.

Outcome of patients with diabetes with negative percutaneous bone biopsy performed for suspicion of osteomyelitis of the foot

AIMS

To assess the outcome of patients with diabetes with suspicion of osteomyelitis of the foot who had undergone a percutaneous bone biopsy that yielded negative microbiological results, with focus on the occurrence of osteomyelitis at the biopsied site.

METHODS

Medical charts of adult patients with diabetes with a negative percutaneous bone biopsy were reviewed. Patients' outcome was evaluated at least 2 years after the initial bone biopsy according to wound healing, the results of a new bone biopsy and bone imaging evaluation when applicable.

RESULTS

From January 2001 to January 2008, 41 patients with diabetes (30 men/11 women; mean age 58.1 ± 9.6 years; mean diabetes duration 15.8 ± 6.7 years) met study criteria. Osteomyelitis was suspected based on combined clinical and imaging diagnostic criteria. On follow-up at a mean duration of 41.2 ± 22.5 months post-bone biopsy, 16 patients had complete wound healing (39.0%). Of the 25 other patients, 15 had a new bone biopsy performed, six of which yielded positive microbiological results, and among the 10 patients who neither healed nor underwent bone biopsy, comparative radiography of the foot showed a stable aspect of the biopsied site in six of them, for whom the data were available. Finally, osteomyelitis of the foot at the site where the initial bone biopsy had been performed was confirmed during follow-up in six patients (14.6%) and was suspected in four additional patients (9.7%).

CONCLUSIONS

The results of the present study suggest that, of patients with diabetes with the suspicion of osteomylelitis and a negative percutaneous bone biopsy, only one out of four will develop osteomyelitis within 2 years of the biopsy.

Prognostic difference between soft tissue abscess and osteomyelitis of the foot in patients with diabetes: data from a consecutive series of 452 hospitalized patients

From January 2008 to December 2010, 452 patients with diabetes were admitted to our diabetic foot unit because of deep soft tissue abscess (group A: n = 210) or chronic osteomyelitis (group B: n = 242). Patients from group A underwent emergency debridement in the operating room. Patients from group B underwent elective surgery. Twenty-six (5.8%) major amputations were performed: of these, 18 (8.57%) were performed in patients from group A and 8 (3.31%) were performed in patients from group B (p = .024). Multivariate analysis showed the independent role on amputation outcome of the abscess (odds ratio, 2.64; p = .029; confidence interval [CI] 1.11 to 6.28), dialysis treatment (odds ratio, 3.17; p = .039, CI 1.06-9.51), and C-reactive protein > 0.5 mg/dL (odds ratio, 3.75; p = .022, CI 1.21-11.64). In group A, 43 (22.6%) patients healed only with drainage, and 147 (70.0%) minor amputations were performed: 53 (36.1%) at the level of the forefoot and 94 (63.9%) at the level of the midfoot. In group B, 234 (96.7%) minor amputations were performed, 208 (88.9%) at the forefoot and 26 (11.1%) at the midfoot level (p < .001). Fourteen postoperative complications occurred in patients from group A and 2 in patients from group B (p < .001). In group A, 3 patients died during hospitalization, 1 from septic shock and 2 from sudden death. None of the group B patients died. This study demonstrates that the severity of a foot soft tissue abscess is not comparable with that of a chronic osteomyelitis not only because of a higher rate of major amputation, but also because of a much more proximal level of minor amputation.

Colony-stimulating factors in the prevention and management of infectious diseases

Colony-stimulating factors (CSFs) are attractive adjunctive anti-infective therapies. Used to enhance innate host defenses against microbial pathogens, the myeloid CSFs increase absolute numbers of circulating innate immune effector cells by accelerating bone marrow production and maturation, or augment the function of those cells through diverse effects on chemotaxis, phagocytosis, and microbicidal functions. This article summarizes the evidence supporting the accepted clinical uses of the myeloid CSFs in patients with congenital or chemotherapy-induced neutropenia, and presents an overview of proposed and emerging uses of the CSFs for the prevention and treatment of infectious diseases in other immunosuppressed and immunocompetent patient populations.

Statistical reliability of bone biopsy for the diagnosis of diabetic foot osteomyelitis

Bone biopsy is often referred to as the reference standard for the diagnosis of diabetic foot osteomyelitis (OM), and it also serves as an important interventional tool with respect to diabetic foot infections and limb salvage. However, the phrase bone biopsy lacks a standardized definition, and the statistical reliability of the pathologic diagnosis has not been previously examined. The objective of the present study was to quantify the reliability of the histopathologic analysis of bone with respect to the diagnosis of diabetic foot OM. Four pathologists, kept unaware of the previous pathology reports and specific patient clinical characteristics, retrospectively reviewed 39 consecutive tissue specimens and were informed only that it was "a specimen of bone taken from a diabetic foot to evaluate for OM." As a primary outcome measure, the pathologists were asked to make 1 of 3 possible diagnoses: (1) no evidence of OM, (2) no definitive findings of OM, but cannot rule it out, or (3) findings consistent with OM. There was complete agreement among all 4 pathologists with respect to the primary diagnosis in 13 (33.33%) of the 39 specimens, with a corresponding kappa coefficient of 0.31. A situation of clinically significant disagreement, or in which at least 1 pathologist diagnosed "no evidence of OM," but at least 1 other pathologist diagnosed "findings consistent with OM," occurred in 16 (41.03%) of the specimens. These results indicate agreement below the level of a "reference standard" and emphasize the need for a more comprehensive diagnostic protocol for diabetic foot OM.

The role of hyperbaric oxygen in the treatment of diabetic foot ulcers

Diabetic foot ulcers are still extremely difficult to heal. Therefore, therapeutic options to improve healing rates are continuously being explored. Hyperbaric oxygen (HBO) has been used in addition to standard treatment of the diabetic foot for more than 20 years. Evidence suggests that HBO reduces amputation rates and increases the likelihood of healing in infected diabetic foot ulcers, in association with improved tissue oxygenation, resulting in better quality of life. Nonetheless, HBO represents an expensive modality, which is only available in few centers. Moreover, adverse events necessitate a closer investigation of its safety. Finally, it is not entirely clear which patients stand to benefit from HBO and how these should be selected. In conclusion, HBO appears promising, but more experience is needed before its broad implementation in the routine care of the diabetic foot.

Osteomyelitis: an update for hospitalists

Osteomyelitis is a common and challenging condition for hospitalists to manage. The 3 main types of osteomyelitis that are commonly seen in the hospital setting are 1) contiguous spread from decubitus or diabetic ulcers, 2) hematogenous spread, such as in vertebral or long bone metaphyses, and 3) infections associated with a prosthetic joint. In patients with diabetes, osteomyelitis is the underlying cause of about 20% of foot infections, and greatly increases the chance that the patient will eventually need an amputation and be subject to perioperative risks. Osteomyelitis from hematogenous spread is increasing. The prevalence of vertebral osteomyelitis is also increasing, particularly in intravenous drug users and patients treated with immune-modulating agents. Prosthetic joint infections are perhaps the most challenging type to treat, and require hospitalists, orthopedic surgeons, and infectious disease specialists to work closely together to plan for effective treatment. Due to increasing antibiotic resistance, the microorganisms involved are also proving more difficult to treat. Emerging resistance to the commonly used antibiotics is resulting in changes in treatment choices. Community-acquired methicillin-resistant Staphylococcus aureus is commonly seen, and there is increasing concern about emerging vancomycin resistance. Treatment of osteomyelitis is still based largely on expert opinion rather than evidence from controlled studies.

Diabetic foot: the orthopedic surgery angle

As diabetes takes on pandemic proportions, it is crucial for the orthopedic surgeon to be aware of the issues involved in diabetic foot. Ulceration is related to neuropathy and to arterial disease, a vital prognostic factor for healing; infection plays an aggravating role, increasing the risk of amputation. At-risk feet need to be screened for. Ulcer classification is essential, to set treatment strategy and determine prognosis. Before any treatment is decided on, neuropathy, vascular insufficiency and infection should individually be assessed by clinical examination and appropriate additional work-up. Despite the International Consensus on the Diabetic Foot recommendations, management of diabetic foot in Europe still varies greatly from country to country, very few of which have established reference centers. Management of diabetic foot remains multidisciplinary; but it has been shown that the orthopedic surgeon should play a central role, providing a biomechanical perspective so as to avoid complications recurrence. Strategy notably includes prevention of at-risk foot, revascularization surgery (which should systematically precede orthopedic surgery in case of critical vascular insufficiency), and treatment of ulcers, whether these latter are associated with osteitis or not. Indications for "minor" amputation should be adequate, and meticulously implemented. "Acute foot" is a medical emergency, entailing massive empirically selected I.V. antibiotics to "cool" the lesion. Prophylactic surgery to limit further risks of ulceration is to be indicated with caution and only when clearly justified. France urgently requires accredited specialized multidisciplinary centers to manage severe lesions: deep and infected ulceration, advanced arteriopathy, and Charcot foot arthropathy.

Seminar Review: A Review of the Basis of Surgical Treatment of Diabetic Foot Infections

Infection is an extremely challenging complication of foot ulcers in patients with diabetes. Surgery as part of a multidisciplinary approach is key in the management of many types of diabetic foot infections (DFIs). Unfortunately, the surgical treatment of DFIs is based more on clinical judgment and less on structured evidence, which leaves unresolved doubts. The clinical presentation of DFIs is varied. This review examines the basis of nonvascular surgical treatment of DFIs, emphasizing the importance of the anatomic concepts of the foot, the variety of its clinical presentations, and the concepts of timing surgery. Recent evidence and case reports based on the author’s experience are presented in 2 parts. The first part examines clinical presentation of infections, whereas the second part deals with imaging, foot anatomy, and some case reports.

Treating osteomyelitis: antibiotics and surgery

BACKGROUND

Osteomyelitis is an inflammatory disorder of bone caused by infection leading to necrosis and destruction. It can affect all ages and involve any bone. Osteomyelitis may become chronic and cause persistent morbidity. Despite new imaging techniques, diagnosis can be difficult and often delayed. Because infection can recur years after apparent "cure," "remission" is a more appropriate term.

METHODS

The study is a nonsystematic review of literature.

RESULTS

Osteomyelitis usually requires some antibiotic treatment, usually administered systemically but sometimes supplemented by antibiotic-containing beads or cement. Acute hematogenous osteomyelitis can be treated with antibiotics alone. Chronic osteomyelitis, often accompanied by necrotic bone, usually requires surgical therapy. Unfortunately, evidence for optimal treatment regimens or therapy durations largely based upon expert opinion, case series, and animal models. Antimicrobial therapy is now complicated by the increasing prevalence of antibiotic-resistant organisms, especially methicillin-resistant Staphylococcus aureus. Without surgical resection of infected bone, antibiotic treatment must be prolonged (≥4 to 6 weeks). Advances in surgical technique have increased the potential for bone (and often limb) salvage and infection remission.

CONCLUSIONS

Osteomyelitis is best managed by a multidisciplinary team. It requires accurate diagnosis and optimization of host defenses, appropriate anti-infective therapy, and often bone débridement and reconstructive surgery. The antibiotic regimen must target the likely (or optimally proven) causative pathogen, with few adverse effects and reasonable costs. The authors offer practical guidance to the medical and surgical aspects of treating osteomyelitis.

Medical therapy of diabetic foot infections

Diabetic foot infections are a common and often serious problem, accounting for more hospital bed days than any other complication of diabetes. Despite advances in antibiotic drug therapy and surgical management, these infections continue to be a major risk factor for amputations of the lower extremity. Although a variety of wound size and depth classification systems have been adapted for use in codifying diabetic foot ulcerations, none are specific to infection. In 2003, the International Working Group on the Diabetic Foot developed guidelines for managing diabetic foot infections, including the first severity scale specific to these infections. The following year, the Infectious Diseases Society of America published their diabetic foot infection guidelines. Herein, we review some of the critical points from the Executive Summary of the Infectious Diseases Society of America document and provide a commentary following each issue to update the reader on any pertinent changes that have occurred since publication of the original document in 2004. The importance of a multidisciplinary limb salvage team, apropos of this special issue jointly published by the American Podiatric Medical Association and the Society for Vascular Surgery, cannot be overstated.

Diagnosing diabetic foot osteomyelitis: is the combination of probe-to-bone test and plain radiography sufficient for high-risk inpatients?

AIMS

To investigate the accuracy of the sequential combination of the probe-to-bone test and plain X-rays for diagnosing osteomyelitis in the foot of patients with diabetes.

METHODS

We prospectively compiled data on a series of 338 patients with diabetes with 356 episodes of foot infection who were hospitalized in the Diabetic Foot Unit of La Paloma Hospital from 1 October 2002 to 31 April 2010. For each patient we did a probe-to-bone test at the time of the initial evaluation and then obtained plain X-rays of the involved foot. All patients with positive results on either the probe-to-bone test or plain X-ray underwent an appropriate surgical procedure, which included obtaining a bone specimen that was processed for histology and culture. We calculated the sensitivity, specificity, predictive values and likelihood ratios of the procedures, using the histopathological diagnosis of osteomyelitis as the criterion standard.

RESULTS

Overall, 72.4% of patients had histologically proven osteomyelitis, 85.2% of whom had positive bone culture. The performance characteristics of both the probe-to-bone test and plain X-rays were excellent. The sequential diagnostic approach had a sensitivity of 0.97, specificity of 0.92, positive predictive value of 0.97, negative predictive value of 0.93, positive likelihood ratio of 12.8 and negative likelihood ratio of 0.02. Only 6.6% of patients with negative results on both diagnostic studies had osteomyelitis.

CONCLUSIONS

Clinicians seeing patients in a setting similar to ours (specialized diabetic foot unit with a high prevalence of osteomyelitis) can confidently diagnose diabetic foot osteomyelitis when either the probe-to-bone test or a plain X-ray, or especially both, are positive.

The treatment of diabetic foot infections

Successful treatment of infection in the feet of patients with diabetes mellitus remains a challenge. Although the diagnosis of infection remains a clinical decision, presentation in feet rendered insensate from diabetic neuropathy plus co-existing vascular insufficiency means presentation is often atypical. Wounds frequently yield polymicrobial growth and differentiating commensal from pathogenic organisms can be difficult; isolates from diabetic foot wounds are often multidrug resistant. Affected patients often have many other co-morbidities, which not only affect the choice of appropriate antimicrobial regimen but also impede healing. Further, much contention surrounds the management of osteomyelitis, with the merits and role of surgery still undecided. In this review we briefly consider the epidemiology and pathogenesis of diabetic foot disease, before discussing emerging best microbiological practice and how this fits with the multidisciplinary approach required to tackle this difficult clinical problem.

Beneficial effects of implementing guidelines on microbiology and costs of infected diabetic foot ulcers

AIMS/HYPOTHESIS

In 2003, guidelines for management of diabetic foot infection (DFI) were written by the authors' team according to the guidelines of the International Working Group on the Diabetic Foot. The effects of implementing these guidelines on the microbiology and costs of infected diabetic foot ulcers were assessed.

METHODS

From 2003 to 2007, potential beneficial effects of implementing these guidelines were assessed by comparison over time of bacteriological data (number of bacterial samples, number of microorganisms isolated in cultures, prevalence of multidrug-resistant organisms [MDRO] and colonising flora), and costs related to use of antimicrobial agents and microbiology laboratory workload.

RESULTS

The study included 405 consecutive diabetic patients referred to the Diabetic Foot Unit for a suspected DFI. From 2003 to 2007, a significant decrease was observed in the median number of bacteria species per sample (from 4.1 to 1.6), prevalence of MDRO (35.2% vs 16.3%) and methicillin-resistant Staphylococcus aureus (52.2% vs 18.9%) (p < 0.001). Moreover, prevalence of pathogens considered as colonisers dramatically fell from 23.1% to 5.8% of all isolates (p < 0.001). In parallel, implementation of guidelines was associated with a saving of euro14,914 (US$20,046) related to a reduced microbiology laboratory workload and euro109,305 (US$147,536) due to reduced prescription of extended-spectrum antibiotic agents.

CONCLUSIONS/INTERPRETATION

Implementation of guidelines for obtaining specimens for culture from patients with DFI is cost-saving and provides interesting quality indicators in the global management of DFI.

Validating the probe-to-bone test and other tests for diagnosing chronic osteomyelitis in the diabetic foot

OBJECTIVE

To compare the diagnostic characteristics of tests used for a prompt diagnosis of chronic osteomyelitis in the diabetic foot, using bone histology as the criterion standard. The tests assessed were probe-to-bone (PTB), clinical signs of infection, radiography signs of osteomyelitis, and ulcer specimen culture.

RESEARCH DESIGN AND METHODS

A prospective study was performed on patients with foot ulcers referred to our diabetic foot clinic. Ulcer infection was diagnosed by recording clinical signs of infection and taking specimens for culture. The presumptive diagnosis of osteomyelitis was based on these results and the findings of a plain X-ray and PTB test. All patients with a clinical suspicion of bone infection were subjected to surgical treatment of the affected bone. During surgery, bone specimens were obtained for a histological diagnosis of osteomyelitis.

RESULTS

Over 2.5 years, 210 foot lesions were consecutively examined and 132 of these wounds with clinical suspicion of infection selected as the study sample. Of these, 105 (79.5%) lesions were diagnosed as osteomyelitis. Among the tests compared, the best results were yielded by the PTB test including an efficiency of 94%, sensitivity of 98%, specificity of 78%, positive predictive value of 95%, and negative predictive value of 91% (P < 0.001, κ 0.803); the positive likelihood ratio was 4.41, and the negative likelihood ratio was 0.02 (95% CI).

CONCLUSIONS

In our outpatient population with a high prevalence of osteomyelitis, the PTB test was of greatest diagnostic value, especially for neuropathic ulcers, and proved to be efficient for detecting osteomyelitis in the diabetic foot.

Medical therapy of diabetic foot infections

Diabetic foot infections are a common and often serious problem, accounting for a greater number of hospital bed days than any other complication of diabetes. Despite advances in both antibiotic therapy and surgical management, these infections continue to be a major risk factor for amputations of the lower extremity. Although a number of wound size and depth classification systems have been adapted for use in codifying diabetic foot ulcerations, none are specific for infection. In 2003, the International Working Group on the Diabetic Foot developed guidelines for managing diabetic foot infections, including the first severity scale specific for these infections. The following year, the Infectious Diseases Society of America (IDSA) published their Diabetic Foot Infection Guidelines. In this article, we review some of the critical points from the Executive Summary of the IDSA document and provide a commentary following each issue to update the reader on any pertinent changes that have occurred since the publication of the original document in 2004. The importance of a multidisciplinary limb salvage team, apropos this special joint issue of the American Podiatric Medical Association and the Society for Vascular Surgery, cannot be overstated.

Midfoot and hindfoot bone marrow edema identified by magnetic resonance imaging in feet of subjects with diabetes and neuropathic ulceration is common but of unknown clinical significance

OBJECTIVE

We conducted a retrospective cohort study assessing the prevalence and clinical and radiological outcome of remote areas of bone marrow edema on magnetic resonance imaging (MRI) in the feet of subjects with diabetes and neuropathic foot ulceration.

RESEARCH DESIGN AND METHODS

MRIs performed over 6 years looking for osteomyelitis associated with neuropathic lesions were assessed for remote areas of signal change.

RESULTS

Seventy MRI studies were assessed. Remote areas of signal change were present in 21 (30%) subjects, involved midfoot or hindfoot in 20 subjects, were associated with younger age and renal replacement therapy, and did not predict future Charcot neuroarthropathy or infection at that site. Repeat MRIs in 11 subjects with such areas found that none had progressed, six had improved, and two had resolved; in 29 subjects without such areas, five had developed new areas.

CONCLUSIONS

Bone marrow edema in the midfoot and hindfoot of subjects with diabetes and neuropathic lesions is common, often transient, and of unknown significance.

Management of diabetic foot infections in an era of increasing microbial resistance

Diabetic foot infections cause substantial morbidity, incur significant costs, and may lead to amputation. Resistant organisms, particularly methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant gram-negative organisms, are becoming more prevalent. Optimal management of diabetic foot infections is multimodal, and includes not only antimicrobial therapy but also biomechanical support and offloading, local wound care, glycemic control, assessment and treatment of underlying vascular disease, and surgical therapy when warranted. Antimicrobial therapy should be targeted at the likely etiologic agents and should take into consideration the depth and severity of infection. With expansion of the reservoir of resistant organisms, obtaining reliable deep cultures can help focus antimicrobial therapy against the dominant pathogens. Newer agents against resistant gram-positive and gram-negative organisms show promise in the treatment of diabetic foot infections.

Review Papers: Current Techniques to Detect Foot Infection in the Diabetic Patient

Diabetic foot infections can be a challenge to diagnose, especially when osteomyelitis is in question. Evaluation of infection should involve a thorough examination of the extremity for clinical signs of infection along with appropriate laboratory and imaging studies. Laboratory markers of inflammation such as peripheral leukocyte count, erythrocyte sedimentation rate, C-reactive protein, and procalcitonin may provide useful information when diagnosing soft tissue and bone infection. However, laboratory markers alone should not be used to diagnose a diabetic foot infection as they are non-specific in nature. Imaging studies may also provide valuable clues regarding the presence of infection. Plain radiographs are a good initial screening tool as they are both inexpensive and easily accessible. However, their sensitivity in diagnosing osteomyelitis is poor. Thus, more advanced imaging such as radionuclide imaging and magnetic resonance imaging are warranted when osteomyelitis is suspected. Magnetic resonance imaging is presently considered the gold standard in diagnosing osteomyelitis, despite its wide variation in reported sensitivity and specificity. However, the significant cost of magnetic resonance imaging prevents its use as a screening tool. Collection of reliable microbiologic data is critical in making a diagnosis as well as for treatment of infection, especially when osteomyelitis is concerned. Deep swabs and transcutaneous bone biopsy are considered the ideal methods of obtaining the necessary information. Finally, monitoring treatment should also be performed with an eye towards both laboratory data and the clinical exam.

Management of osteomyelitis of the foot in diabetes mellitus

Although osteomyelitis occurs in approximately 10-20% of patients with diabetes-related foot ulcers, no widely accepted guideline is available for its treatment. In particular, little consensus exists on the place of surgery. A number of experts claim that early surgical excision of all infected or necrotic bone is essential. Others suggest that surgery should not be performed routinely, but instead only in patients who do not respond to antibiotic treatment or in case of particular clinical indications. Unfortunately, no studies have directly compared the two approaches. Over 500 cases of conservative (that is, nonsurgical) management with resolution rates of 60-80% have been described previously. Most patients in these series, however, received prolonged courses of broad-spectrum antibiotics, which increase the risk of diarrhea caused by Clostridium difficile or the emergence of multidrug-resistant organisms. By contrast, relatively few series of primarily surgical management have been published, with widely differing outcomes, and some of them also reported high recurrence rates. Further research is required to establish the relative importance of each approach, but the available data clearly indicate that a combined assessment and treatment by surgeons and physicians together is essential for many patients.

Percutaneous bone biopsy to distinguish osteomyelitis from charcot osteoarthropathy: two case reports

Level of Evidence: V, Expert Opinion

The treatment of diabetic foot infections: focus on ertapenem

Clinically, 3 distinct stages of diabetic foot infection may be recognized: localized infection, spreading infection and severe infection. Each of these presentations may be complicated by osteomyelitis. Infection can be caused by Gram-positive aerobic, and Gram-negative aerobic and anaerobic bacteria, singly or in combination. The underlying principles are to diagnose infection, culture the bacteria responsible and treat aggressively with antibiotic therapy. Localized infections with limited cellulitis can generally be treated with oral antibiotics on an outpatient basis. Spreading infection should be treated with systemic antibiotics. Severe deep infections need urgent admission to hospital for wide-spectrum intravenous antibiotics. Clinical and microbiological response rates have been similar in trials of various antibiotics and no single agent or combination has emerged as most effective. Recently, clinical and microbiological outcomes for patients treated with ertapenem were equivalent to those for patients treated with piperacillin/tazobactam. It is also important to judge the need for debridement and surgery, to assess the arterial supply to the foot and consider revascularization either by angioplasty or bypass if the foot is ischemic. It is also important to achieve metabolic control. Thus infection in the diabetic foot needs full multidisciplinary treatment.

Conservative management of diabetic forefoot ulceration complicated by underlying osteomyelitis: the benefits of magnetic resonance imaging

AIMS

To assess efficacy of conservative management of neuropathic forefoot ulcers with underlying osteomyelitis in subjects with diabetes when magnetic resonance imaging (MRI) is used to confirm or establish diagnosis and to guide antibiotic duration.

METHODS

A retrospective cohort study over 6 years assessing rates of ulcer healing, relapse and amputation. Antibiotics were continued for 3-month cycles with interval MRI: if the lesion had healed and bone signal change resolved or improved, antibiotics were discontinued; if the lesion had not healed or there was no difference in bone signal change, antibiotics were continued for a further 3-month cycle; clinical or radiological deterioration resulted in endoluminal or open vascular surgical intervention where appropriate, or digital or more proximal amputation.

RESULTS

There were 53 episodes in 47 subjects (mean +/- sd age 62 +/- 13 years, duration of diabetes 19 +/- 13 years, glycated haemoglobin 8.4 +/- 1.6%; six with Type 1 diabetes and seven with end-stage renal failure). Successful healing without relapse was achieved in 40 episodes (75%) [median (range) duration of antibiotics 6 (3-12) months and follow-up post-cessation of antibiotics 15 (3-58) months]. Relapse occurred in six episodes (13%) at 31 (2-38) months post-cessation of antibiotics. There were one major (2%) and eight minor (15%) amputations. Five subjects have died (11%), all without foot ulcers.

CONCLUSIONS

High rates of healing and low rates of amputation were achieved. The use of MRI was associated with long courses of antibiotics, but particularly low relapse rate.