Controversies in diagnosing and managing osteomyelitis of the foot in diabetes

Treatment of Diabetic Foot Osteomyelitis: A Surgical Critique

Osteomyelitis is one of the most frequent infections of the diabetic foot accounting for 10-15% of mild infections and almost 50% of severe infections. The definitive diagnosis of foot osteomyelitis requires obtaining bone samples for microbiological and histopathological studies. The treatment of osteomyelitis of the foot in diabetic patients continues to be debated. Until recently, most experts considered that the standard treatment for diabetic foot osteomyelitis should be the surgical removal of infected bone. Recent data suggest that antibiotic treatment can achieve an apparent remission of osteomyelitis though it is difficult to identify patients for this approach. One of the main arguments used to justify the solely antibiotic treatment of osteomyelitis is the alteration of foot biomechanics produced as a consequence of surgery. Conservative surgery combined with antibiotics is an attractive option in treating diabetic foot osteomyelitis because it may reduce the changes in the biomechanics of the foot and minimize the duration of antibiotic therapy. It is currently accepted that the combination of antibiotics with surgical removal of the infected bone may cure the majority of diabetic foot osteomyelitis. Recent literature emphasizes the role of antibiotics in the management of foot infections while little effort is dedicated to reviewing the surgical treatment of this challenging diabetic complication, apart from amputation. More research, including studies of adjunctive therapies in cases of bone infection in the feet of diabetic patients is required.

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.

Diagnostic performance of FDG-PET, MRI, and plain film radiography (PFR) for the diagnosis of osteomyelitis in the diabetic foot

BACKGROUND

The early and accurate diagnosis of osteomyelitis in the diabetic foot is essential to provide appropriate treatment and obviate long-term complications of the disease. The currently employed non-invasive imaging modalities such as plain film radiography (PFR) lack the sensitivity to accurately exclude osteomyelitis, while magnetic resonance imaging (MRI) is limited by its low specificity and contraindications in certain patients. Therefore, accurate non-invasive detection of osteomyelitis in the diabetic foot remains a challenge. [18F]-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) has been proven useful in other settings to detect infection. In this ongoing prospective study, we assessed the diagnostic performance of FDG-PET to diagnose osteomyelitis in the diabetic foot and compared it with that of MRI and PFR.

METHODS

Patients who met the prespecified criteria for complicated diabetic foot underwent FDG-PET, MRI, and PFR of the feet. Each imaging study was then interpreted in a blinded fashion for presence of osteomyelitis or other abnormalities. The gold standard for diagnosis in each patient was based on surgical, microbiological, and clinical follow-up results.

RESULTS

One hundred ten consecutive patients have been enrolled to date into this prospective project. FDG-PET correctly diagnosed osteomyelitis in 21 of 26 patients and correctly excluded it in 74 of 80, with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 81%, 93%, 78%, 94%, and 90%, respectively. MRI correctly diagnosed osteomyelitis in 20 of 22 and correctly excluded it in 56 of 72, with sensitivity, specificity, PPV, NPV, and accuracy of 91%, 78%, 56%, 97%, and 81%, respectively. PFR correctly diagnosed osteomyelitis in 15 of 24 and correctly excluded it in 65 of 75, with sensitivity, specificity, PPV, NPV, and accuracy of 63%, 87%, 60%, 88%, and 81%, respectively.

CONCLUSION

FDG-PET is a highly specific imaging modality for the diagnosis of osteomyelitis in diabetic foot and, therefore, should be considered to be a useful complimentary imaging modality with MRI. In the setting where MRI is contraindicated, the high sensitivity and specificity of FDG-PET justifies its use after a negative or inconclusive PFR to aid an accurate diagnosis.

Risk factors for developing osteomyelitis in patients with diabetic foot wounds

AIMS

Osteomyelitis worsens the prognosis in the diabetic foot, but predisposing factors remain largely undefined. In a prospectively followed cohort we assessed risk factors for developing osteomyelitis.

METHODS

We enrolled consecutive persons with diabetes who presented to a managed-care diabetes disease management program. The patients underwent standardized assessments. We monitored for all foot complications, defined infections by criteria consistent with International Working Group guidelines, and defined osteomyelitis as a positive culture from a bone specimen.

RESULTS

1666 persons were enrolled, 50% male, mean age 69 years. Over a mean of 27.2 months of follow-up, 151 patients developed foot infections, 30 (19.9%) of which involved bone. Independent risk factors for osteomyelitis were: wounds that extended to bone or joint (relative risk [RR]=23.1), previous history of a wound prior to enrollment (RR=2.2), and recurrent or multiple wounds during the study period (RR=1.9).

CONCLUSIONS

In this study population, managed in a specialized diabetic foot care center, the results suggest that independent risk factors for developing osteomyelitis are deep, recurrent and multiple wounds. These results may help clinicians target their efforts at diagnosing foot osteomyelitis to the highest risk patients.

Unresolved issues in the management of ulcers of the foot in diabetes

Management of diabetic foot ulcers presents a major clinical challenge. The response to treatment is often poor and the outcome disappointing, while the costs are high for both healthcare providers and the patient. In such circumstances, it is essential that management should be based on firm evidence and follow consensus. In the case of the diabetic foot, however, clinical practice can vary widely. It is for these reasons that the International Working Group on the Diabetic Foot has published guidelines for adoption worldwide. The Group has now also completed a series of non-systematic and systematic reviews on the subjects of soft tissue infection, osteomyelitis, offloading and other interventions designed to promote ulcer healing. The current article collates the results of this work in order to demonstrate the extent and quality of the evidence which is available in these areas. In general, the available scientific evidence is thin, leaving many issues unresolved. Although the complex nature of diabetic foot disease presents particular difficulties in the design of robust clinical trials, and the absence of published evidence to support the use of an intervention does not always mean that the intervention is ineffective, there is a clear need for more research in the area. Evidence from sound clinical studies is urgently needed to guide consensus and to underpin clinical practice. It is only in this way that patients suffering with these frequently neglected complications of diabetes can be offered the best hope for a favourable outcome, at the least cost.

Outcomes of surgical treatment of diabetic foot osteomyelitis: a series of 185 patients with histopathological confirmation of bone involvement

AIMS/HYPOTHESIS

We analysed the factors that determine the outcomes of surgical treatment of osteomyelitis of the foot in diabetic patients given early surgical treatment within 12 h of admission and treated with prioritisation of foot-sparing surgery and avoidance of amputation.

METHODS

A consecutive series of 185 diabetic patients with foot osteomyelitis and histopathological confirmation of bone involvement were followed until healing, amputation or death.

RESULTS

Probing to bone was positive in 175 cases (94.5%) and radiological signs of osteomyelitis were found in 157 cases (84.8%). Staphylococcus aureus was the organism isolated in the majority of cultures (51.3%), and in 35 cases (36.8%) it proved to be methicillin-resistant. The surgical treatment performed included 91 conservative surgical procedures, which were defined as those where no amputation of any part of the foot was undertaken (49.1%). A total of 94 patients received some degree of amputation, consisting of 79 foot-level (minor) amputations (42.4%) and 15 major amputations (8%). Five patients died during the perioperative period (2.7%). Histopathological analysis revealed 94 cases (50.8%) of acute osteomyelitis, 43 cases (23.2%) of chronic osteomyelitis, 45 cases (24.3%) of acute exacerbation of chronic osteomyelitis and three remaining cases (1.6%) designated as 'other'. The risks of failure in the case of conservative surgery were exposed bone, the presence of ischaemia and necrotising soft tissue infection.

CONCLUSIONS/INTERPRETATION

Conservative surgery without local or high-level amputation is successful in almost half of the cases of diabetic foot osteomyelitis. Prospective trials should be undertaken to determine the relative roles of conservative surgery versus other approaches.

The diabetic foot

Diabetes is reaching epidemic proportions and with it carries the risk of complications. Disease of the foot is among one of the most feared complications of diabetes. The ultimate endpoint of diabetic foot disease is amputation, which is associated with significant morbidity and mortality, besides having immense social, psychological and financial consequences. As the majority of amputations are preceded by foot ulceration, it is crucial to identify those at an increased risk. Diabetic foot ulcers may develop as a result of neuropathy, ischaemia or both and when infection complicates a foot ulcer, the combination can become limb and life threatening. Structural abnormalities such as calluses, bunions, hammer toes, claw toes, flat foot and rocker bottom foot need to be identified and managed.

Primarily non-surgical management of osteomyelitis of the foot in diabetes

AIMS/HYPOTHESIS

We examined the use of surgery and assessed the response to non-surgical management of osteomyelitis of the foot in diabetic patients.

METHODS

We reviewed the records of all patients presenting to a single specialist centre with osteomyelitis complicating a diabetic foot ulcer over a 5 year period. Details were extracted on antibiotic choice and treatment duration, hospital admission, incidence of minor and major amputation, and 12 month outcomes.

RESULTS

There were 147 patients, with mean age 64.7 years (66% men). Of these, 26 (18%) were admitted to hospital at the time of presentation and managed with intravenous antibiotics; the remainder were managed with oral antibiotics as outpatients. Surgery was undertaken because of life- or limb-threatening infection, or failure to respond, in 34 (23%) patients (minor amputation 28, major amputation six patients). The remaining 113 were managed non-surgically. Remission was induced in 66 (58.4% of 113), while 35 (31%) had a relapse. Of those experiencing relapse, 27 (77%) achieved apparent arrest of the infection with a further course of antibiotics; six underwent minor and two underwent major amputation. Of all 113 whose infection was initially managed without surgery, apparent remission was achieved with antibiotics alone in 93 (82.3%).

CONCLUSIONS/INTERPRETATION

As these observations were made in an unselected case series, they give more insight into the respective roles of surgical and non-surgical management. The results confirm that although urgent surgery is indicated in some patients, non-surgical management of those without limb-threatening infection is associated with a high rate of apparent remission.

The advantages and disadvantages of non-surgical management of the diabetic foot

It is frequently stated that diabetic foot ulcers should be managed by a multidisciplinary team, comprising individuals who can deliver all the necessary and wide-ranging skills: medical and surgical, podiatric, nursing and orthotic. Whilst there are some data to support this multidisciplinary approach there is little to guide us in ensuring the patient is seen by the right professional for the right treatment at the right time. This article will examine the evidence supporting the most effective use of the multidisciplinary team. It will look at medical managements of ulcers including dressings, offloading and the treatment of infection, either cellulitis or osteomyelitis. By contrast, the role of surgery in offloading, and the treatment of osteomyelitis will be examined, as well as the role of vascular surgery. The most important aspect of management choice, however, is the need to focus on the needs of the person with a diabetic foot ulcer rather than simply on the treatment of the ulcer in isolation. Other complications of diabetes, which may have an effect on wound healing such as glycaemic control, renal failure and visual disturbance will be explored.Finally, there will be discussion of the relevance of outcome measure, both of ulcers as well as those more patient-centred. The ways in which these can be used to monitor individual clinical responses to treatment will be described, as well as their potential use as an aid to comparison of the effectiveness of treatment protocols adopted in different centres.

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

The International Working Group on the Diabetic Foot appointed an expert panel to provide evidence-based guidance on the management of osteomyelitis in the diabetic foot. Initially, the panel formulated a consensus scheme for the diagnosis of diabetic foot osteomyelitis (DFO) for research purposes, and undertook a systematic review of the evidence relating to treatment. The consensus diagnostic scheme was based on expert opinion; the systematic review was based on a search for reports of the effectiveness of treatment for DFO published prior to December 2006. The panel reached consensus on a proposed scheme that assesses the probability of DFO, based on clinical findings and the results of imaging and laboratory investigations. The literature review identified 1168 papers, 19 of which fulfilled criteria for detailed data extraction. No significant differences in outcome were associated with any particular treatment strategy. There was no evidence that surgical debridement of the infected bone is routinely necessary. Culture and sensitivity of isolates from bone biopsy may assist in selecting properly targeted antibiotic regimens, but empirical regimens should include agents active against staphylococci, administered either intravenously or orally (with a highly bioavailable agent). There are no data to support the superiority of any particular route of delivery of systemic antibiotics or to inform the optimal duration of antibiotic therapy. No available evidence supports the use of any adjunctive therapies, such as hyperbaric oxygen, granulocyte-colony stimulating factor or larvae. We have proposed a scheme for diagnosing DFO for research purposes. Data to inform treatment choices in DFO are limited, and further research is urgently needed.

Use of the SINBAD classification system and score in comparing outcome of foot ulcer management on three continents

OBJECTIVE

To compare populations with and outcomes of diabetic foot ulcers managed in the U.K., Germany, Tanzania, and Pakistan and to explore the use of a new score of ulcer type in comparing outcomes among different countries.

RESEARCH DESIGN AND METHODS

Data from a series of 449 patients with diabetic foot ulcers managed in the U.K. were used to evaluate the new simplified system of classification and to derive an aggregate score. The use of the score was then explored using data from series managed in Germany (n = 239), Tanzania (n = 479), and Pakistan (n = 173).

RESULTS

A highly significant difference was found in time to healing between ulcers of increasing score in the U.K. series (Kruskal-Wallis test; P = 0). When data from all centers were examined, a step-up in days to healing was noted for those with scores of >or=3 (out of 6). Examination of baseline variables contributing to outcome revealed the following differences among centers: ischemia, ulcer area, and depth contributing to outcome in the U.K.; ischemia, area, depth, and infection in Germany; depth, infection, and neuropathy in Tanzania; and depth alone in Pakistan.

CONCLUSIONS

Any system of classification designed for general implementation must encompass all the variables that contribute to outcome in different communities. Adoption of a simple score based on these variables, the Site, Ischemia, Neuropathy, Bacterial Infection, and Depth (SINBAD) score, may prove useful in predicting ulcer outcome and enabling comparison among different centers.

Outcome of diabetic foot osteomyelitis treated nonsurgically: a retrospective cohort study

OBJECTIVE

The purpose of this article was to identify criteria predictive of remission in nonsurgical treatment of diabetic foot osteomyelitis.

RESEARCH DESIGN AND METHODS

Diabetic patients who were initially treated without orthopedic surgery for osteomyelitis of the toe or metatarsal head of a nonischemic foot between June 2002 and June 2003 in nine French diabetic foot centers were identified, and their medical records were reviewed. Remission was defined as the absence of any sign of infection at the initial or contiguous site assessed at least 1 year after the end of treatment. A total of 24 demographic, clinical, and therapeutic variables including bone versus swab culture-based antibiotic therapy were analyzed.

RESULTS

Fifty consecutive patients aged 62.2 +/- 11.1 years (mean +/- SD) with diabetes duration of 16 +/- 10.9 years were included. The mean duration of antibiotic treatment was 11.5 +/- 4.21 weeks. Bone biopsy was routinely available in four of the nine centers. Overall patient management was similar in the different centers except for the use of rifampin, which was recorded more frequently in patients from centers in which a bone biopsy was available. At the end of a 12.8-month posttreatment mean follow-up, 32 patients (64%) were in remission. Bone culture-based antibiotic therapy was the only variable associated with remission, as determined by both univariate (18 of 32 [56.3%] vs. 4 of 18 [22.2%], P = 0.02) and multivariate analyses (odds ratio 4.78 [95% CI 1.0-22.7], P = 0.04).

CONCLUSIONS

Bone culture-based antibiotic therapy is a factor predictive of success in diabetic patients treated nonsurgically for osteomyelitis of the foot.

Comparison of four systems of classification of diabetic foot ulcers in Tanzania

AIMS

The aim was to compare the use of four different systems of foot ulcer classification in a consecutive population with diabetes presenting to a specialist clinic in Dar es Salaam, Tanzania.

METHODS

Clinical data were collected prospectively in all patients presenting with foot ulcers between 3 January 2003 and 30 September 2005, and were used retrospectively to classify their ulcers using the Meggitt/Wagner, University of Texas (UT), Size (Area and Depth), Sepsis, Arteriopathy, and Denervation [S(AD)SAD] and Perfusion, Extent/size, Depth/tissue loss, Infection and Sensation (PEDIS) systems. Comparison was made between the strength of the associations between baseline characteristics of each system and outcome determined at 5 December 2005, using linear by linear association.

RESULTS

The strongest statistical associations (P < 0.001) were observed between percent healing and Wagner score (chi(2)= 85.923), depth [S(AD)SAD, PEDIS and UT grade, 70.558], infection [S(AD)SAD, 61.774; PEDIS, 37.924] and UT stage (32.929). Weaker but significant (P < 0.001) associations were observed between percent healing and neuropathy [S(AD)SAD, PEDIS 12.475] and peripheral arterial disease [S(AD)SAD, PEDIS 10.799], as well as cross-sectional area [S(AD)SAD 4.387, P = 0.036].

CONCLUSION

The strength of the statistical association between outcome and both neuropathy and infection contrasts with findings in series previously reported from the USA and UK, and highlights the differences which may be found in different populations. These differences have implications for any system of classification chosen to compare the effectiveness of management in different centres in different countries.

Diabetic foot osteomyelitis

Bone infection in the diabetic foot is always a complication of a preexisting infected foot wound. Prevalence can be as high as 66%. Diagnosis can be suspected in two mains conditions: no healing (or no depth decrease) in spite of appropriate care and off-loading, and/or a visible or palpated bone with a metal probe. The first recommended diagnostic step is to perform (and if necessary to repeat) plain radiographs. After a four-week treatment period, if plain radiographs are still normal, suspicion for bone infection will persist in case of bad evolution despite optimized management of off-loading and arterial disease. It is only in such cases that other diagnosis methods than plain radiographs must be used. Staphylococcus aureus is the most common pathogen cultured from bone samples, followed by Staphylococcus epidermidis. Among enterobacteriaceae, Escherichia coli, Klebsiella pneumonia and Proteus sp. are the most common, followed by Pseudomonas aeruginosa. Surprisingly, bacteria usually considered contaminant (as coagulase negative staphylococci (CNS) and Corynebacterium sp.) have been documented to be pathogens in the osteomyelitis of diabetic foot. Traditional approach to treatment of chronic osteomyelitis was by surgical resection of infected and necrotic bone. But new classes of antibiotics have both the required spectrum of activity and the capacity to penetrate and concentrate in the infected bone. Recently, several observations of osteomyelitis remission following non-surgical management with a prolonged course of antibiotics have been published. Lastly, combined approach with local bone excision and antibiotics has been proposed. Prospective trials should be undertaken to determine the relative roles of surgery and antibiotics in managing diabetic foot osteomyelitis.

Osteomyelitis: approach to diagnosis and treatment

Osteomyelitis is a common disease with a variety of clinically and microbiologically distinct subsets. Diagnosis should begin with plain radiographs but may include a variety of imaging modalities. Cultures of the surface of ulcers or draining sinuses are often misleading, and bone cultures are necessary to determine the true pathogens of bone infections. The approach to treatment of osteomyelitis is complex, and often requires a multidisciplinary approach, with input from radiologists, vascular and orthopedic surgeons, infectious disease specialists, and wound care and rehabilitation specialists.

Amputation in diabetic patients

In diabetes-related amputations, the risk of nonhealing or infection of a wound and the need for revision are increased. Medical treatment before amputation should optimize general and local conditions including the regression of edema, the control of infection, and the optimization of glucoregulation. A major argument for foot-sparing surgery is the poor functional recovery after major limb amputation. Diabetic patients are frail, with an increased postoperative morbidity and mortality after major amputation. Factors detrimental to functional outcome are advanced age, end-stage renal disease, dementia, and above-knee amputation. A multidisciplinary approach is required to optimize the results of diabetes-related amputations. The authors discuss medical and technical aspects that may reduce the failure of minor or major diabetes-related amputations.

Update on the treatment of diabetic foot infections

This article brings the practicing clinician up to date on the current concepts regarding the medical treatment of diabetic foot infections. Topics include a review of the Infectious Diseases Society of America Practice Guidelines for the Diagnosis and Treatment of Diabetic Foot Infections and a discussion of newer antibiotics such as linezolid, ertapenem, moxifloxacin, dalbavancin, tigecycline, ceftobiprole and iclaprim.

Surgical management of diabetic foot infections and osteomyelitis

Foot ulceration and subsequent infection are a major complication of diabetes mellitus. Without proper diagnosis and treatment, these infections often lead to amputation. A multidisciplinary team approach is essential to maximize outcomes in the attempt to limit amputation and decrease patient morbidity. Mild to moderate diabetic foot infections often respond favorably to local wound care, offloading, and antibiotic therapy. When conservative measures fail or when faced with limb- or life-threatening infection, surgical intervention, whether it be incision and drainage or possible amputation, is warranted. The authors review underlying pathophysiology of diabetic foot infections and an evidenced-based approach to surgical management, with additional emphasis on treatment of osteomyelitis.

Imaging-Guided Bone Biopsy for Osteomyelitis: Are There Factors Associated with Positive or Negative Cultures?

OBJECTIVE

The objective of our study was to identify the clinical and technical factors associated with positive or negative culture results in histologically positive cases of osteomyelitis obtained from imaging-guided bone biopsies.

MATERIALS AND METHODS

A retrospective review was performed of 800 consecutive patients undergoing imaging-guided core bone biopsies at two institutions. Seventy-five biopsies were performed for suspected osteomyelitis and 41 patients had histologically proven osteomyelitis. A chart review was performed to determine whether the following factors affected the culture result: histologic type of osteomyelitis, antibiotic therapy before biopsy, fever (temperature > or = 38.0 degrees C), elevated WBC count (> or = 10 x 10(3) microL), elevated erythrocyte sedimentation rate (ESR) (> or = 10 mm/h), elevated C-reactive protein value (CRP) (> or = 6 mg/L), the size of the biopsy needle, and the amount of purulent fluid obtained at biopsy.

RESULTS

Of the 41 cases of osteomyelitis, 14 (34%) had positive cultures. Eighteen (44%) of 41 cases were chronic osteomyelitis. Seventeen (41%) of 41 patients received antibiotics before biopsy, seven (17%) were febrile, five (12%) had an elevated WBC count, 16 (39%) had an elevated ESR, and six (15%) had an elevated CRP value. The biopsy needle size ranged from 11- to 18-gauge. These factors did not have any significant association with positive or negative culture results. Purulent fluid was aspirated in 10 (24%) of the 41 cases. In six (15%) of the cases, > or = 2 mL of purulent fluid was aspirated and five (83%) of the six cases were associated with positive culture (p = 0.02).

CONCLUSION

The rate of positive culture results in histologically proven cases of osteomyelitis obtained from imaging-guided bone biopsies is low. Aspirating > or = 2 mL of purulent fluid is associated with a significantly higher rate of positive cultures.

Clinical management of diabetic foot infection: diagnostics, therapeutics and the future

Diabetic foot infection accounts for a substantial global burden of morbidity, psychosocial disruption and economic cost. Recommendations for best practice are continuously evolving in parallel with improvements in imaging modalities, development and clinical use of new antimicrobial agents and data surrounding novel adjunctive strategies. We discuss this complex group of infections with a particular emphasis on medical management of osteomyelitis, while also highlighting the importance of a broad multidisciplinary approach to eradicating infection.

Local biological factors that influence amputations in diabetic patients

Lower extremity amputation is one of the worst complications of diabetes, as it usually has a life expectancy that is below that of most cancers. Four local biologic factors-ulcer, ischemia, neuropathy, and infection-have been shown to be related to amputation. These factors interact with one another, such that neuropathy has been shown to cause ulcers and ischemia and to prevent the healing of ulcers. In addition, ischemia and neuropathy are independent risk factors for infection. More coordinated efforts are needed to create better grading schemes and therapeutic protocols.

The neuropathic diabetic foot

Diabetic foot problems are common throughout the world, and result in major medical, social and economic consequences for the patients, their families, and society. Foot ulcers are likely to be of neuropathic origin and, therefore, are eminently preventable. Individuals with the greatest risk of ulceration can easily be identified by careful clinical examination of their feet: education and frequent follow-up is indicated for these patients. When infection complicates a foot ulcer, the combination can be limb-threatening, or life-threatening. Infection is defined clinically, but wound cultures assist in identification of causative pathogens. Tissue specimens are strongly preferred to wound swabs for wound cultures. Antimicrobial therapy should be guided by culture results, and although such therapy may cure the infection, it does not heal the wound. Alleviation of the mechanical load on ulcers (offloading) should always be a part of treatment. Plantar neuropathic ulcers typically heal in 6 weeks with nonremovable casts, because pressure at the ulcer site is mitigated and compliance is enforced. The success of other approaches to offloading similarly depends on the patient's adherence to the strategy used for pressure relief.

Osteomyelitis in the diabetic foot: diagnosis and management

Neuropathic ulcerations and altered immune function place the diabetic patient at increased risk for polymicrobial osteomyelitis of the foot and ankle. The optimal method for evaluation and management of this difficult condition is controversial, and further studies are needed. Infected ulcers with exposed or palpable bone can be assumed to have underlying osteomyelitis. Although plain film should be ordered in each case, MRI is most often used for evaluation and surgical planning. Difficult cases, such as those associated with Charcot osteoarthropathy, may require labeled leukocyte scanning or bone biopsy to arrive at the diagnosis. A multidisciplinary team approach is best, allowing optimal treatment of all associated conditions that commonly affect patients with diabetes mellitus. Vascular evaluation and intervention are critical in the presence of vascular insufficiency or ischemia. Empiric, usually broad-spectrum antibiotics and meticulous local wound care may achieve remission of mild to moderately severe infections and should be included in all treatment regimens. Severe, infections, ischemia, or sepsis requires an aggressive surgical approach. Bone resection, correction of deformity, or amputation often are necessary and should be done with the goal of salvaging a functional foot.

Complex wounds

Complex wound is the term used more recently to group those well-known difficult wounds, either chronic or acute, that challenge medical and nursing teams. They defy cure using conventional and simple "dressings" therapy and currently have a major socioeconomic impact. The purpose of this review is to bring these wounds to the attention of the health-care community, suggesting that they should be treated by multidisciplinary teams in specialized hospital centers. In most cases, surgical treatment is unavoidable, because the extent of skin and subcutaneous tissue loss requires reconstruction with grafts and flaps. New technologies, such as the negative pressure device, should be introduced. A brief review is provided of the major groups of complex wounds--diabetic wounds, pressure sores, chronic venous ulcers, post-infection soft-tissue gangrenes, and ulcers resulting from vasculitis.

Oral antimicrobial therapy for diabetic foot osteomyelitis

BACKGROUND

Osteomyelitis in the foot of a diabetic individual is a common complication of peripheral neuropathy, peripheral vascular disease, and infection. Operative facilities and home intravenous antibiotic therapy programs may not be available in remote or rural communities. Limited data are available regarding the treatment results of oral antimicrobial therapy, with or without limited office debridement for diabetic foot osteomyelitis.

METHODS

This retrospective medical record review of 325 consecutive diabetic patients who were evaluated at a multidisciplinary foot clinic identified 94 (29%) patients with 117 episodes of osteomyelitis. The most common group of organisms isolated were aerobic gram-positive cocci, and the single most frequent organism was Staphylococcus aureus. A mean of 1.6 +/- 0.8 (range 1 to 4) pathogens were recovered per episode of osteomyelitis. Therapy was guided by culture results. There were 93 episodes of osteomyelitis (79 patients) that were treated with a mean of 3 +/- 1 oral antimicrobial agents (with or without an initial short course of intravenous antimicrobial agents) and had adequate followup to evaluate outcome of treatment; office treatment included bone debridement in 26 (28%) and toe amputation in nine (10%) of the 93 episodes (79 patients).

RESULTS

Of the 93 episodes treated with oral antimicrobial agents (with or without an initial short course of intravenous antimicrobial agents), 75 (80.5%) episodes were put into remission. Mean duration of oral antimicrobial therapy was 40 +/- 30 weeks. Mean relapse-free followup duration was 50 +/- 50 weeks.

CONCLUSIONS

Diabetic foot osteomyelitis was effectively managed with oral antimicrobial therapy with or without limited office debridement in most patients. This regimen may be especially useful in communities where infectious disease specialists and operative resources are limited.

Diabetic foot disorders. A clinical practice guideline (2006 revision)

The prevalence of diabetes mellitus is growing at epidemic proportions in the United States and worldwide. Most alarming is the steady increase in type 2 diabetes, especially among young and obese people. An estimated 7% of the US population has diabetes, and because of the increased longevity of this population, diabetes-associated complications are expected to rise in prevalence. Foot ulcerations, infections, Charcot neuroarthropathy, and peripheral arterial disease frequently result in gangrene and lower limb amputation. Consequently, foot disorders are leading causes of hospitalization for persons with diabetes and account for billion-dollar expenditures annually in the US. Although not all foot complications can be prevented, dramatic reductions in frequency have been achieved by taking a multidisciplinary approach to patient management. Using this concept, the authors present a clinical practice guideline for diabetic foot disorders based on currently available evidence, committee consensus, and current clinical practice. The pathophysiology and treatment of diabetic foot ulcers, infections, and the diabetic Charcot foot are reviewed. While these guidelines cannot and should not dictate the care of all affected patients, they provide evidence-based guidance for general patterns of practice. If these concepts are embraced and incorporated into patient management protocols, a major reduction in diabetic limb amputations is certainly an attainable goal.

Clinical outcomes after closed, staged, and open forefoot amputations

BACKGROUND

Surgical approaches for forefoot osteomyelitis include amputation with immediate wound closure or resection followed by either staged re-resection and wound closure or local care of the open wound for secondary healing. This study evaluated the effectiveness of closed, staged, and open forefoot amputations in preventing major leg amputation and identified those variables that are associated with successful limb preservation.

METHODS

From July 2002 to June 2004, 208 patients with forefoot osteomyelitis or gangrene underwent minor amputation according to a standard treatment algorithm. Wounds with limited cellulitis underwent immediate wound closure (CLOSED), wounds with marginally viable soft tissue underwent open amputation followed by wound closure at 2 to 7 days (STAGED), and wounds with tenosynovitis or extensive necrosis underwent débridement with no attempt at wound closure (OPEN). Patient demographics, need for further operative interventions, time to complete healing, and progression to major amputation were recorded.

RESULTS

With four subjects lost to follow-up, 204 patients (98%) (94 CLOSED, 56 STAGED, and 54 OPEN) were monitored to complete healing, major amputation, or death. OPEN amputations had a significantly reduced initial healing rate (37%, P < .001) and a frequent need for repeat operative intervention (43%), although successful limb salvage was ultimately achieved in 70% of the cases. Initial healing in the CLOSED and STAGED amputation groups was similar (71% and 78%, respectively), leading to excellent early limb salvage (86% and 91%). The median time to healing for closed, staged, and open amputations was 1.2, 1.6, and 4.6 months, respectively (P < .001). Follow-up evaluation demonstrated the initial improvements in limb salvage with the CLOSED and STAGED groups were lost, resulting in similar amputation rates among the three groups of 30% to 35% over 36 months.

CONCLUSIONS

Although open amputation of extensive forefoot infections frequently requires repeat operative interventions and a prolonged time to complete healing, this approach provides limb salvage rates approaching those observed for less invasive infections amenable to immediate closure. Staged closure offers an improved time to healing without negatively impacting the risk of major limb amputation. Independent of their initial operative approach, these patients frequently progress to early leg amputation.

Diagnosis and treatment of diabetic foot infections

EXECUTIVE SUMMARY: 1. Foot infections in patients with diabetes cause substantial morbidity and frequent visits to health care professionals and may lead to amputation of a lower extremity. 2. Diabetic foot infections require attention to local (foot) and systemic (metabolic) issues and coordinated management, preferably by a multidisciplinary foot-care team (A-II). The team managing these infections should include, or have ready access to, an infectious diseases specialist or a medical microbiologist (B-II). 3. The major predisposing factor to these infections is foot ulceration, which is usually related to peripheral neuropathy. Peripheral vascular disease and various immunological disturbances play a secondary role. 4. Aerobic Gram-positive cocci (especially Staphylococcus aureus) are the predominant pathogens in diabetic foot infections. Patients who have chronic wounds or who have recently received antibiotic therapy may also be infected with Gram-negative rods, and those with foot ischemia or gangrene may have obligate anaerobic pathogens. 5. Wound infections must be diagnosed clinically on the basis of local (and occasionally systemic) signs and symptoms of inflammation. Laboratory (including microbiological) investigations are of limited use for diagnosing infection, except in cases of osteomyelitis (B-II). 6. Send appropriately obtained specimens for culture before starting empirical antibiotic therapy in all cases of infection, except perhaps those that are mild and previously untreated (B-III). Tissue specimens obtained by biopsy, ulcer curettage, or aspiration are preferable to wound swab specimens (A-I). 7. Imaging studies may help diagnose or better define deep, soft-tissue purulent collections and are usually needed to detect pathological findings in bone. Plain radiography may be adequate in many cases, but MRI (in preference to isotope scanning) is more sensitive and specific, especially for detection of soft-tissue lesions (A-I). 8. Infections should be categorized by their severity on the basis of readily assessable clinical and laboratory features (B-II). Most important among these are the specific tissues involved, the adequacy of arterial perfusion, and the presence of systemic toxicity or metabolic instability. Categorization helps determine the degree of risk to the patient and the limb and, thus, the urgency and venue of management. 9. Available evidence does not support treating clinically uninfected ulcers with antibiotic therapy (D-III). Antibiotic therapy is necessary for virtually all infected wounds, but it is often insufficient without appropriate wound care. 10. Select an empirical antibiotic regimen on the basis of the severity of the infection and the likely etiologic agent(s) (B-II). Therapy aimed solely at aerobic Gram-positive cocci may be sufficient for mild-to-moderate infections in patients who have not recently received antibiotic therapy (A-II). Broad-spectrum empirical therapy is not routinely required but is indicated for severe infections, pending culture results and antibiotic susceptibility data (B-III). Take into consideration any recent antibiotic therapy and local antibiotic susceptibility data, especially the prevalence of methicillin-resistant S. aureus (MRSA) or other resistant organisms. Definitive therapy should be based on both the culture results and susceptibility data and the clinical response to the empirical regimen (C-III). 11. There is only limited evidence with which to make informed choices among the various topical, oral, and parenteral antibiotic agents. Virtually all severe and some moderate infections require parenteral therapy, at least initially (C-III). Highly bioavailable oral antibiotics can be used in most mild and in many moderate infections, including some cases of osteomyelitis (A-II). Topical therapy may be used for some mild superficial infections (B-I). 12. Continue antibiotic therapy until there is evidence that the infection has resolved but not necessarily until a wound has healed. Suggestions for the duration of antibiotic therapy are as follows: for mild infections, 12 weeks usually suffices, but some require an additional 12 weeks; for moderate and severe infections, usually 24 weeks is sufficient, depending on the structures involved, the adequacy of debridement, the type of soft-tissue wound cover, and wound vascularity (A-II); and for osteomyelitis, generally at least 46 weeks is required, but a shorter duration is sufficient if the entire infected bone is removed, and probably a longer duration is needed if infected bone remains (B-II). 13. If an infection in a clinically stable patient fails to respond to 1 antibiotic courses, consider discontinuing all antimicrobials and, after a few days, obtaining optimal culture specimens (C-III). 14. Seek surgical consultation and, when needed, intervention for infections accompanied by a deep abscess, extensive bone or joint involvement, crepitus, substantial necrosis or gangrene, or necrotizing fasciitis (A-II). Evaluating the limb's arterial supply and revascularizing when indicated are particularly important. Surgeons with experience and interest in the field should be recruited by the foot-care team, if possible. 15. Providing optimal wound care, in addition to appropriate antibiotic treatment of the infection, is crucial for healing (A-I). This includes proper wound cleansing, debridement of any callus and necrotic tissue, and, especially, off-loading of pressure. There is insufficient evidence to recommend use of a specific wound dressing or any type of wound healing agents or products for infected foot wounds. 16. Patients with infected wounds require early and careful follow-up observation to ensure that the selected medical and surgical treatment regimens have been appropriate and effective (B-III). 17. Studies have not adequately defined the role of most adjunctive therapies for diabetic foot infections, but systematic reviews suggest that granulocyte colony-stimulating factors and systemic hyperbaric oxygen therapy may help prevent amputations (B-I). These treatments may be useful for severe infections or for those that have not adequately responded to therapy, despite correcting for all amenable local and systemic adverse factors. 18. Spread of infection to bone (osteitis or osteomyelitis) may be difficult to distinguish from noninfectious osteoarthropathy. Clinical examination and imaging tests may suffice, but bone biopsy is valuable for establishing the diagnosis of osteomyelitis, for defining the pathogenic organism(s), and for determining the antibiotic susceptibilities of such organisms (B-II). 19. Although this field has matured, further research is much needed. The committee especially recommends that adequately powered prospective studies be undertaken to elucidate and validate systems for classifying infection, diagnosing osteomyelitis, defining optimal antibiotic regimens in various situations, and clarifying the role of surgery in treating osteomyelitis (A-III).

Evidence-Based Protocol for Diabetic Foot Ulcers

BACKGROUND

Diabetic foot ulcers are the single biggest risk factor for nontraumatic foot amputations in persons with diabetes. Foot ulcers occur in 12 to 25 percent of persons with diabetes and precede 84 percent of all nontraumatic amputations in this growing population. Because of the high incidence of foot ulcers, amputations remain a source of morbidity and mortality in persons with diabetes. Strict adherence to evidence-based protocols as described herein will prevent the majority of these amputations.

METHODS

The collective experience of treating patients with neuropathic diabetic foot ulcers in four major diabetic foot programs in the United States and Europe was analyzed.

RESULTS

The following protocol was developed for patients with diabetic foot ulcers: (1) establishment of good communication among the patient, the wound healing team, and the primary medical doctor; (2) comprehensive, protocol-driven care of the entire patient, including hemoglobin A1c, microalbuminuria, and cholesterol as well as early treatment of retinopathy, nephropathy, and cardiac disease; (3) weekly objective measurement of the wound with digital photography, planimetry, and documentation of the wound-healing process using the Wound Electronic Medical Record, if available; (4) objective evaluation of blood flow in the lower extremities (e.g., noninvasive flow studies); (5) débridement of hyperkeratotic, infected, and nonviable tissue; (6) use of systemic antibiotics for deep infection, drainage, and cellulitis; (7) off-loading; (8) maintenance of a moist wound bed; (9) use of growth factor and/or cellular therapy if the wound is not healing after 3 weeks with this protocol; and (10) consideration of the use of vacuum-assisted therapy in complex wounds.

CONCLUSIONS

In diabetic foot ulcers, availability of the above modalities, in combination with early recognition and comprehensive treatment, ensures rapid healing, minimizes morbidity and mortality rates, and eliminates toe and limb amputations in the absence of ischemia and osteomyelitis.

Gangrenous necrosis of the diabetic foot caused byFusarium acutatum

Foot infections are common and serious complications of diabetic patients. We report the case of a 68-year-old patient with a diabetic foot infection that developed into a gangrenous necrosis. Fusarium spp. was isolated on two successive occasions with no other associated microorganisms. Histopathology demonstrated invasion of the fungus into the tisssue. These findings suggested an infection rather than colonization. A detailed morphological study showed that the isolate was Fusarium acutatum, which was confirmed by rDNA sequencing. This fungus is found only in Asia and has not been previously reported as a human pathogen.

Culture of Percutaneous Bone Biopsy Specimens For Diagnosis of Diabetic Foot Osteomyelitis: Concordance With Ulcer Swab Cultures

BACKGROUND

We assessed the diagnostic value of swab cultures by comparing them with corresponding cultures of percutaneous bone biopsy specimens for patients with diabetic foot osteomyelitis.

METHODS

The medical charts of patients with foot osteomyelitis who underwent a surgical percutaneous bone biopsy between January 1996 and June 2004 in a single diabetic foot clinic were reviewed. Seventy-six patients with 81 episodes of foot osteomyelitis who had positive results of culture of bone biopsy specimens and who had received no antibiotic therapy for at least 4 weeks before biopsy constituted the study population.

RESULTS

Pathogens isolated from bone samples were predominantly staphylococci (52%) and gram-negative bacilli (18.4%). The distributions of microorganisms in bone and swab cultures were similar, except for coagulase-negative staphylococci, which were more prevalent in bone samples (P < .001). The results for cultures of concomitant foot ulcer swabs were available for 69 of 76 patients. The results of bone and swab cultures were identical for 12 (17.4%) of 69 patients, and bone bacteria were isolated from the corresponding swab culture in 21 (30.4%) of 69 patients. The concordance between the results of cultures of swab and of bone biopsy specimens was 42.8% for Staphylococcus aureus, 28.5% for gram-negative bacilli, and 25.8% for streptococci. The overall concordance for all isolates was 22.5%. No adverse events--such as worsening peripheral vascular disease, fracture, or biopsy-induced bone infection--were observed, but 1 patient experienced an episode of acute Charcot osteoarthropathy 4 weeks after bone biopsy was performed.

CONCLUSIONS

These results suggest that superficial swab cultures do not reliably identify bone bacteria. Percutaneous bone biopsy seems to be safe for patients with diabetic foot osteomyelitis.

The role of proinflammatory cytokines in the cause of neuropathic osteoarthropathy (acute Charcot foot) in diabetes

The pathogenesis of the acute Charcot foot of diabetes remains unclear. All patients with this condition have evidence of peripheral neuropathy, with loss of protective sensation and abnormal foot biomechanics. However, the acute Charcot foot is also characterised by a pronounced inflammatory reaction and the pathogenic significance of this inflammation has received little attention. We suggest that an initial insult--which may or may not be detected--is sufficient to trigger an inflammatory cascade through increased expression of proinflammatory cytokines, including TNFalpha and interleukin 1beta. This cascade then leads to increased expression of the nuclear transcription factor, NF-kappaB, which results in increased osteoclastogenesis. Osteoclasts cause progressive bone lysis, leading to further fracture, which in turn potentiates the inflammatory process. The potential role of proinflammatory cytokines suggests the possibility of new treatments for this sometimes devastating complication of diabetes.

Treatment for diabetic foot ulcers

People with diabetes develop foot ulcers because of neuropathy (sensory, motor, and autonomic deficits), ischaemia, or both. The initiating injury may be from acute mechanical or thermal trauma or from repetitively or continuously applied mechanical stress. Patients with clinically significant limb ischaemia should be assessed by a vascular surgeon to determine the need for angioplasty, stenting, or femorodistal bypass. When infection complicates a foot ulcer, the combination can be limb or life-threatening. Infection is defined clinically, but wound cultures reveal the causative pathogens. Tissue specimens are strongly preferred to wound swabs for wound cultures. Antimicrobial therapy should be guided by culture results, and should aim to cure the infection, not to heal the wound. Alleviation of the mechanical load on ulcers (off-loading) should always be a part of treatment. Neuropathic ulcers typically heal in 6 weeks with total contact casting, because it effectively relieves pressure at the ulcer site and enforces patient compliance. The success of other approaches to off-loading similarly depends on the patients' adherence to the effectiveness of pressure relief. Surgery to heal ulcers and prevent recurrence can include tenotomy, tendon lengthening, reconstruction, or removal of bony prominences. However, these procedures may result in secondary ulceration and other complications. Ulcer recurrence rates are high, but appropriate education for patients, the provision of posthealing footwear, and regular foot care can reduce rates of re-ulceration.

MR imaging of the diabetic foot: diagnostic challenges

Pedal complications of diabetes have long presented a challenge for the clinician and radiologist predominately related to the difficulty in distinguishing infection from neuroarthropathy. The spectrum of diabetic foot infections is broad, ranging from callous and ulcer formation, to septic arthritis, abscess formation, and osteomyelitis. This article summarizes the MR imaging findings in the diabetic foot and the optimal pulse sequences. Focus is placed on aids in differentiating diabetic infection from other entities and increasing the specificity of diagnosing diabetic foot complications.

Is this bone infected or not? Differentiating neuro-osteoarthropathy from osteomyelitis in the diabetic foot

Osteomyelitis (bone infection) and neuro-osteoarthropathy (Charcot arthropathy) are limb-threatening complications of diabetic neuropathy with very different therapies. Distinguishing between them may be difficult, but it is important. In Charcot arthropathy, noninfectious soft tissue inflammation accompanies rapidly progressive destruction, first of joints, then of bone. This occurs in a well-vascularized and severely neuropathic, but nonulcerated, foot. In osteomyelitis, chronic soft tissue ulceration precedes infection of bone, which may be physically exposed. Magnetic resonance imaging and bone biopsy are the preferred diagnostic tests, provided adequate technical and interpretive skills are available.

Amputation as a marker of the quality of foot care in diabetes

Strategic targets for the management of foot ulcers focus on reducing the incidence of amputation. While data on the incidence of amputation can be obtained relatively easily, the figures require very careful interpretation. Variation in the definition of amputation, population selection and the choice of numerator and denominator make comparisons difficult. Major and minor amputation have to be distinguished as they are undertaken for different reasons and are associated with different costs and functional implications. Many factors influence the decision of whether or not to remove a limb. In addition to disease severity, co-morbidities, and social and individual patient factors, many aspects of the structure of care services affect this decision, including access to primary care, quality of primary care, delays in referral, availability and quality of specialist resources, and prevailing medical opinion. It follows that a high incidence of amputation can reflect a higher disease prevalence, late referral, limited resources, or a particularly interventionist approach by a specialist team. Conversely, a low incidence of amputation can indicate a lower disease prevalence or severity, good management of diabetes in primary and secondary care, or a particularly conservative approach by an expert team. An inappropriately conservative approach could conceivably enhance suffering by condemning a person to months of incapacity before they die with an unhealed ulcer. The reported annual incidence of major amputation in industrialised countries ranges from 0.06 to 3.83 per 10(3) people at risk. Some centres have documented that the incidence is falling, but this is often from a baseline value that was unusually high. Other centres have reported that the incidence has not changed. The ultimate target is to achieve not only a decrease in incidence, but also a low overall incidence. This must be accompanied by improvements in morbidity, mortality, and patient function and mood.

Wound-related osteomyelitis: a case of containment not cure

Community nurses need to be aware that some patients with osteomyelitis are treated with antibiotics alone. Such patients often have co-morbidities and quality of life issues that directly impact on the decision to treat osteomyelitis surgically. However, adopting a conservative approach to osteomyelitis management is associated with an increased risk of osteomyelitis recurrence. The rationale for managing chronic wound-related osteomyelitis with antibiotics is discussed. Community nurses caring for patients that have received antibiotics alone to treat osteomyelitis need to be aware of the potential for osteomyelitis recurrence and how to make the diagnosis.