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For citation purposes: Jain AKC. A new classification of diabetic foot osteomyelitis. OA Case Reports 2013 Oct 21;2(13):121.

Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)

Review

Abstract IntroductionDiabetic foot osteomyelitis is one of the most common entities of diabetic foot complications. Involvement of bone increases the risk of amputation in diabetes based upon the site of bone involvement. It is of surprise for one to know that in spite of it being a common condition, there is no specific known classification for diabetic foot osteomyelitis till date. The author, being one of the few handfuls of specialist podiatric surgeons in India, proposes a new classification exclusively for diabetic foot osteomyelitis, which would help in improvising and standardising the practice of diabetic foot. This is the first classification exclusively on diabetic foot osteomyelitis.Conclusion This new classification for diabetic foot osteomyelitis will allow a common language to be communi-cated among the specialist treating a diabetic foot.

IntroductionDiabetic foot is one of the most common and serious complications of diabetes. It is estimated that around 15% of all the diabetic patients will develop a foot ulcer during their lifetime1 and more than 80% of all the non traumatic amputa-tions are preceded by foot ulcer2. It is stated that about one third of diabetic patients who present with foot infec-tions are found to have evidence of osteomyelitis3.

A new classification of diabetic foot osteomyelitis AKC Jain*

It is believed that Nelaton was the first person who coined the term osteomyelitis in 18444. Since then various classifications have been proposed for osteomyelitis that includes Cierny-Mader, Waldvogel, Ger, Kelly, Solagberu, etc.4,5.

The two most commonly used clas-sifications for osteomyelitis are Wald-vogel classification and Cierny-mader Staging (Table 1). Although these two classifications describe the infection and need for surgery, they do not apply for special situations6 (verte-bral osteomyelitis, smaller bones osteomyelitis, etc).

All these classifications are basi-cally general, and are not specific to a diabetic foot. The aim of this review is to discuss a new classification of diabetic foot osteomyelitis.

Peculiarities of diabetic foot osteomyelitisDiabetic foot osteomyelitis is believed to be a difficult and challenging entity to diagnose and manage accurately7. In a diabetic foot, the osteomyelitis occurs via contiguous spread from an adjacent wound in 94% of the cases8. The problem is likely to get worse in a diabetic foot patient during the pres-ence of underlying peripheral arterial disease or foot deformity9.

Also, bilateral foot involvement, rapidity of spread of infection, absence of systemic manifestation of disease, presence of multiple comor-bidities makes the management diffi-cult. Differentiating osteomyelitis and Charcot foot is a diagnostic dilemma even today for the surgeons and it requires expertise.

Osteomyelitis of the forefoot is the most common anatomical region involved followed by mid foot and hind foot. In one study10 from the best

of the diabetic limb salvage institute of India, it was shown that osteomy-elitis accounted for around 16.67% of all the digital amputations occurring in a diabetic foot.

The new classificationOwing to the fact that diabetic foot osteomyelitis is common and pecu-liar; it becomes quite essential to have an independent classification for diabetic foot osteomyelitis. Classifica-tion allows researchers to speak a uniform language globally with respect to a particular disease4. It is currently the need for an hour when it comes to the diabetic foot speciality which is neglected in developing and underdeveloped countries. In fact, one of the main aims of the author is to standardise the practice of a diabetic foot. Just as the TNM (Tumour, Node, and Metastasis) staging forms a common language in oncology, the author’s new classification of diabetic foot complications11, grading of debridement12 and scoring13 and this new classification would definitely equate the diabetic foot speciality to that of the oncology speciality.

According to this simple new clas-sification (Table 2), diabetic foot osteomyelitis is classified into three main types based on the region of foot involved. Type 1 diabetic foot osteomyelitis involves the forefoot, type 2 involves the mid foot and type 3 involves the hind foot. They are further sub grouped into A, B, C, D.

Subgroup-A is a stage when there is no radiological evidence of osteo-myelitis but clinically there is a posi-tive probe to bone test. This subgroup of patients may require bone scan or MRI to confirm the diagnosis. This subgroup of patients may benefit from prolonged antibiotic treatment

* Corresponding author Email: dramitkumarcj@yahoo.in

Department of Surgery, St John’s Medical Col-lege, Sarjapur road, Bangalore 560034, India

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For citation purposes: Jain AKC. A new classification of diabetic foot osteomyelitis. OA Case Reports 2013 Oct 21;2(13):121.

Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)

Review

and no amputation is required in these cases. Figures 1 and 2 are exam-ples of Type 1A osteomyelitis.

In subgroup B, there is an involve-ment of the cortex/medulla, as there is erosion through the cortex. These cases are detected by x-rays. Even in these subgroups, a good debridement and removal of foci along with prolonged antibiotic treatment may suffice. Figure 3 is an example of type 1B diabetic foot osteomyelitis.

The problem comes with C and D subgroups where amputation of the affected region may be needed. In

subgroup C there is destruction of the bone (Figures 4 and 5). This patient requires amputation of the bone. Type 1D may end up in panmetatarsal/

at high risk for major amputation based upon the extent of infection, peripheral vascular disease and other factors. In type 3 diabetic foot osteo-myelitis, in which there is an involve-ment of hind foot, the C (Figure 6) and D subgroups are at the highest risk of major amputation.

Advantages of this new classificationIt is very simple.� Easy to understand and remember.� It is practical in clinical practice.� Very useful as a teaching tool.� It can be used for research purpose.�  This classification can also be used

in non diabetics.

DiscussionThe author has referenced some of its own studies in this review. These referenced studies have been conducted in accordance with the Declaration of Helsinki (1964) and the protocols of these studies have been approved by the relevant ethics committees related to the institution in which they were performed. All

Figure 1: Showing a non healing ulcer of the great toe.

Figure 2: X- ray of the same patient showing Type 1A diabetic foot osteomyelitis. Note the tract. The probe to bone test is positive. The bone appears normal on the x- ray of the foot.

Figure 3: Showing type 1B osteomyelitis involving the distal phalanx of the great toe. Note the cortical erosion of the phalanx.

Figure  4: Showing the sausage shaped great toe.

Figure 5: X- ray of the same patient showing destruction of the distal phalanx. This is type 1C diabetic foot osteomyelitis. It requires amputation of the great toe.

transmetatarsal amputation whereas type 2D may end up in lisfrancs/choparts amputation. Type 2D is also

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For citation purposes: Jain AKC. A new classification of diabetic foot osteomyelitis. OA Case Reports 2013 Oct 21;2(13):121.

Licensee OA Publishing London 2013. Creative Commons Attribution License (CC-BY)

Review

Basis for prevention. Diabetes Care. 1990 May;13(5):513–21.3. Lipsky BA. Osteomyelitis of the foot in diabetic patients. Clin Inf Dis. 1997 Dec; 25(6):1318–26.4. Solagberu BA. A new classification of osteomyelitis for developing countries. East Afr Med J. 2003 Jul;80(7):373–8.5. Mader JT, Shirtliff M, Calhoun JH. Staging and staging application in osteo-myelitis. Clin Inf Dis. 1997 Dec;25(6): 1303–9.6. Carek PJ, Dickerson LM, Sack JL. Diag-nosis and management of osteomyelitis. Am Fam Physician. 2001 Jun;63(12):2413–20.7. Hoffman WB, Khan KH, Kosinski M. Current concepts in treating diabetic foot osteomyelitis. Podiatry today. 2009; 22(10):1–7.8. Nube V, Bolton T, Chua E, Yue D. Osteo-myelitis in the diabetic foot: what lies beneath. Primary intention. 2007 May;15(2):49–57.9. Crim BE, Wukich DK. Osteomyelitis of the foot and ankle in the diabetic foot population: diagnosis and treatment. J Diab Foot Comp. 2009;1(2):26–35.10. Jain AKC, Varma AK, Mol R, Mangala-nandan TS, Bal A, Kumar H. Digital ampu-tations in the diabetic foot. J Diab Foot Comp. 2010;2(1):12–17.11. Jain AKC. A New classification of diabetic foot complications: a simple and effective teaching tool. J Diab Foot Comp. 2012;4(1):1–5.12. Jain AKC. A new classification (grading system) of debridement in diabetic lower limbs. An improvisation and standardization in practice of diabetic lower limb salvage around the world. Med-Science. 2014;3(1):991–1001.13. Jain AKC. The new scoring system for predicting the risk of major amputations in diabetic foot complication. Med-Science. 2014;3(1):1068–78.14. Game FL. Osteomyelitis in the diabetic foot diagnosis and management. Med Clin N Am. 2013 Sep;97(5):947–56.15. Widatalla AH, Mahadi SE, Shawer MA, Mahmoud SM, Abdelmageed AE, Ahmed ME. Diabetic foot infections with osteo-myelitis: efficacy of combined surgical and medical treatment. Diabet Foot Ankle. 2012;3.

human subjects, in these referenced studies, gave informed consent to participate in these studies.

Managing diabetic foot osteomy-elitis has been a challenge to the treating surgeon. Osteomyelitis may complicate between 20–60% of patients presenting with an ulcer in the foot to a specialist centre14. A probe to bone test has been quite helpful clinically in diagnosing osteomyelitis14. It has a predictive value of 89%, sensitivity of 66% and specificity of 85%8,9. An x- ray is often needed for the diagnosis. In the early stages, x- rays may not reveal an osteomyelitis and in such cases, a bone scan [Tc 99m phosphate or indium In 111-labelled white cell

scan] or an MRI is quite helpful8. The sensitivity of an MRI is reported to be between 90–100% while the specificity ranges between 80–100%. However, the gold standard for diag-nosis of osteomyelitis is bone biopsy9.

Management of osteomyelitis of the foot in diabetes varies widely from centre to centre and country to country14. Many believe in surgical excision of all the infected bones while others believe that majority of patients can be managed with antibi-otics alone14. The choice of antibiotics is best guided by culture report. Anti-biotics are initially given parentally and then changed to oral and the duration of the therapy should be a minimum of 6 weeks15.

If one looks at this new classifica-tion, then the general guidelines for the treatment would be antibiotics for subgroups A and B without any amputation until and unless the bone is deformed or destroyed and treat-ment for subgroups C and D would be resection/ amputation based on the anatomic site and the bone involved.

ConclusionThis new classification of diabetic foot osteomyelitis has been devel-oped due to the fact that there is no specific classification for this common foot infection till now and hence it becomes necessary to have one. This classification is very simple, easy to remember and it is practical. This new classification for diabetic foot osteomyelitis will allow a common language to be communicated among the specialist treating diabetic foot.

References1. Singh N, Armstrong DG, Lipsky BA. Preventing foot ulcers in patients with diabetes. JAMA. 2005 Jan;293(2):217–28.2. Pecoraro RE, Reiber GE, Burgess EM. Pathway to diabetic limb amputation.

Figure 6: Showing the destruction of the calcaneum. This is type 3C diabetic foot osteomyelitis. This patient underwent below knee amputation.