Charcot Vs Osteomyelitis: Stop, Think & Treat

September - October 2022

Charcot Vs Osteomyelitis: Stop, Think & Treat Editorial Summary The cost of health care for ulceration and amputation in diabetes is estimated at between £962 million and £1 billion: which is approximately 0.8% to 0.9% of the National Health Service (NHS) budget for England. More than 90% of expenditure was related to ulceration, and 60% was for care in community, outpatient and primary settings. For inpatients it is suggested that ulceration was associated with a length of stay 8.04 days longer than that for diabetes admissions without ulceration. For clinicians it is vital to be able to distinguish between a diabetic foot ulcer and Charcot Neuroarthropathy.1

Introduction

W Dr Ahmad Bilal Senior Fellow in Foot and Ankle Surgery, Manchester University Hospitals Manchester, United Kingdom

Prof Anand Pillai Consultant Orthopaedic Foot & Ankle and Adult Reconstruction Surgeon Manchester, United Kingdom

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ith escalating NHS spend on diabetic foot care, it is a clinical condition that needs more focused attention. Ulceration patients are at risk to develop deformity and ulceration due to neuropathy and loss of protective mechanism.

Almost 50% of patients with a new diabetic foot ulcer had at least one admission within 6 months of their assessment, and those with severe ulcers are likely to have procedures involving foot care, revascularisation and amputation.2

Diabetic foot osteomyelitis (DFO) and Charcot neuroarthropathy (CN) are two common presenting conditions. It is important to bear in mind that presentation of both can be very similar and have some overlapping features, however it is very important to differentiate between the two because of the entirely different pathology and treatment.

DFO often has as its inital presenting sign as soft tissue infection, spreading to the underlying osseus structures. CN on the other hand is a non-infectious destructive process affecting the bones, joints, and soft tissues of the foot and ankle, characterized by inflammation in the earliest phase, and if it remains untreated, leading to deformity and ulceration.

two are: Diagnostic Tools: •

Clinical

•

Imaging

•

Biochemistry

•

Biopsy

Clinical Assessment History and clinical examination both are equally important to make the diagnosis. If the presentation is with an ‘angry’ looking foot with a background of recent infection, fever, systemica illness rather than a localised hot, red, swollen foot then the likelihood of infection is higher. Sometimes in a Charcot Neuroarthropathy there is history of minor trauma which triggers the condition. On clinical examination of a Charcot neuropathy, the foot will be warmer than the contralateral side at by least >2 degrees, however the swelling and oedema in Charcot will subside after 5 - 10 mins of foot elevation which is less likely with infection.

Charcot is most commonly seen in the midfoot and is associated with neuropathy and loss in sensation. Circulation is also generally maintained. Infection is commonly associated with ulceration.

Biochemical Markers The diagnosis is even more challenging in the early red, hot swollen foot (stage 0 Eichenholtz3) in which no radiographic changes or when there is late presentation with osseous changes. In its early stage it can easily be confused with cellulitis and later with osteomyelitis. The diagnostic tools required to differentiate the

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Biochemical markers are a key investigative tool in the clinicians ‘toolbox’ to assist in elucidating the difference between these two conditions.

In Charcot neuroarthropathy there will be mild increase in inflammatory markers (WBC, CRP)

Charcot Vs Osteomyelitis: Stop, Think & Treat

“Utilising a combination of clinical history, clinical examination, boichemical tests and imaging modalities can assist the clinician in making the important clinical distinction between these conditions.”

compared to osteomyelitis where they will increase markedly. Glycaemic control (HbA1c) can be poor in both conditions. Blood markers seldom allow confirmatory diagnosis.4

Charcot. However, they are not available in every hospital and access to these scans can be relatively difficult.

Tissue/ Bone Sampling Imaging Imaging is a modality that when used appropriately in conjunction with clinical history, examination and other tests can allow the clinician to make a more accurate diagnosis.

Different imaging modalities have different roles and help in aiding the diagnosis. Base line imaging consists of weight bearing AP, lateral and oblique view plain radiographs of the foot.

Radiographs in early phases can be entirely normal in both conditions however in later stages destructive fragmentation seen can easily be confused with infective process.

MRI scans are relatively easily available, and this modality gives reliable information to help differentiate between Charcot and Osteomyelitis which will be missed by most plain radiographs.5 However, if oedema is the only finding then it may be difficult to differentiate between the two. Multiple joint involvement can be the clue for Charcot whereas osteomyelitis will cause localised signal changes. The presence of abscesses or sinus tracts are also more likely to be suggestive of infection.

The other imaging modality to diagnose Charcot is SPECT-CT in which there will be an increase uptake in all three phases in both conditions, however in cellulitis uptake will be predominantly in early blood flow. CT part of SPECT-CT also can help in the diagnosis subtle fractures which can mimic Charcot but may requires urgent treatment.6

Microbiology swabs of ulceration can be deceptive due to contaminant skin flora, Deep bone/ tissue sample through the separate entry wound gives valuable information by identifying the microbes and help in treatment with targeted antimicrobials.

Bone biopsy is another invasive procedure which can be done in the outpatient clinic to differentiate infection from non-infective process. Osteomyelitis will show inflammatory cell aggregates however in Charcot, Osteoclast cells are predominant. These procedures require the setup and skill set to conduct these tests.

Diagnosis is vital to treat and protect the diabetic foot and prevent the avoidable amputations.

These similar presenting conditions but different treatment can be very challenging and it important to think and get the right diagnosis before you treat. Rarely both conditions can coexist…. So stop , think and then treat!

References 1. Diabetic MedicineVolume 36, Issue 8 p. 995-1002. Research: Health Economics. The cost of diabetic foot ulcers and amputations to the National Health Service in England M. Kerr, E. Barron, P. Chadwick, T. Evans, W. M. Kong, G. Rayman, M. Sutton-Smith, G. Todd, B. Young, W. J. Jeffcoate. First published: 19 April 2019. https://doi.org/10.1111/dme.13973. Citations: 123 2. National Diabetes Foot care Audit (NDFA) Hospital admission report 2014-2016 Published on Oct 2017 3. Eichenholtz SN. Charcot Joints. Springfield, IL, USA: Charles C. Thomas; 1966 4. Petrova et al . Is there a systemic inflammatory response in the acute charcot foot? Diabetes Care 2007, 30, 997–998.

5. Chantelau, E&Poll, L.W. Evaluation of the Diabetic Charcot Foot by MR Imaging or Plain Radiography - an Observational Study. Exp. Clin. Endocrinol. Diabetes 2006, 114, 428–431 6. Ahluwalia et al ;The Role of Bone Scintigraphy with SPECT/CT in the Characterization and Early Diagnosis of Stage 0 Charcot NeuroarthropathyJ Clin Med. 2020 Dec 21;9(12):4123. doi: 10.3390/jcm9124123.

WBC scans (white cell labelled scans) reliably help to distinguish Osteomyelitis from

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