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Three Part Question

In a [diabetic patient] with a [hot swollen foot and no visable break to the skin] does [MR imaging or plain radiography have a better clinical utility at diagnosing Charcot's osteoarthropathy?]

Clinical Scenario

A 45 year old man with diabetes and peripheral neuropathy presents to the emergency department with a hot, red, swollen foot. There is no break in the skin and the patient cannot recall an injury. You suspect Charcot's arthropathy and wonder if plain x-ray or MR Imaging should be your imaging method of choice.

Search Strategy

(exp diabetes mellitus OR exp diabetic foot) AND (exp magnetic resonance imaging OR MRI.mp. OR exp x-ray OR plain radiograph.mp.) LIMIT to humans AND English language.
Medline 1950 to June 2007 using the Ovid interface and Embase 1996 to week 25 2007.

Search Outcome

The search located 70 papers but only 2 of these were relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Chantelau E 2005 Germany	11 diabetic patients with incipient Charcot foot (early referral-case group) and 13 patients with overt Charcot foot (late referral-control group) without definite fractures on the first x-ray after onset of symptoms who were referred to foot clinic	Clinical trial	extent of fracture and deformity post- total contact casting	1/11 case patients developed extended foot fractures and severe deformity, vs 12/13 control patients (P<0.001	A sample size so small that the level of statistical significance was no reached. There was no blinding.
Chantelau E, Poll LW 2006 Germany	26 diabetic patients with peripheral neuropathy and a diagnosis of Charcot's foot.	observational study	blinded assessment of MR Images and x-ray films for type and frequency of injuries	In stage 0 MRI showed advanced stress bone injuries, oedema of the adjacent soft tissues and joint effusion, x-ray, by contrast did not show any of these abnormalities but displayed normal bone anatomy in all 7 feet (P=0.02)	A very small sample size (26 feet in 20 patients)

Comment(s)

The cited papers both only have very small patient groups, however this is the best available evidence- larger trials would be difficult to conduct owing to the relatively low prevalence of Charcot's arthropathy. The studies concur that MR Imaging has a better clinical utility at diagnosing Charcot's arthropathy than plain x-ray (which does not detect stage 0 changes) and gives more detail about the stage of the disease process.

Clinical Bottom Line

A patient with the clinical diagnosis of Charcot's arthropathy should undergo MR Imaging of the foot.

References

1. Chantelau E The perils of procrastination: effects of early vs. delayed detection and treatment of incipient Charcot fracture Diabetc Medicine 2005;22:1707-12
2. Chantelau E, poll LW Evaluation of the Diabetic Foot by MR Imaging or Plain Radiography- an Observational Study Exp Clin Endocrinol Diabetes 2006; 114:428-31