Aims/hypothesis Our aims were to compare osteoclastic activity between patients with acute Charcot's osteoarthropathy and diabetic and healthy controls, and to determine the effect of the receptor activator of nuclear factor-kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG). Methods Peripheral blood monocytes isolated from nine diabetic Charcot patients, eight diabetic control and eight healthy control participants were cultured in the presence of macrophage-colony stimulating factor (M-CSF) alone, M-CSF and RANKL, and also M-CSF and RANKL with excess concentrations of OPG. Osteoclast formation was assessed by expression of tartrate-resistant acid phosphatase on glass coverslips and resorption on dentine slices. Results In cultures with M-CSF, there was a significant increase in osteoclast formation in Charcot patients compared with healthy and diabetic control participants (p=0.008). A significant increase in bone resorption was also seen in the former, compared with healthy and diabetic control participants (p < 0.0001). The addition of RANKL to the cultures with M-CSF led to marked increase in osteoclastic resorption in Charcot (from 0.264 ± 0.06% to 41.6±8.1%, p<0.0001) and diabetic control (0.000±0.00% to 14.2±16.5%, p<0.0001) patients, and also in healthy control participants (0.004±0.01% to 10.5±1.9%, p<0.0001). Although the addition of OPG to cultures with M-CSF and RANKL led to a marked reduction of resorption in Charcot patients (41.6±8.1% to 5.9±2.4%, p=0.001), this suppression was not as complete as in diabetic control patients (14.2±16.5% to 0.45±0.31%, p=0.001) and in healthy control participants (from 10.5±1.9% to 0.00±0.00%, p<0.0001). Conclusions/interpretation These results indicate that RANKL-mediated osteoclastic resorption occurs in acute Charcot's osteoarthropathy. However, the incomplete inhibition of RANKL after addition of OPG also suggests the existence of a RANKL-independent pathway.

It is extremely important to have a high index of suspicion for Charcot neuro-osteoarthropathy (CN) and to encourage early presentation of the patient. This should be followed by a rapid diagnosis and early intervention, and with such a modern approach many CN can now be healed and deformity prevented. CN can be divided into two phases: acute active phase and chronic stable phase. The acute active phase includes those patients presenting early with normal X-ray and those presenting later with deformity and radiological changes of CN. The acute phase is characterized by unilateral erythema and oedema. The foot is at least 2 degrees C hotter than the contralateral foot. Patients should have initially an X-ray examination which, at this time, may be normal. We then proceed to two investigations: initially a technetium diphosphonate bone scan, which will detect early evidence of bone damage and also locate the site of this damage. If the result of the bone scan is positive, we would proceed to magnetic resonance imaging (MRI) examination, which would describe in more detail the nature of the bony damage. The aim of treatment is immobilization in a plaster cast until there is no longer evidence on X-ray of continuing bone destruction, and the foot temperature is within 2 degrees C of the contralateral foot. An alternative treatment is a prefabricated walking cast, such as the Aircast. A randomized controlled study of a single 90 mg pamidronate infusion has shown a significant reduction of the markers of bone turnover and skin temperature in treated, compared with control subjects although the fall in skin temperature was similar in both groups. There was a similar finding in a recent study with alendronate. Calcitonin has also been used in the acute stage and there was a more rapid transition to the stable chronic phase in the treated group compared with controls. In the chronic stable phase, the foot is no longer warm and red. There may still be oedema but the difference in skin temperature between the feet is usually less than 2 degrees C. The X-ray shows fracture healing, sclerosis and bone remodelling. The patient must now be rehabilitated and gradually moved from cast treatment to suitable footwear. The patient needs close observation to detect any relapse, which will be evident from further swelling and heat in the foot. Careful rehabilitation is always necessary after a long period in a cast.

At the onset of acute Charcot foot, serum concentrations of tumour necrosis factor-α and interleukin-6 were elevated; however, there was a significant reduction in these markers at resolution and these markers may be useful in the assessment of disease activity.

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We describe the use of Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) in the investigation and diagnosis of Charcot neuroarthropathy (CN) in patients with a hot swollen foot but normal radiographs and clinical suspicion of CN, usually termed Stage 0. This was a retrospective cohort review of 46 diabetes patients who underwent 3 phase bone scintigraphy with “High Resolution” SPECT/CT. The imaging demonstrated that Stage 0 Charcot foot has a distinct bone pathology, which can be classified into three groups: (1) fractures on Computed Tomography (CT) with accompanying focal uptake of tracer on SPECT, (2) bony abnormalities apart from fracture on CT with focal uptake of tracer on SPECT, and (3) normal CT but focal bony uptake of tracer on SPECT. The CT component of SPECT/CT detected bony fractures in 59% of patients. Early treatment with below knee cast and follow-up for 24 months showed only 4 patients who developed Stage 1 Eichenholtz Charcot foot. Our findings support the use of 3 phase bone scintigraphy with SPECT/CT in the characterization and early diagnosis of CN. Stage 0 Charcot foot has a distinct bone pathology which requires urgent treatment to prevent progression to Stage 1 Eichenholtz Charcot foot. If SPECT/CT is unavailable, CT alone will detect bone fracture in 59% patients.