Pathophysiology of Charcot's disease

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733015/

Charcot arthropathy of the foot is a rare but devastating complication of diabetes that remains to be a challenging issue for the foot and ankle surgeons. Charcot foot fails to be an obvious diagnostic option that comes to mind, even in a pathognomonic clinical appearance. The rarity of the disorder, more common pathologies that mimic the condition, and the self-limiting prognosis deviate the clinician from the right diagnosis. The clinical challenges in the diagnosis of Charcot foot require in-depth investigations of its enigmatic nature to establish useful guidelines. Yet, this goal seems to be beyond reach, without a holistic view of the immense literature concerning the pathophysiology of the disorder.

In recent studies, many authors have emphasized the disturbance of the inflammatory cycle in the core of Charcot foot pathophysiology. Usually minor injuries which are even unrecognized, local infection or a minor surgery may prompt this sequence of events. Without the protective behavior ensured by the pain, in the insensate, neuropathic foot of a diabetic patient this cycle is flared up by repeated traumatic events. Genetic variations that affect the balance between pre- and anti-inflammatory chemo-attractants may predispose a patient to Charcot foot . This theory which has been proposed by two different studies conducted in different populations is a breakthrough for researchers who dedicated their work to Charcot foot. Genetic variations can explain a patient's tendency to pro-inflammatory status, and ultimately may put forth a solid answer why a majority of neuropathic patients are spared from Charcot arthropathy.

Finally, it is often difficult to isolate and experiment the contribution of a single factor in this complex and multifactorial phenomenon. This fact precludes the construction of experimental models to reveal single factor contributions or gathering of adequate (appropriate) control groups for blinded control studies. This suggestion can be adapted to Charcot foot that develops as a result of a subsequent dysfunction concerning different systems which cannot be separated and observed solely. This stalemate can be addressed with prospective studies and a larger number of patients.

18F-FDG PET and PET/CT for the diagnosis of diabetic foot osteomyelitis

Early detection of the grade of diabetic foot infections helps in planning and treating the infections and also helps in assessing the prognosis and risk of limb loss. 

X-ray of foot, CT scan or MRI scan are helpful to detect the infections in the depths of the wound and bone involvement. But we would like to know the infection much earlier more accurately. PET scans may of some help in detecting the septic complications in the foot, but we don't know if PET CT is any better than the available methods. Recently as study was done and found that PET is no better than the available methods. The accuracy of 18F-FDG-PET and PET/CT for the diagnosis of diabetic foot osteomyelitis is, at the moment, far from encouraging. However, results should still be perhaps described as only preliminary. Indeed, additional investigation is needed, and future works should include more patients and be more precise in the reference method for the confirmation of osteomyelitis. More caution is also required in patient selection, to avoid those with excessive hyper- or hypoglycaemia. Indeed, such glucose fluctuations may, in theory, affect 18F-FDG tissue uptake, although this remains to be quantified. Further work towards standardisation of technological details and options of interpretation is urgently awaited, as well. In Greece, these modalities are only available on a very restricted basis, emphasising the need for further experience. Moreover, their use should be reasonable and affordable, in harmony with the financial restraints due to the current economic crisis. There is, certainly, still a long way to go, but improved early diagnosis of diabetic foot infections is a goal worth pursuing.