Charcot Foot Flashcards
(9 cards)
What is Charcot Foot
Acute, rapid destruction of bone and joints as a result of Neuropathic Osteoarthropathy (Nerve damage leading to Bone/Joint Destruction)
What are the two main theories regarding the pathogenosis of Charcot Foot
Neurotraumatic Theroy = Sensory neuropathy prevents patients from feeling trauma allowing joint subluxation and microtraumas to occur unnoticed
Neurovascular Theory = The neurovascular theory was proposed by Charcot in 1868 and it cenetred around Autonomic neuropathy whereby damnaged nerves cannot regulate blood flow so you end up with increased blood flow increased perfucsion of the bones leading to increased osteoclast activity which causes a decrease in Bone Density around the joints.
RANKL RANK OPG signalling pathway is central to the pathogenisis.
What is RANK L significance in the Pathogensis of Charcot
RANK L is a protein that stimulate Osteocalst activity
Elevations in RANK L increase Bone resorption causing Ostoeolysis (Destruction of Bone Tissue)
What challenges are associated with the early diagnosis of Charcot Foot
Normal Radiographic imaging often shows as normal in The Acute Active stage of Charcot although soft tissue swelling may be present, usually of the dorsum of the foot.
X ray cant accuratley show the stage of Charot because theres no active inflamation on the image
MRI however will show the early signs of Charcot in the Acute phase, things like Bone Marrow Edema, soft tissue Odema and Joint Effusion this is even more impotant when we consider jeffocaote 2015 hypothesis that charcot is a condition of the soft tissue as well as bone.
What is the management for Charcot Foot
Acute Active Charcot requires Immediate Immobilisation using a non removable Total Contact Cast or Below Knee Cast.
Research by Game et al 2012 showed a significant reduction in healing times using a non removable device when compared to a removable device.
Gooday 2023 explains the use of non removable devices vary with clinican preference, knowledge, and skill in TCC application stated as the possible reason for this.
Nice NG19 guidelines suggest the Duration of the casting is dependent upon patient response but continuation of casting advised until the Temprature difference between the active and non affected limb is down to 2 degrees and theres no further radiological changes on imaging. With this said Hinchcliffe 2014 argued that a temprature difference of less the 2 degrees could still mean inflamation and it dosent mean that the charcot is in remission furthermore its not saying that the charcot isnt bilateral which in that case would render the temprature difference test useless.
If an ulcer is present then Total Contact Cast might not be the appropriate therapy as we would likely be seeing the patient 2 to 3 times a week to treat the ulcer so the removal and reapplication of a Total Contact Cast wouldnt be pheasible at that frequencey. In this case an Air Cast Walker or a Pneumatic walking brace would be an appropriate alternative and allow for easy visualisation of the ulcer.
Pharmological treatment
Denosumab - Anti RANKL antibodies that inhibt osteoclast activity
Biosophinates - Also inhibit Osteoclast activity but can cause Renal Impariment and Osteonecrosis of the Jaw
Imaging - MRI to asses disease progression and confirm bone oedema, soft tissue swelling and any sub chondral fractures. Until a complete or significant dissaperance of Bone Marrow edema off loading via total contact cast should be continued. Once this Bone odema has gone off loading via orthapedic shoe can be considered
What are the Differential Diagnosis for Charcot Foot
Gout (excluded by notable increase in Serum Uric Acud level)
Deep Veiv Thrombosis (Excluded through Duplex Imaging)
Cellulitus
Osteoarthritis
What are the Signs and Symptomns of Charcot foot
Red hot swollen foot
Unilateral Erythema and Odema
Temperature difference of around 2 Degrees between affected and non affected foot.
What are some MRI features that can be used to differentiate an active Charcot from Ostoemylitis
Johnson et al., 2009 says that the presence of sinus tracts are usually visible on MRI with Osteomylitis whereas they tend not to be in MRI imaging of a person with Charcot without osteomylitis
The pattern of bone marrow edema presents differently with ostemylitis tending to involve a single bone whereas charcot the edema tends to be periarticular (around the joint) and sub chondoral (below cartlidge)
Ghost sign - So in a patient having a T1 MRI with Osteomylitis the infected bones dissapear but they reappear on T2 scan when contrast dye is added because of inflamattion
Whereas with a charcot foot the bones just look destroyed on both scans because the damage is structural not inflmation
Explain both the good and bad elements of XRAY use in Charcot
Gooday 2023 states that Plain radiographic imaging can be useuseful in showing inital deformity and the extent to which immobilisation and offloading has prevented the progression of bony foot deformity. but it can show active inflamttion making it a measure of outcome rather than disease progression
