Charcot Theories and Pathophysiology: A Narrative Review

Review ARticlelocally, leading to greater osteoclastic activity.7 Osteopenia predisposes the foot to have fracture, dislocation, and collapse of joint with trivial trauma (Fig. 1).8 Neurotraumatic TheoryIt is also known as the German theory.Volkman and Virchow proposed that insensate feet are predisposed to repetitive unrecognized trauma and abnormal loading of joints.Multiple episodes of repetitive trauma and abnormal joint loading lead to joint deterioration (Fig. 2).3,9 The theory is supported by the work done by Armstrong and Lavery, 10,11 where they found that forefoot pressure is significantly higher in patients with CNO as compared to diabetic patients without CNO.They also hypothesized that the forefoot act as a lever due to increased plantar pressure forcing the collapse of the midfoot. IntroductIonCharcot neuropathic osteoarthropathy (CNO), commonly referred to as Charcot's foot, was first described by Sir William Musgrave in 1703, followed by a detailed description by Jean-Martin Charcot as "pied tabatique" in 1883.CNO can be defined as relatively painless, progressive, noninfectious, and degenerative arthropathy involving soft tissues and one or more joints with an underlying neurological deficit. 1 The CNO develops in both diabetes mellitus type 1 (DM-1) and diabetes mellitus type 2 (DM-2), but the risk of development is 3.9 times higher in DM-1. 2 This article will focus on the risk factors which have been attributed to the development of CNO and proposed theories to improve the knowledge for a better understanding of pathophysiology. theorIes o f PathoPhysIology o f charcot Neurovascular TheoryIt is also known as the French theory.It was first proposed by French neurologist Jean-Martin Charcot.He hypothesized that loss of sensation due to neuropathy acted as a barrier to feeling pain and discomfort in patients, which predisposed them to repeated trauma and microfractures.3 Charcot observed that patients with pied tabatique often had nerve damage or arterial disease that led to reduced blood flow and inadequate healing of fractures culminating in joint destruction over a period of time.Charcot patients have been found to have increased blood flow as compared to diabetic patients without Charcot.4 The increased blood flow increases venous pressure enhancing fluid filtration due to capillary leakage.5 The enhanced pressure also leads to increased compartmental pressure and ischemia, compromising the tendons and ligaments and further leading to joint instability.6 Capillary leakage leads to increased delivery of monocyte and osteoclasts 1,