Charcot’s joint

Published on 02/04/2015 by admin

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134 Charcot’s joint

Instruction

Examine this patient’s joints.

Examine the locomotor system in this patient.

Salient features

History

• History of diabetes (Medicine 1972;51:191–210)

• Gait deformity

• Loss of pain threshold

• Atrophy of muscles of the joint.

Examination

• Enlargement of the affected joint (compare with the other side)

• Instability of the joint, in particular hypermobility of the joint

• May be warm, swollen and tender in the early stages

• Enlargement and crepitus may be present in the later stages

• Collapse of the longitudinal arch resulting in a rocker-bottom deformity.

Proceed as follows:

• Check sensation in the affected limb

• Tell the examiner that you would like to investigate as follows:

• Do a thorough neurological examination, looking for loss of proprioception, and/or pain sensation, and vibratory sensation with a 128 Hz tuning fork

• Examine the urine for sugar (looking for evidence of diabetes mellitus).

• Ask for lancinating pains, check posterior column signs and look for Argyll Robertson pupil (tabes dorsalis)

• Check for dissociated sensory loss (syringomyelia)

• Test muscle strength.

Diagnosis

This patient has Charcot’s joint (lesion) caused by diabetes mellitus (aetiology) and has marked deformity of the joint with restricted movement, probably belonging to Rogers and Bevilacqua class 3C or 3D (functional status) (Fig. 134.1).

Fig. 134.1 Rogers and Bevilacqua classification. Moving towards a more complicated Charcot joint or proximally in the foot increases the risk of extremity amputation.

(Adapted from Rogers, Bevilacqua 2008.)

Remember: The 6Ps of prevention of neuropathic foot: podiatry, pulse examination, protective shoes, pressure reduction, prophylactic surgery, preventive education (J Am Podiatr Med Assoc 1997;87:305–12).

Questions

What do you understand by the term Charcot’s joint?

It is a chronic progressive degenerative arthropathy resulting from a disturbance in the sensory innervation of the affected joint. It is a neuropathic arthropathy that is a complication of various disorders affecting the nervous system. It results in gross deformity, osteoarthrosis and new bone formation from repeated trauma.

Mention a few conditions responsible for the development of Charcot’s joints

• Diabetic neuropathy: affecting tarsal joints, tarsometatarsal, metatarsophalangeal joints

• Tabes dorsalis: affecting knee, hip, ankle, lumbar and lower dorsal vertebrae

• Syringomyelia: affecting shoulder, elbow, cervical vertebra

• Myelomeningocoele: affecting ankle, tarsus

• Miscellaneous: hereditary sensory neuropathies, peripheral nerve injury, congenital insensitivity to pain, leprosy, paraplegia (hips).

What is the advantage of measuring skin temperature in Charcot’s foot?

Skin temperature difference between feet, measured with a contact or non-contact thermometer, may be significant. The average difference between the acute Charcot’s foot and the unaffected side is as much as 9°F (5°C). A difference of 4°F (2°C) is considered significant.

How is Charcot’s foot classified?

The Rogers and Bevilacqua classification (Fig. 134.1) combines the features of the clinical examination, radiography (Fig. 134.2) and anatomy. The graph indicates increasing risk for amputation as the Charcot foot becomes ‘more complicated’.

Fig. 134.2 Lateral radiograph showing equinus, tarsometatarsal subluxation and a prominent cuboid plantarly in Charcot foot.

(With permission from Rogers, Bevilacqua 2008.)

What is the pathogenesis of acute Charcot’s foot in diabetics?

It has been suggested that an initial insult triggers an inflammatory cascade through increased expression of proinflammatory cytokines (including tumour necrosis factor-α and interleukin 1β). This cascade results in increased expression of the nuclear transcription factor, NF-κB, which results in increased osteoclastogenesis. Osteoclasts cause progressive bone lysis, leading to further fracture; this, in turn, potentiates the inflammatory process (Lancet 2005; 366:2058–61).

What are the key components of gait?

Gait is classically broken into four components (heel strike, midstance, heel rise and toe push-off; see Fig. 61.1).

Jean Martin Charcot (1825–1893) was a French neurologist. He was a Professor of Pathology in 1872 and Professor of Nervous Diseases in 1882. Other conditions that bear his name include Charcot’s fever (intermittent fever from cholangitis), Charcot’s triad (intention tremor, nystagmus and scanning speech in multiple sclerosis), Charcot–Leyden crystals (seen in the sputum of asthmatics), Charcot–Marie–Tooth disease (peroneal muscular atrophy) and Charcot-Wilbrand syndrome (visual agnosia). Charcot acknowledged that the neuropathic arthropathy had been first reported by the American physician John Kearsley Mitchell (1798–1858) in 1831. Mitchell’s cases were secondary to spinaldamage caused by TB, whereas Charcot’s were the result of tertiary syphilis.

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