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Neuropathic joint disease
Specialty	Rheumatology

Neuropathic arthropathy (also known as Charcot neuroarthropathy, neuropathic arthropathy, or diabetic arthropathy) refers to a progressive fragmentation of bones and joints in the presence of neuropathy. It can occur in any joint where denervation is present, although it most frequently presents in the foot and ankle. It follows an episodic pattern of early inflammation followed by periarticular destruction, bony coalescence, and finally bony remodeling.  This can lead to considerable deformity and morbidity, including limb instability, ulceration, infection, and amputation.

The diagnosis of Charcot neuroarthropathy is made clinically and should be considered whenever a patient presents with warmth and swelling around a joint in the presence of neuropathy. Although counterintuitive, pain is present in many cases despite the neuropathy. Some sort of trauma or microtrauma is thought to initiate the cycle but often patients will not remember because of numbness. Misdiagnosis is common.

Symptoms and signs

The clinical presentation varies depending on the stage of the disease from mild swelling to severe swelling and moderate deformity. Inflammation, erythema, pain and increased skin temperature (3–7 degrees Celsius) around the joint may be noticeable on examination. X-rays may reveal bone resorption and degenerative changes in the joint. These findings in the presence of intact skin and loss of protective sensation are pathognomonic of acute Charcot arthropathy.

Roughly 75% of patients experience pain, but it is less than what would be expected based on the severity of the clinical and radiographic findings.

Pathogenesis

Any condition resulting in decreased peripheral sensation, proprioception, and fine motor control:

• Diabetes mellitus neuropathy (the most common in the U.S. today, resulting in destruction of foot and ankle joints), with Charcot joints in 1/600–700 diabetics; related to long-term high blood glucose levels.
• Alcoholic neuropathy
• Cerebral palsy
• Leprosy
• Syphilis (tabes dorsalis), caused by the organism Treponema pallidum
• Spinal cord injury
• Myelomeningocele
• Syringomyelia
• Intra-articular steroid injections
• Congenital insensitivity to pain
• Peroneal muscular atrophy

Underlying mechanisms

Two primary theories have been advanced:

• Neurotrauma: Loss of peripheral sensation and proprioception leads to repetitive microtrauma to the joint in question; this damage goes unnoticed by the neuropathic patient, and the resultant inflammatory resorption of traumatized bone renders that region weak and susceptible to further trauma. In addition, poor fine motor control generates unnatural pressure on certain joints, leading to additional microtrauma.
• Neurovascular: Neuropathic patients have dysregulated autonomic nervous system reflexes, and de-sensitized joints receive significantly greater blood flow. The resulting hyperemia leads to increased osteoclastic resorption of bone, and this, in concert with mechanical stress, leads to bony destruction.

In reality, both of these mechanisms probably play a role in the development of a Charcot joint.

Joint involvement

Diabetes is the foremost cause in America today for neuropathic joint disease, and the foot is the most affected region. In those with foot deformity, approximately 60% are in the tarsometatarsal joints (medial joints affected more than lateral), 30% metatarsophalangeal joints, and 10% have ankle disease. Over half of diabetic patients with neuropathic joints can recall some kind of precipitating trauma, usually minor.

Patients with neurosyphilis tend to have knee involvement, and patients with syringomyelia of the spinal cord may demonstrate shoulder deformity.

Hip joint destruction is also seen in neuropathic patients.

Diagnosis

Clinical findings

Clinical findings include erythema, edema and increased temperature in the affected joint. In neuropathic foot joints, plantar ulcers may be present. It is often difficult to differentiate osteomyelitis from a Charcot joint, as they may have similar tagged WBC scan and MRI features (joint destruction, dislocation, edema). Definitive diagnosis may require bone or synovial biopsy.

Radiologic findings

First, it is important to recognize that two types of abnormality may be detected. One is termed atrophic, in which there is osteolysis of the distal metatarsals in the forefoot. The more common form of destruction is hypertrophic joint disease, characterized by acute peri-articular fracture and joint dislocation. According to Yochum and Rowe, the "6 D's" of hypertrophy are:

1. Distended joint
2. Density increase
3. Debris production
4. Dislocation
5. Disorganization
6. Destruction

The natural history of the joint destruction process has a classification scheme of its own, offered by Eichenholtz decades ago:

Stage 0: Clinically, there is joint edema, but radiographs are negative. A bone scan may be positive before a radiograph is, making it a sensitive but not very specific modality.

Stage 1: Osseous fragmentation with joint dislocation seen on radiograph ("acute Charcot").

Stage 2: Decreased local edema, with coalescence of fragments and absorption of fine bone debris.

Stage 3: No local edema, with consolidation and remodeling (albeit deformed) of fracture fragments. The foot is now stable.

Atrophic features:

1. "Licked candy stick" appearance, commonly seen at the distal aspect of the metatarsals
2. Diabetic osteolysis
3. Bone resorption

Treatment

Diabetic foot ulcers should be treated via the VIPs—vascular management, infection management and prevention, and pressure relief. Aggressively pursuing these three strategies will progress the healing trajectory of the wound. Pressure relief (offloading) and immobilization at the acute (active) stage are critical to helping ward off further joint destruction in cases of Charcot foot. Total contact casting (TCC) is recommended, but other methods are also available. TCC involves encasing the patient's complete foot, including toes, and the lower leg in a specialist cast that redistributes weight and pressure in the lower leg and foot during everyday movements. This redistributes pressure from the foot into the leg, which is more able to bear weight, to protect the wound, letting it regenerate tissue and heal. TCC also keeps the ankle from rotating during walking, which prevents shearing and twisting forces that can further damage the wound. TCC aids maintenance of quality of life by helping patients to remain mobile.

There are two scenarios in which the use of TCC is appropriate for managing neuropathic arthropathy (Charcot foot), according to the American Orthopaedic Foot and Ankle Society. First, during the initial treatment, when the breakdown is occurring, and the foot is exhibiting edema and erythema; the patient should not bear weight on the foot, and TCC can be used to control and support the foot. Second, when the foot has become deformed and ulceration has occurred; TCC can be used to stabilize and support the foot, and to help move the wound toward healing.

Walking braces controlled by pneumatics are also used. In these patients, surgical correction of a joint is rarely successful in the long term. However, offloading alone does not translate to optimal outcomes without appropriate management of vascular disease and/or infection. Duration and aggressiveness of offloading (non-weight-bearing vs. weight-bearing, non-removable vs. removable device) should be guided by clinical assessment of healing of neuropathic arthropathy based on edema, erythema, and skin temperature changes. It can take six to nine months for the edema and erythema of the affected joint to recede.

Outcome

Outcomes vary depending on the location of the disease, the degree of damage to the joint, and whether surgical repair was necessary. Average healing times vary from 55 to 97 days, depending on location. Up to one to two years may be required for complete healing.

There is a 30% five year mortality rate independent of all other risk factors.

Further reading

• Neuropathic osteoarthropathy by Monica Bhargava, M.D., University of Washington Department of Radiology
• John R. Crockarell; Daugherty, Kay; Jones, Linda Winstead; Frederick M. Azar; Beaty, James H; James H. Calandruccio; Peter G. Carnesale; Kevin B. Cleveland; Andrew H. Crenshaw (2003). Campbell's Operative Orthopedics (10th ed.). Saint Louis, MO: C.V. Mosby. ISBN 0-323-01248-5.
• Gupta R (November 1993). "A short history of neuropathic arthropathy". Clinical Orthopaedics and Related Research (296): 43–9. PMID 8222448.

References

1. ^ Wukich, Dane K.; Sung, Wenjay (November 2009). "Charcot arthropathy of the foot and ankle: modern concepts and management review". Journal of Diabetes and Its Complications. 23 (6): 409–426. doi:10.1016/j.jdiacomp.2008.09.004. PMID 18930414.
2. Sommer, Todd C; Lee, Thomas H (November 2001). "Charcot foot: the diagnostic dilemma". American Family Physician. 64 (9): 1591–1598. PMID 11730314. ProQuest 234285444.
3. S., Rajbhandari; R., Jenkins; C., Davies; S., Tesfaye (1 August 2002). "Charcot neuroarthropathy in diabetes mellitus". Diabetologia. 45 (8): 1085–1096. doi:10.1007/s00125-002-0885-7. PMID 12189438.
4. Charcot Arthropathy at eMedicine
5. Hirsch, M.; San Martin, M.; Krause, D. (March 2021). "Neuropathic osteoarthropathy of the shoulder secondary to syringomyelia". Diagnostic and Interventional Imaging. 102 (3): 193–194. doi:10.1016/j.diii.2020.09.010. PMID 33092999.
6. ^ Snyder, Robert J.; Frykberg, Robert G.; Rogers, Lee C.; Applewhite, Andrew J.; Bell, Desmond; Bohn, Gregory; Fife, Caroline E.; Jensen, Jeffrey; Wilcox, James (November 2014). "The Management of Diabetic Foot Ulcers Through Optimal Off-Loading". Journal of the American Podiatric Medical Association. 104 (6): 555–567. doi:10.7547/8750-7315-104.6.555. PMID 25514266.
7. Raspovic, Anita; Landorf, Karl B (January 2014). "A survey of offloading practices for diabetes-related plantar neuropathic foot ulcers". Journal of Foot and Ankle Research. 7 (1): 35. doi:10.1186/s13047-014-0035-8. PMC 4332025. PMID 25694793.
8. Farid, K; Farid, M; Andrews, CM (June 2008). "Total contact casting as part of an adaptive care approach: a case study". Ostomy/Wound Management. 54 (6): 50–65. PMID 18579926.
9. AOFAS. Foot ulcers and the total contact cast. Accessed 29.07.2015 at: https://www.aofas.org/footcaremd/conditions/diabetic-foot/Pages/Foot-Ulcers-and-the-Total-Contact-Cast.aspx
10. Rogers, Lee C.; Frykberg, Robert G.; Armstrong, David G.; Boulton, Andrew J.M.; Edmonds, Michael; Van, Georges Ha; Hartemann, Agnes; Game, Frances; Jeffcoate, William; Jirkovska, Alexandra; Jude, Edward; Morbach, Stephan; Morrison, William B.; Pinzur, Michael; Pitocco, Dario; Sanders, Lee; Wukich, Dane K.; Uccioli, Luigi (September 2011). "The Charcot Foot in Diabetes". Diabetes Care. 34 (9): 2123–2129. doi:10.2337/dc11-0844. PMC 3161273. PMID 21868781.
11. Armstrong, David G.; Swerdlow, Mark A.; Armstrong, Alexandria A.; Conte, Michael S.; Padula, William V.; Bus, Sicco A. (January 2020). "Five year mortality and direct costs of care for people with diabetic foot complications are comparable to cancer". Journal of Foot and Ankle Research. 13 (1): 16. doi:10.1186/s13047-020-00383-2. PMC 7092527. PMID 32209136.

External links

• Rheumatology
• Inflammatory polyarthropathies