Fact-sheet: Neurogenic arthropathy - Charcot
Updated on 04/18/2018 at 8:21 AM
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Definition
Neuropathic osteoarthropathies (NOA): Osteoarthropathies secondary to various conditions affecting the nervous system: Syringomyelia, sequelae of spinal cord or nerve trauma, congenital malformation, neurotropic infection (syphilis, Leprosy), diabetes, alcohol, prolonged corticosteroid use, trauma, tumor, congenital insensitivity to pain.
Diabetes is the most common cause of NOA in Europe, occurring late in 2 to 5% of diabetic patients, often in the setting of poorly controlled diabetes
Diabetic osteoarthropathy is a complication that manifests, at an early stage, as localized inflammation of the foot or ankle secondary to osteolysis of inflammatory
and neuropathic origin. In the absence of offloading, it
leads to severe bone damage, resulting in high morbidity and mortality. Diagnosis relies on rigorous clinical assessment. Additional radiographic examinations lack specificity but allow assessment of the extent and severity of the involvement.
Clinical features
2 types of neurogenic osteoarthropathy:
- Hypertrophic Form: Location: Knee, ankle, and spine
- Atrophic Form: Location: Hip, shoulder, hand, and forefoot
Neuropathic involvement due to diabetes:
- Sensory disturbances: nociceptive hypoesthesia, absence of deep tendon reflexes
- Motor disturbances: imbalance between extensor and flexor muscles leading to progressive toe deformity (claw toes, prominence of metatarsal heads)
- Autonomic disturbances: dry skin, hyperemia, edema.
=> Risk of ulceration (hyperkeratosis followed by plantar perforating ulcer, Osteomyelitis)
=> Alteration of foot loading responsible for Osteoarthritis and fractures due to microtrauma with bone fragmentation (particularly of the navicular) leading to collapse of the plantar arch and widening of the midfoot
Vascular involvement due to diabetes: macroangiopathy, medial arterial calcification
=> tissue hypoxia, poorer antibiotic diffusion, delayed healing
=> intermittent claudication, inconsistently present (underdiagnosed due to associated sensory disturbances), cold foot, pale foot on elevation and cyanotic in dependent position, atrophic foot, thickened nails, hair loss, poorly palpable pulses
Radiography
Examination of choice: see the Sanders and Frykberg and Eichenholtz classifications
CT
Mono- or oligoarticular involvement, often bilateral and asymmetric
– Hypertrophic Form:
• Well-defined subchondral destruction, with subchondral osteosclerosis
• Exuberant proliferative marginal osteophytosis
• Bone fragmentation and epiphyseal fractures, with intra-articular bone fragments and malalignment or even subluxation
• Negative signs: Late joint space narrowing, no demineralization
– Atrophic Form: (the most common in diabetic neuropathic arthropathy)
• Early joint space narrowing
• Progressive osteolysis with well-defined margins of the articular extremities, producing the classic "licked candy stick" appearance in the hands and feet (MCP, phalanges, MTP)
• Bone fragmentation
• Frequent malalignment and dislocation
+ arterial calcifications
+ late fusion of the tarsal bones (sparing the posterior tarsus)
MRI
MRI can help differentiate infectious lesions from neuropathic osteoarthropathy.
Management
The goal of treatment is to limit deformity through cast immobilization and offloading.
There is insufficient scientific evidence to recommend bisphosphonates (local anti-inflammatory effect but no long-term benefit).
Surgery:
- to prevent ulcerations secondary to deformities
- to prevent systemic infectious complications in cases of local infectious complications (amputation)
Orthopedic footwear +++
Classification
Eichenholtz radiologic classification
- 0: no radiologic abnormality
- I: Acute or developmental phase: hypervascular stage: joint laxity, subluxation, osteochondral fragmentation, debris formation
- II: Coalescent (or subacute) stage: resorption of debris, fusion of bone fragments, formation of sclerosis along bone margins
- Reparative (or chronic) stage: resolution of sclerosis, increased fusion of bone segments
Sanders and Frykberg anatomic classification:
Zone 1: proximal and distal interphalangeal and metatarsophalangeal joints
Zone 2: tarsometatarsal joints (Lisfranc joint)
Zone 3: naviculocuneiform, talonavicular, or calcaneocuboid joint
Zone 4: ankle joint, subtalar joint
Zone 5: calcaneus
Differential diagnosis
Destructive arthropathies: a group of conditions characterized by progressive cartilage deterioration of a joint associated with subchondral osteolysis.
Multiple etiologies:
- Conditions initially affecting the cartilage or synovium: inflammatory rheumatism (rheumatoid arthritis, psoriatic arthritis), metabolic arthropathies (chondrocalcinosis), infectious arthritis (tuberculosis), idiopathic destructive arthropathies...
- Conditions initially affecting subchondral bone: neurogenic osteoarthropathies, avascular necrosis, radiation therapy...
- Miscellaneous arthropathies: hemophilia, dialysis patients, pigmented villonodular synovitis...