Fact-sheet: Neuropathic osteoarthropathy
Updated on 09/17/2021 at 12:16 PM
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Definition
Neurogenic heterotopic ossification (NHO), also known as neurogenic para-osteoarthropathy (NPOA), corresponds to the development of heterotopic bone in periarticular tissues in patients with severe brain injury. It results from autonomic dysregulation. It is associated with: - Joint anesthesia - Deficit of deep sensation - Periarticular and articular lesions Main etiologies: - Diabetes - Neurologic sequelae of severe head trauma - Syringomyelia - Syphilis
Clinical features
Progressive and often painless course, limitation of joint mobility with stiffness and deformities, cutaneous trophic disorders, local vasculonervous and tendinomuscular complications.
Two clinical forms:
- Atrophic, with predominant destruction
- Hypertrophic, with predominant hyperosteogenesis
Radiography
Depending on the form:
Atrophic:
- Bone demineralization
- Early joint space narrowing
- Frequent malalignment
Hypertrophic:
- Exuberant periarticular bone formation that may be complicated by non union or hypertrophic callus formation
- Joint space preserved for a long time
- Little demineralization
CT
Depending on the form: Atrophic: - Bone demineralization - Early joint space narrowing - Frequent malalignment Hypertrophic: - Exuberant periarticular bone formation that may be complicated by non union or hypertrophic callus formation - Joint space preserved for a long time - Little demineralization Contrast injection may be useful to assess vascular relationships, particularly prior to surgical management.
Management
Very early diagnosis of NPOA, based on increased periarticular uptake on scintigraphy and elevated serum alkaline phosphatase, should prompt passive mobilization and joint positioning.
When stiffness and ankylosis lead to severe functional impairment, the only solution is surgical excision of the NPOA; it seems safer to offer this once the NPOA has matured, after a delay of 12 months from the onset of the first signs.
Radiotherapy and nonsteroidal anti-inflammatory drugs have been proposed in the period immediately following surgery, but their effect remains debated.