Musculoskeletal ImagingFusion
the joining or consolidation of separate parts into a single structure. Various types of fusion occur, including developmental (
symphalangism,
coalition, acquired (
ankylosis,
synostosis), and surgical (
arthrodesis;
posterior lumbar interbody fusion). Normal fusions include closure of the growth plate and cranial sutures.
In symphalangism, one phalanx is fused with another within the same digit. Intra-articular bone fusions are also seen in persons with juvenile chronic arthritis, ankylosing spondylitis, Reiters syndrome, psoriatic arthritis, septic arthritis, rheumatoid arthritis, myositis ossificans and inflammatory osteoarthritis.
Congenital fusions of the hands and feet (carpal coalition; tarsal coalition) may occur alone or as part of a malformation syndrome. Tarsal coalition may also be acquired (after infection, surgery, joint disorders, or trauma). Fusion may also occur between the proximal ends of the radius and ulna (radioulnar synostosis) and between adjacent ribs, especially the first and second.
Klippel Feil syndrome is characterized by congenital fusion of two or more cervical vertebrae. In addition, congenital synostosis of vertebral bodies (block vertebrae) may involve portions of the thoracic or lumbar spine. Apophyseal joint fusions accompanied by reactive subchondral bone formation are prominent in ankylosing spondylitis.
Operative fusions include spinal arthrodesis with or without instrumentation, using the anterior or posterior interbody approach, and fusions of the hip, ankle and wrist.
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