synostose

Synostose, or synostosis, is the fusion of two or more bones at a joint or along a sutural line, resulting from bone tissue bridging where movement would normally occur. It can be present at birth (congenital) or develop after birth (acquired). When it affects the skull sutures, it is called craniosynostosis; when it involves other bones, it may be referred to as limb, vertebral, or tarsal synostosis, among others.

Common forms include craniosynostosis, which can alter skull growth and shape and may be associated with increased intracranial pressure or neurodevelopmental concerns; radioulnar synostosis, where the radius and ulna fuse and forearm rotation is limited; and foot conditions such as tarsal coalition, where tarsal bones in the foot fuse and can cause pain and reduced mobility. Synostoses may be isolated or part of a genetic syndrome and can occur in various regions such as the spine, ribs, or facial bones. Acquired synostosis can follow trauma, infection, or inflammatory conditions and may involve heterotopic bone formation.

Diagnosis relies on clinical examination and imaging. X-rays are commonly used for initial assessment; CT scans provide detailed information about bone fusion, especially in cranial or complex cases; MRI may be used to evaluate surrounding soft tissues or brain involvement in craniosynostosis.

Treatment is tailored to the site and symptoms. Asymptomatic cases may require observation. Symptomatic craniosynostosis often necessitates surgical correction to allow brain growth and restore skull shape, while limb synostosis may require surgical release or osteotomy to improve function. Physical therapy and pain management can support non-surgical care. Prognosis varies with the degree of fusion, location, and associated conditions; many individuals achieve good function with appropriate management, though some fused joints may lead to ongoing limitations.