Synostosen

Synostosis, plural synostoses or synostosen in Dutch, is a condition in which adjacent bones become fused, eliminating the normal joint between them. In true synostosis the bridge is osseous, though fibrous or cartilaginous tissue may also contribute to a reduced range of motion.

The condition can be congenital or acquired. Congenital synostoses arise during development and may involve the skull (craniosynostosis), the spine, or limb joints. Craniosynostosis often presents with abnormal head shape and may be isolated or part of a syndrome such as Apert, Crouzon, or Pfeiffer. Acquired synostosis can follow trauma, infection, or chronic inflammation, and may involve joints such as the radioulnar or tibiofibular joints, or spinal segments.

Causes and pathogenesis vary by type. Genetic mutations affecting skeletal development underlie many congenital cases, sometimes with syndromic associations. Trauma or inflammation can initiate abnormal ossification and bony bridging between bones.

Diagnosis relies on clinical examination and imaging. X-ray, computed tomography or magnetic resonance imaging can reveal a bony bridge and determine its extent and location. Functional impact ranges from incidental, asymptomatic fusions to significant restriction of movement or pressure effects (as in cranial cases).

Management is individualized. Asymptomatic synostoses may be observed. Symptomatic or function-limiting cases often require surgical intervention to remove the fused segment or restore growth and motion, with prognosis varying by location and underlying cause. Early treatment in craniosynostosis aims to allow brain growth and reduce intracranial pressure.