Orthopedics - Oleksa A.P. 2006

Congenital Spinal Deformities
Vertebral Fusion (Concrescence)

Congenital vertebral synostoses can be complete or incomplete. They result from underdevelopment of the cartilaginous intervertebral discs in any segment of the spine, though most frequently in the cervical region (Fig. 253). It is particularly common for the fourth cervical vertebra to be fused with the adjacent vertebra above or below it.

Complete blockage involves the fusion of both the vertebral bodies and their posterior elements, whereas incomplete fusion—affecting only the vertebral bodies—is more common. On radiographs, the height and Structure OF THE vertebral bodies appear normal, the vertebrae are solidly fused by bone, and the intervertebral disc is either absent or visible only as remnants of a more translucent tissue.

Complete block of the cervical vertebrae essentially forms The basis of Klippel-Feil Syndrome, as discussed separately. Blockage may also result from synostosis between the atlas and the Occipital bone. The fused atlas can shift over the adjacent vertebra and narrow the foramen occipitale magnum and the dens, thereby compressing the Medulla Oblongata or Spinal Cord and producing corresponding clinical manifestations.

Incomplete synostoses of the thoracic vertebrae are extremely rare. Fusion of the vertebral bodies in the D8-10 region results in a typical Kyphosis. In the lumbar vertebrae, synostoses are generally complete, meaning spinal deformity does not develop. However, various patterns of concrescence can occur, where the articular processes fuse on one side, leading to lateral curvature of the spine. This lateral curvature is consequently localized and stable.

Turner G. once described a case of complete fusion of all vertebrae along the spinal Column.