To determine the normal values and usefulness of the C1/4 space
available for spinal cord (SAC) ratio and C1 inclination angle,
which are new radiological parameters for assessing atlantoaxial
instability in children with Down syndrome. We recruited 272 children with Down syndrome (including 14 who
underwent surgical treatment), and 141 children in the control group.
All were aged between two and 11 years. The C1/4 SAC ratio, C1 inclination
angle, atlas-dens interval (ADI), and SAC were measured in those
with Down syndrome, and the C1/4 SAC ratio and C1 inclination angle
were measured in the control group.Aims
Patients and Methods
We report five children who presented at the mean age of 1.5 years (1.1 to 1.9) with a progressive thoracolumbar kyphosis associated with segmental instability and subluxation of the spine at the level above an anteriorly-wedged hypoplastic vertebra at L1 or L2. The spinal deformity appeared to be developmental and not congenital in origin. The anterior wedging of the vertebra may have been secondary to localised segmental instability and subsequent kyphotic deformity. We suggest the term ‘infantile developmental thoracolumbar kyphosis with segmental subluxation of the spine’ to differentiate this type of deformity from congenital displacement of the spine in which the congenital vertebral anomaly does not resolve. Infantile developmental kyphosis with segmental subluxation of the spine, if progressive, may carry the risk of neurological compromise. In all of our patients the kyphotic deformity progressed over a period of three months and all were treated by localised posterior spinal fusion. At a mean follow-up of 6.6 years (5.0 to 9.0), gradual correction of the kyphosis was seen on serial radiographs as well as reconstitution of the hypoplastic wedged vertebra to normality. Exploration of the arthrodesis was necessary at nine months in one patient who developed a pseudarthrosis.
