In 1986 all 90 children aged 4-19 years with Down's syndrome attending school in the area served by the Southern Derbyshire Health Authority underwent radiography to identify atlantoaxial ...

Eight patients had atlanto-axial instability. Six had interlaminar fusion between atlas and axis. No serious complications were seen. Stability was obtained in all patients postoperatively.

This is because people with Down Syndrome are more likely to have atlanto-axial instability - a condition where there is excessive movement or instability between the first two vertebrae of the spine.