ABSTRACT
This chapter describes Instability at the atlantoaxial level can occur in both the axial or horizontal plane and in the sagittal plane at the atlantoaxial level. At the occipitospinal junction transient instability in the long axis of the spine occurs in distraction injuries in children. Despite the fact that the atlanto-occipital joint usually returns to a stable position with removal of the distraction force, these injuries are often fatal. This condition has a number of aetiological factors. Most involve minor trauma, falls, inflammation or unprotected positioning of the head and neck when the child is under general anaesthetic. Instability in the sagittal plane in Down syndrome is well recognised. The Problems can occur at both the atlanto-occipital level and at the atlantoaxial level. The underlying pathology is one of collagen defects and ligamentous laxity. However, developmental anomalies are not uncommon in Down syndrome. The incidence of instability varies from 9 to 22 percent although symptomatic instability is much less common.
