[Atlanto-axial instability in children with trisomy 21: atlanto-axial (C1-C2) or occipito-axial (O-C2) arthrodesis?].

A retrospective study involving seven cases of operated atlantoaxial (C1-C2) instability in patients with Down Syndrome prompted the authors to raise the following question: which kind of arthrodesis is to be performed for these patients? The possibility of an occipito-atlantal (O-C1) instability, is in fact relatively frequent in this condition, as the authors have observed themselves and in a literature survey; this is an argument for performing an occipito-axial (O-C2) arthrodesis. The difficulties met to reduce the C1-C2 luxation, the frequent pseudarthroses (3 cases in our series) and a tetraplegia following a re-operation for non-union are as many other arguments to perform a O-C2 arthrodesis rather than a C1-C2 arthrodesis.