Long-term outcomes after instrumented occipitocervical and atlantoaxial fusion in young children
Craniocervical junction instability in children is a rare problem, and occipitocervical (O-C2) or atlantoaxial (AA) fusions are the commonly accepted treatments. One of the major theoretical risks is differential growth of the fused vertebrae relative to normal spine, possibly leading to narrowing of the spinal canal, problems with sagittal alignment, or relative shortening of spinal segments. Very little information is available regarding the long term outcomes of these fusions in young children, particularly for instrumented spinal fusions performed with rigid screw/rod techniques.
Kennedy et al. (for the Pediatric Craniocervical Society) report the long-term results (mean follow up 56 months) of 40 fusion operations in children under 6 years old. For patients who underwent AA fusion, 30% of the cervical spine growth in the follow up period occurs across the fused levels. In OC fusion patients, about half had substantial growth across the fused segments, while the remaining children had minimal or decreased growth. About 15% of patient developed hyperlordosis, while none developed kyphosis, swan-neck deformity, or adjacent-level fusion.
This study represents the collected experience of 9 institutions over 15 years. Given the scarcity of pediatric CJ instability and O-C2 or AA fusions, this is likely the best evidence for long-term safety in children.