SAN FRANCISCO — Seventeen children under the age of 6 who underwent occipital cervical fusion using transarticular screws showed normal growth and alignment of the spine an average of 28 months later, Richard C.E. Anderson, M.D., said at a meeting on pediatric neurologic surgery.
Children with atlantoaxial or occipitocervical instability often need surgery to stabilize the spine, but not much is known about the long-term effects of spinal fusion in children younger than 9 years, whose spines are still growing. Patients in this retrospective study averaged 5 years in age at the time of atlantoaxial (C1-C2) or occipitocervical fusion and have been followed for 13-54 months so far. The study compared plain radiographic and CT images taken immediately after surgery with images from both modalities taken at the most recent follow-up.
All patients fused successfully and maintained straight or lordotic spinal shapes, with most spines staying the same or evolving from straight to a lordotic curvature. One went from lordotic to straight, said Dr. Anderson of Columbia University, New York.
The degree of lordosis in a neutral position increased by 12 degrees, from 15 degrees postoperatively to 27 degrees, a nonsignificant increase that trended toward statistical significance, he said. Of the overall spinal growth, an average of approximately 34% occurred within the fusion construct, suggesting normal growth of the spine.
The follow-up imaging showed no kyphosis, osteophyte formation, or long-term instability. “Some previous papers have commented on an unusually high incidence of unintended fusion to adjacent spinal segments,” but this study found no evidence of this, he said at the meeting, jointly sponsored by the American Association of Neurological Surgeons and the Congress of Neurological Surgeons.
A subset analysis of five patients with longer follow-up—more than 48 months each—found similar results. These patients averaged 4 years in age at the time of surgery and were followed for a mean of 50 months.
The preliminary long-term results suggest that there's no increased risk for spinal deformity in children under age 6 undergoing C1-C2 or occipital-C2 fusion. Longer follow-up is needed until their spines reach maturity, and better CT data would be helpful, Dr. Anderson said.
“Really, we want to know how the spinal canal grows,” among other things, he said.
Lateral plain x-ray immediately after C1-C2 fusion (left). After 4 years and 28% vertical growth, there is no deformity to cervical alignment (right). Photos courtesy Dr. Richard C.E. Anderson