Surgical strategies of atlantoaxial dislocation in mucopolysaccharidosis IVa / 中华骨科杂志

ABSTRACT

Objective:To discuss the surgical strategies of atlantoaxial dislocation in children with mucopolysaccharidosis IVA.Methods:8 cases of atlantoaxial dislocation in children with mucopolysaccharidosis IVA treated with posterior atlantoaxial reduction, decompression, bone graft and internal fixation from April, 2019 to October, 2020 were retrospectively analyzed, including 6 males and 2 females, aged 6.2±3.1 years (range, 2-10 years). All the 8 children had lower limb weakness and walking instability, and some of them could not even stand and walk, and all of them had odontoid hypoplasia, atlantoaxial dislocation and systemic skeletal dysplasia. Measures, including American Spinal injury Association (ASIA) grade, modified atlanto-dental interval (mADI) and reduction rate, screw placement type and fusion of bone graft, were recorded and analyzed.Results:The follow-up time was 17.8±7.4 months (range, 8-27 months). The total operation time was 144.0±43.1 mins (range, 90-220 min) and the blood loss during the surgery was 89.1±55.1 ml (range, 15-180 ml). The ASIA grade were 3 cases of "C" level, 4 cases of "D" level and 1 case of "E" level before the operation, and 1 case of "C" level, 1 case of "D" level and 6 cases of "E" level at the latest follow-up. The mADI reduced from 7.38±2.62 mm pre-surgery to 2.50±1.60 mm ( t=5.71, P=0.001). The reduction rate of the latest follow-up mADI was 65.0%±26.3%. 31 pedicle screws were inserted, including 26 Type I screws (83.9%), 4 Type II screws (12.9%) and 1 Type III screw (3.2%), and no injury of spinal cord or blood vessels were observed associated with the Type III screw. One unilateral axial lamina screw was used in 1 case. 5 patients showed fusion (autogenous bone) 6 months after the surgery, 2 patients got fusion (allogeneic bone) 1 year after the surgery, and other patients showed bone graft resorption (allogeneic bone) at the latest follow-up. One patient developed type II respiratory failure on the night of operation and recovered after rescue. Other patients had no complications such as vascular and nerve injury, screw loosening and so on. Conclusion:The majority of children with type IVa mucopolysaccharidosis are accompanied by absence of odontoid process. If such children are complicated with atlantoaxial dislocation and cervical spinal canal stenosis resulting in cervical spinal cord injury, timely surgical intervention should be carried out. Posterior atlantoaxial fusion is a safe and effective surgical method. As children have the characteristics of multi-system involvement, multi-disciplinary cooperation may be needed to ensure perioperative safety.