A modified microsurgical interfacet release and direct distraction technique for management of congenital atlantoaxial dislocation: technical note.

Various techniques have been used for management of congenital atlantoaxial dislocation. Recently, the reduction of atlantoaxial dislocation through a single posterior approach has attracted more and more attention. Here, we present a modified technique including direct interfacet release and distraction between C1 and C2 by a specially designed distractor, posterior internal fixation and bone graft fusion. The illustrated technique was performed in 15 consecutive patients, and the outcomes were recorded and analyzed. Follow-up ranged from 12 to 26 months. Clinical symptoms improved in 14 patients (93.3%) and were stable in 1 patient (6.7%). Radiologically, 60-100% reduction was achieved in 13 patients (86.6%). Bone fusion was obtained in all patients at 12 months after the operation. The two-tailed Wilcoxon signed-rank test was used to analyze the preoperative and postoperative Japanese Orthopedic Association scores (JOA), atlas-dens interval (ADI), and cervicomedullary angle (CMA) (P < 0.001). Our results suggested that this direct interfacet release and distraction technique with a specially designed C1-2 distractor can provide a definite effective C1-2 facet distraction and odontoid process restoration through a single posterior approach.

Interfacet Distraction for Type B-Basilar Invagination Assisted by a Novel Sliding-Traction Head Holder: 2-Dimensional Operative Video.

Type B basilar invagination (BI) refers to odontoid process prolapse into skull base without dislocation, which is often associated with Chiari malformation and syringomyelia.1 Its pathogenesis and treatment are in controversy. Posterior fossa decompression has been introduced to treat the associated Chiari malformation; however, it may not be effective for symptoms with severe ventral nerve compression.2 C1-2 in situ fixation has been reported to treat minor instability in type B BI,3 yet the assessment of minor instability has not been widely accepted. We believe that the pathogenesis is chronic ventral compression of the brainstem. Transoral odontoidectomy is a classic surgical procedure to treat the pathogenesis, but it is associated with high risks of infection, velopharyngeal incompetence, and airway obstruction and often requires posterior surgery for fusion.4 Thus we use an interfacet distraction technique to move the odontoid process down and relieve ventral brainstem compression.5 Therefore interfacet structural support is necessary to maintain the distance of the interfacet. The reason for fixation is that interfacet distraction disrupts atlantoaxial stability. We designed a novel sliding-traction head holder, which can quantitatively tract and stabilize the head without support for the head or face, avoiding the risk of eyeball compression. It adapts to a variety of surgical methods and allows intraoperative changes in the patient's position. Assisted by the device, a satisfied interfacet distraction and a correction of BI were obtained. Video 1 describes how the interfacet distraction technique assisted by a sliding-traction head holder was performed in an illustrative case. The patient consented to the procedure.