Revision surgery of irreducible atlantoaxial dislocation: a retrospective study of 16 cases

Abstract

There is lack data concerning anterior cervical spine revision surgeries; even more data are missing concerning posterior cervical revision surgeries, to determine the feasibility, safety, and clinical efficacy of revision surgery for irreducible atlantoaxial dislocation (RS-IAAD). Patients with IAAD-FS underwent one-stage transoral release and posterior reduction. Their medical history was documented in detail. The JOA score system was used to evaluate each patient's neurological status pre and postoperatively, and serial MRI and radiographs were used to determine the status of the reduction and the autografts. 16 patients (average age, 36 years old) underwent successful surgery. There was no intraoperative or postoperative neurological deficit except in two cases that suffered transient neurological deficit that alleviated after conservative treatment. Solid bony union was seen at the end of 3 months after surgery in all patients. The mean follow-up period was 28.8 months (range 18-66 months). No pseudarthrosis was noted. Anterior transoral release and posterior instrumented fusion remain significant surgeries with the potential for serious complications, but in the current series there were no major complications.

Fig. 1

Surgical illustration. a Irreducible atlantoaxial dislocation:contracted scar tissue, bony graft and instruments in front and rear of C1/2 vertebral, respectively. b Anterior surgical procedure: resection of contracted scar, a 10 mm width bone elevator was placed into C1/2 facet joint to distract the facet joint space of over 3 mm; c Posterior removal of wires, bony graft and C1 posterior arch as well as posterior edge of foramen magnum; C1/2 pedicle screws instrumentation is performed. d Step by step screw tightening cautiously under fluoroscopy and SEP monitor results in C1/2 reduction; Auto-bone graft was performed afterwards

Fig. 2

Case 10, male,17-year-old, diagnosed of congenital atlanto-occipital malformation combined with basilar invagination and C1/2 dislocation. Two years after C1/2 laminectomy and enlargement of foramen magnum, severe C1/2 dislocation was noted with C2 vertebral body and odontoid process into cranial of 25 mm. A revision surgery was performed. a Flexion–extension lateral radiograph prior to revision surgery showed congenital atlanto-occipital malformation, basilar invagination, C1/2 dislocation and swan-neck deformity, C1/2 reduction was not available dynamically. b CT sagittal scan prior to revision surgery showed evidenced of C1/2 laminectomy and enlargement of foramen magnum, no bony graft and instrumentation were evidenced. c MRI sagittal T2-weight showed odontoid process into cranial and compression to the ventral medullary with CMA decreasing to 76°. d One month after revision surgery, lateral X-ray showed reduction of C1, odontoid process out of foramen magnum and correction of deformity. e, f CT sagittal scan and MRI sagittal T2-weight at 1 month after revision surgery. g Twelve months’ follow-up, lateral X-ray showed no instrument failure, no loss of reduction, evidence of bony fusion at craniocervical region and secondary C2/3 disc degeneration. h–i 50 months’ follow-up, lateral X-ray and CT sagittal scan showed bony union and no loss of reduction

Fig. 3

Case 5, 43-year-old male, diagnosed of congenital atlanto-occipital malformation complicated with C1/2 dislocation, 1 year after atlanto-occipital fusion and pedicle screw instrumentation, instrument failure and C1 dislocation developed. A revision surgery was performed. a Internal instrument failure, bony graft absorbance and irreducible C1/2 dislocation is evidenced. b One month after revision surgery, lateral X-ray showed reduction of C1/2 and no signs of instrument failure. c CT sagittal scan at one month showed ADI of 2 mm, canal diameter at C1/2 of 22 mm. d Lateral X-ray of 24 months showed bony fusion, no loose of C1/2 reduction with ADI of 2 mm and no signs of instrument failure