Anterior and posterior approach surgical treatment for irreducible atlantoaxial dislocation associated with odontoid malunion

English Keywords:Atlantoaxial dislocation  Transoral release  Limited odontoidectomy  Pedicle screws  Reduction

English Abstract:

  【Abstract】 Objectives： To explore the clinical efficacy of transoral release, limited odontoidectomy and posterior pedicle screw instrumentation for irreducible atlantoaxial dislocation associated with odontoid malunion. Methods： From January 2008 to January 2011, 7 cases suffering from irreducible atlantoaxial dislocation due to odontoid malunion underwent surgery in our hospital. There were 5 males and 2 females, with an average age of 36.4 years. The preoperative JOA score was 7.3±2.1（range, 5-9）, and the preoperative space available for the cord (SAC) was 8.34±3.68mm(range, 4-12mm). All cases underwent one stage transoral release, limited odontoidectomy and posterior pedicle screw instrumentation. The clinical outcome was reviewed and the degree of reduction and bone fusion were assessed by X-ray, CT scan, three-dimensional CT reconstruction and MRI． Results: The average operative time was 310min(range, 280-360min), and the average blood loss was 670ml(range, 510-930ml). No spinal cord injury was noted. One case was complicated with vertebral artery injury when implanting C2 pedicle screw, but no symptoms was noted during follow-up. One case was complicated with rupture of C2 inferior wall when implanting C2 pedicle screw, but no instrument failure was noted during follow-up. All cases got complete atlantoaxial reduction, and all cases were followed up for an average of 19.6 months(range, 9-36 months), and got bony fusion 6 months later. No instrument failure or recurrence of dislocation was noted. At final follow-up, the JOA score was 13.1±2.1(range, 11-15), which showed significant difference compared with preoperative one(P<0.05), with an average improve rate of 87.4%(range, 78.8%-93.5%). At final follow-up, the SAC was 14.78±2.15mm(range, 11-18mm)，which showed significant difference compared with preoperative one(P<0.05). Conclusions: For irreducible atlantoaxial dislocation due to odontoid malunion, transoral release, limited odontoidectomy and posterior pedicle screw instrumentation is reliable for short-term outcome.