Posterior Atlantoaxial Fusion Using C1 Lateral Mass and C2 Pedicle by Polyaxial Screw in Atlantoaxial Instability

Objective: The aim of this study is to evaluate clinical and radiological outcomes in subjects of atlantoaxial instability which were operated using C1 lateral mass and C2 pedicle screw (Harmes technique). Materials and Methods: Twenty patients with atlantoaxial instability were scheduled at our clinic for atlantoaxial fusion using polyaxial C1 lateral mass and C2 pedicle screw between January 2008 and March 2014. Results: Trauma was the most common cause of atlantoaxial instability, seen in 18 (90%) patients. Modes of trauma were road traffic accident (75%) and falling (15%). Osteoarthritis was observed in 10% of cases. Patients were followed up with radiographs and clinical examinations. Satisfactory screw placement and reduction were achieved in all patients with the average union time of 3.5 months. There were no implant failures, nonunions, vertebral artery injuries or C2 nerve root injuries. Only, surgical site infections occur in 20% of cases that are improved with medical treatment. Conclusions: C1 lateral mass and C2 pedicle polyaxial screw fixation is an effective technique for the fusion of the atlantoaxial complex. It provides the highest fusion rates without any risk of vertebral injury.