Surgical Results of Posterior Arthrodesis in Traumatic Atlantoaxial Instability: Wire Fixation vs Screw Fixation

ABSTRACT

OBJECTIVE: Although posterior wiring techniques have been commonly used with good results in treating the traumatic atlantoaxial instabilities, screw fixation technique has been gaining popularity to secure atlantoaxial arthrodesis in recent years. The purpose of this study is to compare the surgical results of posterior arthrodesis for the traumatic atlantoaxial instability between these two methods. METHODS: Twenty patients underwent 21 procedures over a 6-year period with a mean follow-up of 23 months. The most common condition of traumatic atlantoaxial instability was dens fracture(15 patients) followed by transverse atlantal ligament injury(4 patients), and traumatic os odontoideum(2 patients). Thirteen posterior wiring and eight posterior screw fixations were performed. Among 13 wiring methods, nine Galli fusions, two occipito-cervical fusions, one Brooks fusion, and one C1-C3 fusion were done. RESULTS: No patient developed neurological worsening after surgery. Compared to wire method, all patients of screw group had significant pain reduction when the patients was younger than 50 years old(p=0.01). The postoperative changes in distances of space available for cord(SAC) was not statistically significant between wire and screw methods(p=0.7). The rate of complication(23% in wire vs 25% in screw) was comparable to two methods. Although two screw malposition(25%) among screw fixations were developed, all revealed solid fusion without additional surgeries. The rate of fusion(85% in wire vs 100% in screw) was excellent in screw group. Postoperative loss of reduction, including redisplacement and kyphosis, was present only in wire group(31%). Two(15%) of wire fusions had redisplacement; both of these patients were type 2 dens fracture. Three procedures(23%) of wire fusions resulted in kyphotic change which occurred when delayed surgeries were done between 40 days and 90 days(mean 63 days) after trauma. CONCLUSION: Considering both reduction loss and fusion rate, wire method caused more spinal deformity than screw method(38% vs 0%). This study demonstrates that screw method is a better surgical option for management of traumatic atlantoaxial instability.