C1-2 Fusion Through the Anterior Approach for Failed Odontoid Screw Fixation

Introduction Odontoid fractures occur commonly in a bimodal age distribution. In younger patients the injury is associated with high energy trauma; however fractures in the elderly population are associated with low energy trauma such as falls. Above the age of 70 years, fractures of the odontoid peg are the most common cervical spine injury, with the majority being type II by the Anderson and D’Alonzo classification. These fractures can be managed conservatively with halo jacket stabilisation, or operative fixation. Indications for operative management include posterior displacement of fracture fragment, fracture fragment displacement 4mm, age more than 55 years, non-union, and disruption of the transverse atlantal ligament. Since the dens has 55% less trabecular bone than the C2 body, and the trabecular bone is needed for callus formation and bone healing, there is an increased risk of non-union of type II peg fracture compared with type III. This has lead some authors to suggest that conservative management be reserved only for patients unable to tolerate general anaesthesia. Operative fixation can be carried out through the anterior or posterior approach, but there is some controversy regarding the optimal approach. We describe a novel technique whereby failed fixation of an odontoid fracture was salvaged with replacement of the anterior odontoid screw, and C1-2 trans-articular fixation and fusion, all through the anterior approach. Case report A 67-year-old male sustained a low velocity fall from a bicycle, and hit his helmeted head on concrete. The left side of his head struck the floor. He noticed transient weakness and numbness of the right arm and leg. He was initially assessed and discharged from the accident and emergency department with no significant injury. He presented again two days later with continued neck pain. Computed tomographic (CT) imaging of the cervical spine showed features of atlanto-axial osteoarthritis, and a displaced type II odontoid peg fracture (Figure 1). As the displacement was 10mm and the angulation was 19 degrees, surgical management through an anterior approach was decided upon. Fixation was achieved through a right-sided standard anterior approach with an odontoid screw. During the procedure good