Irreducible Atlanto-Axial Dislocation in Neglected Odontoid Fracture Treated with Single Stage Anterior Release and Posterior Instrumented Fusion

Abstract

It is a well-know fact that type 2 odontoid fractures frequently go into nonunion. If left untreated, patients may develop irreducible atlantoaxial dislocation (AAD). We describe the surgical management of two patients with neglected odontoid fractures and irreducible AAD treated with single stage anterior release followed by posterior instrumented fusion. Both patients presented with history of neglected trauma and progressive myelopathy. Traction under anesthesia failed to achieve reduction of AAD. Anterior release was done by trans-oral approach in one patient and retrophayngeal approach in the other. Posterior fixation was performed with transarticular screws in both the patients. Both patients had full neurological recovery and demonstrated fusion at follow-up. Anterior release followed by posterior instrumented correction may be an effective alternative to the traditional means of treating irreducible dislocations associated with neglected odontoid fractures.

Keywords: Atlantoaxial dislocation; Atlantoaxial joint; Dislocation; Neglected; Odontoid process.

Fig. 1. (A) Lateral X-ray of cervical spine showing atlantoaxial dislocation with localized kyphosis. (B) Computed tomography (CT) scan showing nonunion of type II dens fracture with atlantoaxial dislocation. and clivus canal angle of 114°. (C) Right sided parasagittal CT scan showing normal C1–2 joint. (D) Left sided parasagittal CT scan showing dislocated and arthritic C1–2 joint.

Fig. 2. (A) Fluoroscopic image after giving traction under anesthesia showing irreducible atlantoaxial dislocation. (B) Blunt instrument used to release C1–2 intra-articular adhesions following opening of joint capsule during anterior release. (C) Immediate postoperative X-ray.

Fig. 3. (A) X-ray at follow-up showing normal C1–2 alignment with C1–2 posterior fusion. (B) Computed tomography scan at follow up showing anatomical alignment of craniovertebral junction with a clivus-canal angle of 145°.

Fig. 4. (A) Lateral X-ray of cervical spine showing atlantoaxial dislocation (AAD). (B) Lateral X-ray following traction in ward showing irreducible AAD. (C) Computed tomography scan showing nonunion type II dens fracture. Some new bone formation is seen at the fracture site, which was probably one of the contributing factors preventing reduction. (D) Anatomical C1–2 alignment following anterior release. (E) A sublaminar wire was passed under C1 posterior arch which was used to give a posteriorly directed force to maintain reduction while trans-articular screws were passed. (F) Postoperative X-ray.