A Systematic Review of Surgical Intervention versus Conservative Management in Treatment of Type II Odontoid Fracture in the Elderly

Abstract

he atlas, and axis are part of the craniovertebral junction (CVJ), which is a complex area that houses vital neural and vascular structures while achieving the most mobility of any segment within the spine1. It represents the transition between the brain and cervical spine. The majority of the spine’s rotation, flexion, and extension occur between the occiput, the atlas, and axis2. The atlas lacks a vertebral body and instead articulates with the odontoid process or dens. The atlas also communicates inferiorly with the axis by flat, wide articular facets. The odontoid process and horizontal facets permit rotation of the skull, the predominate motion of the C1–2 vertebral junction 1. Largely C1-C2 segment depends on the ligamentous supports and the integrity of the odontoid for its stability. Fusion of the C1-C2 complex may be required in cases of atlantoaxial instability. Its extreme mobility places heavy demand on the atlantoaxial fixation construct for sufficient rigidity required for its fusion3. The odontoid process (dens, processus epitrophysis) (Fig. 1) of the axis (C2 or vertebra dentata) is the anchoring pivot of the craniovertebral junction (CVJ) and as such unique to the mammalian spinal column 4. It projects superiorly from the C2 vertebral body with a diarthrodial articulation on its ventral surface interfacing with the dorsal concavity within the anterior arch of the atlas. The anatomy of the odontoid process of the axis has many variations that stem from congenital variants or acquired forms, which lead to mild or severe instability of the atlanto-axial joint causing potential defects on the medulla or upper cervical cord with resultant neurological symptoms. A clear understanding of the embryologic and phenotypical variations of the odontoid process is the foundation for enlightened clinical decision-making in the assessment and management of the many disorders associated with the cranio-cervical junction that affect all stages of life.