RESUMO
STUDY DESIGN: A cross-sectional observational study involved the analysis of computed tomography (CT) scan data from 125 Indian subjects of 18 years or older with normal imaging findings. Scans were obtained from patients with head injuries as a part of the screening process along with brain CT scans. PURPOSE: To establish the dimensions of lateral masses of the atlas vertebrae in normal disease-free Indian individuals. OVERVIEW OF LITERATURE: Lateral mass fixation has become the standard of care in fixation of the supra-axial cervical spine. Many studies have investigated the dimensions of lateral masses in cadaveric specimens; however, studies involving the radiological morphometric analysis of the lateral masses of the atlas vertebra in living patients are lacking. METHODS: Subjects underwent craniovertebral junction CT scans during evaluations of head injury. All had normal radiology reports. The CT scans were obtained using a CT Philips Brilliance 64 machine (Philips, Amsterdam, Netherlands) with a slice thickness of 1 mm and then analyzed using Horos software ver. 2.0.2 (Horos Project, Annapolis, MD, USA) on a MacBook. RESULTS: Lateral masses of the atlas vertebrae were found to be larger in males than females and larger on the right than the left side. The angle of permissible medialization was found to be larger on the right side. The analysis of the average dimensions indicated the conventionally described screw positions to be safe. CONCLUSIONS: The present study provides information that may help to establish standard dimensions of lateral masses of the atlas vertebrae among the normal Indian population. We demonstrate that there is no significant difference when compared with the Western population. The results presented here will be of use to clinicians as they may inform preoperative planning for lateral mass fixation surgeries.
RESUMO
A 70 years old lady presented to us with history of a fall 3 months prior. She had suffered a type 2 odontoid fracture with atlantoaxial dislocation, that was not reducible by traction. She had symptoms of neck pain with inability to hold the neck upright. The patient was subsequently planned for anterior release and reduction of odontoid fracture dislocation with posterior stabilization in the same sitting. The patient was treated with cervical skeletal traction and immobilized. However, she developed occipital sore during the period and was mobilized with brace after which she developed myelopathic symptoms and gait disturbance due to the collapse of fracture segment. The patient was planned for anterior release and fixation with contoured reconstruction plate fixing C1 lateral mass to the lateral mass on the right side and C1 lateral mass to C2 body on the left side primarily with distraction of the C1-C2 joint by autologous tricortical iliac bone graft. The posterior stabilization was planned after healing of the sore, and the patient was counseled for the same. However, the patient was lost on follow-up and returned at 3-month postoperative period with collapse of the graft, resubluxation of C1-C2 segment, and failure of anterior fixation. The standard modality of treatment for such cases includes an anterior release of contracted soft tissues and ligaments and posterior stabilization with fusion in a single setting. However, it is the posterior fixation that stabilizes the fracture and prevents it from redislocation. Anterior fixation as a stand-alone treatment in osteoporotic bone has high risks of failure due to severe posterior tensile stresses. This article describes the importance of posterior fixation in osteoporotic bone based on our experience.
