Partial or complete absence of the posterior arch of the atlas is a well-documented anomaly but a relatively rare condition. This condition is usually asymptomatic so most are diagnosed incidentally. There have been a few documented cases of congenital defects of the posterior arch of the atlas combined with atlantoaxial subluxation. We report a very rare case of congenital anomaly of the atlas combined with atlantoaxial subluxation, that can be misdiagnosed as posterior arch fracture.
Adult ; Cervical Atlas/*abnormalities ; Diagnosis, Differential ; Female ; Humans ; Spinal Diseases/*diagnosis

Cervical Atlas ; blood supply ; Humans ; Male ; Middle Aged ; Vertebral Artery ; abnormalities

PURPOSE: Since there has been little reporting on the prevalence or morphologic characteristics of ponticulus posticus in Asians, we retrospectively reviewed cervical 3-dimensional CT scan images and plain radiographs which had been ordered by neurosurgeons or orthopaedic surgeons for evaluation of cervical spine problems to investigate the prevalence and morphologic features of the ponticulus posticus in Koreans. PATIENTS AND METHODS: The presence and types of ponticulus posticus were investigated on 200 consecutive cervical 3-D CT scans. RESULTS: Thirty-one patients, 48 ponticulus posticus, complete or partial, bilateral or unilateral, were identified on the 200 cervical 3-D CT scans; therefore, the prevalence was 15.5% in our patient population. In plain radiographs analysis, the prevalence was 6.95%. CONCLUSION: The ponticulus posticus is a relatively common anomaly in Koreans. Therefore, proper identification of this anomaly on preoperative lateral radiographs should alert surgeons to avoid using the ponticulus posticus as a starting point for a lateral mass screw. Because of its size and shape have wide variation, 3-D CT scanning should be considered before lateral mass screw placement into the posterior arch if its presence is suspected or confirmed on radiographs.
Adult ; Aged ; Cervical Atlas/*abnormalities/*radiography ; Female ; Humans ; Imaging, Three-Dimensional ; Korea/epidemiology ; Male ; Middle Aged ; Musculoskeletal Abnormalities/*ethnology/*radiography ; Prejudice ; Prevalence ; Retrospective Studies ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVETo evaluate the feasibility, safety and efficacy of atlas pedicle screws system fixation and fusion for the treatment of upper cervical diseases.

METHODSTwenty-three consecutive patients with upper cervical disorders requiring stabilization, including 19 cases of atlantoaxial dislocation (4 congenital odontoid disconnections, 6 old odontoid fractures, 4 fresh odontoid fractures of Aderson II C, 3 ruptures of the C(1) transverse ligament, and 2 fractures of C(1)), 2 cases of C2 tumor (instability after the resection of the tumors), and 2 giant neurilemomas of C(2)-C(3)(instability after resection of the tumors), were treated by posterior fixation and fusion with the atlas pedicle screw system, in which the screws were inserted through the posterior arch of C1. The operative time, bleeding volume and complications were reported. All patients were immobilized without external fixation or with rigid cervical collars for 1-3 months. All patients were followed up and evaluated with radiographs and CT.

RESULTSIn the 23 patients, 46 C(1) pedicle screws, 42 C(2) pedicle screws and 6 lower cervical lateral mass screws and 2 lower cervical pedicle screws were placed. The mean operative time and bleeding volume was 2.7 hours and 490 ml respectively. No intraoperative complications were directly related to surgical technique. No neurological, vascular or infective complications were encountered. All patients were followed up for 3-36 months (average 15 months). Firm bony fusion was documented in all patients after 3-6 months. One patient with atlas fracture showed anterior occipitocervical fusion. There was no implant failure.

CONCLUSIONSPosterior fixation and fusion of the atlas pedicle screw system is feasible and safe for the treatment of upper cervical diseases, and may be applicable to a larger number of patients.

Adult ; Bone Screws ; Cervical Atlas ; diagnostic imaging ; injuries ; pathology ; surgery ; Feasibility Studies ; Female ; Fracture Fixation, Internal ; instrumentation ; Humans ; Joint Dislocations ; diagnostic imaging ; surgery ; Male ; Middle Aged ; Odontoid Process ; abnormalities ; diagnostic imaging ; pathology ; surgery ; Spinal Fractures ; diagnostic imaging ; surgery ; Spinal Fusion ; instrumentation ; Spinal Neoplasms ; diagnostic imaging ; pathology ; surgery ; Tomography, X-Ray Computed ; Treatment Outcome