Stabilization of subaxial cervical spines by lateral mass screw fixation with modified Magerl's technique.

BACKGROUND: There are various techniques in lateral mass screw placement in the cervical spine currently available, including the Roy-Camille, Magerl, Anderson, and An techniques. Each has different entrance points and trajectories for screw insertion, and some even have different methods for different level of the subaxial cervical spine. The potential risk of vascular and neurologic injury varies with different techniques and different levels of the cervical spine. We proposed a modified technique with a universal method of screw placement suitable for stabilization of every level of the subaxial cervical spines, from C3 to C7. We have applied this modified technique on a large series of patients and obtained satisfactory results.

METHODS: A retrospective study was conducted of the charts, records, and clinical follow-up of 115 patients who received internal fixation with lateral mass screws and rods in the Department of Neurosurgery of Taipei Veterans General Hospital (Taipei, Taiwan) from 2004 to 2006. All patients received lateral mass screw placement in various levels of the subaxial cervical spines. The clinical and radiologic follow-up were carefully evaluated and analyzed.

RESULTS: All 115 patients with different pathological situations requiring stabilization received instrumentations with polyaxial screws and rod systems, in which 673 screws in total were used in various levels of the cervical spine between C3 and C7: 129 screws in C3, 115 in C4, 193 in C5, 101 in C6, and 135 in C7. The most often used screw length was 16 mm (385/673, 57%). Good bony fusion was observed in all patients except 1 (99.1%). The mean follow-up period was 14 months (4-35 months). No neurologic or vascular injury was noted clinically. Follow-up radiologic examinations found that the screw placements were well positioned.

CONCLUSIONS: Based on our experience, lateral mass fixation of subaxial cervical spines with our modified technique is safe and effective. This technique of lateral mass screw placement yielded good fusion rate with very few complications and can be considered as a good alternative compared to techniques previously reported by other authors. It can eliminate the need of different techniques for different level to be fixed. In the selected cases, skipped level fixation with this technique is also satisfactory.