The feasibility of microscope-assisted "free-hand" C1 lateral mass screw insertion without fluoroscopy.

STUDY DESIGN: Retrospective study.

OBJECTIVE: To determine if C1 lateral mass screws could be safely inserted without the use of fluoroscopy.

SUMMARY OF BACKGROUND DATA: Standard surgical technique for C1 lateral mass screw placement uses intraoperative fluoroscopy. However, intraoperative fluoroscopy is time consuming, cumbersome, and exposes both the patient and surgical team to radiation.

METHODS: Radiographic analysis and chart review. Surgical technique was analyzed in 3 components: feasibility to complete the screw insertion without intraoperative fluoroscopic guidance; occurrence of any intraoperative, perioperative complications; and radiologic assessment of screw positions on roentgenogram.

RESULTS: Forty-six C1 lateral mass screws were inserted in 24 consecutive patients who underwent posterior cervical fusion. There were 19 female and 5 male. The mean age was 63 +/- 18 years at the time of surgery. All C1 lateral mass screws were inserted unicortically using a microscope-assisted "free-hand" technique. The average intraoperative blood loss in C1-C2 fusion was 123 +/- 50 mL. The mean operative time for each C1-C2 fusion was 133 +/- 30 minutes. Satisfactory positions of C1 screws were noted in intraoperative and postoperative radiograph examinations. There was no mortality or wound infection. There was no cortical breach along the screw path palpated intraoperatively. No vertebral artery injury or cerebral spinal fluid leakage during the screw insertion was observed. However, one patient with a prior posterior cervical operation had a dural tear during the exposure, another had new occipital neuralgia, and a third patient had a symptomatic occipitocervical joint violation by a C1 screw, which was diagnosed only on computed tomography scans. The symptoms resolved after the C1 screws were removed.

CONCLUSIONS: Microscope-assisted "free-hand" C1 lateral mass screws insertion is a feasible and reproducible technique. which offers an alternative method of screw insertion without cumbersome and potentially harmful fluoroscopy.