Study Design. Retrospective cohort study.
Objective. To assess the safety and accuracy of subaxial cervical pedicle screw placement with freehand technique and to report the technical nuances.
Summary of Background Data. Although the efficacy and safety of freehand screw fixation in thoracic and lumbar vertebrae is proven, reports on this technique of screw insertion in the subaxial cervical spine are lacking.
Methods. From March 2012 to September 2013, 45 consecutive patients underwent posterior cervical fusion. The diagnoses were trauma (22 patients), degenerative disease (18 patients), discitis/osteomyelitis (2 patients), pathological fracture (2 patients), and postlaminoplasty kyphosis (1 patient). Preoperative computed tomography (CT) was performed in all patients. We included patients whose outer diameter of the pedicle was greater than 3.0 mm. The standard entry points were modified according to the CT anatomy of each patient. A small pilot hole was fashioned at a predetermined entry point. Then, a 2.5-mm diameter curved pedicle probe was slowly inserted with a medial trajectory into the pedicle. After ball-tip probing and tapping, the screw was inserted. If ball-tip probing was suggestive of risk to neurovascular structures, conversion to a lateral mass screw was performed. Postoperatively, a CT scan was performed in all patients and the conversion rate from pedicle to lateral mass screw was recorded. The breech rate of pedicle screws was also analyzed.
Results. There were 256 planned pedicle screws and 20 incidences (7.8%) of conversion to lateral mass screws. Lateral wall violation was observed in 14 pedicle screws (accuracy rate: 94.1%) on the postoperative CT scan. No medial, superior, and inferior pedicle wall violations were observed. There was no patient who developed symptoms related to vertebral artery stenosis.
Conclusion. Adherence to the surgical tips presented in this article may lead to safe and effective freehand placement of cervical pedicle screws.
Level of Evidence: 3
Although the efficacy and safety of freehand screw fixation in thoracic and lumbar vertebrae is proven, any scientific reports on this technique of screw insertion in the subaxial cervical spine are lacking. Therefore, we provide detailed technical tips for safe insertion of subaxial cervical pedicle screw with freehand technique.
*Department of Neurological Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea; and
†Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Address correspondence and reprint requests to Seung Chul Rhim, MD, PhD, Department of Neurological Surgery, Asan Medical Center, College of Medicine, University of Ulsan, 388-1 Pungnap-2dong, Songpa-gu, Seoul 138-736, Korea; E-mail address: email@example.com
Acknowledgment date: October 23, 2013. Acceptance date: November 8, 2013.
The manuscript submitted does not contain information about medical device(s)/drug(s).
No funds were received in support of this work.
No relevant financial activities outside the submitted work.