gms | German Medical Science

Objective: The application of the Magerl technique for transarticular screw fixation of C1/C2 in cases of atlantoaxial instability poses considerable difficulties due to the highly variable anatomy of the upper cervical spine and involved vascular structures. The aim of this study is to evaluate the success rate and the accuracy of screw fixation using intraoperative three-dimensional fluoroscopy-based navigation.

Method: We retrospectively analyzed 21 patients, who underwent a posterior C1-2 transarticular screw fixation using intraoperative three-dimensional fluoroscopy-based navigation. Radiological imaging was carried out in all patients for diagnosis (pre-operative CT) and control after screw placement (3D fluoroscopy, X-ray imaging). The screw position was classified according to Madawi.

Results: The mean patient age was 64.7 years. Atlantoaxial instability was caused by odontoid fracture in 12 patients, rheumatoid arthritis in four, os odontoideum and spondylolisthesis in two patients, respectively and Morbus Bechterew in one patient. Four patients had an additional atlas fracture and four a pseudarthrosis of the odontoid. Two patients underwent prior anterior odontoid screw fixation. 42 transarticular C1/C2 screws and 2 lateral mass screws were placed in 21 patients. The mean operation time was 146,8 minutes. In one patient, one screw had to be repositioned intraoperatively after 3D fluoroscopy had shown misplacement. In two patients one of the transarticular screws did not penetrate C1, due to the given anatomy and subluxation, respectively. The latter two screws did not need to be repositioned as the contralateral one was perfectly aligned, leading to sufficient stability. There were three complications in two patients (9.5%). There were two cases of screw misplacements, both in the same patient: one screw breached the left vertebral artery, and both screw tips did not grip C1, necessating additional placement of lateral mass screws in C1. There was one surgical revision due to impaired wound healing.

Conclusions: With the use of three-dimensional fluoroscopy-based neuronavigation, posterior transarticular screw placement according to the Magerl technique can be carried out with a high degree of accuracy.