Pedicle screw insersion of the C7 vertebra using an anteroposterior fluoroscopic imaging ~10 mm probing technique~

Abstract

Introduction: C7 pedicle screw (C7 PS) insertion is usually performed under lateral fluoroscopy, but the shoulder girdles frequently obstruct a clear image of the pedicles. As a solution to this problem, we performed C7 PS insertion using an anteroposterior fluoroscopic image. The aim of this study was to introduce and evaluate the efficacy of the new C7 PS placement technique.

Methods: From April 2015 to October 2018, 36 PS were inserted using an anteroposterior fluoroscopic image in 21 consecutive cases (A group). When the probe was inserted at a depth of 10 mm from the anatomical entry point, the tip position of the probe was confirmed at the inner edge of the pedicle by anteroposterior fluoroscopy. Before April 2015, 40 PS were inserted under lateral fluoroscopy in 20 cases (L group). We analyzed the rate of screw malposition using postoperative CT, and compared the both groups. Screw deviation of 2 mm or more, grade 2 or higher in the Neo classification, was defined as malposition. Complication associated with the screw malposition was investigated.

Results: There were no differences in demographic factors (age, gender, disease, BMI) between two groups. The rates of malposition were 20% (8 screws) in L group and 2.7% (1 screw) in A group, respectively. This difference was statistically significant (P=0.04). No complications associated with the screw malposition were found in both groups.

Conclusions: Safe and accurate C7 pedicle screw placement was performed by confirming the tip position at 10 mm probing by anteroposterior fluoroscopy.