Intraoperative technique to define the safe lateral limits of anterior cervical corpectomy - A cadaveric study

Study design: We describe a surgical radiographic technique during anterior cervical corpectomy to define the safe lateral limit of dissection. Objective: To assess the radiographic technique accuracy using computed tomography (CT) measurements on cadaveric specimens. Two clinical cases are presented. Summary of background data: During anterior cervical surgery loss of orientation can lead to eccentric decompression and vertebral artery injury. Methods: A two-level corpectomy on 4 cadaveric samples was filled with radioopaque dye. An "introperative" antero-posterior x-ray was used to measure the narrowest distance from dye column to uncovertebral joints. A CT scan confirmed the distance from corpectomy to vertebral arteries., Results: The distance between the x-ray dye column and uncovertebral joints averaged 2.7 mm (range, 0 to 7 +/- 2.2 mm). A CT scan demonstrated the distance from corpectomy to vertebral artery averaged 4.5 mm (range, 0 to 10 +/- 4.4 mm). The measured distance underestimated the true distance by an average of 1.8 mm (range, 0 to 8 +/- 2.2 mm). Conclusion: An intraoperative radiographic technique can estimate the lateral distance between the corpectomy and vertebral arteries by measuring the distance from the dye column to uncovertebral joints. The dye radiographic technique provides the surgeon an additional margin of safety.