Unilateral lag-screw technique for an isolated anterior 1/4 atlas fracture

Abstract

Study design: Fractures of the atlas are classified based on the fracture location and associated ligamentous injury. Among patients with atlas fractures treated using external immobilization, nonunion of the fracture could be seen.

Objective: Ideally, treatment strategy for an unstable atlas fracture would involve limited fixation to maintain the fracture fragments in a reduced position without restricting the range of motion (ROM) of the atlantoaxial and atlantooccipital joints.

Summary of background data: Such a result can be established using either transoral limited internal fixation or limited posterior lateral mass fixation. However, due to high infection risk and technical difficulty, posterior approaches are preferred but none of these techniques can fully address anterior 1/4 atlas fractures such as in this case.

Materials and methods: A novel open and direct technique in which a unilateral lag screw was placed to reduce and stabilize a progressively widening isolated right-sided anterior 1/4 single fracture of C1 that was initially treated with a rigid cervical collar is described.

Results: Radiological studies made after the surgery showed no implant failure, good cervical alignment, and good reduction with fusion of C1.

Conclusions: It is suggested that isolated C1 fractures can be surgically reduced and immobilized using a lateral compression screw to allow union and maintain both C1-0 and C1-2 motions, and in our knowledge this is the first description of the use of a lag screw to achieve reduction of distracted anterior 1/4 fracture fragments of the C1 from a posterior approach. This technique has the potential to become a valuable adjunct to the surgeon's armamentarium, in our opinion, only for fractures with distracted or comminuted fragments whose alignment would not be expected to significantly change with classical lateral mass screw reduction.

Keywords: Atlas; fracture; lag screw; nonfusion; screw; unilateral.

Figure 1

(a and b) Axial view of computed tomographic scan through the atlas demonstrating a right anterior 1/4 isolated fracture with mild distraction (the fracture line goes through the right anterior part of lateral mass)

Figure 2

(a-c) Axial view of noncontrast computed tomographic scan taken in the early postoperative period showing C1 reduction with the lag screw crossing the fracture line

Figure 3

(a and b) The postoperative lateral and open-mouth radiographs at the late follow-up, revealing no implant failure, good cervical alignment, and good reduction with well-positioned screw placement in the C1

Figure 4

(a-c) Axial view of computed tomographic scan obtained in the late follow-up period up through the atlas demonstrating good bony fusion and good reduction with well-positioned screw placement in the right anterior 1/2 single fracture line that also goes through the right anterior part of lateral mass

Figure 5

3-dimensional reformatted CT images of the late follow-up images in the axial, sagittal, and coronal planes from thin-section CT scan, demonstrating good reduction with well-positioned screw placement through the right anterior 1/2 single fracture line