Methods: A biomechanical study conducted on cadaveric specimens. Objective: The objectives of the study were (1) to determine whether a 3-column injury at the cervicothoracic junction may be stabilized with only posterior instrumentation and (2) to determine optimal cross-link position.

Background: Previous literature has suggested that 3-column cervicothoracic injury requires both anterior and posterior instrumentation to restore spinal stability.

Methods: Multidirectional flexibility analysis was performed under axial rotation, flexion extension, and lateral bending. After intact analysis, C7-T1 was destabilized simulating a 2-column injury and specimens instrumented from C6-T2 with lateral mass (C6) and pedicle (C7-T2) screws using dual diameter rods and retested. C7-T1 was further destabilized to a 3-column injury and specimens retested once again. The addition of a cross-link in either the cervical, thoracic, or combined positions was also analyzed. Range of motion (ROM) at C7-T1 and of the whole construct was recorded using optoelectronic markers and data normalized to intact condition (% intact). Statistical significance criterion was set at P<0.05.

Results: Greater than 75% reduction of intact ROM was achieved after posterior-only instrumentation of a 3-column injury (P<0.05) using modern instrumentation and technique. For a 2-column injury, no significant difference (P>0.05) was found with or without cross-links. ROM at C7-T1 was effectively reduced by 85% or more compared with intact preinjury motion in all planes. A trend toward increased stability at C7-T1 was noted from the application of a thoracic cross-link versus a cervical cross-link.

Conclusions: A 3-column injury at the cervicothoracic junction may be stabilized from a biomechanical standpoint using posterior-only instrumentation. The addition of 2 cross-links further stabilizes the cervicothoracic junction in a 3-column injury. A thoracic cross-link was not significantly different from 2 cross-links. The use of a cross-link in 2-column flexion distraction injuries at the cervicothoracic junction may be unnecessary.