Role of tectorial membrane in the stability of the upper cervical spine.

The purpose of this in vitro experimental study was to determine the role of the tectorial membrane in providing stability to the upper cervical spine. Five fresh human cadaveric specimens from the occiput to C3 were studied with a flexibility protocol: we applied the physiological moments of flexion, extension, right/left axial torques, and right/left lateral bendings (up to 1.5 N m), and recorded the ensuing three-dimensional intervertebral motions. Tests were performed in the intact state and then after transection of the tectorial membrane. This injury resulted in significant increases in flexion (6.7°, 28.4%) and axial rotation (5.9°, 7.8%) of C0C1C2 complex. Flexion increased at both C0C1 and C0C2 joints, while axial rotation increased mainly at C0C1 joint. There were minimal changes in lateral bending (2.3°, 8.0%) and no changes in extension (0.7°, 3.5%).