Comparison of the maximum possible lengths of insertable screws in the Subaxial Cervical Spine.

Abstract

BACKGROUND\nLateral mass screws are the most commonly used fixation technique in the Subaxial Cervical Spine (SCS), their main advantages being that they are easy to insert and safe in their application. Pedicle screws are significantly longer, are quite challenging to insert in most settings and are accompanied by the risk of serious complications such as vascular and neural injuries. We have therefore developed a new technique, which permits safe insertion of long screws in the SCS.\n\n\nMETHODS\nA radiological evaluation was carried out to determine the maximum possible insertable screw length in the SCS when using the following techniques: pedicle, lateral mass (Magerl s) and Attallah screws. Scans of 66 cervical spines were analysed to determine the maximum possible screw lengths of all three screw insertion techniques, based on the standard description through the vertebrae from C3 to C7.\n\n\nRESULTS\nThe maximum possible length of the Attallah screw of 20.7 ± 2.5mm (mean value ± SD) is only 2.4mm shorter than the pedicle screw (23.1 ± 1.8mm) along the SCS. The lateral mass screw is with 10.2 ± 1.3mm full 12.9mm shorter than the pedicle screw.\n\n\nCONCLUSIONS\nThe maximum possible length of the Attallah screw is close to that of the pedicle screw and significantly greater than that of the lateral mass screw. We provide a fixation method comparable to the pedicle screw in its strength and to the lateral mass screw in its safety.