Translaminar Facet Screw Fixation

Introduction Lumbar fusion has proven to be an accepted treatment for a variety of indications. Pedicle screw fixation has historically been the gold standard for providing stabilization to the lumbar motion segment while the fusion matures. However, numerous studies have reported high complication rates, increased pain, and juxtalevel degeneration due to the size of the pedicle screw instrumentation, the necessary wide soft tissue dissection, and exposure of the cephalad facet joint (4,7,10,13,25). These criticisms of pedicle screw fixation have necessitated more minimally invasive techniques and less bulky instrumentation. Facet screw fixation was first described in 1948 by King (23). His technique involved short screws placed horizontally across the facet joint. (Figure 1) The screw enters the inferior articular process just medial to the joint and crosses the joint into the ipsilateral superior articular process. Improvements on this technique were made in 1959 by Boucher (5). His method used the same starting point as King, but the screw is directed more vertical into the base of the pedicle thereby increasing the length of screw in the caudal vertebrae. (Figure 2) Magerl changed the starting point of the screw to the junction of the contralateral spinous process and lamina. This translaminar technique described by Magerl in 1984 maximizes the strength and length of the screw both proximal and distal to the facet joint (26). (Figure 3) This technique involves a midline incision with dissection only out to the facet joints. The transverse processes and cephalad juxtalevel facet joints are not exposed. The screw used is significantly longer than that used by both Boucher and King due to an entry point at the base of the contralateral spinous process. This improves the technique by increasing the effective working length of the screw on both sides of the facet joint resulting in increased strength of the fixation. This review focuses on the advantages of translaminar facet screws as established in both the literature and in our experience. Translaminar facet instrumentation involves minimally invasive techniques without significant soft tissue dissection. Improvements over pedicle screw fixation have been shown in biomechanical stability and stiffness, complication rates, reoperation rates, operative time, blood loss, and patient perceived outcomes. Additionally, current intraoperative surgical image navigation techniques are rapidly improving which have increased the accuracy and decreased the operative time in placement of these screws.