Percutaneous Translaminar Facet Pedicle Screw Fixation

Published on 10/03/2015 by admin

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Last modified 10/03/2015

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Chapter 31 Percutaneous Translaminar Facet Pedicle Screw Fixation

Chan-Shik Shim, MD, PhD, Jee-Soo Jang, MD, PhD, Sang-Ho Lee, MD, PhD

Percutaneous translaminar facet pedicle screw fixation is a minimally invasive posterior supplementary fixation method to anterior lumbar interbody fusion (ALIF) [1–3]. The screws are inserted percutaneously through stab wounds under fluoroscopic guidance.

Biomechanical studies of ALIF revealed that it does not limit extension and axial rotation of the spinal motion segment [4–6]. However, supplementary translaminar facet fixation has been shown to be an effective method to stabilize extension and axial rotation [7,8]. Translaminar facet screw fixation has also been demonstrated to enhance fusion [9–16].

The percutaneous translaminar facet pedicle screw fixation method described here is a modification of the translaminar facet fixation method first described by Magerl [17], in which the screw is inserted into the pedicle through the facet joints. Transfacet pedicle screw fixation showed biomechanical stability equivalent to that of conventional pedicle screw fixation when it is used to augment to ALIF [18].

Percutaneous translaminar facet pedicle screw fixation gives immediate postoperative spinal stabilization after ALIF and therefore enhances fusion while preserving posterior spinal elements [1,2,15]. The advantages of percutaneous translaminar facet screw fixation are that it is a safe, economical, efficient, and minimally invasive procedure [3].

Procedures

Preoperative Measurement of Laminar Angles

1. The patient is repositioned in prone after the ALIF under the general anesthesia.

2. An axial magnetic resonance image or computed tomography scan is obtained that shows the lamina of the upper vertebral body of the segment to be fused.

3. A lamina angle line extending to the skin is drawn, and the distance from this line to the midline of the body is measured (Fig. 31-1A). The measured distance represents the distance of the skin entry point from the midline. In the operating room, the distance lines are drawn on the patient’s back as two paravertebral vertical lines (Fig. 31-1B).

Figure 31–1 Measurement of laminar angles. (A) On a preoperative computed tomography scan, a lamina angle line is drawn that extends to the skin, and the distance from this line to the midline of the body is measured. The measured distance represents the distance of the skin entry point from the midline. (B) In the operating room, the distance lines are drawn on the patient’s back as two paravertebral vertical lines which are at same distance from the midline.

Intraoperative Measurement of Caudal Angle

1. After ALIF, the patient is placed in the prone position.

2. A bone biopsy needle is placed on the patient’s skin under fluoroscopic guidance so that its trajectory is from the pedicle of the upper vertebra of the motion segment to be fused, passing the cranial one third of the base of the spinous process, to the superolateral quadrant of the opposite pedicle of the lower vertebra. Lines are drawn on the patient’s back that correspond with the needle placement. These are the caudal angle lines of the screw trajectory (Fig. 31-2).

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