Chapter 31 Percutaneous Translaminar Facet Pedicle Screw Fixation

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].

Indications and contraindications

Box 31.1 lists the indications for and contraindications to percutaneous translaminar facet screw fixation.

BOX 31.1 Indications for and Contraindications to Percutaneous Translaminar Facet Pedicle Screw Fixation

Indications

Degenerative disc disease

Degenerative lumbar instability

Grade I degenerative spondylolisthesis

Degenerative flat back deformity

Contraindications

Spondylolytic spondylolisthesis

Severe osteoporosis

Severe kyphoscoliosis

Instrumentation

The following instruments are needed for percutaneous translaminar facet screw fixation:

Bone biopsy needle

Kirschner wire

Electrical drill

Cannulated screws

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).

Figure 31–2 Intraoperative measurement of the caudal angle. A bone biopsy needle is placed on the patient’s skin (A and C) 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 (B and D).

Insertion of the Translaminar Facet Screw

1. The point of skin entry is at the intersection of the caudal angle line with the paravertebral line representing the distance from the midline of the spine (Fig. 31-3A).

2. A bone biopsy needle is inserted into the skin through a stab wound at the entry point after skin infiltration of 5 mL of 1% lidocaine and intravenous injection of 30 mg of ketolorac. The needle is introduced along the laminar angle and caudal angle until the tip of the needle is anchored at the cranial one third of the base of the spinous process (Fig. 31-3B).

3. The needle is then withdrawn, and a Kirschner wire is inserted. With an electrically powered drill, the wire is drilled toward the superolateral quadrant of the opposite pedicle of the lower vertebra, through the lamina and facet joint, under fluoroscopic guidance (Fig. 31-4A). The same procedure is performed on the other side (Fig. 31-4B).

4. Cannulated lag screws, 46 or 50 mm long, are inserted along the Kirschner wires until the heads of the screws engage the base of the spinous process (Fig. 31-5). The stab wounds are closed.

Figure 31–3 Insertion of translaminar facet screw. (A) The point of skin entry is at the intersection of the caudal angle line with the paravertebral line representing the distance from the midline of the spine. (B) The needle is introduced along the laminar angle and caudal angle until the tip of the needle anchored at the cranial one third of the base of the spinous process.

Figure 31–4 A) The stylet is withdrawn and a Kirschner wire is inserted. With an electrically powered drill, the wire is drilled toward the superolateral quadrant of the opposite pedicle of the lower vertebra, through the lamina and facet joint, under fluoroscopic guidance. (B) The same procedure is performed on the opposite side.

Figure 31–5 Cannulated lag screws, 46 or 50 mm long, are inserted along the Kirschner wires (A and B) until the heads of the screws engage the base of the spinous process at fluoroscopic AP (C) and lateral view (D).

Postoperative management

The patient is allowed to ambulate with a semi-rigid lumbar brace whenever he or she can. With the initiation of ambulation, computed tomography is performed to check the position the screws.

Assessment of the progression of fusion is performed at regular follow-up visits (usually every 3 to 6 months after the operation) by means of computed tomography and dynamic lateral plain radiography.

CASE STUDY 31.1 Degenerative Spondylolisthesis At L4-L5 Treated With Mini-Open Alif Followed By Percutaneous Translaminar Facet Pedicle Screw Fixation

A 64-year-old woman with degenerative spondylolisthesis at L4-L5 was treated with mini-open ALIF followed by percutaneous translaminar facet pedicle screw fixation. Assessment computed tomography performed 2 years after the operation confirmed solid bony union in the cages and the grafts between them (Fig. 31-6).

Figure 31–6 Case Study 31.1: (A and B) Degenerative spondylolisthesis at L4-L5. (C and D) Mini-open ALIF followed by percutaneous translaminar facet pedicle screw fixation was performed. (E) to (H) Sequential computerized tomography slices obtained 2 years after the operation show solid bony union in the cages and the grafts between them.

CASE STUDY 31.2 Lumbar Degenerative Kyphosis Treated With Alif At L3-L4, L4-L5, and L5-S1 With Percutaneous Translaminar Facet Pedicle Screw Fixation

A 57-year-old woman with lumbar degenerative kyphosis was treated with ALIF at L3-L4, L4-L5, and L5-S1 with percutaneous translaminar facet pedicle screw fixation. Plain radiographs taken 1 year postoperatively showed restoration of the lumbar lordosis from the kyphotic deformity and solid bony union at the interbody spaces (Fig. 31-7).

Figure 31–7 Case Study 31.2: (A and B) Preoperative radiographs show lumbar degenerative kyphosis at L3-L4, L4-L5, and L5-S1. (C and D) Plain radiographs taken 1 year after ALIF with percutaneous translaminar facet pedicle screw fixation showed restoration of the lumbar lordosis from the kyphotic deformity and solid bony union at the interbody spaces.

CASE STUDY 31.3

A 65-year-old woman with degenerative flat back deformity was treated with ALIF and percutaneous translaminar facet pedicle screw fixation at L5-S1. During the insertion of the Kirschner wire, repeated drilling was done to make a perfect path for the screw. The patient awoke with radicular pain and a fracture of the tip of the superior articular process of the sacrum. After a postoperative computed tomography scan showed compression of the exiting L5 root, revision surgery was performed to remove the fractured bony fragment. The screw was removed, and pedicle screw fixation was performed (Fig. 31-8).

Figure 31–8 Case Study 31.3: Postoperative CT scan obtained after ALIF with percutaneous translaminar facet pedicle screw fixation at L5-S1 shows compression of the exiting L5 root. Revision surgery was required to remove the fractured bony fragment.