Percutaneous Pedicle Screw Fixation

Chapter 30 Percutaneous Pedicle Screw Fixation

Sang-Ho Lee, MD, PhD, Won-Gyu Choi, MD, PhD, Sung-Bae Ban, MD

Anterior lumbar interbody fusion (ALIF) has advantages over other fusion procedures, such as shorter operating time, lower blood loss, and no epidural complications [1–6]. However, in the case of spondylolytic or degenerative spondylolisthesis at multiple vertebral levels, higher pseudarthrosis rates have been reported with ALIF [7,8].

Percutaneous pedicle screw fixation (PPF) was developed as a minimally invasive posterior augmentation for ALIF [9]. At present, the PPF technique has been applied to a wide range of fusion procedures, including mini–open transforaminal lumbar interbody fusion (TLIF) [10].

Advantages

The potential advantages of PPF are as follows [10–12]:

image Immediate spinal stabilization without the need for posterior decompression
image Preservation of the posterior spinal elements
image A small skin incision
image Less blood loss, paraspinal muscle damage, and postoperative pain
image Better cosmetic result

Indications

Currently, PPF has been applied to a wide range of procedures, TLIF, posterior lumbar interbody fusion (PLIF), and posterolateral fusion. PPF is most useful in the following minimally invasive lumbar fusion techniques:

image Mini–open TLIF, especially with the use of a tubal retractor
image Laparoscopic transperitoneal ALIF
image Mini–open retroperitoneal ALIF
image Minimally invasive PLIF

Contraindications

PPF should not be used in patients with the following conditions:

image Requiring more than three motion segments fixation
image Spondylolisthesis of severity greater than grade II
image Severe scoliosis
image Previous pedicle fixation

Preoperative preparation

image Computed tomography is used to ascertain the size of the pedicle and to plan the length and direction of the screw (Fig. 30-1).
image Dynamic studies, such as flexion and extension radiographs, are helpful in the evaluation of spinal stability, particularly in the patient with spondylolisthesis.
image For older women, a bone density study helps determine whether the bone mineral content is adequate for pedicle screw fixation. In patients with severe osteoporosis, vertebral augmentation by vertebroplasty is needed (Fig. 30-2).
image

Figure 30–1 Computed tomography for measuring the size of the pedicle and to plan for the length (both arrows) and direction of the screw. L, left; P, posterior.

image

Figure 30–2 Vertebroplasty can increase the pullout strength of the pedicle screw and can prevent the subsidence of the implant due to osteoporosis. Bone cement inserted at L5 and S1 vertebral bodies were confirmed at fluoroscopic AP (A) and lateral view (B).

Procedures

Until recently, difficulty was always encountered with percutaneous placement of connecting rods. The innovation of the CD HORIZON Sextant system (Medtronic, Inc., Minneapolis, MN) has overcome the need for open rod placement.

Procedure for Percutaneous Pedicle Screw in General

1. The patient’s written informed consent is obtained.
2. The patient is placed in a prone position with the abdomen free. The procedure is performed under C-arm (fluoroscopic) guidance.
3. The back is prepared and draped in a sterile fashion.
4. With a No. 11 scalpel blade, the surgeon makes a 15-mm-long incision for each screw over the spinous process at the level to be fused (Fig. 30-3).
5. A 14-gauge vertebroplasty needle is positioned with its tip on the lateral margin of the pedicle oval and advanced until the stylet tip has abutted the bone under anteroposterior view (Fig. 30-4).
6. The surgeon advances the needle through the cortex by tapping its back end with a mallet on a lateral fluoroscopic view. The lateral view shows the needle passing parallel to the superior and inferior edges of the pedicle. With the needle tip located on the posterior vertebral bodyline on a lateral view, the intrapedicular location of the needle is confirmed on the anteroposterior view (Fig. 30-5).
7. After confirmation of placement, the needle is advanced so its tip is at the junction of the middle and posterior thirds of the vertebral body.
8. The stylet is replaced by a 200-mm-long Kirschner wire, and then a series of sequential dilations is performed along the Kirschner wire.
9. With the Kirschner wire still in place, a hole is drilled in the pedicle with a 5.0-mm cannulated drill bit.
10. After removing the Kirschner wire, the surgeon places a long straight beaded-tip probe into the pedicle and evaluates the pedicle walls are for possible perforation.
11. The surgeon inserts a pedicle screw into the prepared hole using the same orientation as for the Kirschner wire and under fluoroscopic guidance.
12. The same procedure is repeated for the other target pedicles.
13. The surgeon makes a soft tissue tunnel that connects the two pedicle screw heads in a each side is made using a custom-made curved passer through the same stab wound and muscle layer (Fig. 30-6).
14. Then the surgeon inserts a longitudinal connector (rod or plate) and passes it firmly through both screw heads (Fig. 30-7).
15. Fluoroscopic confirmation of the connector passage through the screw heads is obtained in both planes to ensure proper positioning of the connector.
16. A locking bolt is introduced into the screw head through the same stab wound and is tightened under fluoroscopic guidance or direct vision with brief retraction of the stab wound. While tightening a screw-connector construct, the surgeon uses the remaining screw path to give anti-torque and some compression force.
17. The same procedure is performed on the contralateral side of the spine, after which all incisions are irrigated and closed.
18. Finally, only a single deep stitch is needed at each screw entry incision (Fig. 30-8).
image

Figure 30–3 Skin entry points are determined by placing a bone biopsy needle on the skin and 15-mm-long incisions for each screw are drawn at the level to be fused.

image image image

Figure 30–4 (A) Intraoperative photography during insertion of 14-gauge vertebroplasty needles toward the pedicles and vertebra bodies; (B) Confirmation of proper needle positions through whole length of pedicles on fluoroscopic lateral view; (C) Proper needle positions with their tips on the lateral margin of the pedicle oval and advanced until the stylet tip has abutted the bone under anteroposterior view.

image image

Figure 30–5 Pedicle screws are inserted into the vertebral bodies at L4 (A) and L5 (B) along the Kirschner wire under the fluoroscopic guidance.

image

Figure 30–6 A soft tissue tunnel that connects two pedicle screw heads is made using a custom-made curved passer through the same stab wound and muscle layer.

image image image

Figure 30–7 A longitudinal connector (rod or plate) are inserted and passed firmly through both screw heads at one side (A) and contralateral side. (B) under AP fluoroscopic guidance. Proper position of connector is then confirmed by fluoroscopic lateral view (C).

Related posts:

Lateral Interbody Fusion Using the XLIF System Minimally Invasive Percutaneous Lumbar Fusion Technique Paravertebral Block Anterior Endoscopic Cervical Microdecompression of Disc and Foramen Outcome Measurements for Minimally Invasive Percutaneous Spine Techniques Spinal Cord Stimulation

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Aug 5, 2016 | Posted by in NEUROSURGERY | Comments Off on Percutaneous Pedicle Screw Fixation

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