Chapter 29 Percutaneous Transforaminal Lumbar Interbody Stabilization

Percutaneous endoscopic transforaminal discectomy has been an effective alternative to microdiscectomy for patients with soft lumbar disc herniations [1–5]. However, it is ineffective in the presence of lumbar segmental instability due to degenerative disc disease. Percutaneous transforaminal lumbar interbody stabilization (PTLIS) is a new surgical method for treating lumbar segmental instability due to degenerative disc disease and low-grade degenerative spondylolisthesis.

The specially designed B-Twin expandable holder (Disc-O-Tech Medical Technologies Ltd., Herzliya, Israel), which is made of titanium, is used as an interbody spacer to achieve stability without open discectomy and fusion [6–11]. In cases of failure, this minimally invasive procedure does not impede conventional surgical approaches.

Advantages

The major advantages of PTLIS are as follows:

It requires a small insertion diameter.

There is no soft tissue and bone damage.

The facet joints are not destroyed.

Stability is not compromised.

There is no dural sac or root manipulation.

There is less risk of cerebrospinal fluid fistula and neurologic compromise.

The amount of bleeding is negligible.

There is a lower risk of infection.

The procedure can be done alone or supplemented with pedicle screw fixation.

Indications

PTLIS is performed for the following conditions:

Degenerative disc disease (DDD)

Internal disc derangement syndrome (IDD)

Herniated lumbar discs with segmental instability

Degenerative spondylolisthesis

Spinal stenosis with segmental instability

Recurrent disc herniation

Contraindications

The contraindications to PTLIS include the following:

Infectious conditions such as tuberculosis

Severe osteoporosis

More than grade II spondylolisthesis

Spine infection, tumor, metabolic bone disease

Complications

The following complications have occurred with PTLIS:

Deterioration of the spinal curvature

Implant migration or malpositioning

Device deformity or breakage

Infection

Bone fracture at the level of surgery

Discitis, arachnoiditis, or other inflammation

Subsidence

Preoperative preparation

Patient Symptoms

The patient in whom PTLIS is performed suffers from low back pain with or without leg pain due to instability.

Imaging Diagnosis

PTLIS is performed in patients in whom imaging detects the following:

Magnetic resonance imaging findings correspond with physical findings.

Computed tomography depicts a soft disc herniation.

Plain films are used preoperatively for intervertebral space measurement.

Instrumentation

The implant is supplied preloaded on its delivery system. It is inserted into the intervertebral space in a narrowed tube configuration and is expanded once in place.

Prior to surgery, the required implant diameter is determined through the use of lateral and anteroposterior radiographs and computed tomography or magnetic resonance imaging. The intervertebral space is measured, and 10% to 20% is added to determine the appropriate expanded diameter of the device (Table 29.1). This diameter determines the implant to be selected.

Table 29.1 Selection of Size of B-Twin Implant*

The length of the intervertebral space (the anteroposterior borders of the vertebral body) should be at least 28 mm for the use of the trapezoid implants. Verification of implant diameter and length is also performed during surgery, as detailed in the later Figures 29-1 to 29-8 illustrate the instrumentation for PTLIS.

Figure 29–1 Rigid working channel scope (KISS, EKL, UK).

Figure 29–2 Rigid working channel scope (Yeung Endoscopic Spine System [YESS] scope (Richard Wolf Medical Instruments, Knittlingen, Germany).

Figure 29–3 Bipolar flexible radiofrequency probe (Ellman Trigger-Flex Bipolar System, Ellman Innovations, Hewlett, NY). (A) The whole bipolar frequency probe, (B) The flexible tip of probe.

Figure 29–4 Side-firing holmium:yttrium-aluminum-garnet Laser (Trimedyne Inc, Irvine, CA). (A) The laser delivery device, (B) The side-firing tip of device.

Figure 29–5 Serial dilators (A) The tip of dilating obturator (B) and working cannula (C).

Figure 29–6 Microforceps (A) and the endoscopic view of the disc fragment which is grabbed by microforcep (B).

Figure 29–7 Single-use delivery system for the B-Twin implant (Disc-O-Tech Medical Technologies, Herzliya, Israel).

Figure 29–8 The stages of the B-Twin implant (Disc-O-Tech Medical Technologies, Herzliya, Israel) from unexpanded to full expanded cage which is detached at last.

Anesthesia

Preoperative antibiotics (usually 1.0 g of cefazolin) and sedatives are given.

Communication between the surgeon and the patient is necessary during the procedure. The operation is typically conducted with the use of local anesthesia and analgesia via neuroleptics so that the surgeon may know immediately of any changes in symptoms and signs. General anesthesia may be used in the few patients who wish it or cannot tolerate the position. With general anesthesia, however, the urgent need for conversion to open surgery may not be detected early.

A solution of 1% lidocaine is usually used to infiltrate the skin and subcutaneous tissue (Fig. 29-9). To minimize the thickening of underlying tissues and to allow a minute palpation of the spinal axis, we prefer to not infiltrate more deeply with lidocaine.

Figure 29–9 The patient is placed prone on a radiolucent table (A) and the tract is infiltrated with local anesthesia (B).

Procedure

1. The patient’s written informed consent is obtained.

2. The patient is placed prone on a radiolucent table, with mild flexion of the back. The back is prepared and draped in the usual sterile fashion.

3. With the help of a metallic needle, skin markings are made with a marking pen to indicate the midline and the correct surgical level through the use of anteroposterior and lateral C-arm (fluoroscopic) images. The surgeon marks the lesion by counting the lumbar vertebrae from the sacrum.

4. The skin entry point is typically approximately 8 to 11 cm from the midline. To determine the appropriate entry point, preoperative imaging studies and intraoperative fluoroscopy should be performed.

5. An 18-gauge spinal needle is inserted after infiltration of local anesthetics. The needle tip is positioned at the mid-pedicular line in the anteroposterior projection (Fig. 29-10), and on the posterior vertebral line in the lateral projection. At this time, a transforaminal epidural infiltration through the spinal needle with 0.5% lidocaine is recommended to effectively prevent approach-related pain and discomfort.

6. Under fluoroscopy and local anesthesia, a guidewire is inserted through the needle on both sides. After the needle is withdrawn, a tapered cannulated obturator is slid over the guidewire and introduced gently into the foramen. The tip of the obturator should be held firmly by foraminal bony structures and should contact the anular surface.

7. The next step is the introduction of a beveled working cannula over the obturator. The bevel-ended, oval working cannula guarantees a safer and less painful transforaminal anular contact than the standard working cannula.

8. After percutaneous endoscopic discectomy using microforceps and a holmium:yttrium-aluminum-garnet (Ho:YAG) laser (Figs. 29-11 and 29-12), the endoscope is withdrawn and the end plates are prepared under C-arm guidance.

9. Then, the B-Twin implant is introduced into the intervertebral space in a narrowed form.

10. The implant is expanded to its final form segment by segment through rotation of the expander rotational handle. It is then fixed to the disc space to maintain the disc height (Figs. 29-13 and 29-14).

11. Finally, a sterile dressing is applied with one point subcutaneous suture.

Figure 29–10 An 18-gauge needle tip is positioned at the mid-pedicular line in the anteroposterior projection (B) and on the posterior vertebral line in the lateral projection. Serial dilations are performed with a guidewire and a series of dilators (A).

Figure 29–11 Mechanical discectomy using microforceps is performed through the rigid working channel scope under endoscopic (A) and fluoroscopic control (B).

Figure 29–12 The intraoperative view of using a side-firing holmium:yttrium-aliminum-garnet laser for removal of remnant osseous fragments and thickened ligamentous material (A). The laser is used until the epidural space and dura are visualized (B).

Figure 29–13 Intraoperative view of rotating the expander handle of B-Twin implant (A) and its fluoroscopic lateral view for confirmation of proper insertion of the implant into the disc space (B).

Figure 29–14 The AP fluoroscopic view of two implants are inserted toward the center of disc space (A) and final view of skin surface which a sterile dressing is applied with one point subcutaneous suture (B).

Postprocedural management

Patients should be observed for 3 hours to detect possible complications. All patients are permitted to go home on the day of surgery.

Patients needs bed rest for at least one night.

Postoperative oral antibiotics and analgesics are recommended for 3 to 10 days.

A lumbar brace is recommended for 3 to 14 days, depending on the individual patient’s condition.

Mild physical therapy may be helpful for fast recovery within 2 weeks postoperatively. If the pain and discomfort remain, complementary epidural injection of steroids with lidocaine may be added so that no further open procedure is necessary.

Four to 6 weeks postoperatively, twice-weekly rehabilitation exercises for back muscle strengthening and improvement of range of motion are recommended for 3 months.

CASE STUDY 29.1 L5-S1 Instability Stabilized By B-Twin Expandable Holder

A 35-year-old man with suffered from low back pain and pain in both legs for 8 months. Preoperative radiographs demonstrated L5-S1 instability (Fig. 29-15 A and B). He underwent percutaneous endoscopic lumbar discectomy and stabilization using the B-Twin expandable holder. Postoperative radiographs showed improvement of the patient’s lordosis (Fig. 29-15C and D).

Figure 29–15 Preoperative extension (A) and flexion (B) radiographs showing segmental instability. Postoperative extension (C) and flexion (D) radiographs demonstrating improvement in the lordosis.

CASE STUDY 29.2 L4-L5 Instability Stabilized By B-Twin Expandable Holder

A 52-year-old woman with had suffered from low back pain and pain in both legs for 5 years. Preoperative radiographs demonstrated L4-L5 instability (Fig. 29-16A to C). The patient underwent percutaneous endoscopic lumbar discectomy and stabilization using the B-Twin expandable holder. Postoperative radiographs demonstrated improvement of lordosis without laminectomy (Fig. 29-16D to F).

Figure 29–16 Preoperative anteroposterior (A) extension (B) and flexion (C) radiographs showing segmental instability. Postoperative anteroposterior (D) extension (E) and flexion (F) radiographs demonstrating improvement of lordosis without laminectomy.