Percutaneous Lumbar Restabilization via a Posterolateral Approach

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Chapter 32 Percutaneous Lumbar Restabilization via a Posterolateral Approach

Minimally invasive percutaneous lumbar restabilization via a posterolateral approach is a valid and less aggressive procedure than conventional open surgery for the treatment of lumbar segmental insufficiency (LSI) or micro-instability. The potential for performing a percutaneous lumbar restabilization has been made possible by the development of a new expandable titanium device available in several sizes (B-Twin System [Disc-O-Tech Medical Technologies Ltd., Herzliya, Israel] or intervertebral holder [IVH]), which should serve as the first device of its nature in a series of new-generation implants conceived for the less invasive treatment of a number of spine conditions [1–5].

The advantages of this surgical option include the following:

The procedure is performed with use of local anesthesia and minimal sedation if necessary (with an anesthesiologist standing by).

It minimizes iatrogenic lesions by avoiding the intraspinal route and paravertebral muscle trauma.

It does not exclude the use of other percutaneous restabilization techniques, and if necessary, more standard procedures can be carried out in a second step or stage.

It represents an optimization of stand-alone interbody fusion concepts.

It allows for quick mobilization and recovery and, therefore, prompt physiotherapeutic adjuvant treatment and a faster return to normal daily life.

The primary indication for percutaneous lumbar restabilization with the expandable interbody device is the treatment of lumbar segmental instability at the lower lumbar level (Fig. 32-1). This clinical feature is characterized by typical signs and symptoms associated with clear radiologic criteria (Table 32.1).

Figure 32–1 Characteristics of the B-Twin Intervertebral Holder system (Disc-O-Tech Medical Technologies Ltd., Herzliya, Israel) (IVH). The titanium expandable device is used for percutaneous lumbar restabilization procedures. The IVH can be inserted as a 5-mm-diameter tube (A) and then expanded up to 15 mm in diameter (B) assuming a lordotic shape within the intervertebral space. Note the greater contact surface at the level of the end plates on x-ray (C) and schematic drawing (D).

Table 32.1 Clinical and Radiologic Features of Lumbar Segmental Insufficiency (LSI)

Clinical Features
Clinical anamnesis	Mechanical lumbar pain that increases with physical stress and decreases with rest Episodes of hyperalgic blocks that are triggered by certain positions or postures (e.g., prolonged sitting or standing) or specific movements, such as flexion/rotation or flexion-extension
Clinical characteristics	Single- or multiple-segment pain at the level of the interspinous ligaments and/or facet joints produced in hyperextension and/or rotation The patient presents a disharmonic flexion-extension

Pathognomonic Radiologic Signs’
Conventional radiography	Sintering of the disc space (reduction of the disc height) Retrolisthesis or pseudolisthesis Vacuum phenomenon of the disc Macnab sign
Functional x-ray study	Dynamic sagittal instability (flexion-extension > 6 mm)
Magnetic resonance imaging: the stage or degree of LSI and with regard to the Modic changes described below	Local kyphosis and/or posterior articular subluxation on both T1-weighted and T2-weighted sequences
Modic changes	Type I: Disruption and fissuring at the level of the end plates with low signal on T1-weighted images and increased signal on T2-weighted images
	Type II: Fatty conversion with increased signal on T1-weighted images and isointense or increased signal on T2-weighted images
	Type III: Marked sclerosis (osteochondrosis) with low or no signal on both T1- and T2-weighted images

’ To confirm the diagnosis of LSI, the patient must exhibit at least three of the radiologic signs or criteria listed in this table in addition to the standard clinical signs and corresponding anamnesis.

This surgical option may also be contemplated in the treatment of patients with failed back surgery syndrome if no decompression of the nerve roots or foramen is required and if there is no recurrent disc herniation. There is strong evidence that the device offers distraction by “jacking up” the segment, leading to a restabilization of the instable segment. The device also serves as an internal “strengthener” for the fusion process. There is an immediate reduction of the hypermobility contributing to the clinical indication of micro-instability, which is favorable for the fusion process over the months following surgery.

In cases of LSI, the disc of the mobile segment is often the cause of the degeneration of the segment (comprising the two adjacent vertebrae and the disc in between). Thus pain relief can be achieved by immediate restabilization with the device, and the pain relief can be maintained long term owing to the longer, definite bony fusion produced (spondylodesis).

Indications and Contraindications

See Table 32.1 for the indications for percutaneous lumbar restabilization via a posterolateral approach. Box 32.1 lists the contraindications. Degree of disc removal remains a matter of debate because the surgeon is limited as to the degree of motion (in-and-out movements and technical limitation to go laterally in the working channel). Eroders cannot be used for the percutaneous application of the device. They are used strictly in the microsurgical reduced open application. The curette and possibly a shaver must be used in the percutaneous technique.

BOX 32.1 Contraindications to Minimally Invasive Percutaneous Lumbar Restabilization via a Posterolateral Approach

Stenosis

Free sequestrated fragment displaced caudally or cranially in the spinal canal

Listhesis

Acute or rapidly progressing neurologic deficits

Extreme epidural and peridural fibrosis that may first require a epidurolysis

Patient Selection

For a proper patient selection, the clinical criteria for low back pain and hyperalgic blocks should prevail over the presence of associated leg pain, and the suspected diagnosis must be confirmed by the imaging data (Box 32.2).

BOX 32.2 Required Diagnostic Screening for Suspected Diagnosis of Lumbar Segmental Insufficiency

Plain x-rays and functional study of the lumbar spine in anteroposterior, lateral, and oblique projections.

Magnetic resonance imaging (MRI) study.

Discography (especially when several levels are suspected or are seen to be pathologic on the MRI study. Usually performed during the preoperative evaluation and preferably should be done by the surgeon who will operate on the patient.

Neurophysiologic screening.

Complications

Box 32.3 lists the possible complications of percutaneous lumbar restabilization via a posterolateral approach along with their prevention and treatment.

BOX 32.3 Possible Complications of and Limiting Factors for Lumbar Segmental Insufficiency Treatment ’

High iliac crest: Operation in the L5-S1 disc space may necessitate a mini–open microsurgical interlaminar approach through a reduced partial hemilaminectomy.

A narrow intervertebral disc diameter: The implant is 25 mm in length when expanded.

Hematoma, either superficial (subcutaneous tissue) or deep-layers (psoas major and minor muscles).

Transient dysesthesia: posterolateral approach—“sunburn syndrome”’

Lumbar plexopathy: Possible if the approach is within 8 cm of the midline; therefore the entry point should be at least 10 cm from the midline ’

^’ These last two complications may require gabapentin medication and/or pharmacologic blocks of the dorsal root ganglion.

Procedure

Patient Position

This procedure requires a posterolateral percutaneous approach to the disc space with the patient in a prone position. It is also necessary to reduce the physiologic lordosis through the use of a Kambin frame (Fig. 32-2) or an articulated surgical table (Fig. 32-3).

Figure 32–2 The Kambin frame itself (A) and a patient positioned on the frame (B).

Figure 32–3 Note the electrodes on a patient’s skin (A) and the intraoperative monitor (B). An example of a patient’s graphs on monitor (C) and the patient positioned on the surgical table with reduction of the physiologic lumbar lordosis (D).

Anesthesia

The procedure is performed with use of local anesthesia with monitoring and an anesthesiologist on standby if needed.

Instrumentation

The following instruments and equipment are needed for percutaneous lumbar restabilization via a posterolateral approach:

Kirschner wire

Implant set with corresponding instruments (Fig. 32-4)

Rongeurs or disc shaver (optional)

C-arm (fluoroscope)

Sterile draping

Neurologic monitoring equipment (optional but advisable)

Percutaneous robot guide (Fig. 32-5) (optional)

Figure 32–4 Instrument set. (A) The different funnels, the dummies, and the various-sized eroders for the end plate preparation along with the universal interchangeable handle. (B) The eroders are sized from 7 to 13 mm. The preloaded device in its closed (C) and expanded modes (D). (E) Close-up shape of the expanded mode. (F) The delivery system with the preloaded device comes sterilely packaged.

Figure 32–5 The use of a spine robot can be an advantage for navigation and percutaneous delivery of the device as depicted here (SpineAssist, Mazor Surgical Technologies Ltd, Caesarea, Israel).

Surgical Procedure

Figures 32-6 to 32-17 illustrate the steps of percutaneous lumbar restabilization via a posterolateral approach, which are as follows:

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

2. With the patient in the prone position, a single-antibiotic perioperative injection is given (e.g., cefuroxime 1.5 g). Basic monitoring is set up, including instruments for blood pressure, pulse and respiratory rates, oximetry, and electrocardiography. Distal neurophysiologic monitoring, as shown in Figure 32-3, is recommended.

3. Local anesthesia is given (1% lidocaine 20 mL, usually 10 mL per each side).

4. Analgesia and sedation are given if needed (50 μg fentanyl, 30 mg ketorolac, and 2-3 μg midazolam). Analgesia/anesthesia may be given via a continuous epidural catheter if needed.

5. After the skin entry point is determined as shown in Figure 32-6, the landmarks for the posterolateral approach to the disc space are drawn on the patient’s skin.

6. The Kirschner wire is inserted, unilaterally at first then bilaterally, under C-arm guidance (Fig. 32-7).

7. A 6-mm working channel is inserted (Fig. 32-8).

8. The discectomy is performed with use of specially designed instruments, and the end plates are scratched with a Caspar curette (Fig. 32-9). The use of a shaver is optional.

9. A dummy device is introduced for confirmation of correct implant positioning (Fig. 32-10).

10. The bone graft is loaded and inserted (see Fig. 32-11; we use bone substitute mixed with a few milliliters of the patients blood to create a paste).

11. The intervertebral holder system or B-Twin is supplied in sterile packaging in its reduced diameter of 5 mm, preloaded on the delivery system (Fig. 32-12). (For the choice of implant size see Table 32.2.)

12. The delivery system is first introduced parallel to the disc space and is then turned perpendicular to the disc space via the handle (Fig. 32-13).

13. The delivery handle is turned clockwise while the expansion of the device is monitored with the moving marker on the handle and under fluoroscopy (Figs. 32-14 and 32-15).

14. The implant is expanded and positioned appropriately.

15. If the device must be removed (explanted), this maneuver can be accomplished with the special extractor, which is docked on the device and contracts the device as it extracts it (Fig. 32-16).

16. Intraoperative documentation is obtained with fluoroscopic images in anteroposterior and lateral views (Fig. 32-17).

17. Because the incision on each side is only approximately 1 cm long, the skin can be closed with a single suture.

Figure 32–6 Schematic representation of the method to determine the entry point on the skin and the target in the anteroposterior (A and C) and lateral fluoroscopic projections (B). It is interesting to note that the surgeon can often overcome or compensate for the presence of a high iliac crest when treating the L5-S1 level: The entry point used is similar to the L4-L5 entry point, but then the instruments are directed downward to the L5-S1 level.

Figure 32–7 Needle and Kirschner wire insertion from left side of body (A) and contralateral side (B).

Figure 32–8 Introduction of the serial dilators (A) and 6-mm working channel with the corresponding fluoroscopic control of both working channels in place (bilaterally) (B and C). The intraoperative picture of insertion of working channels (D) and schematic 3-D drawing of proper position of working channel in disc space (E).

Figure 32–9 Disc removal with rongeurs (A and B) and end plate scratching with a curette (C and D).

Figure 32–10 The 25-mm dummy is placed through the working channel into the disc space (A) and its final proper position in disc (B).

Figure 32–11 Preparation of the bone graft with its loading (A) and insertion into the disc space before introduction of the implant (B, C and D).

Figure 32–12 The B-Twin device comes preloaded and in sterile packaging.

Figure 32–13 Schematic drawing of insertion of the B-Twin device (A) and its introperative picture (B).

Figure 32–14 After confirmation of proper insertion of the implant into the disc space (A) the expansion process is completed (B). During the expansion process, the surgeon can control and follow the progression by means of a marker on the delivery handle (C).

Figure 33–15 Fluoroscopic picture of the expansion.

Figure 32–16 If needed, explantation can be accomplished with the special extractor, which that is docked on the device and then basically “re-closes” the device as it extracts it (A) Posterolateral view, (B) Anterolateral view.

Figure 32–17 Intraoperative fluoroscopic view of two implants are inserted toward the center of disc space (A) and the corresponding schematic representation from AP (B) and lateral view (C).

Table 32.2 Physiotherapeutic Key Points and General Therapeutic Guidelines

Goals

To return the patient to a functional lifestyle in the most efficient manner possible.

To decrease pain and increase core strength.

To set realistic expectations with the patient prior to treatment, therapy, or surgery.

What is functional core strengthening?

Specific functional core training innervates and strengthens the primary spine stabilizers in a functional way that simulates “real-life” movements and activities

Primary stabilizers: transverse abdominis, internal oblique, and multifidus muscles

Secondary stabilizers: psoas and abdominal muscle groups, and hip/pelvic and lower extremity muscle groups

General guidelines for starting therapy

1. Stabilizing patient’s pain levels via adjunctive treatments allows for a more successful result in functional core training

2. Begin therapy if patient is tolerating activity of daily living (ADL) without significant difficulties and can walk short distances without increased pain

3. Encourage walking

4. Average number of visits: 8-2

A progressive program from lower to higher level functional exercises 1. Clinical findings, therapy protocols, and operative report explained to the patient in “layman’s terms” 2. Pain reduction 3. Flexibility 4. Drawing-in maneuver 5. Basic stabilization 6. Body mechanics education 7. Lower extremity strengthening 8. Balance and proprioception 9. Conditioning 10. Home exercise program 11. Attempt to instill importance of lifestyle change!