Unilateral Biportal Endoscopic Decompression for Lumbar Spinal Stenosis

10 Unilateral Biportal Endoscopic Decompression for Lumbar Spinal Stenosis

Jin Hwa Eum, Sang Kyu Son, Ketan Deshpande, and Alfonso García

10.1 Introduction

Traditionally, lumbar stenosis is treated with an open decompressive laminectomy, a foraminotomy, or fusion surgeries.1,2,3,4 Recently, minimally invasive spinal surgical methods have developed to improve muscle preservation and other surrounding normal anatomical structures.^3,5,6 Microscopic bilateral decompression via a unilateral approach has been used in the treatment of lumbar spinal stenosis.^3,5 Percutaneous endoscopic interlaminar decompression for lumbar stenosis remains a challenging procedure even for an experienced endoscopic surgeon.⁷ Additionally, vision is restricted and technical difficulties can arise in spite of using a microscope or uniportal spinal endoscope. Our technique of unilateral biportal endoscopy (UBE) is a modification of percutaneous uniportal interlaminar epidural endoscopic surgery. The UBE decompression method is based on the same operative technique as other surgical procedures, such as ipsilateral microscopic laminotomy and bilateral decompression, with patients in the prone position. Compared with open microscopic spinal surgery, the UBE technique can reduce muscle injury and allow excellent visualization of the contralateral traversing root. This chapter introduces and describes the technique for UBE decompression in the treatment of lumbar spinal stenosis (Video 10.1).^8,9

10.2 Equipment

Equipment used in the unilateral biportal endoscopic procedure is as follows. During the procedure, we use a 3.5-mm spherical bur (Conmed Linvatec, Utica, NY), a 0°, 4-mm diameter arthroscope (Conmed Linvatec, Utica, NY), a bipolar flexible radiofrequency probe (Ellman), serial dilators, a specially designed dissector, a pressure pump irrigation system (Smith & Nephew Inc., Memphis, TN), and standard laminectomy instruments, such as hook dissectors, Kerrison punches, and pituitary forceps.

10.3 Surgical Procedure

The UBE procedure is similar to knee arthroscopy. Two portals are used: one portal is used for continuous irrigation and endoscopic viewing and the other portal is used for insertion and manipulation of the instruments used in decompression (e.g., in laminotomy and flavectomy). See Fig. 10.1 for a right-sided UBE procedure.

10.3.1 Position and Anesthesia

The procedures are performed with the patient under general or epidural anesthesia on a radiolucent operating table over a Wilson frame. The patient is placed in the prone position to minimize abdominal pressure. A waterproof surgical drape is applied after induction of anesthesia.

Fig. 10.1 Right-sided L4–L5 unilateral biportal endoscopy (UBE). Anteroposterior diagram of the working portal, represented by the red dot, and the scope portal, represented by the blue dot.

10.3.2 Target Point

The target pathologic stenotic level is identified under fluoroscopic guidance. The exact target point is the intersection between the lower lamina margin and 1 cm lateral to the spinous process ipsilaterally, as determined through the associated lateralizing symptoms. In the absence of lateralizing signs or symptoms, a left-sided approach is preferred for a right-handed surgeon.

10.3.3 Working Channel Portal

To establish the working channel portal, a 1.5-cm skin incision is made slightly obliquely above the target point, following the direction of the multifidus muscle fibers. Serial dilators are then inserted toward the lower lamina. Following removal of the dilators, a specially designed dissector is used on the lower lamina. Interlaminar soft tissue is dissected medially to laterally toward the medial margin of the facet joint capsule (Fig. 10.2, Fig. 10.3, Fig. 10.4).

Fig. 10.2 (a,b) For a right-sided L4–L5 approach, first the target point is localized under C-arm fluoroscopy. A slightly oblique 1.5-cm skin incision is made above the lower margin of the L4 lamina, following the direction of the multifidus muscle. After proper dilation and muscle dissection, a second, oblique incision is made just 1.5 cm distal to the first incision.

Fig. 10.3 (a) Right-sided L4–L5 unilateral biportal endoscopy (UBE). Anteroposterior C-arm view of the initial dilator introduced through the working channel portal and aimed to the inferior margin of the L4 lamina, close to the base of the corresponding spinous process. (b) After the working portal incision is made, the surgeon introduces a dilator and checks, using C-arm fluoroscopy, for the target point.

10.3.4 Endoscopic Portal

The endoscopic portal is always made to the left of the working channel portal; that is, if a right-sided approach is needed, then this portal will be made distal to the working channel (for a right-handed surgeon), and if a left-sided approach is needed, then the endoscopic portal will be made proximal to the working channel. An easy way to remember this is that a right-handed surgeon will hold the scope with the left hand and the instruments with the right hand.

The second portal is made through a 1.0-cm skin incision ~ 2 to 3 cm above the upper edge of the first caudal port skin incision; the second portal serves to accommodate the insertion of a 6-mm diameter cannula and scope. A 0°, endoscope is inserted through the cranial portal after insertion of the cannula.

A saline irrigation pump is connected to the endoscope and is set to a pressure of 20 to 30 mm Hg during the procedure; a continuous, controlled flow of saline solution irrigation is essential to prevent excessive elevation of the epidural pressure. Surgical instruments are inserted through the caudal working portal (Fig. 10.1, Fig. 10.5).

Fig. 10.4 (a) Right-sided L4–L5 unilateral biportal endoscopy (UBE). Anteroposterior C-arm view of the muscle dissector introduced through the working channel portal and aimed to the inferior margin of the L4 lamina, close to the base of the corresponding spinous process. (b) Corresponding to Fig. 10.4a. After initial dilation of a dissector is introduced to partially detach muscle from the base of the spinous process, and the position is verified with C-arm fluoroscopy.

Fig. 10.5 (a) Right-sided L4–L5 unilateral biportal endoscopy (UBE). Lateral diagram of the working portal (represented by the red dot) and the scope portal (blue dot). The translucent oval and the blue arrows represent the viewing field and instrument working angles, respectively. (b) Surgeon’s frontal view of a left-sided UBE approach. Notice that a right-handed surgeon will hold the endoscope and camera with the left hand and the instruments with the right hand.

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