Chapter 27 Full-Endoscopic Interlaminar Lumbar Discectomy and Spinal Decompression

Endoscopic interlaminar access denotes a newly developed method for fully endoscopic uniportal operation of the lumbar spinal canal and the adjacent structures under fluoroscopic guidance and continuous fluid flow via a minimally traumatizing access through the interlaminar window.

Minimally invasive techniques can reduce damage to tissues and limit the consequences of necessary tissue damage [1,2]. Endoscopic operations possess advantages that raise these procedures to the standard in many areas. Working with lens optics under lavage provides excellent visual conditions, and bleeding can be reduced. Also, the use of the laser or high-frequency bipolar current is possible in the immediate vicinity of neural structures [3]. The prerequisite for any minimally invasive technique is that the technical possibilities of such operations guarantee attainment of the operative goal [4].

The most common fully endoscopic uniportal procedure is the transforaminal or extraforaminal operation with posterolateral access (Fig. 27-1) [5–8]. It is seldom technically possible to perform retrograde resection of disorders within the spinal canal intradiscally. For this reason, the newly developed lateral access is necessary within the transforaminal technique to reach such structures because of the bony boundaries of the intervertebral foramen and the access pathway through the soft tissue (Fig. 27-2) [9]. At the caudal levels, this access may be hindered by the pelvis. Additionally, the boundaries of the foramen hamper mobility during the procedure and limit the available room to work in the spinal canal.

Figure 27–1 Intraoperative view of endoscopic transforaminal operation with posterolateral access.

Figure 27–2 Intraoperative view of endoscopic transforaminal operation with lateral access to reach the spinal canal directly under fluoroscopic guidance.

The fully endoscopic uniportal interlaminar technique can be used for transforaminal lumbar problems that are technically inoperable. The spinal canal is reached through the interlaminar window and enables working comparable to that with conventional techniques but in a minimally invasive procedure (Fig. 27-3) [1,10,11]. The known problems of open, microscopic, and endoscopically assisted techniques can be reduced [1,2].

Figure 27–3 Intraoperative view of endoscopic operation with interlaminar access.

At the same time, technical problems have been solved by the development of new lens endoscopes with intra-endoscopic 4.2-mm working canals and corresponding new instruments, shavers, and burs (Fig. 27-4). This development also enables the resection of bones as in arthroscopic surgery [10,11].

Figure 27–4 New endoscope with 4.2-millimeter work canal and corresponding new instruments, shavers, and burs enable resection of bones.

The combination of new operative accesses and technical advances for the first time enables a fully endoscopic procedure under fluoroscopic guidance that is equal, taking the indication criteria into account, to conventional operations. Basically, the transforaminal procedure has more limitations than the interlaminar but at the same time shows better tissue sparing. Owing to the anatomical and pathologic situation, 40% of fully endoscopic procedures are lateral transforaminal and 60% are interlaminar.

Advantages

Conventional open operating procedures are indispensable today and will remain so in the future. The possible complications of and injuries from such procedures are known [12–19]. At the least, new techniques must be as capable of attaining the operative goals as the established procedures [4].

The fully endoscopic uniportal interlaminar operation, as a truly minimally invasive procedure, offers advantages over conventional procedures, listed later. They correspond largely to the advantages of microscopically assisted surgery, cited in each case, over conventional open surgery. The fully endoscopic interlaminar operation can thus be classified as the next step in technical advances in surgical techniques. There is, as yet, no unequivocal scientific proof of this assertion, but such proof is also lacking for microscopically assisted operating and arthroscopic techniques.

The advantages of the fully endoscopic uniportal interlaminar operation over a conventional open procedure are as follows:

Good presentation of structures, excellent visual conditions, improved illumination

Expanded field of vision thanks to 25-degree-angle optics

Sufficient working space within the spinal canal and its adjacent structures

Sparing of epidural lubricant tissue, with reduced epidural scarring

Minimized bony and ligamentous resection, according to current knowledge, resulting in reduction of operation-induced instabilities

No greater difficulty of subsequent operations

Reduced traumatization of the surrounding tissue

Lower rate of complications, such as dural injury, bleeding, and infections

Short hospitalization, rapid rehabilitation, high rate of return to athletic and occupational activity levels

No increase in morbidity of concurrent diseases or advanced age

High patient acceptance

Can be used in technically inoperable transforaminal pathologies

Good visibility for assistants

Disadvantages

With complete omission of bony resection in the fully endoscopic uniportal interlaminar operation, the mobility within the spinal canal is limited by the size of the interlaminar window. At spinal levels L5 through S1, the dimensions of the window often hinder access if no bone is removed. Greater bony resections with high-speed drills or larger punches are technically more demanding in minimally invasive procedures than in conventional procedures.

Unlike the transforaminal access, the interlaminar procedure requires a defect in the ligamentum flavum and a potential resection of bony structures, despite being minimally invasive. Thus,the fully endoscopic uniportal transforaminal operation can be rated as less traumatizing and may offer advantages in appropriate indications and when its clear limits are taken into account.

Indications

The indications for the operation correspond to today’s valid standards [20]. Most experience has been gained in the therapy of disc herniations and lateral spinal canal stenosis. Extensive central spinal canal stenosis has been operated on for only a short time, and the procedure is still under development. Existing concurrent pathologies, such as instabilities, must be treated at the same time as appropriate. The following indications are currently clearly defined: