Application and Techniques
Full-Endoscopic Spine Surgery
Full-endoscopic approaches represent the next step in the evolution of minimally invasive spine surgery. The pathologies being addressed and the fundamental interventions being performed to address these pathologies (e.g., removal of herniated disc, resection of bony stenosis) are essentially the same for open, MIS, and endoscopic approaches. Likewise, the methods and instrumentation are entirely analogous between MIS and endoscopic techniques. They are all operations performed under direct visualization with a light source and high definition magnifying optics; access is established with tissue dilators and tube retractors; soft tissue is removed with forceps, and bone is resected with Kerrisons and rotary burrs.
The most important difference between endoscopic and other, more invasive, approaches to spine surgery is the amount of tissue that must be disrupted in order to gain access to the pathology. The smaller diameter dilator and tubular retractor used in endoscopy can be inserted to their target with minimal separation of muscle planes, and minimal resection of bone and ligament. This is in contrast to more invasive approaches that may require the cutting and stripping of muscles, and the resection of significant amounts of bone and ligamentum flavum just to gain access to the pathology. The reduced trauma associated with the endoscopic approach can provide patients with a faster recovery, earlier return to work, less postoperative pain, a more cosmetic incision, and an overall higher satisfaction with the surgery.1
Multiple endoscopic techniques and accompanying instrument sets have been developed for a multitude of spine surgeries, including several approaches to the lumbar and cervical spine, and dorsal ramus rhizotomy. The exact approach to be used is dictated by surgeon preference, anatomy, and the location of the pathology. All techniques begin with the fluoroscopic targeting of the anatomy and the establishment of an access channel with a small tubular retractor. The appropriate endoscope is inserted in the tube to provide direct visualization throughout the procedure.
The following is a summary of the techniques developed by Richard Wolf surgeons, each with specific associated instrumentation, and each taught and supported by Richard Wolf Medical Instruments.
1. Ruetten, et. al., Full-Endoscopic Interlaminar and Transforaminal Lumbar Discectomy Versus Conventional Microsurgical Technique A Prospective, Randomized, Controlled Study, Spine, April 2008, 33:9 (940-948)
Transforaminal (“Inside Out”) Decompression
This is the most widely used endoscopic technique for addressing herniated discs. This is a posterolateral approach in which the working sleeve passes through Kambin’s triangle and inserts into the interior of the disc and annulus. This straightforward approach is easy to learn and allows for decompression of the disc with good access to foraminal, extraforaminal and far lateral herniations. With experience, more central herniations and foraminal stenosis can also be addressed with this approach. Click here for more details.
Extraforaminal (“Outside In”) Decompression
This is a posterolateral approach in which the tip of the working sleeve is targeted onto a bony landmark (e.g, pedicle or SAP) adjacent to the foramen. This gives the endoscope a view of the extraforaminal anatomy and allows for directly visualized resection of the foraminal bone or extruded nucleus fragments without having to enter the disc. Click here for more details.
This is a posterior approach very similar to that used in microdiscectomy. The working sleeve targets the interlaminar window and bone burrs are used, if necessary, to enlarge the window enough to permit passage of an 8 mm working sleeve. After incising the ligamentum flavum, central and paracentral herniations, as well as lateral recess stenosis, can be addressed. Click here for more details.
Central Canal Stenosis Decompression
This surgery uses the interlaminar approach to decompress neural structures in the central spinal canal. A larger diameter working sleeve and endoscope permit passage of full-size burrs and Kerrisons to resect the laminae and medial facet under direct visualization through an incision much smaller than is typical of an open laminotomy. The hypertrophied ligamentum flavum can then be resected as necessary to complete the decompression of the nerves. Click here for more details.
Dorsal Ramus Rhizotomy
This surgery addresses painful facet joints by transecting the innervating medial branches of the dorsal ramus. Using a posterior approach, the dilator and working sleeve are directed to the transverse process, allowing the endoscope to directly visualize the region of the medial branch. An RF probe is used to ablate a segment of the medial branch providing a more definitive treatment than is possible with standard RFA.
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Anterior Approach Decompression
This procedure allows access to herniations that lie just ventral to, and between the lateral margins of, the spinal cord. An anterior approach is used to insert a specially designed oval working sleeve and complementary endoscope into the disc. Small instruments are passed through the nucleus to the posterior aspect of the disc where herniated tissue can be removed under direct visualization. Click here for more details.
Posterior Approach Decompression
This procedure allows access to cervical herniations that are lateral to the margins of the spinal cord, as well as permitting foraminal decompression. A posterior approach, similar to the lumbar interlaminar approach, is employed to reach the posterior structures. Burrs are used to create access and perform a foraminotomy as necessary. The ligamentum flavum can then be incised to permit exposure and removal of herniated disc material. Click here for more details.