J Chiu. SMART® Endoscopic Spine System for Lumbar Microdecompressive Surgery. The Internet Journal of Minimally Invasive Spinal Technology. 2006 Volume 1 Number 1.
With the explosive demand and rapid development of outpatient endoscopic minimally invasive lumbar surgical technique, a SMART® endoscopic lumbar spine system was developed. This microdecompressive lumbar spine surgery is performed with a small skin incision, dilatation surgical technology, and an endoscopic-assisted spinal surgical system with gradual progressive serial tubular retractors and superior lighting for better visualization of the operative field in performing endoscopic minimally invasive spinal surgery (MISS). This SMART®
Endolumbar System (Karl Storz GmbH & Co., Tuttlingen, Germany) incorporates the advantages of posterior paramedian endoscopic assisted microdecompressive surgical spinal system and posterolateral endoscopic lumbar system. This versatile SMART® endoscopic spine system with various sized working channels provides a generous and optimal access for endoscopic microdecompression of herniated lumbar discs, degenerative spinal disease, spinal stenosis, and removal of intraspinal lesions as well as creating an access for spinal arthroplasty and spinal fixation. With the unique features of this SMART® system, the surgeon can take advantage of microscopic, endoscopic, or direct vision for microdecompressive spinal surgery. It bridges endoscopic and conventional spinal surgery. This less traumatic and easier outpatient MISS treatment appears to be safe, and efficacious, leads to excellent results, speedier recovery, and significant economic savings. The SMART® endoscopic spine system, surgical indications, operative techniques, and the potential complications and their avoidance are described and discussed herein.
Low back pain secondary to lumbar disc herniation is a relatively common occurrence, resulting in approximately 300,000 lumbar procedures in the United States each year and 600,000 in the rest of the world. Because conventional posterior laminectomy and discectomy with or without fusion are more traumatic and potentially destabilizing, the development of minimally invasive spinal surgery (MISS) has been of particular interest to surgeons and patients alike.1,2,3,4,5,6 Not long ago MISS was thought to be impossible and impractical. The MISS revolution has virtually impacted every surgical specialty with the same objective as the traditional open spinal surgery for neurodecompression but with the benefits of smaller incisions, less tissue trauma, enhanced illumination and visualization, and as an outpatient procedure with faster recovery and significant economic savings.7,8,9,10,11,12,13,14,15,16,17,18 MISS has rapidly come of age as a result of improved endoscopic and microspinal surgical instruments, the explosive development of biocomputer technology, digital video imaging, ultrafast spinal scans, and tissue modulation technology.
A less-traumatic MISS approach can be viewed as being essentially spinal motion preservation surgery compared with open fusion surgery, after which a patient's condition often became worse.2,3,4,5,6,7,8 It may not be the final step in some patient's spinal treatment regimen. Rather, it can be an effective middle stage leading to recovery and follow-up therapy.7
Evolution and progress in developing innovative endoscopic surgical instruments for MISS — spinal endoscopes, intra-operative digital fluoroscopy systems, and digital video systems, as well as a range of laser technologies (tissue modulation technology) — have all demonstrated their clinical usefulness and are advancing MISS techniques.6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 MISS procedures have in fact progressed to the point where they are now commonly performed either in an office-based or freestanding surgical center.6,7,8,13,14,15,16,17 In the future, various computer-aided innovations such as surgical robotic systems and image-guided technology will offer new surgical advantages and enhancements to patient care.7
Thus far, a significant percentage of spinal surgeries has already been modified or replaced with MISS techniques.14,15 In view of this development, a new algorithm for the treatment of degenerative spinal disease is needed, as illustrated in Table 1.7 A patient's treatment begins conservatively with physical therapy and exercise, which may continue for 8 to 24 weeks. If no improvement is found after at least 12 weeks, the patient is considered to be showing signs of possible nerve damage. Physical findings should suggest continuing nerve damage. Proof of those findings can include lab testing, electromyography (EMG), or x-ray studies. The next step is then to determine the appropriate type of surgery to be performed.6,7,8,10,11,12,13,14,16,17
Bridging Endoscopic and Conventional Spinal Surgery
Currently, endoscopic spine surgery often uses small incisions through which instruments of less than 3 mm are used. Percutaneous approaches using these small instruments work well for many simple nerve decompression procedures. Some MISS requires a larger access than that offered by pure endoscopic techniques. The new SMART® Endoscopic Spine System (Karl Storz GmbH & Co., Tuttlingen, Germany) tubular access set for posterior approaches to the spine is designed to provide the necessary bridge between traditional and endoscopic spine surgical techniques.21,22 This system allows MISS procedures to be performed at various sized tubular access openings, thus providing the spine surgeon with both selection of access size and imaging type. Because of the unique features of the SMART® endoscopic tubular access set, the surgeon can take advantage of microscopic, endoscopic, or direct-vision imaging during spinal surgery.
Progressive sequential dilators allow the use of muscle-sparing dilatation techniques that gently spread the muscle fibers, rather than cutting them, with traditional microsurgical techniques. Because the surgeon can choose the size of the access, many procedures can be done using minimal access to arthroplasty techniques. A full range of strong Kerrison forceps, aggressive tissue-cutting forceps, trephines, microcurettes, and strong curettes provide the surgeon with the tools necessary to remove the cause of nerve decompression. Bipolar forceps provide a means of coagulation if bleeding should occur.
The SMART® endoscopic tubular access set also allows procedures in a continuous fluid irrigation mode, for laser and thermal therapies, and a dry well mode for manual tissue removal.
This SMART® Endolumbar spine tubular access surgery offers a range of benefits and advantages in spine procedures. First and foremost, it offers true minimal access and can be used in outpatient procedures using conscious sedation, as well as more complicated spinal procedures under general anesthesia. Using the SMART® endoscopic tubular access set, MISS offers the patient reduced postsurgical pain and a quicker recovery. Using the SMART® endoscopic tubular access system preserves muscle tissues, resulting in a faster recovery and allowing patients to begin postsurgical physical therapy sooner. The main advantages are:
Small skin incision
Atraumatic dilation using sequential dilators
Integral visualization and illumination of the operative field through the endoscope
Accommodates the use of direct visualization, loops, operative microscope, endoscopic, or hybrid surgical techniques
Stable triangulation between the cannula and endoscopic sheath removes the need for a separate holding system and frees up space in the surgical field
Minimally invasive spinal surgery
Using the SMART® endoscopic tubular access set, surgeons are able to remove larger spinal lesions and decompress nerves with visual confirmation using minimal access techniques.
Surgical Instruments and Preparation
Surgical instruments are necessary to perform endoscopically assisted lumbar spinal surgery with the following SMART® Endoscopic Spine System (Figs. 1a–1e):21,22
18 gauge spinal needle
Progressive serial dilator set
Progressive serial tubular retractors or trocars (working channels)
Endoscopic sheath, obturators (sharp and blunt), and 0° and 30° OD 4 mm, 18 cm telescopes
Digital three-chip video camera and light cable
Endoscopic video tower (Fig. 1f) with monitor, camera system, DVD recorder, xenon light source, and printer
Endoscopic Spinal Instruments
Trephines — 3 mm and 4.5 mm
Bayonet shaped dissector
Microspoon curette size 0
Probe and nerve hooks — 90° W4 13 cm
Bipolar forceps — bayonet shaped
Kerrison bone punches — 45° and 90° 3 mm
Tissue forceps — bayonet with teeth
Pituitary forceps for grasping — oval 3.5 mm and 5.5 mm
Endoscope holder (optional)
The surgeon may choose the access size, based on the procedure to be performed, and use monitored IV conscious sedation combined with local anesthesia. This allows the procedures performed on a higher anesthestic risk patients. The anesthesiologist or the anesthetist often administers 2 g of Ancef and 8 mg dexamethosone IV at the start of the procedure.
The use of surface EEG monitoring provides an added precision of anesthesia delivery and offers an additional safeguard for patients undergoing MISS, as well as an early warning system during procedures performed on patients under general anesthesia. Additionally, sterile needle electrodes are used for continuous neurophysiological (EMG) monitoring during the surgery to avoid or prevent undue trauma to the nerve root.23
Operating Room Setup
The patient is usually positioned on a set of bolsters (Fig. 2a) in a prone position (Fig. 2b) for lumbar spine surgery. A head holder with a reflective mirror is used for visualization of the patient's eyes and nasal/oral area.21,22,24
Localization and Portal of Entry
Using fluoroscopic guidance, the exact path of entry is determined. Using a “bulls-eye” target placement device, the exact point of entry (portal of entry) can be determined (Fig. 3), usually approximately 1.5 to 2 cm away from the midline at the spinal lateral recess. A positioning spinal needle is then guided to the exact target location. Next, a guide wire is inserted through the needle to the target zone and the puncture needle removed.15,21
Skin Incision and Approach
An approximately 12 mm to 14 mm long, vertical skin incision is made (Fig. 4). The fascia is then excised using dissecting scissors and the first dilator is introduced over the guide wire, separating the paravertebral muscle all the way to the target site. Little if any bleeding should occur during this process. Any bleeding can be controlled with bipolar coagulation.22
Dilation and Formation of the Access
Once the first dilator is placed, sequential dilators (Fig. 5) can be added to enlarge the skin and muscle opening without cutting the muscle (dilatation technology), if necessary, up to 20 mm. Once the appropriate access size has been reached, the SMART® access cannula or trocar (tubular retractor) can be advanced over the dilator using a gentle twisting motion until the target site (lumbar lamina) is reached(Fig. 6). C-arm fluoroscopy can be used to confirm the location of the instruments. Removal of the dilators is then performed to allow visual access so that the target is visible 21,22
Inserting the Endoscope
After visual confirmation is obtained through the access cannula, the dilator is reinserted into the cannula. An arthroscopic sheath with an obturator (sharp or blunt) is inserted through a screw opening on the attached side arm of the working cannula (Figs. 7a & 7b). The SMART® cannula set is designed to allow proper triangulation of the sheath to the cannula endoscopic portal on the distal end of the cannula. The sheath and obturator are advanced until the obturator touches the dilator. At this point, the dilator is removed from the cannula and the sheath gently advanced to just inside the access cannula. The side arm screw is tightened to hold the arthroscope sheath, the obturator is removed, and the endoscope is inserted and locked in place by the bayonet locking mechanism (Figs. 8a–8c). The video camera is then attached to the endoscope to bring the image onto the viewing monitor.22
The endoscope can be used as a primary or auxiliary imaging device, providing improved illumination and magnification of the operative site. It provides visibility and reduces the danger of damage to neural structures during the endoscopically assisted lumbar spine surgery. Fluoroscopy is used to confirm the position of the SMART® tubular retractor (Fig. 9).
When the tubular retractor is in place, the surgeon can also use alternate methods of visualization, switching between endoscopic and direct viewing, microscopic and endoscopic viewing, or endoscopic viewing alone to accomplish the lumbar microdecompressive surgery. As the surgeon becomes accustomed to the endoscopic view, the microscope may be abandoned, allowing better and wider endoscopic visualization of the entire operative site.
Partial caudal laminotomy and medial portion articular process can be resected with a Kerrison bone punch, the curette, or a rasp (Figs. 10a–10d). The ligamentum flavum is then removed (Figs. 11a & 11b) with a rongeur or by incision to expose the lateral lumbar gutter, dural sheath, and lumbar nerve root (Fig. 12). This bony resection facilitates access to the herniated lumbar disc without excessive retraction of the nerve root.
After dissection and retraction of the nerve root with the nerve root retractor, the protruded disc is identified and microdecompressive discectomy is performed (Figs. 13a–13c). The SMART® instruments are removed gradually. If necessary, hemostasis can be accomplished with bipolar coagulation. The lumbar fascia and skin edges are closed with simple sutures.
Often the SMART® Endoscopic Spine System can also be used effectively for decompression of lumbar spinal stenosis and the removal of intraspinal lesions, e.g., synovial cysts (Figs. 14a–14c), large sequestrated lumbar disc fragments, and tumors in the spinal canal.
Post surgically, ambulation begins immediately after recovery and the patient is usually discharged 1 hour after the procedure. They may shower and drive a car the following day. Applying an ice pack is helpful. Nonsteroidal anti-inflammatory drugs (NSAIDs) are prescribed as well as mild analgesics and muscle relaxants as needed. The patient can return to usual activities in 10 days to 2 weeks, provided heavy labor and prolonged sitting are not involved. A mild progressive exercise program can begin the day after the surgery.
Obviously, the SMART® Endoscopic Spine System for lumbar spine surgery provides an effective bridge between traditional spine surgery and endoscopic spinal surgery.21,22 The SMART® endoscopic lumbar spine surgery is an effective, safe, less traumatic, and easier form of spine surgery that offers treatment options for nerve decompression, including bulging or herniated discs, bone spurs, degenerative spinal disease, spondylosis, and spinal stenosis. In addition, this technique preserves spinal segmental motion and provides excellent access for spinal arthroplasty.7,21,22
This SMART® endoscopic tubular access system offers a number of advantages over existing MISS access approaches. The SMART® system can be used in a dry or fluid medium, can use various imaging combinations, and allows both local anesthesia with conscious sedation, and general anesthesia applications.
Most often, the SMART® cannulae allows triangulation of the endoscope micro spinal instruments in the operative field for better visualization which eliminates the bulky holding arms and allows some lateral movement of the cannula within the surgical field. The SMART® tubular access set increases the options available to a spine surgeon, providing true MISS procedures.22
The SMART® Endolumbar Spine System with various sizes of tubular access or trocars (working channels) provides a generous and optimal access for endoscopic MISS of microdecompression of herniated lumbar discs, degenerative spinal disease, spinal stenosis, and removal of intraspinal lesions as well as creating an access for spinal arthroplasty and spinal fixation.
With the unique features of the SMART® system, the surgeon can take advantage of microscopic, endoscopic, or direct vision for microdecompressive spinal surgery. This system bridges endoscopic and conventional spinal surgery. This less traumatic, easier, safe and efficacious outpatient MISS treatment leads to excellent results, speedier recovery, and significant economic savings.
John C. Chiu, M.D., D.Sc., F.R.C.S Department of Neurospine Surgery California Center for Minimally Invasive Spine Surgery California Spine Institute Medical Center 1001 Newbury Road Thousand Oaks, CA 91320 Telephone: (805) 375-7900 Fax: (805) 375-7906 Email: email@example.com