John C. Chiu, M.D., F.R.C.S., D.Sc.
Director, Department Neurospine Surgery
California Center for Minimally Invasive Spine Surgery
California Spine Institute Medical Center
Thousand Oaks California USA
Citation:
John C. Chiu: SMART® Endoscopic Spine System for Lumbar Microdecompressive
Surgery . The Internet Journal of Minimally Invasive Spinal Technology. 2007. 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,
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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.
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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.
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, 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 officebased 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.
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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.
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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.
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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,
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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.
Advantages
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:
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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
Faster recovery 21 , 22
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
Figure 1a: "Bulls eye" target device, guide wire, SMART tubular serial retractors
(progressive ID 8.3mm, 12.4mm, 16.5mm, 20.6mm) Gradual dilators, serial, progressive sizes, OD, 4.6mm, 8.1mm, 12.1mm, 14.5mm, 16.2mm, 18.5mm,
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20.2mm
Figure 1b: Endoscopic Sheath with 2 rotatable stop cocks, 5.5 mm, Obturator,
Sharp, Obturator, Blunt Hopkins Telescope II -
0° Hopkins Telescope II - 30°,
Kerrison Bone Punch 45° - 3 mm, Kerrison Bone Punch 90° -3 mm, Trephine 3 mm
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Trephine 4.5 mm
Figure 1c: Nerve Retractor 15 cm working length, 130 degree angle at handle - 4 mm Dissector, Bayonet shaped, Bipolar Forceps, bayonet-shaped, Bipolar
Coagulating Forceps, Spoon Curette Size 0 Rasp, Nerve Hook 90 ° Nerve Hook 90
° Width 4mm, 13 cm, Freer Elevator double ended,
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Figure 1d: T-A Grasping Forceps 7mm jaws -3.5 mm, T-A forceps, biopsy, 3mm
Jaws Forceps, spoon oval - 5.5mm forceps, spoon oval- 3.5mm, cutting forceps
Figure 1e: Tissue Forceps Bayonette w teeth, Fergusson Suction tube,
Osteotome - 7mm, Chisel - 4 mm, Periosteal elevator -14mm, Mallet
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Access System
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“Bulls-eye” locator
18 gauge spinal needle
Guide wire
Progressive serial dilator set
Progressive serial tubular retractors or trocars (working channels)
Visualization Equipment
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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
Figure 1f: Endoscopic video tower - AIDA (OR1 - Karl Storz Endoskope) with endo-video monitor, DVD recorder, Xenon light source, endoscope, camera, and
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printer.
Endoscopic Spinal Instruments
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Trephines — 3 mm and 4.5 mm
Bayonet shaped dissector
Microspoon curette size 0
Standard curettes
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)
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Anesthesia
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.
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Patient Positioning
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.
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Figure 2a: A set of bolsters for lumbar spine surgery, head holder with reflective mirror for visualization of patient's eyes and nasal/oral area
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Figure 2b: In prone position on 2 bolsters
Localization and Portal of Entry
Using flu oroscopic 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.
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Figure 3: Under fluoroscopic guidance the portal of entry and (point of incision) by placing the "bull's-eye" target device at the point of incision ( at lateral recess)
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
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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.
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Figure 4: Small skin incision is made at the marked point identified by "bull's eye" target device (approximately 12-14 mm.)
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). Carm 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
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Figure 5: Dilator over guide wire in position
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Figure 6: Illustration of placing the cannula (tubular retractor) over the dilator
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.
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Figure 7a: Introduction of endoscopic sheath and obturator
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Figure 7b: Illustration of introduction of endoscopic sheath and obturator
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Figure 8a: Endoscope in place for operation
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Figure 8b: Endoscope in place for operation
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Figure 8c:Illustration of endoscope in place for operation
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 lu mbar spine surgery. Fluoroscopy is used to confirm the position of the SMART® tubular retractor (Fig. 9).
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Figure 9: Fluoroscopic x-ray images of SMART system in surgery - rongeur for laminotomy, discectome in disc space, and curette in action
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.
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Figure 10a: Endoscopic view of the image of the rongeur performing caudal laminotomy for superior lamina
Figure 10b: Curetting hypertrophic facet joint
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Figure 10c: Curetting lumbar lamina
Figure 10d: Decompression of the inferior surface of lamina with a rasp
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Figure 11a: Illustration of Incision and resection of ligamentum flavum
Figure 11b: Endoscopic view of Incision and resection of ligamentum flavum
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Figure 12: Endoscopic view of dissection of nerve root and dura along lateral lumbar gutter
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.
Figure 13a: A very large extruded and herniated lumbar disc
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Figure 13b: Endoscopic view of the large extruded herniated lumbar disc
Figure 13c: Removal of a large extruded lumbar disc
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.
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Figure 14a: Large lumbar juxtafacet synovial cyst, at L4-L5 sagital view MRI
Figure 14b: Large lumbar juxtafacet synovial cyst, at L4-L5 axial view MRI
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Figure 14c:Endoscopic view of the residual cyst (short arrow) of a large synovial cyst excised along the lumbar gutter and the dural sac (long arrow)
Postoperative Care
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.
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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.
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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.
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The SMART® tubular access set increases the options available to a spine surgeon, providing true MISS procedures.
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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 f eatures 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.
Address for Correspondence To
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: chiu@spinecenter.com
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