43 MIS-TLIF Comparison: Four Surgeons and Regions
43.1 How I Do It
Summary
Here, we highlight the MIS-TLIF technique by dividing it into various “steps”: Incision planning, screw insertion, facetectomy, disc/cage insertion, and rod placement/closure. To date, there is no consensus about the order of these steps, but we know that certain order is preferred by some authors, and we would like to offer the readers some more options to create a successful technique on their own.
Authors from different geographical areas around the globe sent in their case descriptions in the following format:
•General description of the patient
•Incision planning: Some authors use navigation (see Chapter 39), while others use X-ray to identify the pedicles. If a single level is treated, separate incisions (4) or connecting incisions, pedicle to pedicle, can be made (2).
•Screw insertion: Can vary from single step, K-wire, navigated insertion
•Facetectomy: This can be performed with osteotomes or with the aid of a high-speed drill bit.
•Disc/cage: Some authors use banana cages and bullet cages for sagittal balance and coronal balance improvement. Also, graft before the cage or graft inside and after the cage, fibrillar hemostatics around the cage or expandable cages are used (see Chapter 39).
•Rod placement and closure: Although there is not much variability in this step, it is worth noticing that some authors perform unilateral or bilateral facetectomies and place one rod before the other to achieve better compression or distraction, depending upon the case and step of the procedure.
Keywords: transforaminal fusion, interbody fusion, lumbar fusion, expandable cage
| Region: Asia Dr. Seang-Beng Tan | Region: North America Dr. Kevin Foley |
| Step 1: Representative case, initial setup, and incision planning | Step 1: Representative case, initial setup, and incision planning |
•A vertical line is drawn over the spinous processes. Then two subsequent lines parallel to the first are drawn, typically 3.5 to 4 cm, on either side of the initial line. •The actual distance of the two lines from the midline depends upon the size of the patient and can be measured from the preoperative magnetic resonance imaging (MRI) or computed tomography (CT). •A spinal needle is then placed on the ipsilateral side of the intended facetectomy, starting from the outer line and angled toward the facet joint. An anteroposterior (AP) fluoro-shot is taken. •An incision, approximately 3 cm long, centered over the spinal needle is made and it is deepened down to the fascia. |
•MRI and X rays of the representative case. •Patients are placed in the prone position on a flat-top Jackson table with gel chest rolls. •The C-arm fluoroscope is then brought into AP position to capture the appropriate fluoroscopic image, which produces a “true AP” view of each vertebral body. •A lateral fluoroscopic image is also taken, and the C-arm coordinates recorded for a “true lateral” image for each level. •A lateral fluoroscopic image is also taken, and the C-arm coordinates recorded for a “true lateral” image for each level. •In obese patients in whom the spinous processes cannot be easily palpated, the midline can be confirmed with an AP fluoroscopic image. Using lateral fluoroscopy, a 22-gauge spinal needle is inserted through one of the paramedian lines to localize the incision; the needle should be directed slightly medially, approximately 20 to 30 degrees. |
| Region: Latin America Dr. Nestor Taboada | Region: Europe Dr. Guiseppe Barbagallo |
| Step 1: Representative case, initial setup, and incision planning | Step 1: Representative case, initial setup, and incision planning |
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•With the image intensifier, the midline is marked on the skin as both L4L5 pedicles, the disc space, and the tip of L5 transverse process on the side where the cage will be inserted. •To properly visualize the pedicles, the end plates must not be superimposed, and the spinous process must be centered. In some cases, it is necessary to rotate the table slightly until these parameters are achieved. It is always preferable to keep the C-arm at “zero or neutral” so that the surgeon does not lose the “feeling” during the placement of the screws and the cage. •The initial AP views (two on average) allow the identification and marking of L4L5 pedicles, spinous process, and end plate. If the patient has a rotational deformity which requires the table to be moved, the views can increase (double). •About 1-cm lateral to the mark of the pedicles, which corresponds on average to 3 to 4 cm off the midline, skin is infiltrated with 2 mL of xylocaine with epinephrine at the three points of introduction of screws and 5 mL of xylocaine with epinephrine at the site where decompression will be performed and the cage will be inserted. The skin incision at L5 level, where the cage will be introduced and decompression will happen, is approximately 2 cm long. •The scalpel incisions of the skin and then fascia allow adequate introduction of dilators and retractor. Using the previously placed K-wire and cannula in the L5 pedicle, the dilators are introduced, turning them constantly in a clockwise direction, to separate as much muscle as possible, supported on the pedicle and the facet complex. | •We start the fluoroscopy-guided surgical procedure on the contralateral side. •Under AP fluoroscopic control, a K-wire or a knife is placed in line with the outer border of the ipsilateral pedicles, about 2 cm laterally, to mark the skin incision and entry point.
•Percutaneous instruments and screws will follow a lateral to medial trajectory. Such technique allows achieving better triangulation of the screws, with their tips aiming toward the vertebral body midline, thus increasing the biomechanical efficiency of the implant. •In cases of navigation-guided surgery, percutaneous screw trajectory is checked by navigating the projection of passive navigation probe, and skin incisions are marked accordingly. •We prefer to use small multiple skin incisions to insert the percutaneous screws; however, a single, longer skin incision can also be used. Skin and prevertebral fascia are separately incised and, in cases of copious bleeding from soft tissues, hemostasis is obtained with bipolar forceps. |
| Region: Asia Dr. Seang-Beng Tan | Region: North America Dr. Kevin Foley |
| Step 2: Facetectomy | Step 2: Screw Placement |
•With the muscles split using the hemostat, a blunt trochar is then placed directly over the facet joint. •While wanding the trochar, it is also used as a feeler to confirm that the outer edge of the facet joint is palpable. •Finally, a 20 mm tube is placed over the dilator and locked into position. •The operating table is now tilted 20 to 30 degrees away from the surgeon. •A right-angled osteotome is then used to osteotomize the lateral facet.
•The starting point of the osteotomy should be in the middle of the tube, assuming that the tube had been previously centered over the disc space. The lateral facet is then removed using large pituitary rongeurs and used for bone graft. |
•Under fluoroscopic guidance, pedicle access needles are used to cannulate and safely traverse the pedicles. Although this step may be done using AP views alone, we prefer to use lateral views as well. •A true AP fluoroscopic image is obtained to confirm the medial-lateral coordinate for the entry point (the needle tip is adjusted as necessary to achieve this). •For a left pedicle, the ideal entry point is at the 9 o’clock position, whereas for a right pedicle the ideal entry is at the 3 o’clock position. Once the entry point is confirmed on AP, the needle is directed 20 to 30 degrees medially and malleted to penetrate the bony cortex and advanced into the pedicle to just proximal to the vertical midline of the pedicle. •Once the access needle is in proper position, the inner trochar is removed and a K-wire is inserted through the needle and into the vertebral body. The access needle is then removed, making sure the Kwire remains in place. The proximal end of the K-wire is then attached to the drape using a hemostat. The same sequence is then repeated for the remaining pedicles. |
| Region: Latin America Dr. Nestor Taboada | Region: Europe Dr. Giuseppe Barbagallo |
| Step 2: Screw placement | Step 2: Screw placement |
•In our service, the four pedicles are cannulated with Jamshidi needles, through which the K-wires are introduced. •On the contralateral side of where the TLIF is to be made, the two cannulated screws with their respective work sleeves are placed. •On the TLIF (facetectomy) side, the K-wire of L4 is fixed to the operative field and the dilators are inserted through the K-wire of L5. Finally, the retractor is positioned to perform the decompression and placement of the cage. During the introduction of the Jamshidi needles, the surgeon and his assistant position two needles at the time, first L4 bilaterally and when the midpoint of the pedicle is reached, it is confirmed with a lateral view to determine that needles are already in the vertebral body and continue the introduction of the needle avoiding violating medial or lateral wall. The same process is done at the same time in L5 and in this way the number of views is decreased. Once the pedicles are cannulated, decompression is performed (next step). | •A Jamshidi needle, followed by a K-wire, is inserted into the pedicle according to the standard technique; cannulated screws are then inserted over K-wires under navigation or fluoroscopic guidance.
•K-wires must always be meticulously checked during screw insertion, particularly in osteoporotic patients, because impingement of the screw’s tip on the K-wire can push the wire anteriorly and cause breakage of anterior vertebral wall. •Fluoroscopic check during this step is advised. On the contralateral side (i.e., the side selected for facetectomy and TLIF), after identifying the pedicles as described above, a single skin incision linking together the pedicles above and below the index disc level for the m-open TLIF is performed. •A Jamshidi needle is then inserted into the first pedicle, and through it a K-wire is passed and left in place. •The wire is bent down and secured with a towel clip. The same technique is applied to the other pedicle before positioning a tubular retractor, either fixed or expandable, which is then secured to the table with a self-retaining articulated arm.
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| Region: Asia Dr. Seang-Beng Tan | Region: North America Dr. Kevin Foley |
| Step 3: Discectomy | Step 3: Facetectomy |
•At this point in time, the facet capsule would have to be removed first. •If the disc space cannot be entered, then the location is marked with a right-angled osteotome, and a lateral fluoro-shot is taken with the osteotome in position.
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•After infiltrating local anesthetic into the subfascial musculature, a K-wire and sequential tubular dilators are inserted through one of the previously created 2.5-cm skin incisions. The side of placement of the tubular retractor is dictated by the side of the patient’s leg pain. •A 22-mm-diameter tubular retractor of appropriate length is inserted over the final dilator, after which the dilators are removed.
•For a typical unilateral decompression, we dock the tube over the facet complex. If we are planning a bilateral decompression, we dock the tube as far medially as possible, against the base of the spinous process (this facilitates performing an “over the top” approach to the contralateral portion of the decompression). •The ideal position of the 22-mm tube under lateral fluoroscopy should be between the pedicles and pointing toward the disc space. •Following soft-tissue removal, the facet joint line should be visible between the lamina and the inferior articular process medially, and the superior articular process laterally. If necessary, the 22-mm tube can be moved by inserting the largest dilator and “wanding” the tube in the appropriate direction to gain access to adjacent anatomy. •The microscope is now utilized to proceed with the decompression within the 22-mm tube. Residual soft tissue overlying the bone at the base of the tubular retractor is removed with a combination of monopolar cautery and pituitary rongeurs. •Short and long ball–hook probes can then be used to confirm that the nerve roots have been fully decompressed. An ideal TLIF exposure includes resection of enough of the facet complex to leave significant space lateral to the dural sac at the level of the disc space. |
| Region: Latin America Dr. Nestor Taboada | Region: Europe Dr. Giuseppe Barbagallo |
| Step 3: Facetectomy | Step 3: Facetectomy |
•Once the facet complex is identified, it must be determined if only the external facet is to be resected to introduce the TLIF cage, or if it is necessary to also resect the internal facet to release the L5 root and/or over the top.
•It is recommended to use a 90-degree osteotome that does not obstruct the tubular vision (Fig. 45.21). The first cut is directed vertical and intra-articular, reaching the base of the pedicle; the second cut is perpendicular to the first one at the base of the external facet, trying not to exceed in depth the union with the transverse process. Then with the same osteotome, the external facet is released. •Using a high-speed drill with a small tip (3 mm), the remaining external facet and part of the internal facet are drilled, allowing a 1-cm square window. It is preferable to identify the disc by resecting the capsular ligament and identifying the fat surrounding the emerging root, in this case L4, and in this triangle, perform the discectomy.
•In patients with severe spinal stenosis associated with listhesis, once the internal capsule is milled, the L5 root exposed, and the foramen is extended, the tube is tilted, visualizing the ipsilateral lamina that is completely drilled from superior to inferior, avoiding a tunnel decompression (the ligamentum flavum must be preserved). •The base of the spinous process and the internal border of the contralateral lamina over ligamentum flavum are drilled until a dome is visualized which is the contralateral facet that must be drilled. At this point, if the ligamentum flavum has been resected, reject the dural sac rostral in order to visualize the contralateral L5 root. With angulated Kerrison, resect the roof of the contralateral L5 foramen; unlike what it seems it is more comfortable to resect the contralateral foramen roof of L5 root. •Using the tip of the bayonet dissector positioned over the foramen, AP fluoroscopy is taken to verify that the contralateral foramen has been reached. This means we have completed our “over the top” approach. | •TLIF is usually performed on the side where worse radicular symptoms are reported or, in cases with bilateral symptoms, on the side where the compressive disease is more severe on imaging. In multilevel cases, when two adjacent TLIFs from the same side are planned, single skin and fascia incisions, including all the three pedicles and the two intervening disc spaces, are made; other pedicle screws can be inserted through additional, smaller skin incisions. •When both the pedicles are identified and K-wires left inside each vertebral body, as described above, a tubular retractor is positioned over the facet joint covering the index disc space. Under AP fluoroscopy, sequential dilating tubes are inserted to progressively and bluntly split the paraspinal muscles over the index facet joint. An expandable tubular retractor, held in place by an articulated-arm clamp, is then docked over it and secured to the table. The articulated-arm clamp must be oriented and fixed, avoiding superimposition of its projection over the disc space on fluoroscopic images. Its medial-lateral and cranial-caudal position is checked with AP fluoroscopy. •The microscope is then brought in place. •If required for further safety, particularly during the initial learning curve, after stripping the muscles off the facet joint, and slightly angulating the microscope, it is possible to see the K-wires entering the cranial and caudal pedicles on the inner surface of the tubular retractor’s blades. •A high-speed drill and/or Kerrison rongeur are used to perform the facetectomy. We use 5 or 6 mm spherical cutting burr to remove the external cortical bone of the facets and the cancellous bone. A diamond burr is used for the inner cortical surface, close to the neural structures. After removing the facet joint, the ipsilateral lamina, and the base of the spinous process (in cases requiring medial decompression), the ligamentum flavum is exposed and dissected off the dura; its resection is completed with Kerrison rongeurs. Small bony fragments can be harvested and used to fill the intervertebral cage(s).
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| Region: Asia Dr. Seang-Beng Tan | Region: North America Dr. Kevin Foley |
| Step 4: Cage insertion | Step 4: Discectomy and cage insertion |
•Once the disc is exposed, an annulotomy is done with a scalpel. •Having done so, the osteotome can be rotated 90 degrees, thereby distracting the disc space. •The length of the cage in general is measured preoperatively on the MRI or CT, but the most commonly used length would be 23 or 27 mm. •A funnel is inserted into the disc space and bone grafting is performed.
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•The identification of the exiting and traversing nerve roots will yield the safe entry zone for discectomy. •A bayoneted 15-blade is then used to perform a large annulotomy. Disc material can be retrieved with pituitary rongeurs. •We start with a disc osteotome to begin the distraction process. Once adequate interbody height has been restored, we proceed with the next step (contralateral screw-rod fixation) to maintain the distraction. •Trials are used to determine the proper dimensions of the chosen interbody fusion device. •The harvested autograft bone dust is packed into the expandable device. •The combined autograft and cancellous allograft bone is placed into the disc space and packed contralaterally and ipsilaterally, leaving a channel for placement of the interbody fusion device. •The provisionally tightened set screw on the contralateral screw-rod construct is loosened so that the interbody implant can be expanded with minimal resistance. Following this expansion, the set screw is fully tightened. |
| Region: Latin America Dr. Nestor Taboada | Region: Europe Dr. Barbagallo |
| Step 4: Discectomy and cage insertion | Step 4: Discectomy and cage insertion |
•First, we coagulate the vessels over the disc in the safety triangle using bipolar cautery (intensity of 8). With the scalpel, a box annulotomy of approximately 1 cm is performed, and with straight and 30-degree alligator forceps, the initial discectomy is performed. •The interspace is filled with autologous bone taken from the remains of the facet complex and ipsilateral lamina combined with bone matrix and blood taken from the vertebral body at the time of cannulation with the Jamshidi needles.
•Once the cage is inserted, medial facetectomy and “over the top” approach can be performed if necessary. •Leaving the internal facet intact until the positioning of the cage avoids the contact of the implant with the L5 root and the dural sac, and thus possible tears or direct injuries of these structures can be avoided. •Bullet-type cages are preferred as they are more comfortable to position in the TLIF; when you use banana-type cages. •Once the cage is positioned, in a lateral view evaluate the depth of the cage and in an AP view evaluate that it is as medial as possible; in other words, the tantalum lines should be seen at the level of the spinous process. | •After dissection of the epidural plexus, the dural sac is gently retracted. •In this phase, it is important to maintain the visual control of the nerve root axilla and avoid excessive traction, which can cause a dural tear. •The posterior longitudinal ligament and the annulus are incised to gain access to the disc space. •Disc fragments are initially removed with punches; then spreaders and shavers of progressively increasing size are used to fragment the disc and remove the cartilaginous end plates. •A proper end plate preparation is essential to enhance chances of fusion. After completing the discectomy, a cage trial is inserted and fluoroscopically checked. Banana-shaped cages are used to obtain a better restoration of segmental lordosis. •Conversely, bullet cages are preferred in cases of coronal imbalance. •During disc preparation and cage insertion, if necessary, the contralateral screws and rod can be used to apply some intervertebral distraction and facilitate both the access to and the maneuvers within the disc space as well as cage insertion.
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| Region: Asia Dr. Seang-Beng Tan | Region: North America Dr. Kevin Foley |
| Step 5: Screw + rod placement | Step 5: Rod placement and closure |
•Bilateral K-wires are inserted inside the pedicles using the percutaneous fluoroscopy technique (AP/LAT or Bullseye) (top images a and b). Cannulated screws are inserted over the K-wires (lower images a).
•For multiple-level fixation, intraoperative cone CT imaging with computer navigation–assisted pedicle screws, or preoperative CT imaging with intraoperative robot–assisted pedicle screws may be helpful in reducing radiation exposure to the surgical team. •The rod length is predicted with the aid of special tools from the set. •The rod is guided down and secured in place with two caps, leaving them loose enough to hold the rod but allowing rod sliding to allow compression. •Compression of the screws is done especially when banana cages are used in order to create segmental lordosis and to favor graft compression.
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•The tubular retractor is removed after hemostasis has been confirmed; bipolar cautery and thrombin-soaked absorbable gelatin sponge are used as necessary. Following this, the microscope can be taken out of the field. • •An ipsilateral, percutaneous pedicle screw-rod construct is then placed and the K-wires are removed. •Final lateral and AP fluoroscopic images are obtained to confirm proper hardware placement, and the C-arm is removed from the field.
•The fascia is closed with 2–0 absorbable sutures. The subcutaneous tissues are reapproximated with 3–0 absorbable sutures. The skin is reapproximated with Steri-Strips and dressed. Drain is unnecessary. |
| Region: Latin America Dr. Nestor Taboada | Region: Europe Dr. Giuseppe Barbagallo |
| Step 5: Rod placement and closure | Step 5: Rod placement and closure |
•When an “over the top” approach is performed, an Absorbable Hemostat (Surgicel Fibrillar) is very useful to control layer bleeding (Video 43.1). •Before closing, the wounds are washed with 0.9% saline solution and the muscle plane is infiltrated with xylocaine without epinephrine at 1%, since the passing of the percutaneous bar can generate bruises along the way that can be painful in the postoperative period. •The first percutaneously introduced rod to which compression is given is ipsilateral to the cage, then compression is applied to the contralateral rod and a final lateral image is obtained to verify compression.
| •Rods are curved according to physiological spinal curvature at the targeted levels. Rods are inserted through the screw extensions, starting from the caudal or cranial end according to the case. •The correct length, shape, and position of the rod are checked fluoroscopically, both in AP and lateral views. •Screw extenders are removed, and final AP and lateral fluoroscopic images are obtained. Deep fascia and subcutaneous layers are sutured with 2–0 absorbable stitches. Metal clips are applied to the skin.
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Video 43.1MIS TLIF cage insertion with K-wire through the retractor.
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