SURGICAL TECHNIQUE
Minimally Invasive Transforaminal Lumbar Interbody Fusion Junyoung Ahn, BS, Ehsan Tabaraee, MD, and Kern Singh, MD
Abstract: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is performed via tubular dilators thereby preserving the integrity of the paraspinal musculature. The decreased soft tissue disruption in the MIS technique has been associated with significantly decreased blood loss, shorter length of hospitalization, and an expedited return to work while maintaining comparable arthrodesis rates when compared with the open technique particularly in the setting of spondylolisthesis (isthmic and degenerative), recurrent symptomatic disk herniation, spinal stenosis, pseudoarthrosis, iatrogenic instability, and spinal trauma. The purpose of this article and the accompanying video wass to demonstrate the techniques for a primary, single-level MIS TLIF. Key Words: transforaminal lumbar, interbody fusion, spine surgery (J Spinal Disord Tech 2015;28:222–225)
Intraoperative fluoroscopy (C-arm) Surgical loupes or microscope Tubular dilators Expandable versus fixed Guide wires and Jamshidi needle (CareFusion, San Diego, CA) Percutaneous pedicle screws Interbody trial spacer and cage
Positioning Following successful intubation, the patient is positioned prone on a Jackson table. The patient’s arms are abducted and flexed to 90 degrees. Appropriate padding is placed under the pressure points. A chest roll may be utilized to increase the lumbar lordosis facilitating reconstruction with the spinal instrumentation. The intraoperative C-arm should be positioned opposite of the surgeon and pathology (Fig. 1).
INDICATIONS
SURGICAL TECHNIQUE
The indications for a minimally invasive transforaminal lumbar interbody fusion include the following: Nonunion Iatrogenic instability Recurrent, symptomatic disk herniation Spinal stenosis in the setting of instability:
Under fluoroscopic guidance, the appropriate level is localized. From the anteroposterior (AP) perspective, the pedicles (left and right) should be equidistant from the midline (spinous process).
Spondylolisthesis (low grade; Meyerding grade I or II) i Isthmic ii Degenerative
OPERATING ROOM SET-UP
Step 1: Localization
Step 2: Incision A 2–3 cm incision is made immediately lateral to the pedicle on the side of the pathology. An incision can be made on the contralateral side for percutaneous pedicle screw placement in the setting of bilateral instrumentation.
Instruments/Materials Required
Step 3: Exposure and Visualization
Jackson table
The Jamshidi needle is advanced, moving through the fascia and between the paraspinal musculature until the needle reaches the junction of the transverse process and the facet complex.
Received for publication April 16, 2015; accepted May 13, 2015. From the Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL. The authors declare no conflict of interest. Reprints: Kern Singh, MD, Rush University Medical Center, 1611W. Harrison St., Suite #300, Chicago, IL 60612 (e-mail: kern.singh@ rushortho.com). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www.jspinaldisorders.com. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
222 | www.jspinaldisorders.com
This junction is located at the 2 o’clock position of the right pedicle and at the 10 o’clock position of the left pedicle as confirmed by AP fluoroscopy (Fig. 2). Under fluoroscopic guidance, the Jamshidi needle is incrementally (5 mm) advanced into the pedicle. Caution should be taken to not advanced the Jamshidi needle past the medial edge of the pedicle on the AP fluoroscopic image. J Spinal Disord Tech
Volume 28, Number 6, July 2015
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 6, July 2015
Minimally Invasive TLIF
FIGURE 1. Photograph of a patient positioned prone on a Jackson table with appropriate padding, abducted shoulders, and flexed arms.
The Jamshidi needle is advanced 1.5–2 cm into the pedicle after which a Kirschner guide wire is placed into the needle shaft. The tip of the guide wire should be advanced until it appears to just cross the medial edge of the pedicle as confirmed by AP fluoroscopy (Fig. 3). At this time, a lateral fluoroscopic image is obtained to confirm that the guide wire has crossed the posterior wall of the vertebral body. iii Note: The Jamshidi needle should be redirected if it has been advanced beyond the medial edge of the pedicle on the AP fluoroscopic image and the posterior wall of the vertebral body has not been traversed on the lateral image. Following the placement of guide wires at the pedicles above and below the level of fusion, an initial dilator is introduced between the guide wires. Following sequential dilation, a 21 mm tubular retractor is introduced and docked onto the pars interarticularis at the level of the target disk space. Adequate visualization is achieved by removing the remaining soft tissue and muscles utilizing electrocautery and pituitary rongeurs.
FIGURE 3. Anteroposterior intraoperative fluoroscopic image demonstrating appropriate placement of the guide wires directed to the pedicles above and below the target level. Note the medial wall of the pedicles are not crossed by the guide wires in the anteroposterior plane.
Step 4: Laminectomy The lamina, pars interarticularis, and the facet joint are visualized. The lamina and the medial edge of the pars interarticularis are removed utilizing a high-speed burr. The local bone graft obtained from the laminectomy can be saved in a suction canister. This bone graft can be used as a bulking agent for the intervertebral space.
Step 5: Bilateral Decompression To perform a bilateral decompression, the tubular retractor is medialized and the spinous process is undercut. To ensure safety, the underlying ligamentum flavum serves as a barrier between the burr and the dura. Both sets of the traversing nerve roots (now free and mobile) should be visualized. A wide decompression of the thecal sac is achieved.
Step 6: Facetectomy
FIGURE 2. Anteroposterior intraoperative fluoroscopic image demonstrating the Jamshidi needle positioned at the 2 o’clock position of the right pedicle. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
The removal of the pars interarticularis can be done very quickly with the use of a burr and a lateral fluoroscopic image. The pars should be resected in line with the inferior endplate of the superior level. Resecting the pars any higher will result in unnecessary exposure of the exiting nerve root. www.jspinaldisorders.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
223
J Spinal Disord Tech
Ahn et al
The facetectomy is performed and the inferior articular process can be removed en bloc. The inferior articular process can be cleaned of soft tissue and morselized on the back table in order for it to be used as bone graft in the intervertebral disk space. The superior articular process (of the inferior level) is resected until the medial and superior wall of the pedicle is abutted. This step is important to create a large working zone in the transforaminal space.
Step 7: Removal of the Ligamentum Flavum A curved microcurette is utilized to reflect the ligamentum flavum as 2 large pieces on each side of the spinal canal.
Step 8: Preparation of the Intervertebral Disk Space The epidural veins overlying the intervertebral disk space are identified and coagulated utilizing an electrocautery device (Fig. 4). The transforaminal space is visualized and the anatomical landmarks should be noted including (1) traversing nerve root (medial), (2) exiting nerve root (superior and lateral at the disk space), and the (3) the pedicle of the inferior level (inferior).
Step 9: Preparation of the End Plate This step is not demonstrated in the video, Supplemental Digital Content 1, http://links.lww.com/JSDT/A6. Pituitary rongeurs, curettes, and end plate shavers are utilized to prepare the end plate using lateral fluoroscopic visualization. Care should be taken when using end plate shavers in the setting of osteoporosis as end plate violations can occur resulting in intervertebral cage subsidence.
Volume 28, Number 6, July 2015
Step 10: Trial and Placement of the Interbody Cage The trial interbody cage is placed and sized to restore the appropriate lumbar lordosis. The disk space may be filled with local bone graft or a bone graft substitute to enhance fusion. Bone is typically placed in the anterior portion of the disk space, followed by the intervertebral cage. It is the senior author’s preference to also back fill bone behind the cage to maximize graft-end plate contact. Under fluoroscopic guidance, the interbody cage should be gently impacted into appropriate position with the ideal placement of the cage being in the anterior third of the disk space to maximize lordosis.
Step 11: Percutaneous Pedicle Screw Placement The cannulated trocar (guide needle) is placed at the 2 o’clock (right pedicle) or the 10 o’clock (left pedicle) positions at the upper outer aspect. Starting point and the trajectory is verified utilizing fluoroscopy before advancement of the cannulated trocar. A lateral fluoroscopic image is obtained to confirm that the cannulated trocar has advanced beyond the posterior vertebral body margin to ensure that a medial wall violation has not occurred. Following confirmation, the inner sleeve is removed and the Kirschner wires are advanced through the cannulated guide needle. After securing the Kirschner wires in the vertebral body, the outer sleeves are removed and the wires secured to the surgical drapes. At this point, the decompression and interbody device placement are completed (see above). Pedicle taps are introduced over the guide wires and advanced towards the pedicles. (Fig. 5). EMG-evoked potentials are utilized to detect any breach of the medial wall of the pedicle. Following removal of the pedicle taps, cannulated pedicle screws are advanced over the Kirschner wire. Under EMG monitoring the screws are placed over the Kirschner wire and into the pedicles. Care should be taken to confirm via fluoroscopic imaging that the screw is advanced collinear to the Kirschner wire to prevent any bending or breakage of the wire. Following placement of the screws, the extensions are aligned. A contoured rod can then be passed underneath the fascia. After securing the connecting rode with the set screws, fluoroscopic imaging confirms appropriate positioning of the instrumentation.
POSTOPERATIVE PROTOCOL FIGURE 4. Tubular retractor image demonstrating the visualization of the intervertebral disk space following coagulation of the overlying epidural veins.
224 | www.jspinaldisorders.com
Complications Incidental durotomies may present as posture-dependent headaches with accompanying nausea and vomiting. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 6, July 2015
FIGURE 5. “Bulls-eye” intra-operative fluoroscopic image demonstrating the center placement of the guide wires within the pedicle.
Most cases of durotomy may be treated conservatively utilizing a collagen sponge and a tight fascial closure. Early postoperative mobilization may be recommended if the patient is asymptomatic.
Minimally Invasive TLIF
FIGURE 7. Postoperative mid-sagittal computed tomographic image demonstrating a solid arthrodesis with significant bridging bone following an L4–5 MIS TLIF.
Dural repair kits are also available and it is the senior author’s preference to use 4-0 nylon suture along with an arthroscopic knot passer to perform the dural repair.
PEARLS AND PITFALLS Lumbar pedicles are medially angulated (posterior to anterior) in the transverse plane. Obese patients require a slightly more lateral incision. The laminectomy and the facetectomy should be performed under direct and fluoroscopic visualization. Hypertrophy of superior articular process of the inferior level may cause stenosis at the lateral recess. Care should be taken to address this stenosis as it occurs at the disk space level and distal to the TLIF working zone. Lateral fluoroscopic imaging during the end plate preparation is imperative to avoid inadvertent penetration of the end plate and anterior longitudinal ligament.
FIGURE 6. A 40-year-old female who underwent and L4-5 MIS TLIF for degenerative spondylolisthesis and spinal stenosis. Postoperative coronal computed tomographic (CT) image demonstrating pedicle screws at the L4 and L5 pedicles with >50% bone bridging in the interbody cage. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jspinaldisorders.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
225
Minimally Invasive Transforaminal Lumbar Interbody Fusion Junyoung Ahn, BS, Ehsan Tabaraee, MD, and Kern Singh, MD
Abstract: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is performed via tubular dilators thereby preserving the integrity of the paraspinal musculature. The decreased soft tissue disruption in the MIS technique has been associated with significantly decreased blood loss, shorter length of hospitalization, and an expedited return to work while maintaining comparable arthrodesis rates when compared with the open technique particularly in the setting of spondylolisthesis (isthmic and degenerative), recurrent symptomatic disk herniation, spinal stenosis, pseudoarthrosis, iatrogenic instability, and spinal trauma. The purpose of this article and the accompanying video wass to demonstrate the techniques for a primary, single-level MIS TLIF. Key Words: transforaminal lumbar, interbody fusion, spine surgery (J Spinal Disord Tech 2015;28:222–225)
Intraoperative fluoroscopy (C-arm) Surgical loupes or microscope Tubular dilators Expandable versus fixed Guide wires and Jamshidi needle (CareFusion, San Diego, CA) Percutaneous pedicle screws Interbody trial spacer and cage
Positioning Following successful intubation, the patient is positioned prone on a Jackson table. The patient’s arms are abducted and flexed to 90 degrees. Appropriate padding is placed under the pressure points. A chest roll may be utilized to increase the lumbar lordosis facilitating reconstruction with the spinal instrumentation. The intraoperative C-arm should be positioned opposite of the surgeon and pathology (Fig. 1).
INDICATIONS
SURGICAL TECHNIQUE
The indications for a minimally invasive transforaminal lumbar interbody fusion include the following: Nonunion Iatrogenic instability Recurrent, symptomatic disk herniation Spinal stenosis in the setting of instability:
Under fluoroscopic guidance, the appropriate level is localized. From the anteroposterior (AP) perspective, the pedicles (left and right) should be equidistant from the midline (spinous process).
Spondylolisthesis (low grade; Meyerding grade I or II) i Isthmic ii Degenerative
OPERATING ROOM SET-UP
Step 1: Localization
Step 2: Incision A 2–3 cm incision is made immediately lateral to the pedicle on the side of the pathology. An incision can be made on the contralateral side for percutaneous pedicle screw placement in the setting of bilateral instrumentation.
Instruments/Materials Required
Step 3: Exposure and Visualization
Jackson table
The Jamshidi needle is advanced, moving through the fascia and between the paraspinal musculature until the needle reaches the junction of the transverse process and the facet complex.
Received for publication April 16, 2015; accepted May 13, 2015. From the Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL. The authors declare no conflict of interest. Reprints: Kern Singh, MD, Rush University Medical Center, 1611W. Harrison St., Suite #300, Chicago, IL 60612 (e-mail: kern.singh@ rushortho.com). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www.jspinaldisorders.com. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
222 | www.jspinaldisorders.com
This junction is located at the 2 o’clock position of the right pedicle and at the 10 o’clock position of the left pedicle as confirmed by AP fluoroscopy (Fig. 2). Under fluoroscopic guidance, the Jamshidi needle is incrementally (5 mm) advanced into the pedicle. Caution should be taken to not advanced the Jamshidi needle past the medial edge of the pedicle on the AP fluoroscopic image. J Spinal Disord Tech
Volume 28, Number 6, July 2015
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 6, July 2015
Minimally Invasive TLIF
FIGURE 1. Photograph of a patient positioned prone on a Jackson table with appropriate padding, abducted shoulders, and flexed arms.
The Jamshidi needle is advanced 1.5–2 cm into the pedicle after which a Kirschner guide wire is placed into the needle shaft. The tip of the guide wire should be advanced until it appears to just cross the medial edge of the pedicle as confirmed by AP fluoroscopy (Fig. 3). At this time, a lateral fluoroscopic image is obtained to confirm that the guide wire has crossed the posterior wall of the vertebral body. iii Note: The Jamshidi needle should be redirected if it has been advanced beyond the medial edge of the pedicle on the AP fluoroscopic image and the posterior wall of the vertebral body has not been traversed on the lateral image. Following the placement of guide wires at the pedicles above and below the level of fusion, an initial dilator is introduced between the guide wires. Following sequential dilation, a 21 mm tubular retractor is introduced and docked onto the pars interarticularis at the level of the target disk space. Adequate visualization is achieved by removing the remaining soft tissue and muscles utilizing electrocautery and pituitary rongeurs.
FIGURE 3. Anteroposterior intraoperative fluoroscopic image demonstrating appropriate placement of the guide wires directed to the pedicles above and below the target level. Note the medial wall of the pedicles are not crossed by the guide wires in the anteroposterior plane.
Step 4: Laminectomy The lamina, pars interarticularis, and the facet joint are visualized. The lamina and the medial edge of the pars interarticularis are removed utilizing a high-speed burr. The local bone graft obtained from the laminectomy can be saved in a suction canister. This bone graft can be used as a bulking agent for the intervertebral space.
Step 5: Bilateral Decompression To perform a bilateral decompression, the tubular retractor is medialized and the spinous process is undercut. To ensure safety, the underlying ligamentum flavum serves as a barrier between the burr and the dura. Both sets of the traversing nerve roots (now free and mobile) should be visualized. A wide decompression of the thecal sac is achieved.
Step 6: Facetectomy
FIGURE 2. Anteroposterior intraoperative fluoroscopic image demonstrating the Jamshidi needle positioned at the 2 o’clock position of the right pedicle. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
The removal of the pars interarticularis can be done very quickly with the use of a burr and a lateral fluoroscopic image. The pars should be resected in line with the inferior endplate of the superior level. Resecting the pars any higher will result in unnecessary exposure of the exiting nerve root. www.jspinaldisorders.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
223
J Spinal Disord Tech
Ahn et al
The facetectomy is performed and the inferior articular process can be removed en bloc. The inferior articular process can be cleaned of soft tissue and morselized on the back table in order for it to be used as bone graft in the intervertebral disk space. The superior articular process (of the inferior level) is resected until the medial and superior wall of the pedicle is abutted. This step is important to create a large working zone in the transforaminal space.
Step 7: Removal of the Ligamentum Flavum A curved microcurette is utilized to reflect the ligamentum flavum as 2 large pieces on each side of the spinal canal.
Step 8: Preparation of the Intervertebral Disk Space The epidural veins overlying the intervertebral disk space are identified and coagulated utilizing an electrocautery device (Fig. 4). The transforaminal space is visualized and the anatomical landmarks should be noted including (1) traversing nerve root (medial), (2) exiting nerve root (superior and lateral at the disk space), and the (3) the pedicle of the inferior level (inferior).
Step 9: Preparation of the End Plate This step is not demonstrated in the video, Supplemental Digital Content 1, http://links.lww.com/JSDT/A6. Pituitary rongeurs, curettes, and end plate shavers are utilized to prepare the end plate using lateral fluoroscopic visualization. Care should be taken when using end plate shavers in the setting of osteoporosis as end plate violations can occur resulting in intervertebral cage subsidence.
Volume 28, Number 6, July 2015
Step 10: Trial and Placement of the Interbody Cage The trial interbody cage is placed and sized to restore the appropriate lumbar lordosis. The disk space may be filled with local bone graft or a bone graft substitute to enhance fusion. Bone is typically placed in the anterior portion of the disk space, followed by the intervertebral cage. It is the senior author’s preference to also back fill bone behind the cage to maximize graft-end plate contact. Under fluoroscopic guidance, the interbody cage should be gently impacted into appropriate position with the ideal placement of the cage being in the anterior third of the disk space to maximize lordosis.
Step 11: Percutaneous Pedicle Screw Placement The cannulated trocar (guide needle) is placed at the 2 o’clock (right pedicle) or the 10 o’clock (left pedicle) positions at the upper outer aspect. Starting point and the trajectory is verified utilizing fluoroscopy before advancement of the cannulated trocar. A lateral fluoroscopic image is obtained to confirm that the cannulated trocar has advanced beyond the posterior vertebral body margin to ensure that a medial wall violation has not occurred. Following confirmation, the inner sleeve is removed and the Kirschner wires are advanced through the cannulated guide needle. After securing the Kirschner wires in the vertebral body, the outer sleeves are removed and the wires secured to the surgical drapes. At this point, the decompression and interbody device placement are completed (see above). Pedicle taps are introduced over the guide wires and advanced towards the pedicles. (Fig. 5). EMG-evoked potentials are utilized to detect any breach of the medial wall of the pedicle. Following removal of the pedicle taps, cannulated pedicle screws are advanced over the Kirschner wire. Under EMG monitoring the screws are placed over the Kirschner wire and into the pedicles. Care should be taken to confirm via fluoroscopic imaging that the screw is advanced collinear to the Kirschner wire to prevent any bending or breakage of the wire. Following placement of the screws, the extensions are aligned. A contoured rod can then be passed underneath the fascia. After securing the connecting rode with the set screws, fluoroscopic imaging confirms appropriate positioning of the instrumentation.
POSTOPERATIVE PROTOCOL FIGURE 4. Tubular retractor image demonstrating the visualization of the intervertebral disk space following coagulation of the overlying epidural veins.
224 | www.jspinaldisorders.com
Complications Incidental durotomies may present as posture-dependent headaches with accompanying nausea and vomiting. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
J Spinal Disord Tech
Volume 28, Number 6, July 2015
FIGURE 5. “Bulls-eye” intra-operative fluoroscopic image demonstrating the center placement of the guide wires within the pedicle.
Most cases of durotomy may be treated conservatively utilizing a collagen sponge and a tight fascial closure. Early postoperative mobilization may be recommended if the patient is asymptomatic.
Minimally Invasive TLIF
FIGURE 7. Postoperative mid-sagittal computed tomographic image demonstrating a solid arthrodesis with significant bridging bone following an L4–5 MIS TLIF.
Dural repair kits are also available and it is the senior author’s preference to use 4-0 nylon suture along with an arthroscopic knot passer to perform the dural repair.
PEARLS AND PITFALLS Lumbar pedicles are medially angulated (posterior to anterior) in the transverse plane. Obese patients require a slightly more lateral incision. The laminectomy and the facetectomy should be performed under direct and fluoroscopic visualization. Hypertrophy of superior articular process of the inferior level may cause stenosis at the lateral recess. Care should be taken to address this stenosis as it occurs at the disk space level and distal to the TLIF working zone. Lateral fluoroscopic imaging during the end plate preparation is imperative to avoid inadvertent penetration of the end plate and anterior longitudinal ligament.
FIGURE 6. A 40-year-old female who underwent and L4-5 MIS TLIF for degenerative spondylolisthesis and spinal stenosis. Postoperative coronal computed tomographic (CT) image demonstrating pedicle screws at the L4 and L5 pedicles with >50% bone bridging in the interbody cage. Copyright
r
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.jspinaldisorders.com |
Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
225
