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Feasibility of the mini-open vertebral column resection for severe thoracic kyphosis
Journal of Clinical Neuroscience 21 (2014) 841–845
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Operative Technique
Feasibility of the mini-open vertebral column resection for severe thoracic kyphosis Dean Chou ⇑, Darryl Lau, Esha Roy Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, Box 0112, San Francisco, CA 94143, USA
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 9 October 2013
Keywords: Corpectomy Kyphosis Mini-open Minimally invasive Thoracic spine Vertebral column resection Vertebrectomy
a b s t r a c t Severe thoracic kyphosis caused by pathologic fractures often needs to be corrected by resection of the collapsed vertebral body, reconstruction of the anterior spinal column, and correction of the kyphosis with long-segment fixation. The resection of this pathologic bone functions essentially as a vertebral column resection. With the advent of minimally invasive technology, the powerful corrective forces afforded in open cases can be applied using a less invasive approach. In this article, we describe a mini-open posterior technique for thoracic kyphosis via a vertebrectomy and cantilever technique. Two patients underwent kyphosis correction via mini-open vertebrectomy. One patient was corrected from 92 degrees to 65 degrees, and the second patient was corrected from 70 degrees to 53 degrees. Both patients underwent a mini-open approach. Cantilever correction was accomplished over an expandable cage with a minimally invasive pedicle screw system. We describe our technique of mini-open vertebral column resection and kyphosis correction in the thoracic spine. Ó 2013 Elsevier Ltd. All rights reserved.
1. Background and importance The surgical correction of severe thoracic kyphosis usually requires an osteotomy to mobilize the spine and long segment fixation for correction and stabilization. Options include multiple Ponte/Smith-Peterson osteotomies, pedicle subtraction osteotomy (PSO), or vertebral column resection (VCR) [1–3]. Although Ponte/Smith-Peterson osteotomies may be advantageous for smooth-gradual kyphoses such as Scheurmann’s kyphosis, this may not be the case for sharp-angular kyphoses in the thoracic spine with vertebral body compromise. The VCR is a good option for many reasons. First, the correction gained can be significant, as much as 60 degrees. Second, there is less posterior column spinal shortening compared to a PSO, which can be limited because of the spinal cord’s inability to withstand severe deformation and kinking. Third, the thoracic VCR is commonly performed for many other pathologies such as tumor or infection, and thus, it may be a much more comfortable operation for many surgeons who perform posterior vertebrectomies (costo-transversectomies, transpedicular corpectomies, or extracavitary approaches). A vertebrectomy with circumferential bone removal in the face of a severe deformity functions essentially as a VCR. Until recently, the standard posterior thoracic vertebrectomy has been performed through large, open exposures, with muscle and fascial dissection of seven levels or more [1–4]. However, with ⇑ Corresponding author. Tel.: +1 415 353 9095; fax: +1 415 353 3907. E-mail address: [email protected] (D. Chou). 0967-5868/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jocn.2013.10.001
more recent advances in minimally invasive (MI) techniques, vertebrectomies are now being performed in a MI fashion or in a mini-open fashion [5,6]. We have previously described the miniopen transpedicular corpectomy as a novel technique to perform posteriorly-based corpectomies [6]. As an extension of this previously described technique, we describe how we utilized this approach to correct kyphosis via a mini-open vertebrectomy (which functions essentially as a VCR) and long segment fixation.
2. Clinical presentation We describe the clinical presentation of case examples of severe kyphosis, indications for surgery, and description of our technique.
2.1. Patient 1 A 61-year-old woman with metastatic breast cancer to T6 presented with difficulty walking and gait imbalance. Neurological examination was significant for 4/5 strength and ankle clonus in bilateral lower extremities. Standing lateral radiograph demonstrated 70 degrees of kyphosis in the thoracic region (measured from T2 to T12) (Fig. 1A). MRI revealed a T6 pathological fracture and draping of the spinal cord over the T6 apical kyphosis/deformity (Fig. 1B). The patient underwent a mini-open T6 vertebrectomy with long segment posterior fusion for kyphosis correction (Supp. Video 1).
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Fig. 1. (A) Preoperative 3 foot lateral scoliosis radiograph showing thoracic kyphosis of 70°. (B) Preoperative sagittal T2-weighted MRI demonstrating draping of the spinal cord over the kyphotic apex, with T6 pathological fracture. (C) Postoperative 3 foot lateral scoliosis radiograph showing thoracic kyphosis correction to 53°.
2.2. Patient 2 An 82-year-old woman who had undergone two prior kyphoplasties for kyphoscoliosis presented with progressively worsening pain. The patient had been relegated to sitting in a lounge chair for most of the day. Standing radiographs demonstrated 92 degrees of kyphosis (measured from T2 to T12), and compression fractures (two treated with kyphoplasty at T10 and T12) with an apex of her kyphosis at T11 (Fig. 2A). The patient underwent kyphosis correction via a mini-open vertebrectomy at T11 with polymethylmethacrylate (PMMA)-augmented posterior instrumentation from T5 to L3 (Supp. Video 1). 3. Operative techniques 3.1. Pedicle screw fixation The patient is positioned prone on a radiolucent operating room table. The skin is opened midline, but the fascia is preserved. The MI screws are placed transfascially in the same manner that they are placed percutaneously. We first placed Jamshidi needles (CareFusion, San Diego, CA, USA) into the pedicles using anteriorposterior and lateral fluoroscopy. Kirschner wires (K-wires) are then placed into the pedicles. The fascia is then opened over each K-wire with a #15 blade to accommodate the screws. A tap is then placed over the K-wires, the tap is removed, and then the screws are placed under fluoroscopic guidance. The K-wires are subsequently removed. 3.2. Mini-open transpedicular vertebrectomy This technique is described in detail elsewhere [6], but we will briefly mention our technique here. The fascia over the vertebral body, superior lamina, and inferior lamina, is opened to facilitate the corpectomy. The fascia is held open using a self-retaining retractor, and the laminectomy is performed. A temporary rod is placed, the transpedicular corpectomy is performed, and the discs and posterior longitudinal ligament are removed. We then perform
Fig. 2. (A) Preoperative lateral 3 foot scoliosis radiograph showing thoracic kyphosis of 92°. (B) Postoperative lateral 3 foot scoliosis radiograph showing thoracic kyphosis corrected to 65°.
a trap-door rib head osteotomy to mobilize the rib, and the rib is separated from the vertebral body [7,8]. An appropriate sized expandable cage is placed into the defect. For kyphosis correction, a cage with the largest footplate possible is used, but we do not
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necessarily expand the cage to its maximal height. This is to allow for enough motion of the spine to use the cage as a pivot point and to allow us to bring the spine back to correct the kyphosis. We place the cage as ventrally as possible to rest on the anterior apophyseal ring of the vertebral body, which is the strongest part of the vertebral body (Fig. 3). 3.3. Kyphosis correction Once the cage is in an appropriate position, we choose the thoracic kyphosis and lumbar lordosis to which we wish to correct the spine, and the rod is then bent into the desired position. The rod is then threaded subfascially into the proximal screws and locked into position with the set screws (Fig. 4). In order to properly perform the cantilever maneuver, the fascia over the distal screws must be cut continuously, not just over each screw, in order to allow the rod to be seated into all distal screws at once. This is done with a blade, linking each of the slotted tabs with a single fascial incision. We then gently cantilever the rod down into the distal screws, always evaluating the spinal cord to ensure no significant buckling occurs (Fig. 5, Supp. Video 1). The distal set screws are placed, but not locked tight. Compressing the screws over the cage can then facilitate further kyphosis correction. Motor evoked potentials are checked every 5 min for the next 15 min to ensure no changes occur. If motor changes occur, the cord is inspected to ensure there is no excessive kinking, and the correction can be loosened to check if motor evoked potentials return.
Fig. 4. Intraoperative photograph demonstrating a rod contoured to the desired kyphosis and threaded into proximal screws subfascially. This figure is available in colour at www.sciencedirect.com.
3.4. Fusion and closure Next, arthrodesis is performed over the vertebrectomy site with either autologous iliac crest graft or allograft. We use a cross-linker because of the severe instability that ensues after the vertebral column bone removal. The fascia over the vertebrectomy site and over the screw sites are closed in the usual fashion with interrupted sutures. 4. Outcomes 4.1. Patient 1 There were no intraoperative or postoperative complications. The patient’s postoperative standing 3 foot radiographs demonstrated her thoracic kyphosis improved from 70 degrees to 53 degrees (Fig. 1C). Her myelopathy and ability to ambulate improved
Fig. 5. Intraoperative photograph demonstrating the contour of the spine after the corrective cantilever maneuver has been performed and the rod placed into caudal screws. This figure is available in colour at www.sciencedirect.com.
as well. At last follow-up, it was found that the patient unfortunately died 9 months after surgery from her metastatic disease. 4.2. Patient 2 Although the patient’s kyphosis correction went well, she experienced two complications postoperatively. The patient had a pulmonary embolus secondary to PMMA embolization, which was treated with anti-coagulation. For 3 weeks, the patient’s pain dramatically improved, but she subsequently developed new right leg radiculopathy secondary to an L4 compression fracture. This was treated with an epidural injection, which reduced her pain significantly. At 6 month follow up, it was found that the patient was ambulating with her walker height raised to accommodate her new posture, and her Cobb angle was corrected from 92 degrees to 65 degrees (Fig. 2B). 5. Discussion
Fig. 3. Intraoperative photograph of cage reconstruction being performed. This figure is available in colour at www.sciencedirect.com.
Posterior based corpectomies and vertebrectomies have been well described, and variations on rib head resection have resulted
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in the terms, ‘‘transpedicular corpectomy’’, ‘‘costotransversectory’’, and ‘‘lateral extracavitary approach.’’ When removing the entire vertebral segment for a deformity correction, the term ‘‘vertebral column resection’’ has been used. Regardless of the nomenclature used, the operations essentially accomplish the same goal: the removal of the vertebral body from a posterior approach and reconstruction of the anterior spinal column. Add onto this the MI or mini-open approach, and the goal of the operation still remains the same. Traditionally, vertebrectomy is performed through a circumferential approach to the spine, but more recently many surgeons have conducted alternative spatial approaches to VCR [1–4,9]. Currently, posterior-only approaches to vertebrectomy to correct spinal deformity and kyphosis are becoming more common practice [2,10]. The correction gained with VCR can be significant; as much as 60 degrees can be corrected. In addition, posterior approaches to multi-level vertebrectomy and corpectomy have been shown to be feasible and have comparable morbidity to single level procedures [11]. The concept of MI surgery continues to evolve. Although a true MI approach is ideal, there are instances in which a mini-open approach to the spine provides similar outcomes and still is less invasive than open approaches. Kaiser et al. and Chung et al. independently compared MI (laparoscopic) anterior lumbar interbody fusion (ALIF) surgeries to mini-open ALIF, and both found that there was no advantage to performing a ‘‘true’’ MI ALIF over a mini-open one [12,13]. Chi et al. described a mini-open transpedicular thoracic discectomy, and revealed that patients who underwent the mini-open discectomy had less blood loss, earlier postoperative improvement, and decreased postoperative pain compared to the patients who had the open transpedicular discectomy [5]. Thus, there is evidence that as the concept of MI surgery evolves, there may be an increasing role for mini-open procedures in decreasing morbidity, as well as expanding the ability to perform traditionally more difficult open procedures in a MI fashion. We have previously described the mini-open transpedicular corpectomy, which is essentially a hybrid technique using percutaneous screws with a small opening for the actual transpedicular corpectomy [6]. However, many pathological processes, such as tumor or infection, are also accompanied by significant kyphosis and spinal deformities. Therefore in addition to the localized spinal pathology, it is important to carefully and correctly address the kyphosis associated with the disease. Given the significant advances in percutaneous screw technology, kyphosis correction, even in severe deformities, is feasible with a less invasive mini-open approach. The surgical technique and skills required to perform the miniopen VCR is readily adaptable to surgeons who are comfortable with performing open posterior vertebrectomies (costo-transversectomies, transpedicular corpectomies, or extracavitary approaches) and percutaneous instrumentation and fusion. In the mini-open approach, once the screws are placed, the corpectomy, reconstruction, and cantilever correction are very similar to open surgery. The cantilever procedure does have some nuances as the fascia over the screws that are receiving the rod must be cut in a continuous fashion. The rod can be technically threaded subfascially over both caudal and rostral receiving screws, but the correction power of the rod is minimal this way. The reason for this is because the fascia limits the height from which the rod can be cantilevered. We have found it much more effective and ergonomic to correct the kyphosis using a single fascial opening for the caudal receiving screws, yet still threading the rod subfascially for the rostral screws. Another major advantage of the mini-open cantilever procedure is that it avoids an extensive midline incision above and below the vertebrectomy site, and therefore, the mini-open approach protects the musculature and posterior tension band, especially when fusing across spinal junctions.
With regards to the fusion at adjacent non-corpectomy levels, we rely on the data by Dai et al. and Wang et al. [14,15]. In these two studies with 5 and 7 years of follow-up, pedicle screw fixation without fusion did not result in implant failure or necessitate the need for revision surgery (although this was for trauma patients). Our experience of having performed the mini-open transpedicular corpectomy for the past 4 years is also consistent with these two studies. If fusion is absolutely necessary, then it is certainly possible to perform arthrodesis at all instrumented levels with the percutaneous system. After the K-wire is placed, the facet itself can be exposed either with a series of dilators or a small self-retaining retractor. The facet then can be decorticated and graft material can be placed for arthrodesis. However, now that we are correcting kyphoses with percutaneous screw fixation, we may begin to see manifestations of proximal junction kyphosis and implant failure because of the requirement for larger corrective forces placed upon the spine [16]. For fusion over the corpectomy site, we based our graft material on the patient’s overall prognosis and baseline factors. For metastatic cancer where survival is short, allograft was used around the cage. If the patient is expected to live a normal life span (such as an osteomyelitis patient or low grade tumor), iliac crest graft was harvested and used for fusion. In an elderly patient with a kyphosis from either a compression or a burst fracture, we used local vertebrectomy bone for fusion to avoid the morbidity of iliac crest graft. It remains unclear whether there are significant drawbacks to fusing only at the level of the vertebrectomy and not fusing the perivertebrectomy levels. Nonetheless this technique can be easily modified to address this issue if it arises. 6. Conclusion Kyphosis correction can be performed with a mini-open vertebrectomy functioning essentially as a VCR, especially with the advent of more powerful MI instrumentation. However, longer term studies will be needed to prove the durability of the operation. Conflicts of Interest/Disclosures Dr. Chou has received honoraria from Globus, Depuy and Orthofix for teaching. No funding was provided for this study. Otherwise, the authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.jocn.2013.10.001. References [1] Boachie-Adjei O, Bradford DS. Vertebral column resection and arthrodesis for complex spinal deformities. J Spinal Disord 1991;4:193–202. [2] Lenke LG, Sides BA, Koester LA, et al. Vertebral column resection for the treatment of severe spinal deformity. Clin Orthop Relat Res 2010;468:687–99. [3] Hamzaoglu A, Alanay A, Ozturk C, et al. Posterior vertebral column resection in severe spinal deformities: a total of 102 cases. Spine (Phila Pa 1976) 2011;36:E340–4. [4] Wang Y, Zhang Y, Zhang X, et al. Posterior-only multilevel modified vertebral column resection for extremely severe Pott’s kyphotic deformity. Eur Spine J 2009;18:1436–41. [5] Chi JH, Dhall SS, Kanter AS, et al. The Mini-Open transpedicular thoracic discectomy: surgical technique and assessment. Neurosurg Focus 2008;25:E5. [6] Chou D, Lu DC. Mini-open transpedicular corpectomies with expandable cage reconstruction. Technical note. J Neurosurg Spine 2011;14:71–7. [7] Chou D, Wang VY. Trap-door rib-head osteotomies for posterior placement of expandable cages after transpedicular corpectomy: an alternative to lateral
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[8]
[9]
[10]
[11]
extracavitary and costotransversectomy approaches. J Neurosurg Spine 2009;10:40–5. Chou D, Eltgroth M, Yang I, et al. Rib head disarticulation for multilevel transpedicular thoracic corpectomies and expandable cage reconstruction. Neurol India 2009;57:469–74. Helenius I, Serlo J, Pajulo O. The incidence and outcomes of vertebral column resection in paediatric patients: a population-based, multicentre, follow-up study. J Bone Joint Surg Br 2012;94:950–5. Pappou IP, Papadopoulos EC, Swanson AN, et al. Pott disease in the thoracolumbar spine with marked kyphosis and progressive paraplegia necessitating posterior vertebral column resection and anterior reconstruction with a cage. Spine (Phila Pa 1976) 2006;31:E123–7. Lau D, Song Y, Guan Z, et al. Perioperative characteristics, complications, and outcomes of single-level versus multilevel thoracic corpectomies via modified costotransversectomy approach. Spine (Phila Pa 1976) 2013;38:523–30.
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[12] Chung SK, Lee SH, Lim SR, et al. Comparative study of laparoscopic L5–S1 fusion versus open mini-ALIF, with a minimum 2-year follow-up. Eur Spine J 2003;12:613–7. [13] Kaiser MG, Haid Jr RW, Subach BR, et al. Comparison of the mini-open versus laparoscopic approach for anterior lumbar interbody fusion: a retrospective review. Neurosurgery 2002;51:97–103 [discussion 103–5]. [14] Dai LY, Jiang LS, Jiang SD. Posterior short-segment fixation with or without fusion for thoracolumbar burst fractures. A five to seven-year prospective randomized study. J Bone Joint Surg Am 2009;91:1033–41. [15] Wang ST, Ma HL, Liu CL, et al. Is fusion necessary for surgically treated burst fractures of the thoracolumbar and lumbar spine? A prospective, randomized study. Spine (Phila Pa 1976) 2006;31:2646–52 [discussion 2653]. [16] Marou K, Ha Y, Inoue S, et al. Predictive factors for proximal junctional kyphosis in long fusions to the sacrum in adult spinal deformity. Spine (Phila Pa 1976) 2013;38:E1469–76.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Operative Technique
Feasibility of the mini-open vertebral column resection for severe thoracic kyphosis Dean Chou ⇑, Darryl Lau, Esha Roy Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, Box 0112, San Francisco, CA 94143, USA
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 9 October 2013
Keywords: Corpectomy Kyphosis Mini-open Minimally invasive Thoracic spine Vertebral column resection Vertebrectomy
a b s t r a c t Severe thoracic kyphosis caused by pathologic fractures often needs to be corrected by resection of the collapsed vertebral body, reconstruction of the anterior spinal column, and correction of the kyphosis with long-segment fixation. The resection of this pathologic bone functions essentially as a vertebral column resection. With the advent of minimally invasive technology, the powerful corrective forces afforded in open cases can be applied using a less invasive approach. In this article, we describe a mini-open posterior technique for thoracic kyphosis via a vertebrectomy and cantilever technique. Two patients underwent kyphosis correction via mini-open vertebrectomy. One patient was corrected from 92 degrees to 65 degrees, and the second patient was corrected from 70 degrees to 53 degrees. Both patients underwent a mini-open approach. Cantilever correction was accomplished over an expandable cage with a minimally invasive pedicle screw system. We describe our technique of mini-open vertebral column resection and kyphosis correction in the thoracic spine. Ó 2013 Elsevier Ltd. All rights reserved.
1. Background and importance The surgical correction of severe thoracic kyphosis usually requires an osteotomy to mobilize the spine and long segment fixation for correction and stabilization. Options include multiple Ponte/Smith-Peterson osteotomies, pedicle subtraction osteotomy (PSO), or vertebral column resection (VCR) [1–3]. Although Ponte/Smith-Peterson osteotomies may be advantageous for smooth-gradual kyphoses such as Scheurmann’s kyphosis, this may not be the case for sharp-angular kyphoses in the thoracic spine with vertebral body compromise. The VCR is a good option for many reasons. First, the correction gained can be significant, as much as 60 degrees. Second, there is less posterior column spinal shortening compared to a PSO, which can be limited because of the spinal cord’s inability to withstand severe deformation and kinking. Third, the thoracic VCR is commonly performed for many other pathologies such as tumor or infection, and thus, it may be a much more comfortable operation for many surgeons who perform posterior vertebrectomies (costo-transversectomies, transpedicular corpectomies, or extracavitary approaches). A vertebrectomy with circumferential bone removal in the face of a severe deformity functions essentially as a VCR. Until recently, the standard posterior thoracic vertebrectomy has been performed through large, open exposures, with muscle and fascial dissection of seven levels or more [1–4]. However, with ⇑ Corresponding author. Tel.: +1 415 353 9095; fax: +1 415 353 3907. E-mail address: [email protected] (D. Chou). 0967-5868/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jocn.2013.10.001
more recent advances in minimally invasive (MI) techniques, vertebrectomies are now being performed in a MI fashion or in a mini-open fashion [5,6]. We have previously described the miniopen transpedicular corpectomy as a novel technique to perform posteriorly-based corpectomies [6]. As an extension of this previously described technique, we describe how we utilized this approach to correct kyphosis via a mini-open vertebrectomy (which functions essentially as a VCR) and long segment fixation.
2. Clinical presentation We describe the clinical presentation of case examples of severe kyphosis, indications for surgery, and description of our technique.
2.1. Patient 1 A 61-year-old woman with metastatic breast cancer to T6 presented with difficulty walking and gait imbalance. Neurological examination was significant for 4/5 strength and ankle clonus in bilateral lower extremities. Standing lateral radiograph demonstrated 70 degrees of kyphosis in the thoracic region (measured from T2 to T12) (Fig. 1A). MRI revealed a T6 pathological fracture and draping of the spinal cord over the T6 apical kyphosis/deformity (Fig. 1B). The patient underwent a mini-open T6 vertebrectomy with long segment posterior fusion for kyphosis correction (Supp. Video 1).
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Fig. 1. (A) Preoperative 3 foot lateral scoliosis radiograph showing thoracic kyphosis of 70°. (B) Preoperative sagittal T2-weighted MRI demonstrating draping of the spinal cord over the kyphotic apex, with T6 pathological fracture. (C) Postoperative 3 foot lateral scoliosis radiograph showing thoracic kyphosis correction to 53°.
2.2. Patient 2 An 82-year-old woman who had undergone two prior kyphoplasties for kyphoscoliosis presented with progressively worsening pain. The patient had been relegated to sitting in a lounge chair for most of the day. Standing radiographs demonstrated 92 degrees of kyphosis (measured from T2 to T12), and compression fractures (two treated with kyphoplasty at T10 and T12) with an apex of her kyphosis at T11 (Fig. 2A). The patient underwent kyphosis correction via a mini-open vertebrectomy at T11 with polymethylmethacrylate (PMMA)-augmented posterior instrumentation from T5 to L3 (Supp. Video 1). 3. Operative techniques 3.1. Pedicle screw fixation The patient is positioned prone on a radiolucent operating room table. The skin is opened midline, but the fascia is preserved. The MI screws are placed transfascially in the same manner that they are placed percutaneously. We first placed Jamshidi needles (CareFusion, San Diego, CA, USA) into the pedicles using anteriorposterior and lateral fluoroscopy. Kirschner wires (K-wires) are then placed into the pedicles. The fascia is then opened over each K-wire with a #15 blade to accommodate the screws. A tap is then placed over the K-wires, the tap is removed, and then the screws are placed under fluoroscopic guidance. The K-wires are subsequently removed. 3.2. Mini-open transpedicular vertebrectomy This technique is described in detail elsewhere [6], but we will briefly mention our technique here. The fascia over the vertebral body, superior lamina, and inferior lamina, is opened to facilitate the corpectomy. The fascia is held open using a self-retaining retractor, and the laminectomy is performed. A temporary rod is placed, the transpedicular corpectomy is performed, and the discs and posterior longitudinal ligament are removed. We then perform
Fig. 2. (A) Preoperative lateral 3 foot scoliosis radiograph showing thoracic kyphosis of 92°. (B) Postoperative lateral 3 foot scoliosis radiograph showing thoracic kyphosis corrected to 65°.
a trap-door rib head osteotomy to mobilize the rib, and the rib is separated from the vertebral body [7,8]. An appropriate sized expandable cage is placed into the defect. For kyphosis correction, a cage with the largest footplate possible is used, but we do not
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necessarily expand the cage to its maximal height. This is to allow for enough motion of the spine to use the cage as a pivot point and to allow us to bring the spine back to correct the kyphosis. We place the cage as ventrally as possible to rest on the anterior apophyseal ring of the vertebral body, which is the strongest part of the vertebral body (Fig. 3). 3.3. Kyphosis correction Once the cage is in an appropriate position, we choose the thoracic kyphosis and lumbar lordosis to which we wish to correct the spine, and the rod is then bent into the desired position. The rod is then threaded subfascially into the proximal screws and locked into position with the set screws (Fig. 4). In order to properly perform the cantilever maneuver, the fascia over the distal screws must be cut continuously, not just over each screw, in order to allow the rod to be seated into all distal screws at once. This is done with a blade, linking each of the slotted tabs with a single fascial incision. We then gently cantilever the rod down into the distal screws, always evaluating the spinal cord to ensure no significant buckling occurs (Fig. 5, Supp. Video 1). The distal set screws are placed, but not locked tight. Compressing the screws over the cage can then facilitate further kyphosis correction. Motor evoked potentials are checked every 5 min for the next 15 min to ensure no changes occur. If motor changes occur, the cord is inspected to ensure there is no excessive kinking, and the correction can be loosened to check if motor evoked potentials return.
Fig. 4. Intraoperative photograph demonstrating a rod contoured to the desired kyphosis and threaded into proximal screws subfascially. This figure is available in colour at www.sciencedirect.com.
3.4. Fusion and closure Next, arthrodesis is performed over the vertebrectomy site with either autologous iliac crest graft or allograft. We use a cross-linker because of the severe instability that ensues after the vertebral column bone removal. The fascia over the vertebrectomy site and over the screw sites are closed in the usual fashion with interrupted sutures. 4. Outcomes 4.1. Patient 1 There were no intraoperative or postoperative complications. The patient’s postoperative standing 3 foot radiographs demonstrated her thoracic kyphosis improved from 70 degrees to 53 degrees (Fig. 1C). Her myelopathy and ability to ambulate improved
Fig. 5. Intraoperative photograph demonstrating the contour of the spine after the corrective cantilever maneuver has been performed and the rod placed into caudal screws. This figure is available in colour at www.sciencedirect.com.
as well. At last follow-up, it was found that the patient unfortunately died 9 months after surgery from her metastatic disease. 4.2. Patient 2 Although the patient’s kyphosis correction went well, she experienced two complications postoperatively. The patient had a pulmonary embolus secondary to PMMA embolization, which was treated with anti-coagulation. For 3 weeks, the patient’s pain dramatically improved, but she subsequently developed new right leg radiculopathy secondary to an L4 compression fracture. This was treated with an epidural injection, which reduced her pain significantly. At 6 month follow up, it was found that the patient was ambulating with her walker height raised to accommodate her new posture, and her Cobb angle was corrected from 92 degrees to 65 degrees (Fig. 2B). 5. Discussion
Fig. 3. Intraoperative photograph of cage reconstruction being performed. This figure is available in colour at www.sciencedirect.com.
Posterior based corpectomies and vertebrectomies have been well described, and variations on rib head resection have resulted
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in the terms, ‘‘transpedicular corpectomy’’, ‘‘costotransversectory’’, and ‘‘lateral extracavitary approach.’’ When removing the entire vertebral segment for a deformity correction, the term ‘‘vertebral column resection’’ has been used. Regardless of the nomenclature used, the operations essentially accomplish the same goal: the removal of the vertebral body from a posterior approach and reconstruction of the anterior spinal column. Add onto this the MI or mini-open approach, and the goal of the operation still remains the same. Traditionally, vertebrectomy is performed through a circumferential approach to the spine, but more recently many surgeons have conducted alternative spatial approaches to VCR [1–4,9]. Currently, posterior-only approaches to vertebrectomy to correct spinal deformity and kyphosis are becoming more common practice [2,10]. The correction gained with VCR can be significant; as much as 60 degrees can be corrected. In addition, posterior approaches to multi-level vertebrectomy and corpectomy have been shown to be feasible and have comparable morbidity to single level procedures [11]. The concept of MI surgery continues to evolve. Although a true MI approach is ideal, there are instances in which a mini-open approach to the spine provides similar outcomes and still is less invasive than open approaches. Kaiser et al. and Chung et al. independently compared MI (laparoscopic) anterior lumbar interbody fusion (ALIF) surgeries to mini-open ALIF, and both found that there was no advantage to performing a ‘‘true’’ MI ALIF over a mini-open one [12,13]. Chi et al. described a mini-open transpedicular thoracic discectomy, and revealed that patients who underwent the mini-open discectomy had less blood loss, earlier postoperative improvement, and decreased postoperative pain compared to the patients who had the open transpedicular discectomy [5]. Thus, there is evidence that as the concept of MI surgery evolves, there may be an increasing role for mini-open procedures in decreasing morbidity, as well as expanding the ability to perform traditionally more difficult open procedures in a MI fashion. We have previously described the mini-open transpedicular corpectomy, which is essentially a hybrid technique using percutaneous screws with a small opening for the actual transpedicular corpectomy [6]. However, many pathological processes, such as tumor or infection, are also accompanied by significant kyphosis and spinal deformities. Therefore in addition to the localized spinal pathology, it is important to carefully and correctly address the kyphosis associated with the disease. Given the significant advances in percutaneous screw technology, kyphosis correction, even in severe deformities, is feasible with a less invasive mini-open approach. The surgical technique and skills required to perform the miniopen VCR is readily adaptable to surgeons who are comfortable with performing open posterior vertebrectomies (costo-transversectomies, transpedicular corpectomies, or extracavitary approaches) and percutaneous instrumentation and fusion. In the mini-open approach, once the screws are placed, the corpectomy, reconstruction, and cantilever correction are very similar to open surgery. The cantilever procedure does have some nuances as the fascia over the screws that are receiving the rod must be cut in a continuous fashion. The rod can be technically threaded subfascially over both caudal and rostral receiving screws, but the correction power of the rod is minimal this way. The reason for this is because the fascia limits the height from which the rod can be cantilevered. We have found it much more effective and ergonomic to correct the kyphosis using a single fascial opening for the caudal receiving screws, yet still threading the rod subfascially for the rostral screws. Another major advantage of the mini-open cantilever procedure is that it avoids an extensive midline incision above and below the vertebrectomy site, and therefore, the mini-open approach protects the musculature and posterior tension band, especially when fusing across spinal junctions.
With regards to the fusion at adjacent non-corpectomy levels, we rely on the data by Dai et al. and Wang et al. [14,15]. In these two studies with 5 and 7 years of follow-up, pedicle screw fixation without fusion did not result in implant failure or necessitate the need for revision surgery (although this was for trauma patients). Our experience of having performed the mini-open transpedicular corpectomy for the past 4 years is also consistent with these two studies. If fusion is absolutely necessary, then it is certainly possible to perform arthrodesis at all instrumented levels with the percutaneous system. After the K-wire is placed, the facet itself can be exposed either with a series of dilators or a small self-retaining retractor. The facet then can be decorticated and graft material can be placed for arthrodesis. However, now that we are correcting kyphoses with percutaneous screw fixation, we may begin to see manifestations of proximal junction kyphosis and implant failure because of the requirement for larger corrective forces placed upon the spine [16]. For fusion over the corpectomy site, we based our graft material on the patient’s overall prognosis and baseline factors. For metastatic cancer where survival is short, allograft was used around the cage. If the patient is expected to live a normal life span (such as an osteomyelitis patient or low grade tumor), iliac crest graft was harvested and used for fusion. In an elderly patient with a kyphosis from either a compression or a burst fracture, we used local vertebrectomy bone for fusion to avoid the morbidity of iliac crest graft. It remains unclear whether there are significant drawbacks to fusing only at the level of the vertebrectomy and not fusing the perivertebrectomy levels. Nonetheless this technique can be easily modified to address this issue if it arises. 6. Conclusion Kyphosis correction can be performed with a mini-open vertebrectomy functioning essentially as a VCR, especially with the advent of more powerful MI instrumentation. However, longer term studies will be needed to prove the durability of the operation. Conflicts of Interest/Disclosures Dr. Chou has received honoraria from Globus, Depuy and Orthofix for teaching. No funding was provided for this study. Otherwise, the authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.jocn.2013.10.001. References [1] Boachie-Adjei O, Bradford DS. Vertebral column resection and arthrodesis for complex spinal deformities. J Spinal Disord 1991;4:193–202. [2] Lenke LG, Sides BA, Koester LA, et al. Vertebral column resection for the treatment of severe spinal deformity. Clin Orthop Relat Res 2010;468:687–99. [3] Hamzaoglu A, Alanay A, Ozturk C, et al. Posterior vertebral column resection in severe spinal deformities: a total of 102 cases. Spine (Phila Pa 1976) 2011;36:E340–4. [4] Wang Y, Zhang Y, Zhang X, et al. Posterior-only multilevel modified vertebral column resection for extremely severe Pott’s kyphotic deformity. Eur Spine J 2009;18:1436–41. [5] Chi JH, Dhall SS, Kanter AS, et al. The Mini-Open transpedicular thoracic discectomy: surgical technique and assessment. Neurosurg Focus 2008;25:E5. [6] Chou D, Lu DC. Mini-open transpedicular corpectomies with expandable cage reconstruction. Technical note. J Neurosurg Spine 2011;14:71–7. [7] Chou D, Wang VY. Trap-door rib-head osteotomies for posterior placement of expandable cages after transpedicular corpectomy: an alternative to lateral
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[12] Chung SK, Lee SH, Lim SR, et al. Comparative study of laparoscopic L5–S1 fusion versus open mini-ALIF, with a minimum 2-year follow-up. Eur Spine J 2003;12:613–7. [13] Kaiser MG, Haid Jr RW, Subach BR, et al. Comparison of the mini-open versus laparoscopic approach for anterior lumbar interbody fusion: a retrospective review. Neurosurgery 2002;51:97–103 [discussion 103–5]. [14] Dai LY, Jiang LS, Jiang SD. Posterior short-segment fixation with or without fusion for thoracolumbar burst fractures. A five to seven-year prospective randomized study. J Bone Joint Surg Am 2009;91:1033–41. [15] Wang ST, Ma HL, Liu CL, et al. Is fusion necessary for surgically treated burst fractures of the thoracolumbar and lumbar spine? A prospective, randomized study. Spine (Phila Pa 1976) 2006;31:2646–52 [discussion 2653]. [16] Marou K, Ha Y, Inoue S, et al. Predictive factors for proximal junctional kyphosis in long fusions to the sacrum in adult spinal deformity. Spine (Phila Pa 1976) 2013;38:E1469–76.