|Year : 2018 | Volume
| Issue : 1 | Page : 50-55
The expandable transforaminal lumbar interbody fusion – Two years follow-up
Joseph Gamal Boktor1, Rhys D Pockett2, Navin Verghese1
1 Department of Spine, Morriston Hospital, Swansea, UK
2 Swansea Centre for Health Economics, College of human and Health Sciences, Swansea University, Swansea, UK
|Date of Web Publication||19-Apr-2018|
Dr. Joseph Gamal Boktor
Spinal Fellow Morriston Hospital, Wales
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Study Design: This was a retrospective, observational study.
Objectives: We hypothesize that the expandable transforaminal lumbar interbody fusion (TLIF) cage achieves satisfactory clinical outcomes while allowing for safe placement, improvement, and maintenance of foraminal and disc dimensions at 24 months postsurgery with low risk of cage migration, subsidence, and nerve injury.
Methods: TLIF with expandable cages was performed in 54 patients (62 levels) over a 24-month-period using open midline or minimally invasive surgery techniques with placement of Globus Caliber, Rise, or Altera expandable cages. All patients underwent clinical and radiological assessment at 6 weeks, 6 months, 1, and 2 years postoperatively. Clinical outcome was measured by Oswestry disability index (ODI), visual analog pain score for both back and leg (visual analog scores [VASs]). Radiological assessment was done by X-ray standing lateral position.
Results: There were significant clinical improvements in ODI, VAS leg, and VAS back at all postoperative time points. Disc height, foraminal height, focal Cobb angle, and global Cobb angle were significantly increased and maintained at all time points for 24 months (P < 0.001). Dural tear occurred in one patient (1.9%). There were neither intra- or postoperative neurological complications nor cage subsidence nor migration.
Conclusions: These preliminary results indicate that the use of an expandable interbody cage achieves good clinical outcomes by improving and maintaining foraminal dimensions and disc height with minimal complication rate.
Keywords: Back pain, expandable interbody cage, interbody fusion, transforaminal lumbar interbody fusion
|How to cite this article:|
Boktor JG, Pockett RD, Verghese N. The expandable transforaminal lumbar interbody fusion – Two years follow-up. J Craniovert Jun Spine 2018;9:50-5
|How to cite this URL:|
Boktor JG, Pockett RD, Verghese N. The expandable transforaminal lumbar interbody fusion – Two years follow-up. J Craniovert Jun Spine [serial online] 2018 [cited 2022 May 21];9:50-5. Available from: https://www.jcvjs.com/text.asp?2018/9/1/50/230610
| Introduction|| |
Posterior lumbar fusion (PLF) is a common surgical method of treating patients with spinal back and leg pain secondary to instability and stenosis. If performed with interbody grafting, it may improve fusions rates, restoration of spinal canal dimensions, and lumbar lordosis which in turn may improve pain and clinical outcomes. Interbody grafting can be performed through posterior lumbar interbody fusion (PLIF), lateral lumbar interbody fusion (LLIF), and anterior lumbar interbody fusion (ALIF) approaches. Transforaminal approaches transforaminal lumbar interbody fusion (TLIF) has the benefit of being placed through a single posterior approach through a unilateral corridor and not requiring an approach close to the vascular structures. However, due to the narrow neural corridor, it is associated with an increased risk of dural injury  and compromised cage size, leading to increased risk of cage subsidence.
The more recently developed expandable TLIF cages have the potential advantages of less neurological injury as well as less impaction needed while inserting the cage. Furthermore, the more line to line fit of the cage after expansion may allow for greater indirect decompression as well as less risk of cage migration and subsidence. The counterargument is that the process of expansion may increase the risk of endplate damage and hence subsidence. Furthermore, the expansion may leave a void across which fusion may not occur and therefore may compromise fusion rates.
Despite over 100,000 expandable TLIF cages being implanted worldwide, this study to our knowledge is the largest 2-year follow-up single-surgeon series in one spine centre relating to the expandable TLIF. The objective of this study is to show that clinical outcomes and radiographic assessments improved postsurgery and that these improvements were maintained at 24 months postsurgery with minimal complication rate.
| Methods|| |
A total of 62 expandable cage TLIFs were undertaken in 54 patients by one surgeon at one spinal unit between December 2013 and December 2015. There were three types of expandable cage included in this study: Globus Caliber, Rise, or Altera. The minimum follow-up was 1 year clinically and radiologically, and the maximum follow-up was 3 years (average follow-up is 23.5 months). All patients underwent clinical and radiological assessment at 6 weeks, 6 months, 1 years, and 2 years postoperatively. The preoperative patients' demographics are summarized in [Table 1].
The patients fulfilled the following criteria: persistent stenotic leg pain more than 6 months with failed conservative treatment; radiological evidence of foraminal stenosis and/or spondylolisthesis with presence of spinal canal stenosis; and complete medical records. Data were collected retrospectively, using the preoperative hospital admission sheets, operative notes, postoperative follow-up, outpatient clinic documentations, and the British Spine Registry. Neither Institutional Review Board approval nor other similar entity approval was needed.
Antibiotics are administered. The patient is positioned prone on a Jackson table with pads. Fluoroscopy image intensifier guidance is used as deemed appropriate. In the context of unilateral leg pain secondary to foraminal stenosis, a minimally invasive procedure is performed with percutaneous pedicle screws and screw-based retractor (Nuvasive MASTLIF) through which the facetectomy, exiting root decompression, and discectomy were performed. In the context of bilateral leg pain, an open or mini open TLIF is performed (Globus revere pedicle or creo mediocortical trajectory screws, respectively). Following careful disc and endplate preparation, the size of the expandable cage is estimated. Local bone and demineralized bone matrix are placed anterior and lateral to the cage and within. Further posterolateral graft is also placed. Screws are connected with lordotic rods and judicious compression or distraction applied to achieve further lordosis or indirect decompression, respectively [Figure 1]. Wounds are closed in layers with suction drain in situ. All patients are mobilized day 1 postoperatively as comfort allowed. Drain and catheter are removed day 1 or 2 postoperatively. Postoperative standing X-rays are performed before discharge.
|Figure 1: (a) Cage insertion, (b) Cage distraction, (c) Compression on screws to restore lordosis|
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Clinical outcome was assessed using the Oswestry disability index (ODI) and visual analog score (VAS) for leg and back pain. Radiological assessment was performed blindly by one spinal fellow with 5-year-experience in spine surgery using intraobserver studies over 3-month period. The assessment included as follows: (1) Disc height ratio was calculated as the ratio between the disc height and the height of the superior vertebral body. Disc height was measured as perpendicular distance between the two cartilagenous endplates in the middle of the vertebra above. (2) Neuroforaminal height ratio was measured using the ratio with the vertebral body above. Neuroforaminal height was measured using line between the middle of the edge of superior and inferior pedicles. (3) Local Cobb angle (defined as the angle between the upper and lower edges of the intervertebral disc) and global Cobb angle (defined as the angle between the lower endplate of the L5 and the upper endplate of L1) [Figure 2]a. (4) Fusion rate was determined using Brantigan and Steffe criteria for interbody fusion  [Table 2] only solid radiographic fusion is counted as Fused. Probable fusion is considered not fused.
|Figure 2: (a) Measuring variable angles and neural dimensions: (1) Red line: neuroforaminal height. (2) Blue line: Disc height. (3) Yellow line: Focal and Global Cobb angle, (b) Follow-up X-ray|
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Standing Lateral view Dorsolumbar radiographs were performed immediately postoperatively and every 6 month after surgery for minimum of 2 years.
Paired samples t-tests were conducted to investigate whether there was a difference in patient reported pain between presurgery, 12 months postsurgery, and 24 months post-surgery, as identified using the ODI, VAS back, and VAS leg instruments. Paired samples t-tests were also conducted to investigate whether there was a difference in radiographic assessments (intervertebral disc height, neuroforaminal height, focal Cobb angle, and global Cobb angle between presurgery and 6, 12, and 24 months postsurgery, respectively).
| Results|| |
The data collected from 54 patients (62 fusion levels as some patients had more than one level fusion) of surgically managed with expandable cages were analyzed [Table 3]. Nearly 68% of patients had 2 years of follow-up. The average operative time was 132 min (126 for single level and 168 for two levels). The average blood loss was 167 ml (154 for single level and 241 for two levels). The average hospital stay was 4 days. The complications were as follows: dural tear was noted in one patient (1.9%). no deep infection was noted, no root injury, no persistent back pain, and neither cage migration nor subsidence were reported. There was no significant difference between the three cage types used. There was also no significant difference between MIS and open surgery.
All patients had pain relief by the final follow-up. Mean ODI score improved significantly from 61.4 ± 17 preoperatively to 40 ± 18.8 at 12 months postoperatively, to 38.3 ± 22.1 at 24 months; P < 0.001 in all follow-ups [Figure 3]. Mean back pain VAS improved significantly from 7.7 ± 2.3 preoperatively to 4.7 ± 2.7 at 12 months postoperatively, to 4.6 ± 3.3 at 24 months; P < 0.001 in all follow-ups [Figure 4]. Mean leg pain VAS decreased significantly from 7.8 ± 2.5 preoperatively to 3.5 ± 2.8 at 12 months postoperatively, to 3.7 ± 3.2 at 24 months; P < 0.001 in all follow-ups [Figure 5].
|Figure 3: Mean Oswestry disability index changes over 24-month follow-up|
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|Figure 4: Mean visual analog score back pain and leg pain over 24-month follow-up|
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Fusion rate was satisfactory, reaching 93% Grade 5 by Brantigan and Steffe classification by 12 months and 100% by 24 months. Radiological assessment from the 2-year follow-up in 37 patients (41 levels) was as follows: intervertebral disc heights changed from 8.8 ± 2.7 preoperatively to 14 ± 2.2 postoperatively to 13.9 ± 2.1 at 6 months follow-up, to 13.6 ± 2.2 at 1 year and 13.3 ± 2.6 at 2 years. P <0.001in all follow-ups [Figure 5]. Neuroforaminal height changed from 17.4 ± 3.1 preoperatively to 21.3 ± 3 postoperatively to 20.6 ± 2.7 at 6 months postoperatively, to 20.3 ± 2.9 at 1 year and 19 ± 2.7 at 2 years. P <0.001 in all follow-ups [Figure 6]. Focal Cobb angle improved from 7 ± 4.5 preoperatively to 10.2 ± 4.1 postoperatively to 9.7 ± 3.8 at 6 months follow-up, to 9.7 ± 4.2 at 1 year and 7.3 ± 3.3 at 2 years. P <0.001 in all follow-ups [Figure 7]. Global Cobb angle improved from 42.2 ± 15.1 preoperatively to 49.4 ± 13.9 postoperatively, to 49.5 ± 13.9 at 6 months follow-up, to 48.9 ± 14.4 at 1 year and 45.4 ± 16 at 2 years; P < 0.001 in all follow-up [Figure 8].
Radiological assessment for 37 patients (41 levels) preoperative and at 2 years showed also significant maintained improvement in disc height from 8.3 ± 3 to 13.3 ± 2.6, neuroforaminal height from 17 ± 3.4 to 19 ± 2.7, focal Cobb angle from 5.5 ± 4.3 to 7.3 ± 3.3, and global Cobb angle from 40.9 ± 15.7 to 45.4 ± 16. P <0.001 in all follow-ups [Table 4].
|Table 4: Radiological outcome for 37 patients with 2 year follow up preoperatively and at 2 years.|
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| Discussion|| |
Spinal leg pain may be as a result of disc and foraminal collapse compressing the exiting nerve root. In such circumstances, an uninstrumented decompression alone may not achieve the required root decompression to provide leg pain relief. Therefore, a fusion can be performed to restore the foraminal dimensions and achieve indirect decompression of the root with or without supplemental direct decompression. It is also frequently performed in the setting of instability and symptomatic spondylolisthesis. Several types of lumbar fusion have been performed including PLF as well as interbody grafting options from posterior PLIF, ALIF, LLIF, and the transforaminal (TLIF) approaches.
Interbody fusion for back pain was pioneered by Cloward in 1940, using tricortical iliac graft. In 1985, Cloward claimed 87%–92% clinical success and 92% fusion success in his 40-year-experience. In 1993, Brantigan and Steffee developed the first interbody synthetic cage which was carbon-fiber-reinforced implant and achieved 100% fusion rate in 26 patients in 2-year follow-up.
MIS with lumbar interbody fusion using an interbody cage was introduced in 2002 by Foley and Lefkowitz, This surgery offered the advantages of the MIS techniques with less bleeding, less infection, and less postoperative pain; however, the radiological outcome was not statistically different from the open TLIF.,,,,
In 2005, McAfee et al. published a retrospective study on radiological outcomes of static TLIF cages on 120 patients with spondylolisthesis with minimal follow-up 2 years. The results demonstrated that TLIF cages maintained an increase of disc height by 68%. Intraoperative complications included dural tear in seven patients (5.8%). Revision surgery was needed in three patients (2.5%), two due to deep infection (1.6%), and one complicated with cage migration (0.8%).
In 2011, Rouben et al. analyzed retrospectively 169 patients treated by MIS static TLIF cages for back pain with an average follow-up of 49 months. There was a significant improvement in clinical outcome with a fusion rate of 96%. Complications were adjacent segment disease in three patients and pseudoarthrosis in one patient with a total of four patients requiring revision surgery (2.3%).
In 2010, Aoki et al. noted cage migration within 3 months of static TLIF in a case series of 125 patients (3.2%). Two of them had unilateral fixation. They explained this due to the presence of scoliotic curve and undersized cages.
In 2015, Phan et al. systematically reviewed and compared ALIF versus TLIF including six electronic databases. The TLIF group showed dural tear incidence of 3.8%.
In 2016, Kim et al. published a study about MIS expandable cage TLIF on 50 patients demonstrating maintenance of disc dimensions in single- and double-level primary fixation. There were no significant intraoperative or perioperative complications, dural tear, and infection reported. Postoperative radiographs showed no evidence of cage migration, subsidence, or collapse and suggested fusion at all operative levels by 12 months and 24 months (93%, 97%), respectively. This study highlighted the potential benefits of the expandable cage with regard to reduced implantation-related complication rates. However, very few further studies exist in the literature.
Our study included 54 patients. There was minimally invasive and open surgery with clinical and radiological follow-up for 2 years. The results indicate a similar rate of fusion to static cage TLIFs, yet with low complication rate and hospital stay while restoring and maintaining the inteverterbral and neuroforaminal height, and focal and global Cobb angle over 2-year follow-up. It is noted that focal Cobb angle remains static while Global Cobb angle was less maintained due to associated pathology in upper lumbar spine segments which is not related to the fusion and nonadjacent segment disease [Table 5].
|Table 5: Comparison between previous studies and current study regarding Interbody fusion with cage.|
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Limitation to the study
It was performed retrospectively with lack of control group. Computerized tomography scanning would provide more accurate information regarding fusions rates but would subject the patient group to increased radiation which we felt unnecessary in patients with no clinical indication to be scanned.
| Conclusions|| |
These preliminary results indicate that the use of an expandable interbody cage minimizes approach-related neural injury and achieves good clinical as well as radiological outcomes by improving and maintaining foraminal dimensions and disc height with no evidence of cage migration or subsidence in our series. We recommend longer term follow-up and a randomized controlled trial comparing expandable with static interbody cages.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]