Transforaminal Lumbar Interbody Fusion Cage Research Articles

Modified far lateral endoscopic transforaminal lumbar interbody fusion using a biportal endoscopic approach: technical report and preliminary results.

Endoscopic transforaminal lumbar interbody fusion (TLIF) has the disadvantage of the small cage size and by consequence risk for cage subsidence. We succeeded to insert a large oblique lumbar interbody fusion (OLIF) cage during biportal endoscopic TLIF. Unilateral total facetectomy was performed to expose the exiting and traversing nerve roots. The distance between the exiting and traversing nerve roots was measured before OLIF cage insertion. We inserted an OLIF cage instead of a TLIF cage. We successfully performed modified far lateral biportal endoscopic TLIF using large OLIF cages. Modified far lateral biportal endoscopic TLIF is usually suitable for the L4-5 and L5-S1 levels.

Transforaminal Endoscopic Surgical Treatment for Posterior Migration of Polyetheretherketone Transforaminal Lumbar Interbody Fusion Cage: Case Series

This study aims to report the clinical outcome of treating lumbar radiculopathy in the setting of retropulsed polyetheretherketone (PEEK) transforaminal lumbar interbody fusion (TLIF) cages with transforaminal endoscopic spine surgery. A retrospective study of 8 patients with lumbar radiculopathy in the setting of a retropulsed PEEK TLIF cage were included from January 2014 to January 2019. The inclusion criteria were 1) lumbar radiculopathy in the setting of a retropulsed PEEK TLIF cage causing nerve compression and 2) follow-up at least 1 year. Patients were asked to complete the following questionnaires for outcome evaluation: visual analog scales (VAS) for leg pain and the Oswestry Disability Index (ODI). Eight patients underwent transforaminal endoscopic surgery for treatment of radiculopathy in the setting of a retropulsed PEEK TLIF cage in the 5-year period evaluated. One year after surgery, the VAS and ODI scores showed a significant decrease: average preoperative VAS and ODI scores were 6.9 ± 1.2 and 50.5 ± 10.9, and 1-year postoperative VAS and ODI scores were 2.3 ± 1.3 and 17.3 ± 5.1. Transforaminal endoscopic spine surgery for the treatment of a retropulsed PEEK TLIF cage is a safe and effective approach with low morbidity and acceptable complication rates for patients with radiculopathy secondary to a retropulsed PEEK TLIF cage. Compared with a more invasive approach to removing or drilling the PEEK TLIF cage, endoscopic spine surgery could achieve a similar improvement in the patient-reported outcomes with possibly fewer complications.

Anterior Lumbar Interbody Fusion With Cage Retrieval for the Treatment of Pseudarthrosis After Transforaminal Lumbar Interbody Fusion: A Single-Institution Case Series

The treatment of pseudarthrosis after transforaminal lumbar interbody fusion (TLIF) can be challenging, particularly when anterior column reconstruction is required. There are limited data on TLIF cage removal through an anterior approach. To assess the safety and efficacy of anterior lumbar interbody fusion (ALIF) as a treatment for pseudarthrosis after TLIF. ALIFs performed at a single academic medical center were reviewed to identify cases performed for the treatment of pseudarthrosis after TLIF. Patient demographics, surgical characteristics, perioperative complications, and 1-yr radiographic data were collected. A total of 84 patients were identified with mean age of 59 yr and 37 women (44.0%). A total of 16 patients (19.0%) underwent removal of 2 interbody cages for a total of 99 implants removed with distribution as follows: 1 L2/3 (0.9%), 6 L3/4 (5.7%), 37 L4/5 (41.5%), and 55 L5/S1 (51.9%). There were 2 intraoperative venous injuries (2.4%) and postoperative complications were as follows: 7 ileus (8.3%), 5 wound-related (6.0%), 1 rectus hematoma (1.1%), and 12 medical complications (14.3%), including 6 pulmonary (7.1%), 3 cardiac (3.6%), and 6 urinary tract infections (7.1%). Among 58 patients with at least 1-yr follow-up, 56 (96.6%) had solid fusion. There were 5 cases of subsidence (6.0%), none of which required surgical revision. Two patients (2.4%) required additional surgery at the level of ALIF for pseudarthrosis. ALIF is a safe and effective technique for the treatment of TLIF cage pseudarthrosis with a favorable risk profile.

265. Lumbar vertebral body Hounsfield units are associated with cage subsidence after transforaminal lumbar interbody fusion

BACKGROUND CONTEXT Postoperative subsidence of transforaminal lumbar interbody fusion (TLIF) interbody cages can result in loss of lordosis and foraminal height, and in some cases recurrence of nerve root impingement and radicular symptoms. Hounsfield unit (HU) values as measured on computed tomography (CT) can be used in the assessment of bone quality and bone mineral density. PURPOSE Determine the association between HU measurement of the first lumbar vertebral body and cage subsidence after TLIF. We hypothesized that the HU measured in the vertebral body of L1 would be lower in patients with postoperative TLIF cage subsidence. STUDY DESIGN/SETTING Retrospective case-control study. PATIENT SAMPLE NA OUTCOME MEASURES NA METHODS We retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. Postoperative imaging studies (radiographs and CT) were evaluated for evidence of implant subsidence. Hounsfield unit values were obtained from the first lumbar vertebral body on postoperative CT scan. Primary outcomes of this study were presence of cage subsidence and measured HU value of first lumbar vertebral body. RESULTS We identified 89 patients with complete imaging who met our inclusion criteria, with a mean clinical follow up of 27 months. Forty-five patients (50.5%) had evidence of interbody cage subsidence. Average cage subsidence was 5.5mm, with a range of 2.2 to 10.8mm. We found implant height was significantly higher in the subsidence group (12.6mm) when compared to the nonsubsidence group (11.2mm). First lumbar vertebral body coronal (170.69±15.61 vs 138.64±14.21; P=0.003), sagittal (175.14±17.26 vs 140.16±13.71; P=0.002), axial (157.57±12.26 vs 134.35±12.30.83; P=0.009), and average HU (167.8±14.04 vs 137.71±12.83; P=0.002) were significantly higher in the non-subsided group vs subsided group (167.8±14.04 vs 137.71±12.83; P=0.002). The subsidence group had a fusion rate of 82% compared to 93% in the nonsubsidence group, although this finding did not reach statistical significance (p=0.08). CONCLUSIONS We found that HU measurements of the first lumbar vertebra are significantly higher in patients without evidence of TLIF cage subsidence when compared to patients with cage subsidence. We identified a trend toward a decreased fusion rate in the subsidence group, yet this finding was not statistically significant. Our findings suggest that HU measurements may function as a surrogate measurement for bone mineral density, and as a predictor for cage subsidence following TLIF. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Lumbar disc height and vertebral Hounsfield units: association with interbody cage subsidence.

Postoperative subsidence of transforaminal lumbar interbody fusion (TLIF) cages can result in loss of lordosis and foraminal height, and potential recurrence of nerve root impingement. The objectives of this study were to determine factors associated with TLIF cage subsidence. Specifically, the authors sought to determine if preoperative disc height compared to cage height could be used to predict TLIF interbody cage subsidence, and if decreased postoperative vertebral Hounsfield units (HUs) predisposed to cage subsidence. The authors retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. The preoperative disc height was measured for the operative and adjacent-level disc on MRI. The difference between cage and disc heights was measured and compared between the subsidence and nonsubsidence groups. The average HUs of the L1 vertebral body were measured on CT scans. Eighty-nine patients were identified with complete imaging and follow-up information. Forty-five patients (50.6%) had evidence of interbody cage subsidence on follow-up CT. The average cage subsidence was 5.5 mm (range 2.2-10.8 mm). The average implant height was significantly higher in the subsidence group compared to the nonsubsidence group (12.6 vs 11.2 mm). Additionally, the difference between cage height and preoperative adjacent-level disc height was also significantly larger in the subsidence group (3.8 vs 1.2 mm). First lumbar vertebral body (L1) HUs were significantly higher in the nonsubsidence versus the subsidence group (167.8 vs 137.71 HUs, p = 0.002). Multivariate logistic regression analysis identified suprajacent disc height and L1 HUs to be independent predictors of interbody cage subsidence. Receiver operating characteristic curves identified a suprajacent to cage height difference > 1.3 mm to have a 93.3% sensitivity for cage subsidence. This study is the first of its kind to demonstrate the association between vertebral body HUs and suprajacent disc height with the development of interbody cage subsidence after TLIF. The authors found that patients with lower HUs in the L1 vertebral body were more likely to experience subsidence, regardless of surgical level. Additionally, the study demonstrated that interbody cage height > 1.3 mm above the height of the suprajacent level is an independent risk factor for cage subsidence, with 93.3% sensitivity. These findings suggest that these factors may be utilized to create a template preoperatively for intraoperative cage selection.

Technique of Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

Biportal endoscopic transforaminal lumbar interbody fusion (TLIF) may have advantages of minimally invasive fusion surgery as well as those of endoscopic surgery. The purpose of this study was to present the biportal endoscopic TLIF technique along with video presentations and a review of the literature on this technique. Basically, the biportal endoscopic TLIF technique is similar to minimally invasive TLIF with a tubular retractor. There were 2 options in the biportal endoscopic TLIF procedures. The first was the insertion of one long TLIF cage and the other was the insertion of 2 short posterior lumbar interbody fusion (PLIF) cages. After the interbody fusion procedures, percutaneous pedicles screw fixation was performed. Biportal endoscopic TLIF achieved complete neural decompression through laminectomy and facetectomy like conventional TLIF. Endplate preparation was performed completely under a clear and magnified endoscopic view. It was also feasible to insert a large TLIF cage or 2 cages for PLIF without exiting nerve root injury. Biportal endoscopic TLIF might have the advantages of endoscopic surgery as well as minimally invasive fusion surgery. Direct neural decompression, endplate preparation under endoscopic guidance, and the insertion of a large TLIF cage or 2 PLIF cages may be the merits of biportal endoscopic lumbar fusion procedures.

Evaluation of the clinical and demographic data of patients requiring revision after lumbar spinal stenosis surger

Aim: This study aimed to evaluate the clinical and demographic data of patients requiring revision surgery after lumbar spinal stenosis (LSS) surgery and to provide a guide us in choosing primary surgical options.Material and Methods: This study was conducted as a single-center, descriptive, and retrospective study. LSS patients, who were operated upon using the same implant technique between 2012 and 2017, and subsequently underwent revision surgery due to implant failure and operated by the same surgeon were included. Medical records, preoperative and postoperative two-plan radiographs, and computed tomography (CT) scans of the primary and revision surgeries of the patients were evaluated.Results: A total of 19 patients (5 males, 14 females) with a mean age of 64.16 ± 7.9 years (range: 47 to 77 years) were included in the study. Most of the patients who underwent revision surgery were over 65 years of age and had a normal body mass index (BMI). In addition, 16 patients (84.2%) who underwent revision surgery were operated without transforaminal lumbar inter-body fusion (non-TLIF). L5-S1 was the most commonly seen level for spinal stenosis revision. The mean revision time was 245.26 ± 65.1 days (range: 135 to 342).Conclusion: Debates are ongoing between transforaminal lumbar inter-body fusion (TLIF) and non-TLIF surgery. In light of the data obtained through this study, we think that TLIF cage surgery should be included in the primary surgical procedure, especially at the lumbosacral junction, where it is difficult to obtain fusion to avoid revision in patients undergoing LSS surgery.

Surgical Strategies for the Treatment of Lumbar Pseudarthrosis in Degenerative Spine Surgery: A Literature Review and Case Study.

Pseudarthrosis after lumbar fusion can generate pain and disability and often requires revision. However, results of revision procedures have historically been relatively poor. The aim of this review was to examine the current evidence related to the management of lumbar pseudarthrosis, with a focus on revision after failure of posterolateral fusion or lumbar interbody fusion. A review of orthopedic spine literature published before March 2019 was conducted using PubMed and Google Scholar. Studies addressing revision after failed posterolateral fusions and after failed interbody fusion were selected. We also present a case of successful revision after failed transforaminal lumbar interbody fusion (TLIF). The review revealed that persistent pseudarthrosis after revision posterolateral fusion occurs at rates of 35 to 51%. No significant difference has been demonstrated in rates of successful fusion after anterior lumbar interbody fusion (ALIF) and ALIF with revision posterolateral fusion for pseudarthroses after failed TLIF procedures (81% versus 88%), although ALIF alone may be appealing because it avoids further disruption of the posterior musculature. No significant differences have been observed in quality-of-life scores among patients undergoing revision after posterolateral fusion, TLIF, ALIF, or ALIF with posterior fusion. Failed TLIF cages may be extracted and replaced through an anterior or lateral approach. If the geometry of the failed cage permits insertion of a second cage, a contralateral approach may be used. Revision retroperitoneal approaches are associated with higher complication rates. The management of lumbar pseudarthrosis requires careful planning, as well as intra-operative attention to detail, for revision surgery to be successful. Circumferential procedures have shown success in revision posterolateral and interbody fusion failures.

Cone Beam Intraoperative Computed Tomography-based Image Guidance for Minimally Invasive Transforaminal Interbody Fusion.

Transforaminal lumbar interbody fusion (TLIF) is commonly used for the treatment of spinal stenosis, degenerative disc disease, and spondylolisthesis. Minimally invasive surgery (MIS) approaches have been applied to this technique with an associated decrease in estimated blood loss (EBL), length of hospital stay, and infection rates, while preserving outcomes with traditional open surgery. Previous MIS TLIF techniques involve significant fluoroscopy that subjects the patient, surgeon, and operating room staff to non-trivial levels of radiation exposure, particularly for complex multi-level procedures. We present a technique that utilizes an intraoperative computed tomography (CT) scan to aid in placement of pedicle screws, followed by traditional fluoroscopy for confirmation of cage placement. Patients are positioned in the standard fashion and a reference arc is placed in the posterior superior iliac spine (PSIS) followed by intraoperative CT scan. This allows for image-guidance-based placement of pedicle screws through a one-inch skin incision on each side. Unlike traditional MIS-TLIF that requires significant fluoroscopic imaging during this stage, the operation can now be performed without any additional radiation exposure to the patient or operating room staff. After completion of the facetectomy and discectomy, final TLIF cage placement is confirmed with fluoroscopy. This technique has the potential to decrease operative time and minimize total radiation exposure.

Transforaminal lumbar interbody fusion for lumbar disc disease and listhesis – Is it advantageous?

Introduction: Among various spine disorders, degenerative conditions like lumbar disc disease and spondylolisthesis are commonly encountered. Surgery is the option if conservative management fails. Fusion is the only option to alleviate instability. Transforaminal Lumbar Interbody Fusion (TLIF) is a promising procedure to achieve this goal. The aim of our study was to evaluate whether unilateral TLIF with one cage is comparable with other established techniques. Materials and Methods: This is a prospective study with 11 males & 11 females who have undergone TLIF for disc disease and low grade listhesis. A single TLIF cage was used for single level pathologies. In one patient with contiguous two level disc disease, two level TLIF was performed. Results: Results were analysed with respect to intra-op parameters (like surgery duration, blood loss, etc.) and post-op parameters (like fusion, pain relief, etc.). Oswestry Disability Index was used to measure functional outcome. There was a statistically significant improvement in post-op scores (p Conclusion: Proper patient selection and surgeon’s expertise are important for a successful outcome. TLIF has many advantages when compared to other fusion techniques. It is an ideal management for treating degenerative disc disease and listhesis of low grades. Keywords: Transforaminal, Lumbar interbody fusion, Spondylolisthesis, Lumbar disc disease, Degenerative, Radiculopathy.

Technical Consideration for TLIF Cage Retrieval and Deformity Correction With Anterior Interbody Fusion in Lumbar Revision Surgeries

IntroductionSymptomatic pseudoarthrosis after transforaminal lumbar interbody fusion (TLIF) could result in sagittal malalignment. Revision posterior surgery with TLIF cage removal poses a challenge intraoperatively. The authors have proposed salvage anterior approach for cage removal and have discussed unique experience with the correction in their deformity patients. MethodsAll patients with symptoms of clinical deformity or symptomatic pseudoarthrosis operated from January of 2012 to February of 2018 were included in the study. TLIF cage removal followed by anterior lumbar interbody fusion (ALIF) surgery was performed in all patients. Radiographic sagittal parameters including thoracic kyphosis (TK; T4–T12), sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), the mismatch between pelvic incidence (PI) and LL (PI-LL), sacral slope (SS), pelvic tilt (PT), and PI were analyzed. Results6 patients (mean age of 57 years, 83% female) underwent TLIF retrieval through anterior approach and ALIF with hyperlordotic cages (HLCs), followed by posterior spinal fusion surgery. Described technique entails use of tailored instruments with sequential gentle distraction of end plates with TLIF spreader could facilitate in the cage removal. Mean number of interbody levels fused pre as well as post were 1.5. The radiographic sagittal parameters from preoperative versus postoperative standing were as follows: T4–T12 TK, 16° vs. 37.6°; LL, −25° vs. −47.6°; PT, 36° vs. 26°; PI-LL, 35° vs. 12.4°; SVA, 12° vs. 5.6°; and TPA, 44° vs. 25°, with p<.001. Mean number of instrumented level fused were 8.1. Using linear regression analysis, change from pre-to postoperative standing in LL predicted pre-to postoperative change in SVA and TPA for global correction (R= −0.30 and −0.80, respectively). ConclusionsAnterior approach is a suitable technique for TLIF cage removal while preserving the end plates for subsequent optimal interbody fusion at the index level in symptomatic pseudoarthrosis patients or those with clinical deformity. ALIF with HLCs with or without Ponte osteotomy can restore segmental and overall sagittal alignment.

Management of Infected Transforaminal Lumbar Interbody Fusion Cage in Posterior Degenerative Lumbar Spine Surgery

The postoperative infection rates for transforaminal lumbar interbody fusion (TLIF) have ranged from <2% to 4%. However, no consensus has been reached on the treatment strategies. TLIF cage preservation or revision surgery for lumbar spine reconstruction are 2 possible treatments. We aimed to determine the most effective method for organ/space infection control. The data from 4923 patients who had undergone TLIF with cage and posterior pedicle-screw instrumentation for spondylolysis or degenerative spondylolisthesis from January 2008 to December 2015 were retrospectively analyzed. Of the 4923 patients, 32 (0.65%) had developed organ/space infection of the interbody cage and were divided into 2 groups: those whose interbody cage was removed for revision (group 1) and those who interbody cage was retained (group 2). We compared the initial management of both groups in terms of age, sex, elapsed time to diagnosis, changes in spinal lordotic angle, visual analog scale score, fusion status, and Kirkaldy-Willis functional outcomes. The 32 patients with organ/space infection had a mean age of 66.3 years and a follow-up period of 23.8 months. Significant differences were observed in the mean elapsed time to diagnosis (P= 0.004), lordotic angle correction at the disease level (P= 0.03), and Kirkaldy-Wallis functional outcomes (P= 0.01). Of the 17 patients undergoing debridement for implant retention, 9 (52.9%) exhibited poor results. The most important factor contributing to TLIF cage retention failure was epidural fibrosis of the previous transforaminal route and biofilm adhesion on interbody devices affecting infection clearance. Thus, we would recommend a combined anterior and posterior approach or the transforaminal route for radical debridement with cage removal and fusion to achieve better clinical outcomes.

Does the Cage Position in Transforaminal Lumbar Interbody Fusion Determine Unilateral versus Bilateral Screw Placement?: A Review of the Literature.

This literature review examines the relative placement of the interbody cage with respect to the unilateral screw construct to address the need for bilateral screw placement versus unilateral screw placement. Transforaminal lumbar interbody fusion (TLIF) has become a widely used technique for correcting lumbar intervertebral pathologies. This review addresses the necessity for further study on the effects of the relative position of intervertebral cage placement on the outcome of lumbar spine surgery after TLIF with unilateral pedicle screw fixation. Previous studies have addressed various factors, including posterior screw fixation, cage size, cage shape, and number of levels fused, that impact the biomechanics of the lumbar spine following TLIF. A simple survey of the literature was conducted. A search of the English literature was conducted using the keywords ‘TLIF,’ ‘transforaminal lumbar interbody fusion,’ ‘graft placement,’ ‘graft position,’ ‘cage position,’ ‘cage placement,’ ‘unilateral pedicle screw,’ ‘unilateral TLIF cage placement,’ ‘lumbar biomechanics,’ ‘lumbar stability,’ ‘lumbar fusion,’ and ‘lumbar intervertebral cage’ with various combinations of the operators ‘AND’ and ‘OR’ and no date restrictions. Seventeen articles in the English literature that were most relevant to this research question were identified. To the best of our knowledge, there are no published data addressing the effects of cage placement relative to the unilateral screw on lumbar stability in TLIF with unilateral pedicle screw fixation. Investigation of the effects of cage placement is, thus, warranted to achieve optimal clinical outcomes in patients undergoing TLIF with unilateral pedicle screw fixation.

Biomechanics of an Expandable Lumbar Interbody Fusion Cage Deployed Through Transforaminal Approach.

A novel expandable lumbar interbody fusion cage has been developed which allows for a broad endplate footprint similar to an anterior lumbar interbody fusion; however, it is deployed from a minimally invasive transforaminal unilateral approach. The perceived benefit is a stable circumferential fusion from a single approach that maintains the anterior tension band of the anterior longitudinal ligament. The purpose of this biomechanics laboratory study was to evaluate the biomechanical stability of an expandable lumbar interbody cage inserted using a transforaminal approach and deployed in situ compared to a traditional lumbar interbody cage inserted using an anterior approach (control device). Twelve cadaveric spine specimens (L1-5) were tested intact and after implantation of both the control and experimental devices in 2 (L2-3 and L3-4) segments of each specimen; the assignments of the control and experimental devices to these segments were alternated. Effect of supplemental pedicle screw-rod stabilization was also assessed. Moments were applied to the specimens in flexionextension (FE), lateral bending (LB), and axial rotation (AR). The effect of physiologic preload on construct stability was evaluated in FE. Segmental motions were measured using an optoelectronic motion measurement system. The deployable expendable transforaminal lumbar interbody fusion (TLIF) cage and control devices significantly reduced FE motion with and without compressive preload when compared to the intact condition (P < .05). Segmental motions in LB and AR were also significantly reduced with both devices (P < .05). Under no preload, the deployable expendable TLIF cage construct resulted in significantly smaller FE motion compared to the control cage construct (P < .01). Under all other testing modes (FE under 400N preload, LB, and AR), the postoperative motions of the 2 constructs did not differ statistically (P > .05). Adding bilateral pedicle screws resulted in further reduction of range of motion for all loading modes compared to intact condition, with no statistical difference between the 2 constructs (P > .05). The ability of the deployable expendable interbody cage in reducing segmental motions was equivalent to the control cage when used as a standalone construct and also when supplemented with bilateral pedicle screw-rod instrumentation. The larger footprint of the fully deployed TLIF cage combined with preservation of the anterior soft-tissue tension band may provide a better biomechanical fusion environment by combining the advantages of the traditional anterior lumbar interbody fusion and TLIF approaches.

Friday, September 28, 2018 1:00 PM–2:30 PM abstracts: achieving lumbar interbody fusion: 196. Preoperative disc height predicts TLIF cage subsidence

BACKGROUND CONTEXT Postoperative subsidence of the transforaminal lumbar interbody fusion (TLIF) cages can result in loss of lordosis and foraminal height, and in some cases recurrence of nerve root impingement and radicular symptoms. PURPOSE The purpose of this study is to determine factors associated with TLIF cage subsidence. Specifically, we sought to determine if preoperative disc height compared to cage height could be used to predict TLIF interbody cage subsidence. STUDY DESIGN/SETTING Retrospective case-control study. PATIENT SAMPLE We identified 127 patients with complete imaging who met our inclusion criteria, with a mean clinical follow up of 27 months. OUTCOME MEASURES The primary outcome of this study was presence of cage subsidence identified with radiograph or CT. METHODS We retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. Postoperative imaging studies (radiographs and CT) were evaluated for evidence of implant subsidence. Preoperative disc height was measured for the operative and adjacent level disc heights. The delta between cage height and disc heights were measured and compared between groups. RESULTS Fifty four patients (44.3%) had evidence of interbody cage subsidence. Average cage subsidence was 5.5mm, with a range of 2.2–10.8mm. We found implant height was significantly higher in the subsidence group (12.6mm) when compared to the nonsubsidence group (11.2mm). Additionally, the delta between cage height and preoperative disc height was significantly larger in the subsidence group delta (5.5mm vs. 3.9mm). Similarly, the delta between cage height and preoperative adjacent level disc height was also significantly larger (1.2mm vs. 3.8mm). CONCLUSIONS This study demonstrates that preoperative disc height and preoperative adjacent level disc height can be used to template TLIF cage height to potentially decrease rates of subsidence. Larger cages subsided more frequently than smaller cages. Patients with evidence of subsidence had larger deltas between cage height and preoperative disc height. Similarly, a significant difference existed if preoperative adjacent level disc height was compared to cage height. This demonstrates that preoperative imaging should be used for TLIF cage height templating to avoid subsidence.

Length of Lumbar Interbody Cage Using Radiological Measurements of Chinese Endplates and the Apophyseal Ring

To radiologically measure the parameters of endplates and the apophyseal ring and to suggest an applicable length for a lumbar interbody cage for Chinese patients. Twenty-four volunteers were enrolled to undergo lumbar computed tomography (CT). On the endplate plane, the diameters of the endplates (L1-S1) were measured along the axis of the cage with different lumbar interbody fusion procedures. Whereas the mid-oblique diameter (mid-OD) and maximum oblique diameter (max-OD) were defined as the minimal and maximal diameters of the endplates in transforaminal lumbar interbody fusion (TLIF), side-sagittal diameter (side-SD), mid-sagittal diameter (mid-SD), and transverse diameter (TD) represented the diameters of endplates in posterior lumbar interbody fusion (PLIF), anterior lumbar interbody fusion (ALIF); and oblique lateral interbody fusion (OLIF)/extreme lateral interbody fusion (XLIF), /direct lateral interbody fusion (DLIF), respectively. R1-R10 were the widths of the apophyseal ring covered by diameters at both ends. We used the proposed formula to calculate the cage length: 1) minimal length of TLIF cage= mid-OD- ½ (R1+ R2), 2) maximal length of TLIF cage= max-OD- ½ (R3+ R4), 3) length of PLIF cage= side-SD- ½ (R5+ R6), 4) length of OLIF/XLIF/DLIF cage= TD- ½ (R7+ R8), and 5) length of ALIF cage= mid-SD- ½ (R9+ R10). The lengths of the TLIF cage were more than 30 mm for men and 26 mm for women in L1/2-L4/5, with a large range in L5-S1. For PLIF, the lengths were 28 to 30 mm for men and 24 to 26 mm for women in L1/2-L4/5, with 26 mm and 22 mm, respectively, in L5-S1. For the OLIF/XLIF/DLIF cage, the lengths were 38 mm in L1/2 and 41 to 43 mm in L2/3-L4/5 for men and 35 mm in L1/2-L2/3 and 38 mm in L3/4-L4/5 for women. The ALIF cage lengths were 27 mm in L1/2 and L5-S1 and 29 mm in L2/3-L4/5 for men and 23 mm in L1/2 and L5-S1 and 25 mm in L2/3-L4/5 for women. The choice of an appropriate length for a lumbar interbody cage should be based on the procedure and fusion level, which can match the endplates anatomically. The size of the lumbar interbody cage is affected by many factors, and a simple calculation may not be clinically relevant.

Safety of a novel modular cage for transforaminal lumbar interbody fusion - clinical cohort study in 20 patients with degenerative disc disease.

Introduction: Transforaminal lumbar interbody fusion (TLIF) is used to reconstruct disc height and reduce degenerative deformity in spinal fusion. Patients with osteoporosis are at high risk of TLIF cage subsidence; possibly due to the relatively small footprint compared to anterior interbody devices. Recently, modular TLIF cage with an integral rail and slot system was developed to reduce cage subsidence and allow early rehabilitation.Objective: To study the safety of a modular TLIF device in patients with degenerative disc disorders (DDD) with regard to surgical complications, non-union, and subsidence.Methods: Patients with DDD treated with a modular TLIF cage (Polyetheretherketone (PEEK), VTI interfuse S) were analysed retrospectively with one-year follow-up. Lumbar sagittal parameters were collected preoperatively, postoperatively and at one year follow-up. Cage subsidence, fusion rate, screw loosening and proportion of endplate coverage were assessed in computed tomography scan.Results: 20 patients (age 66 ± 10 years, 65% female, BMI 28 ± 5 kg/m2) with a total of 37 fusion levels were included. 15 patients had degenerative spondylosis and 5 patients had degenerative scoliosis. The cages covered >60% of the vertebral body diameters. Lumbar lordosis angle and segmental disc angle increased from 45.2 ± 14.5 and 7.3 ± 3.6 to 52.7 ± 9.1 and 10.5 ± 3.5 (p = 0.029 and 0.0002) postoperatively for each parameter respectively without loss of correction at one year follow up. One case of deep postoperative infection occurred (5%). No cage subsidence occurred. No non-union or screw loosening occurred.Conclusions: The modular TLIF cage was safe with regard to subsidence and union-rate. It restored and maintained lumbar lordosis angle, segmental disc angle and disc height, which can be attributed to the large footprint of this modular cage.

Posterior lumbar interbody fusion using single polyetheretherketone transforaminal lumbar interbody fusion cage: a single-surgeon experience

Study design This is a prospective nonrandomized single-surgeon experience of posterior lumbar interbody fusion (PLIF) using a single polyetheretherketone (PEEK) transforaminal lumbar interbody fusion (TLIF) cage in degenerative lumbar disorders. Summary of background data The PLIF procedure has gained popularity, with different indications. TLIF PEEK cages can be used either singly or doubly. There are several practical problems encountered in the TLIF procedure with implantation of two cages. Objectives The aim of this work is to evaluate single-surgeon experience of early results of PLIF using a single PEEK TLIF cage in degenerative lumbar disorders. Patients and methods The study included 19 consecutive cases with degenerative lumbar disorders. There were 12 female and seven male patients. Their age ranged between 22 and 68 years. The follow-up period ranged between 6 and 16 months. All patients were diagnosed using MRI. Postoperative and follow-up radiography and multislice computed tomography were used to verify the screws and position of the cage, to exclude cage subsidence or migration, and to show the fusion status. The Visual Analog Scale (VAS) for back and leg pain was used. Results All the patients had good cage positioning and none had instrumentation failure or screw loosening. Postoperative intervertebral height in all the patients was better than the preoperative ones. Moreover, cage migration, retropulsion, subsidence, or pseudoarthrosis was not observed at the end of follow-up. VAS for leg pain showed a statistically significant improvement from 7.9 preoperatively to 2.8 at the end of follow-up. VAS for back pain also showed a statistically significant improvement from 6.8 preoperatively to 3.7 at the end of follow-up. Conclusion Early results of PLIF using a single PEEK TLIF cage in degenerative lumbar disorders are encouraging. However, longer follow-up is still necessary.

MIS Expandable Interbody Spacers: A Literature Review and Biomechanical Comparison of an Expandable MIS TLIF With Conventional TLIF and ALIF.

Biomechanical study and review of literature on expandable lumbar interbody fusion constructs. To evaluate the biomechanical stability of expandable interbody devices. Lumbar interbody implants placed from an anterior or lateral approach are desirable due to their large size, providing a stable fusion environment. Posterior implants are typically limited by their access corridor. Expandable footprint transforaminal lumbar interbody fusion (TLIF) interbodies may allow for a minimally invasive TLIF approach with the biomechanical benefits of an anterior lumbar interbody fusion (ALIF)-sized graft; however, this requires experimental investigation. Six cadaveric L1-sacrum segments were tested intact with pure moments of ± 7.5 N m in flexion-extension, lateral bending, and axial rotation. Specimens received at L4-5 either a medial-lateral expandable TLIF cage (MLX-TLIF) or a conventional polyether ether ketone (PEEK) banana-shaped TLIF cage (Conv-TLIF) first. Both were tested with unilateral and bilateral pedicle screw (PS) fixation. Testing was repeated with the alternate cage and fixation. Motion marker arrays were fixed to L4 and L5 to assess range of motion. Results were compared with published data for a PEEK ALIF cage with anterior plate and a PEEK ALIF cage with bilateral PS fixation, tested under the same conditions. The most rigid construct was ALIF with bilateral PS fixation in flexion-extension and axial rotation, whereas MLX with bilateral PS was most rigid in lateral bending. Conv-TLIF with unilateral PS was the least rigid construct. MLX-TLIF with unilateral PS provided similar range of motion to Conv-TLIF with bilateral PS in flexion-extension and lateral bending, and ALIF with anterior plate in lateral bending. The MLX-TLIF cage with unilateral PS fixation provided comparable stability to conventional TLIF with bilateral PS fixation and ALIF with anterior plate treatments. The large footprint of the expandable cage may reduce the TLIF supplemental fixation demands and facilitate minimally invasive single-position surgery. If needed, additional stability may be achieved by using bilateral PS. N/A.

Biomechanical analysis of an expandable lateral cage and a static transforaminal lumbar interbody fusion cage with posterior instrumentation in an in vitro spondylolisthesis model

Insufficient biomechanical data exist from comparisons of the stability of expandable lateral cages with that of static transforaminal lumbar interbody fusion (TLIF) cages. The purpose of this biomechanical study was to compare the relative rigidity of L4-5 expandable lateral interbody constructs with or without additive pedicle screw fixation with that of L4-5 static TLIF cages in a novel cadaveric spondylolisthesis model. Eight human cadaver spines were used in this study. A spondylolisthesis model was created at the L4-5 level by creating 2 injuries. First, in each cadaver, a nucleotomy from 2 channels through the anterior side was created. Second, the cartilage of the facet joint was burred down to create a gap of 4 mm. Light-emitting-diode tracking markers were placed at L-3, L-4, L-5, and S-1. Specimens were tested in the following scenarios: intact model, bilateral pedicle screws, expandable lateral 18-mm-wide cage (alone, with unilateral pedicle screws [UPSs], and with bilateral pedicle screws [BPSs]), expandable lateral 22-mm-wide cage (alone, with UPSs, and with BPSs), and TLIF (alone, with UPSs, and with BPSs). Four of the spines were tested with the expandable lateral cages (18-mm cage followed by the 22-mm cage), and 4 of the spines were tested with the TLIF construct. All these constructs were tested in flexion-extension, axial rotation, and lateral bending. The TLIF-alone construct was significantly less stable than the 18- and 22-mm-wide lateral lumbar interbody fusion (LLIF) constructs and the TLIF constructs with either UPSs or BPSs. The LLIF constructs alone were significantly less stable than the TLIF construct with BPSs. However, there was no significant difference between the 18-mm LLIF construct with UPSs and the TLIF construct with BPSs in any of the loading modes. Expandable lateral cages with UPSs provide stability equivalent to that of a TLIF construct with BPSs in a degenerative spondylolisthesis model.