Extraforaminal Lumbar Interbody Fusion Research Articles

Biportal endoscopic extraforaminal lumbar interbody fusion using a 3D-printed porous titanium cage with large footprints: technical note and preliminary results.

The aim of this study was to introduce biportal endoscopic extraforaminal lumbar interbody fusion (BE-EFLIF), which involves insertion of a cage through a more lateral side as compared to the conventional corridor of transforaminal lumbar interbody fusion. We described the advantages and surgical steps of 3D-printed porous titanium cage with large footprints insertion through multi-portal approach, and preliminary results of this technique. This retrospective study included 12 consecutive patients who underwent BE-EFLIF for symptomatic single-level lumbar degenerative disease. Clinical outcomes, including a visual analog scale (VAS) for back and leg pain and the Oswestry disability index (ODI), were collected at preoperative months 1 and 3, and 6 months postoperatively. In addition, perioperative data and radiographic parameters were analyzed. The mean patient age, follow-up period, operation time, and volume of surgical drainage were 68.3 ± 8.4 years, 7.6 ± 2.8 months, 188.3 ± 42.4 min, 92.5 ± 49.6 mL, respectively. There were no transfusion cases. All patients showed significant improvement in VAS and ODI postoperatively, and these were maintained for 6 months after surgery (P < 0.001). The anterior and posterior disc heights significantly increased after surgery (P < 0.001), and the cage was ideally positioned in all patients. There were no incidences of early cage subsidence or other complications. BE-EFLIF using a 3D-printed porous titanium cage with large footprints is a feasible option for minimally invasive lumbar interbody fusion. This technique is expected to reduce the risk of cage subsidence and improve the fusion rate.

Microendoscopy-assisted extraforaminal lumbar interbody fusion for treating single-level spondylodesis

BackgroundLumbar interbody fusion is a standard technique for treating degenerative lumbar disorders involving instability. Due to its invasiveness, a minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF), was introduced. On surgically approaching posterolaterally, the posterior muscles and spinal canal are barely invaded. Despite its theoretical advantage, ELIF is technically demanding and has not been popularised. Therefore, we developed a microendoscopy-assisted ELIF (mELIF) technique which was designed to be safe and less invasive. Here, we aimed to report on the surgical technique and clinical results.MethodsUsing a posterolateral approach similar to that of lateral disc herniation surgery, a tubular retractor, 16 or 18 mm in diameter, was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was cleaned. A cage and local bone graft were inserted into the disc space. All disc-related procedures were performed under microendoscopy. The spinal canal was not invaded. Bilateral percutaneous screw-rod constructs were inserted and fixed.ResultsFifty-five patients underwent the procedure. The Oswestry Disability Index and visual analogue scale scores greatly improved. Over 90% of the patients obtained excellent or good results based on Macnab’s criteria. There were neither major adverse clinical effects nor the need for additional surgery.ConclusionsmELIF is minimally invasive because the spinal canal and posterior muscles are barely invaded. It produces good clinical results with fewer complications. This technique can be applied in most single-level spondylodesis cases, including those involving L5/S1 disorders.

Microendoscopy-assisted extraforaminal lumbar interbody fusion for treating single-level spondylodesis

Study design: technical note, retrospective case series. Objectives: Lumbar interbody fusion is a standard technique for treating degenerative lumbar disorders involving instability. Due to its invasiveness, a minimally invasive technique, Extraforaminal Lumbar Interbody Fusion (ELIF), was introduced. On surgically approaching posterolaterally, the posterior muscles and spinal canal are barely invaded. Despite its theoretical advantage, ELIF is technically demanding and has not been popularised. Therefore, we developed a microendoscopy-assisted ELIF (mELIF) technique which was designed to be safe and less invasive. Here, we aimed to report on the surgical technique and clinical results. Methods: Using a posterolateral approach similar to that of lateral disc herniation surgery, a tubular retractor, 16 or 18 mm in diameter, was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was cleaned. A cage and local bone graft were inserted into the disc space. All disc-related procedures were performed under microendoscopy. The spinal canal was not invaded. Bilateral percutaneous screw-rod constructs were inserted and fixed. Results: Fifty-five patients underwent the procedure. The Oswestry Disability Index and visual analogue scale scores greatly improved. Over 90% of the patients obtained excellent or good results based on Macnab’s criteria. There were neither major adverse clinical effects nor the need for additional surgery. Conclusions: mELIF is minimally invasive because the spinal canal and posterior muscles are barely invaded. It produces good clinical results with fewer complications. This technique can be applied in most single-level spondylodesis cases, including those involving L5/S1 disorders.

How I do it? Extraforaminal lumbar interbody fusion assisted with biportal endoscopic technique.

The biportal endoscope-assisted unilateral foraminal approach is an option for various foraminal pathologies. Lumbar interbody fusion is the standard treatment for foraminal stenosis because both direct and indirect neural decompressions can be obtained. We used the biportal endoscopic technique for extraforaminal lumbar interbody fusion (BE-EFLIF) and have described the steps, with discussion regarding the indications, advantages, possible complications, and ways to overcome complications. BE-EFLIF achieves direct neural decompression of lateral spinal canal under endoscopic visualization. It achieves indirect neural decompression using a large footprint lordotic interbody cage, while preserving the lumbar posterior arch as much as possible.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

BACKGROUND CONTEXT Lumbar fusion surgery can be performed through either anterior, lateral or posterior approaches. Although the relative advantage of anterior lumbar surgeries for the restoration of sagittal balance in spinal deformity is well-acknowledged, the comparative utility of these approaches in maintaining sagittal alignment following single level lumbar fusion remains unclear. PURPOSE A systematic review of the current literature was performed to assess the relative change in sagittal lumbar parameters including whole lumbar lordosis (WLL), segmental lumbar lordosis (SLL) and disc height (DH) following lumbar fusion using various approaches. STUDY DESIGN/SETTING Systematic review and meta-analysis. PATIENT SAMPLE All subjects in studies reporting imaging outcomes following single-level lumbar fusion, according to inclusion and exclusion criteria. OUTCOME MEASURES Lumbar sagittal parameters (SLL and WLL) and DH. METHODS A computerized literature search of all articles published up to April 17, 2017 was performed using PubMed and Cochrane databases. The following keywords were used: “anterior lumbar interbody fusion”, “ALIF”, “posterior lumbar interbody fusion”, “PLIF”, “trans-foraminal lumbar interbody fusion”, “TLIF”, “lumbar 360° fusion”, “circumferential lumbar fusion”, “combined anterior and posterior lumbar fusion”, “extreme lateral interbody fusion”, “LLIF”, “lateral lumbar interbody fusion”, “LLIF”, “direct lateral interbody fusion”, “DLIF”, “extraforaminal lumbar interbody fusion”, “ELIF”, with different combinations of operators including “AND”, “NOT” and “OR”. All studies were scored based on Methodological Index for NonRandomized Studies (MINORS) criteria. Pairwise comparisons of the fusion approach effect sizes were performed for the three imaging parameters. RESULTS A total of 1,563 articles under “ALIF”, 2,075 articles under “PLIF”, 1,032 articles under “TLIF”, 1,082 articles under “LLIF” and 894 under “circumferential lumbar fusion” were identified. The articles were further stratified on the basis of number of fusion levels. Only studies reporting relevant imaging outcomes following single-level fusion for degenerative pathologies were included in the final analysis. Using this strategy, a total of 14, 27, 25, 11 and 3 studies were included under ALIF, PLIF, TLIF, minimally invasive-TLIF and LLIF, respectively. Based on pairwise comparisons, ALIF significantly improved WLL and DH restoration as compared to all the other fusion modalities [ALIF vs. PLIF:2.5 (0.5–4.6) vs. 1.5 (0.2–2.4), p CONCLUSIONS Based on a systematic review of the literature, ALIF offers a significantly improved restoration of lumbar sagittal parameters following single-level lumbar fusion.

Minimally invasive extraforaminal lumbar interbody fusion

ResumenObjetivo:El objetivo del presente trabajo es mostrar la indicación, técnica quirúrgica, resultados y complicaciones de la vía de abordaje extraforaminal para fusión intersomática (ELIF) mínimamente invasiva.Introducción:El ELIF se caracteriza por la remoción del proceso articular superior (PAS) y el acceso a la raíz intracanalicular y disco a través del triángulo de seguridad de Kambin.Material y Métodos:Estudio retrospectivo de 40 pacientes operados consecutivamente entre el 2013 y 2015. Se incluyeron pacientes con lumbalgia o dolor radicular por enfermedad degenerativa discal, espondilolistesis grado 1 y 2, hernia discal recurrente y estenosis receso-foraminales. Se utilizó la escala visual analógica, el índice de Oswestry, la escala de Weiner y los criterios de MacNab modificados para evaluar el dolor, resultados clínico-funcionales y satisfacción del paciente al año de la cirugía. Las complicaciones fueron documentadas de acuerdo a su gravedad en 4 grados.Resultados:25 mujeres/15 hombres con una edad promedio de 57 años. El 47.5% fueron tratados por espondilolistesis, el 25% por estenosis receso-foraminal. Se colocaron 54 cajas intersomáticas y 188 tornillos pediculares percutáneos. La duración quirúrgica promedio fue 245 (±25.4) minutos. El tiempo de internación promedio fue 3.5 (±0.49) días. Presentamos 9 complicaciones Grado 1 y una complicación Grado 2. La escala de ODI preoperatoria promedio fue de 51.9 ± 4.96, al año de 12.2 ± 3.19, evidenciando una mejoría significativa (P < 0.0001). La EVA promedio para lumbalgia mejoró de 8.81 ± 0.62 a 2.12 ± 0.89 (P < 0.0001). El 77.5% presentó fusión en los grados 1 y 2 de Bridwel al año del procedimiento quirúrgico.Conclusión:El ELIF es una alternativa de tratamiento quirúrgico segura y eficaz. Se pueden lograr resultados clínicos satisfactorios comparables con las técnicas tradicionales con la resección facetaria limitada al proceso articular superior.

Nerve Root and Lumbar Plexus Proximity to Different Extraforaminal Lumbar Interbody Fusion Trajectories: A Cadaver Study.

Cadaver study. To investigate the safety of the extraforaminal lumbar interbody fusion approach. Over the last decade the number of techniques available for lumbar interbody fusion has increased. Recent interest has developed in an extraforaminal approach to the intervertebral disc to reduce the morbidity associated with facetectomy. The safety of this extraforaminal corridor with regards to the exiting nerve root and lumbar plexus has yet to be assessed. With the cadaver prone, the C-arm was positioned over the disc of interest and aligned perpendicular to the superior endplate of the inferior vertebral body, with the superior articular process bisecting the available disc space. Three needles were passed into the disc and labeled medial, middle, and lateral. After needle placement, each nerve root and the lumbar plexus were dissected. The distance of each needle to these structures was measured and discectomy was performed to assess potential graft length from a transforaminal and extraforaminal approach. We performed the method on levels L1-L5 bilaterally on 2 cadavers, totaling 16 attempts for each needle position. The average distance to nerve of the medial approach (3.2±1.1 mm) was statistically greater than both the middle (1.1±1.4 mm) and lateral (-0.2±2.9 mm) approaches (P<0.0001 for both). The distance to plexus of the medial approach (14.3±6.2 mm) was greater than the middle (9.2±6.1 mm) approach and statistically greater than the lateral (5.2±5.6 mm) approach (P=0.001). There was a greater graft length available by the extraforaminal lumbar interbody fusion approach (36.1±2.7 mm) than the transforaminal lumbar interbody fusion approach (29.3±3.5 mm, P<0.0001). The safest trajectory was the medial, passing adjacent to the superior articular process. The close proximity, however, means that neuromonitoring and tubular dilators would be necessary to use this technique in a clinical setting. Level V.

Minimal invasive lumbar spine revision surgery at distance from the dura and postsurgical scar tissue: Extraforaminal Lumbar Interbody Fusion (ELIF)

Lumbar spine revision surgery is considered as challenging and related to longer operation time and complications because of the loss of anatomical landmarks and the formation of postoperative epidural fibrosis. Minimal invasive lumbar spinal surgery techniques have been refined over the last 5 years but the reexposure of the dura, the formation of postsurgical scar tissue and related dural tears remain a source of complications.For lumbar spinal revision surgery we advocate the minimal invasive Extraforaminal Lumbar Interbody Fusion (ELIF) technique. It employs a working corridor of 45° relative to the midline. This angle permits bypassing laterally the dural sac and postoperative epidural fibrosis so that dural tears do not occur.ELIF is performed without an expandable tubular retractor system, it is atraumatic following the natural intermuscular cleavage plane between the multifidus muscle and the longissimus thoracis muscle pars lumborum. Postoperatively the muscles do not show signs atrophy or fatty degeneration. In case of discectomy alone there is no need for the removal of the facets, if intracanalar lesions are targeted the partial removal of the superior facet is sufficient.ELIF represents an alternative to posterior lumbar interbody fusion (PLIF), conventional open transforaminal lumbar interbody fusion (TLIF), and minimal invasive (MIS) TLIF for lumbar spinal revision surgery.

Extraforaminal Lumbar Interbody Fusion at the L5-S1 Level: Technical Considerations and Feasibility.

Background Extraforaminal lumbar interbody fusion (ELIF) surgery is a muscle-sparing approach that allows the treatment of various degenerative spinal diseases. It is technical challenging to perform the ELIF approach at the L5-S1 level because the sacral ala obstructs the view of the intervertebral disk space. Methods We reported earlier on the ELIF technique in which the intervertebral disk is targeted at an angle of 45 degrees relative to the midline. In this article we describe the technical process we developed to overcome the anatomic relation between the sacral ala and the intervertebral disk space L5-S1 that hinders the ELIF approach at this level. We then report in a retrospective analysis on the short-term clinical and radiologic outcome of 100 consecutive patients with degenerative L5-S1 pathologies who underwent ELIF surgery. Results The L5-S1 ELIF approach could be realized in all patients. The short-term clinical outcome was evaluated 5 months after surgery: 92% of the patients were satisfied with their postoperative result; 8% had a poor result. Overall, 17% of the patients presented light radicular or low back pain not influencing their daily activity, and 82% of the patients working before surgery returned to work 3 to 7 months after surgery. The radiologic outcome was documented by computed tomography at 5 months after surgery and showed fusion in 99% of the patients. Lumbar magnetic resonance imaging performed in 5 patients at 6 months after surgery revealed the integrity of the paraspinal muscles. Conclusions ELIF surgery at the L5-S1 level is technically feasible for various degenerative spinal diseases. Analysis of the clinical and radiologic data in a consecutive retrospective cohort of patients who underwent this surgical procedure showed a good short-term clinical outcome and fusion rate.

A Biomechanical Stability Study of Extraforaminal Lumbar Interbody Fusion on the Cadaveric Lumbar Spine Specimens.

BackgroundTransforaminal lumbar interbody fusion (TLIF) is an effective surgery for lumbar degenerative disease. However, this fusion technique requires resection of inferior facet joint to provide access for superior facet joint resection, which results in reduced lumbar spinal stability and unnecessary trauma. We have previously developed extraforaminal lumbar interbody fusion (ELIF) that can avoid back muscle injury with direct nerve root decompression. This study aims to show that ELIF enhances lumbar spinal stability in comparison to TLIF by comparing lumbar spinal stability of L4–L5 range of motion (ROM) on 12 cadaveric spine specimens after performing TLIF or ELIF.Methods12 cadaveric spine specimens were randomly divided and treated in accordance with the different internal fixations, including ELIF with a unilateral pedicle screw (ELIF+UPS), TLIF with a unilateral pedicle screw (TLIF+UPS), TLIF with a bilateral pedicle screw (TLIF+BPS), ELIF with a unilateral pedicle screw and translaminar facet screw (ELIF+UPS+TLFS) and ELIF with a bilateral pedicle screw (ELIF+BPS). The treatment groups were exposed to a 400-N load and 6 N·m movement force to calculate the angular displacement of L4-L5 during anterior flexion, posterior extension, lateral flexion and rotation operation conditions.ResultsThe ROM in ELIF+UPS group was smaller than that of TLIF+UPS group under all operating conditions, with the significant differences in left lateral flexion and right rotation by 36.15% and 25.97% respectively. The ROM in ELIF+UPS group was higher than that in TLIF+BPS group. The ROM in the ELIF+UPS+TLFS group was much smaller than that in the ELIF+UPS group, but was not significantly different than that in the TLIF+BPS group.ConclusionsDespite that TLIF+BPS has great stability, which can be comparable by that of ELIF+UPS. Additionally, ELIF stability can be further improved by using translaminar facet screws without causing more tissue damage to patient.

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Epidural Fibrosis Seen from a Different Angle: Extraforaminal Lumbar Interbody Fusion.

Background Postoperative epidural fibrosis (PEF) localized around the exposed dura and nerve roots is a known radiologic entity seen after lumbar surgery. Although excessive PEF is associated with residual and new lumbar pain and radiculopathy, its role as the generator of the pain is still discussed. Various materials acting as an adhesion barrier have been tested. There is no undebated class I evidence that any one of them is suitable to reduce or avoid PEF and provide a better clinical outcome. In revision surgery, the dissection of epidural scar tissue is time consuming and related to an elevated risk of dural tear and nerve damage. To avoid the formation of posterior PEF, we propose a surgical approach whose working corridor is situated lateral to the dural sac and the nerve roots: the extraforaminal lumbar interbody fusion (ELIF) technique. Methods Description of ELIF surgical technique. Conclusions The ELIF technique is a muscle-sparing approach to the intervertebral disk space and the spinal canal that avoids the formation of posterior PEF. It represents an option to treat various degenerative lumbar spinal diseases as well as offering another approach for revision surgery in patients who have developed PEF.

Unilateral Extraforaminal Lumbar Interbody Fusion (ELIF): Surgical Technique and Clinical Outcome in 107 Patients.

Description of the technique and retrospective study of patients treated with unilateral extraforaminal lumbar interbody fusion (ELIF) for degenerative lumbar spinal disorders. To investigate clinical and radiologic outcome of patients treated with unilateral ELIF. Lumbar interbody fusion is the classic treatment for higher grades of degenerative disk disease or lumbar segment instability and is performed by posterior (PLIF), posterolateral, or anterior (ALIF) approaches. Those techniques are well established with known limitations and complications. Today, minimally invasive procedures generate more interest especially in terms of muscle damage to achieve better functional outcome. We introduce a unilateral extraforaminal fusion technique which respects neural as well as muscle structures aiming to preserve function. Intraoperative and perioperative data, neurological status, Oswestry Disability Index, the Visual Analogue Scale for leg and back pain, and patient satisfaction were investigated preoperatively and at latest follow-up. Fusion status was controlled by x-ray and CT scans at a 6 months' follow-up investigation. A total of 107 patients [female/male: 67/40; average age, 52.8 (± 13.8) y] were included at a maximum of 31(± 9.4) months. Complications occurred in 4% of patients. Transient radicular pain was investigated in 16 patients. The Oswestry Disability Index and the Visual Analogue Scale for back and leg pain improved significantly. Patients showed a short hospital stay and high percentage of return to work ratio (70%). Fusion was achieved in 97% of patients. The unilateral ELIF fusion technique demonstrates encouraging clinical and radiologic midterm outcome that for some indications is comparable with established fusion techniques.

Design of minimally invasive extraforaminal lumbar interbody fusion (ELIF) based on 3D printing technology

Objective To design a new operation, extraforaminal lumbar interbody fusion (ELIF), with the help of 3D printing technology and to discuss the efficiency of using 3D printing technology in the clinical research. Methods A healthy male volunteer recruited for this study underwent CT scan of his lumbar vertebrae. He was 26 years old, 172 cm in height and 67 kg in weight. Software Mimics V14.0 was used to read and reconstruct his CT scan data into 3D images. We observed the anatomical bone structures and nerve roots of the intervertebral foramen on 3D reconstruction images in Mimics to analyze the anatomic features of this area. The self-designed ELIF, pedicle screw insertion and cage placement were simulated via digital technology in Mimics. 3D printing technology was then used to manufacture a real object to test ELIF on it. The feasibility of this new approach was further tested in a cadaveric specimen. Results In our designed ELIF, an incision of 6 cm lateral from the central line and 45° from the sagittal plane was made to fully expose the foraminal area. ELIF made it simple and visualized to fully expose the target intervertebral disk and nerve roots, and posteriorly the superior and inferior articular processes and joint capsules as well. ELIF also made it feasible to remove only the superior facet but save the inferior facet. There was enough room to fully reveal and excise the intervertebral disc, and place the cage after distraction of nerve roots through the intervertebral foramen. The test results on the 3D printing object and the cadaveric specimen were consistent. Conclusions 3D printing technology is an effective, reliable and economic method to design an operation. Our results suggest that ELIF is a safe, more minimally invasive and efficient operation to treat degenerative lumbar diseases. Key words: Lumbar vertebrae; Spinal fusion; Surgical procedures, minimally invasive; 3D printing technology

Minimally Invasive Extraforaminal Lumbar Interbody Fusion for Revision Surgery: A Technique through Kambin's Triangle.

ObjectiveThe purpose of this study was to evaluate the clinical outcomes of minimally invasive extraforaminal lumbar interbody fusion (ELIF) for revision surgery.MethodsFrom January 2011 to December 2012, 12 patients who underwent minimally invasive ELIF through the Kambin's triangle for revision surgery were included in this study. All patients underwent the surgical procedure in the following sequence: (1) epidural anesthesia, (2) exposing the Kambin's triangle toward the lateral part of the dura (partial resection of the superior articular process), (3) bilateral cage insertion for reinforcement of stabilization and fusion, and (4) percutaneous transpedicular screwing. Clinical outcomes were assessed using the visual analogue scale (VAS), and Oswestry disability index (ODI). Imaging and clinical findings including surgical techniques, clinical outcomes, and related complications were depicted and analyzed.ResultsThe mean age of the patients (5 men, 7 women) was 60.7±13.4 years, and the mean follow-up period was 27.1±4.9 months. The mean VAS (back and leg) score improved significantly at final follow-up. The mean ODI score decreased as follows: preoperative, 76.78±6.08; 3 months after the surgery, 37.74±6.67; and at final follow-up, 29.91±2.98. Two patients presented with transient nerve root irritation, but there were no cases of incidental dural tear or serious infection. No significant neurological deterioration or major complication was noted in any of the patients.ConclusionMinimally invasive ELIF for revision surgery is an effective surgical option with a low complication rate.

Digitalized design of extraforaminal lumbar interbody fusion: a computer-based simulation and cadaveric study.

PurposeThis study aims to investigate the feasibility of a novel lumbar approach named extraforaminal lumbar interbody fusion (ELIF), a newly emerging minimally invasive technique for treating degenerative lumbar disorders, using a digitalized simulation and a cadaveric study.MethodsThe ELIF surgical procedure was simulated using the Mimics surgical simulator and included dissection of the superior articular process, dilation of the vertebral foramen, and placement of pedicle screws and a cage. ELIF anatomical measures were documented using a digitalized technique and subsequently validated on fresh cadavers.ResultsThe use of the Mimics allowed for the vivid simulation of ELIF surgical procedures, while the cadaveric study proved the feasibility of this novel approach. ELIF had a relatively lateral access approach that was located 8–9 cm lateral to the median line with an access depth of approximately 9 cm through the intermuscular space. Dissection of the superior articular processes could fully expose the target intervertebral discs and facilitate a more inclined placement of the pedicle screws and cage with robust enhancement.ConclusionsAccording to the computer-based simulation and cadaveric study, it is feasible to perform ELIF. Further research including biomechanical study is needed to prove ELIF has a superior ability to preserve the posterior tension bands of the spinal column, with similar effects on spinal decompression, fixation, and fusion, and if it can enhance post-fusion spinal stability and expedites postoperative recovery.

Extraforaminal lumbar interbody fusion for cage migration after screw removal: a case report.

The use of titanium cages for posterior lumbar interbody fusion (PLIF) has gained popularity because it offers the advantages of anterior column support and stabilization. However, cage migration into the spinal canal may have severe or disastrous consequences. Here, the authors report an unexpected case of posterior migration of fusion cages after screw removal in a patient that underwent PLIF 12 months previously. Removal of the offending cages through revision extraforaminal lumbar interbody fusion (ELIF) with percutaneous screw fixation successfully managed this complication. As far as the authors' knowledge, this is the first case report to describe this sort of complication, and cautions that care must be taken to prevent cage migration.

Submuskulärer Zugang zur Lendenwirbelsäule und extraforaminale Cage-Implantation

The posterior median approach to the lumbar spine may cause significant injury to the erector spinae muscles (ESM) which is minimized using the paralateral approach suggested by Ray. We have adopted this approach and have extended it into the disc space to allow cage implantation from outside the foramen (EPLIF - extraforaminal posterior lumbar interbody fusion). The initial exposure of the posterior vertebral elements between the ESM and the deep lumbar fascia is sufficient to attain the entry points of pedicle screws. The intervertebral foramen and posterior annulus fibrosus are then exposed after which distant lateral disc herniations may be removed, the foramen/lateral recess may be decompressed or an EPLIF performed following clearing and vertical distraction of the disc space. This is followed by ipsilateral transpedicular fixation (TpF), contralateral fixation (second approach) by TpF or translaminar screws. Indications are given for foraminal and extraforaminal disc herniation, stenosis of the foramen and/or of the lateral recess, posterolateral fusion, TpF and EPLIF. The submuscular approach and EPLIF have proven to be valuable alternatives to standard techniques.

Extraforaminal Lumbar Interbody Fusion for the Treatment of Isthmic Spondylolisthesis

A preliminary study about extraforaminal lumbar interbody fusion (ELIF) technique for the treatment of isthmic spondylolisthesis. To introduce a new surgical fusion technique for isthmic spondylolisthesis with minimally invasive procedure. Posterolateral fusion, posterior lumbar interbody fusion, and anterior lumbar interbody fusion with posterior fixation are the options of the surgical treatment for isthmic spondylolisthesis. Still, complications can be related to these approaches. The authors tried to approach directly to lesion-the exiting nerve root, to decompress and to stabilize with minimally invasive procedure. Through extraforaminal approach, we can expose the exiting nerve root only to perform interbody fusion without intra-abdominal dissection or exposing central dura and traversing nerve root. Five patients with isthmic spondylolisthesis underwent ELIF with percutaneous pedicle screw fixation (PPF) between August 2005 and April 2007. In all subjects, the 3-cm-long posterior skin incisions were made bilaterally about 6 to 8 cm lateral from the midline. The multifidus muscle was separated with blunt dissection from the longissimus muscles. We identified the isthmus and neural foramen, removed fibrocartilage and the lateral border of ligamentum flavum covering the exiting nerve root, separated the soft tissue attached to the root and the transverse process, and retracted the root to perform discectomy. We prepared the endplates, cages with allograft, inserted them under C-arm fluoroscopic guidance, and performed the procedures on the contralateral side. After the arthrodesis, posterior instrumentation was augmented with PPF. Five patients underwent ELIF+PPF; despite a small number of cases, the outcomes were satisfactory. ELIF technique makes exposing only the exiting nerve root easy to perform interbody fusion without violating either the abdominal cavity or the posterior musculoligamentous and the bony stabilizers of the spine. This may be considered as one of the minimally invasive surgical options for isthmic spondylolisthesis.

Biomechanical evaluation of the ventral and lateral surface shear strain distributions in central compared with dorsolateral placement of cages for lumbar interbody fusion

The purpose of this study was to measure and compare the ventral and lateral surface strain distributions and stiffness for two types of interbody cage placement: 1) central placement for anterior lumbar interbody fusion (ALIF); and 2) dorsolateral placement for extraforaminal lumbar interbody fusion (ELIF). Two functional spine units were obtained for testing in each of 13 cadaveric spines, yielding 26 segments (three of which were not used because of bone abnormalities). Bilateral strain gauges were mounted adjacent to the endplate on the lateral and ventral walls of each vertebral body in the 23 motion segments. Each segment was cyclically tested in compression, flexion, and extension in the following conditions: while intact, postdiscectomy, and instrumented with interbody fusion cages placed using both insertion techniques. No significant differences were observed between ALIF and ELIF in compressive stiffness, bending stiffness in flexion and extension (p > or = 0.1), ventral and lateral strain distribution during the intact tests (p > or = 0.24), and during the flexion tests after fusion (p > or = 0.22). In compression, higher ventral and lower lateral strain was observed in the ALIF than in the ELIF group (ventral, p = 0.05; lateral, p = 0.04), and in extension, higher ventral (p = 0.01) and higher lateral strain (p = 0.002) was observed in the ELIF than in the ALIF group. Preservation of the ventral anulus and dorsolateral placement of the interbody cages during ELIF allow alternate load transfer pathways through the dorsolateral vertebral wall and ventral anulus that are not observed following ALIF. These may be associated with a lower incidence of subsidence and a higher rate of fusion due to a more concentrated application of bone healing-enhancing compression forces during the fusion and healing process.