Anterior Cage Research Articles

EFFICACY OF CAGE PLACEMENT WITHOUT PLATE IN PATIENTS WITH CERVICAL MYELOPATHY WITH SINGLE-LEVEL AFFECTION

ABSTRACT Objective: To determine the efficacy of PEEK (Poly-ether-ether-ketone) cage without plate for the treatment of single-level cervical spondylosis. Methods: Ten patients with cervical myelopathy data, with a single-level root condition, seen at the outpatient clinic of the Neurosurgery Service, operated in 2016, mean age 53 years, 6 (60%) female, 4 (40%) obese, 3 (30%) smokers. The Cloward technique was used by anterior approach, discectomy, and PEEK cage placement. Results: At six months of surgery, 100% of the patients had increased intervertebral space, with a 100% reduction in osteophytes; only one patient had dysphagia, no patient had lesion of the adjacent segment and 10% had persistent root pathology. Cervical lordosis was observed in 90% of the patients and arthrodesis in 100% of the cases. Conclusions: Anterior approach arthrodesis using PEEK cage without cervical plate is effective as a treatment of cervical myelopathy in a single level.

Circumferential Fusion through All-Posterior Approach in Andersson Lesion.

Study DesignRetrospective case series.PurposeTo assess safety and efficacy of single stage, posterior stabilisation and anterior cage reconstruction through the transforaminal or lateral extra-cavitary route for Andersson lesions.Overview of LiteraturePseudoarthrosis in ankylosing spondylitis (Andersson lesion, AL) can cause progressive kyphosis and neurological deficit. Management involves early recognition and surgical stabilisation in patients with instability. However, the need and safety of anterior reconstruction of the vertebral body defect remains unclear.MethodsTwenty consecutive patients with AL whom presented with instability back pain and or neurological deficit were managed by single stage posterior approach with long segment pedicle screw fixation and anterior vertebral reconstruction. Radiological evaluation included- the regional kyphotic angle, measurement of anterior defect in computed tomography (CT) scan and the spinal cord status in magnetic resonance imaging. Radiological outcomes were assessed for fusion and kyphosis correction. Functional outcomes were assessed with visual analogue scale (VAS), ankylosing spondylitis quality of life (ASQoL) and Oswestry disability index (ODI).ResultsThe mean age of the patients was 50.1 years (male, 18; female, 2). The levels affected include thoracolumbar (n=12), lower thoracic (n=5) and lumbar (n=3) regions. The mean level of fixation was 6.2±2.4 vertebrae. The mean anterior column defect was 1.6±0.6 cm. The mean surgical duration, blood loss and hospital stay were 112 minutes, 452 mL and 6.2 days, respectively. The mean followup was 2.1 years. At final follow up, VAS for back pain improved from 8.2 to 2.4 while ODI improved from 62.7 to 18.5 (p <0.05) and ASQoL improved from 14.3±2.08 to 7.90±1.48 (p <0.05). All patients had achieved radiological union at a mean 7.2±4.6 months. The mean regional kyphotic angle was 27° preoperatively, 16.7° postoperatively and 18.1° at the final follow-up.ConclusionsPosterior stabilisation and anterior reconstruction with cage through an all-posterior approach is safe and can achieve good results in Andersson lesions.

Do position and size matter? An analysis of cage and placement variables for optimum lordosis in PLIF reconstruction

PurposeTo examine monosegmental lordosis after posterior lumbar interbody fusion (PLIF) surgery and relate lordosis to cage size, shape, and placement.MethodsEighty-three consecutive patients underwent single-level PLIF with paired identical lordotic cages involving a wide decompression and bilateral facetectomies. Cage parameters relating to size (height, lordosis, and length) and placement (expressed as a ratio relative to the length of the inferior vertebral endplate) were recorded. Centre point ratio (CPR) was the distance to the centre of both cages and indicated mean position of both cages. Posterior gap ratio (PGR) was the distance to the most posterior cage and indicated position and cage length indirectly. Relationships between lordosis and cage parameters were explored.ResultsMean lordosis increased by 5.98° (SD 6.86°). The cages used varied in length from 20 to 27 mm, in lordosis from 10° to 18°, and in anterior cage height from 10 to 17 mm. The mean cage placement as determined by CPR was 0.54 and by PGR was 0.16. The significant correlations were: both CPR and PGR with lordosis gain at surgery (r = 0.597 and 0.537, respectively, p < 0.001 both), cage lordosis with the final lordosis (r = 0.234, p < 0.05), and anterior cage height was negatively correlated with a change in lordosis (r = −0.297, p < 0.01).ConclusionCage size, shape, and position, in addition to surgical technique, determine lordosis during PLIF surgery. Anterior placement with sufficient “clear space” behind the cages is recommended. In addition, cages should be of moderate height and length, so that they act as an effective pivot for lordosis.

Implantation of the anterior atlantoaxial lateral mass intervertebral cage using the transoral approach.

The purpose of this study was to evaluate the possibility of implanting the anterior atlantoaxial lateral mass intervertebral cage, a new type of fixation, by the transoral approach. This study examined the possibility of implantation invivo by the quantitative measurement on the dry atlantoaxial bone and implantation of the anterior atlantoaxial lateral mass intervertebral cage in specimens. Anterior atlantoaxial lateral mass intervertebral cages were implanted in 10 atlantoaxial joint specimens using the transoral approach. Eight anatomical parameters (width, the thickness, ordinates, abscissas, and declination angles of the mass) from each of the 30 dry atlas and axis bone specimens were measured. These parameters determined the size and the design of the cage and the way of implantation. The course of the vertebral artery forms the safe boundary for transoral surgery. The shape of the area of work exposure was an inverted trapezoid. In specimens, the anterior atlantoaxial lateral mass intervertebral cages could be successfully implanted using the transoral approach. The parameters of the human atlantoaxial lateral masses exposed anteriorly showed that there was enough space, for the safe anterior implantation of the cage. The surgery using the transoral atlantoaxial reduction and plate makes possible the implantation of the anterior cage. The implantation of anterior atlantoaxial lateral mass intervertebral cage through transoral approach is possible.

Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

An idealized biomechanical model. The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001). In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage. N/A.

Radiological Outcome of Lumbar Lordosis Restored following Extreme Lateral Interbody Fusion (XLIF) plus Pedicle Screw Insertion (PSI)

Introduction Radiological outcome of Lumbar Lordosis restored following Extreme Lateral Interbody Fusion (XLIF) plus Pedicle Screw Insertion (PSI). Improving sagittal alignment in the lumbosacral spine following fusion for degenerative spinal disease remains an important goal of surgery. Numerous surgical techniques have been promoted as improving lumbar lordosis, elevating the height of the disk, and facilitating the decompression of the neural elements. Interbody support techniques are frequently cited as a reliable method of maintaining or improving segmental sagittal profile. The historical use of structural autograft has recently been supplemented by the increasing popularity of synthetic cages. Numerous cage configurations are available. Wedge-shaped cages are generally preferred because studies have shown this geometric shape to have a significant impact on the improvement of lordosis. Anterior cages have been cited as the most reliable method to restore anterior lordosis and disk space height. Posteriorly placed wedged cages have been shown in a prospective randomized study to maintain but not improve segmental lordosis following a posterior lumbar interbody fusion combined with pedicle instrumentation. In his study we observed that XLIF cages increases disc height, opening neural foramen, indirectly opening spinal canal by stretching out retrobuldged posterior longitudinal ligament and restoring biomechanics by correcting lumbar lordosis Material and Methods This is a retrospective study to review all cases of degenerative disc disease of lumbar spine that underwent Extreme Lateral Interbody Fusion (XLIF) and Pedicle Screw Insertion (PSI) from 1st June 2009 to 31st May 2011. From June 2009 to May 2011, 17 patients (14 female, 3male) were included. The electronic patient record which includes preoperative and postoperative radiographic results were reviewed and abstracted into an electronic database. Data entered in Data Form then in Excel sheet, number of disc involved, type of surgery anterior instrumentation (Extreme lateral Interbody fusion XLIF), posterior instrumentation (pedicle screw fixation PSF), Posterolateral bone grafting, both Pre &amp; immediate postsurgical Cobb angles and disc heights were measured. Results From June 2009 to May 2011, 17 patients (14 female, 3male) were included. The mean patient's age at surgery was 61.88years (range 47–80). The mean of Preop disc height was 8.54mm and the mean Post XLIF disc height was 13.01mm. The mean of Preop Global Lumbar Lordosis (Cobb Angle) was 30.72° (range 7.80°-54°.90°) as well as the mean of Post XLIF Global Lumbar Lordosis (Cobb Angle) was 29.48° (range 9.70°-59°). The number of disc involved was one in 12 cases, two in 2 cases and three in 3 cases. Sixteen cases were underwent Anterior and Posterior instrumentation except one patient who underwent stand alone XLIF cage. The Posterolateral bone grafting was done in four cases. Through using a McNemar-Bowker Test, there is a strong association between the Pre-Op Disc Height and the Post-XLIF Disc Height, P –value &lt; 0.05. In addition, There is a strong association between the PRE-OP GLOBAL LUMBAR LORDOSIS (Cobb Angle) and the POST- XLIF GLOBAL LUMBAR LORDOSIS (Cobb Angle) P-value &lt; 0.05. Conclusion XLIF cages increases disc height, opening neural foramen, indirectly opening spinal canal by stretching out retrobuldged posterior longitudinal ligament and restoring biomechanics by correcting lumbar lordosis

Kyphotic Deformity Associated with Acute Tubercular Spondylodiscitis Treated by Single Stage Posterior only Surgery

Introduction Acute tuberculous spondylodiscitis with thoracic kyphosis is conventionally treated by anterior or combined reconstruction techniques. Posterior based sagittal correction in active tubercular infection is an emerging alternative technique. Our aim was to evaluate posterior only deformity correction technique in acute tuberculosis kyphosis for safety and outcomes. Methods Sixty-seven patients with acute thoracic kyphosis due to tuberculosis were treated by all-posterior deformity correction with or without an anterior cage. Peri-operative complications, neurological improvement, pain scores, kyphosis correction, final deformity at last follow up and fusion were studied pre-operatively, immediately after surgery and at last follow up. Results The mean age was 47.6 ±12.2 years. Indications for surgery were persistent pain ( n = 12), neurological deficit ( n = 27) and kyphosis ( n = 28). The mean follow-up was 36.4 ± 12.1 months. The mean VAS improved from 7.2 ±1.2 to 1.6 ±0.9. The mean kyphotic angle improved from 26.4 ±4.6° to 12.4 ±2.4°. There was loss of correction by 2.7° and the final kyphosis was 15.2 ± 1.8°. Neurology improved in all patients by at least one ASIA grade. The mean vertebral body loss was 0.8 ± 0.4 (where 1=one vertebral body). Thirty seven patients with vertebral loss &gt; 0.5 or pre-operative kyphosis &gt; 30 degress had transpedicular/transformaninal reconstruction of anterior column with a cage while the remaining thirty had posterior shortening only. Bony fusion was obtained in all patients. There were no implant failures. Post-operative complications included dural tear ( n = 2), temporary neural deficit ( n = 2), wound infection ( n = 4), girdle paresthesia ( n = 3), lumbar hernia ( n = 2), disease recurrence ( n = 1). Conclusion All-posterior single stage kyphosis correction and global reconstruction in acute tuberculous kyphosis is a safe technique with good functional and radiological outcomes. The use of titanium cages and pedicle screws in the infected vertebral body milieu was observed to be safe.

PEEK Rods for Posterior Lumbar Fixation: Pros and Cons: The First French Series

Introduction The ideal lumbar spine fixation system should provide sufficient stability while preserving natural posturing and spinal alignment with limited risk of adjacent level degeneration. While rigid fixation systems may contribute to stress shielding in anterior column increasing consecutively adjacent segment degeneration, Polyetherethrketone (PEEK) Rods provide a modulus of elasticity close to cancellous bone that may decrease these risks. Biomechanical studies comparing rigid fixation using titanium Rods with PEEK Rods posterior systems have shown a comparable intervertebral stability with the two systems nevertheless PEEK was associated with a lower risk of screw mobilization in poor bone, an increased anterior physiological load and a reduced stress on bone-screw interface that may predict lower risk of adjacent level degeneration. We performed a retrospective study in a french cohort of patients who underwent posterior lumbar fixation using PEEK Rods to investigate clinical indications and clinical outcomes in real life settings. Material and Methods Between June 2011 and July 2014, 48 patients who underwent posterior lumbar fixation using PEEK Rods were included in our study for retrospective review. Surgery was performed using 5,5mm pre-bent PEEK Rods with Titanium monoaxial screws for 1 to 4 level posterior lumbar fixation with a maximum length of 160 mm. Clinical outcomes were assessed using Oswestry Disability Index (ODI), reoperation rate, complications, radiographs and MRI. The patients satisfaction was also evaluated using the Patient Satisfaction Index (PSI). Results The population included 28 males and 20 females with an average age of 61 years. The main indication for surgery was spinal decompression with stabilization (44,6%). A majority of patients (29/60,4%) presented surgical antecedents including recurrent disc herniation, posterior decompression, posterior fusion with instrumentation and stabilization with interspinous devices. Patients underwent surgery on one (18/37,5%) or multiple levels (30/62,5%). Patients had surgery with anterior cages for fusion (PLIF), posterior dynamic fixation or hybrid systems combining fusion and non-fusion. The most frequent surgeries were performed on L4L5S1 as hybrid systems. At 2 years follow-up, the mean ODI score was improved by 29% (from 67% to 38%) and the mean PSI was 1,8 on a scale ranging from 1 to 4 (1: completely satisfied. 4: same or worse condition than before surgery). There was no reoperation for 89,7% patients, no migration for 94,7%, no screw breakage for 84,2% (never for one single level fixation) and no rod breakage. We reported 15% patients with post-operative adjacent level degeneration. For 21% patients with pre-operative signs, the degeneration was no more observed on the last MRI evaluation after 2 years. Conclusion PEEK Rods provide a safe and effective system that can be either used as a fusion system promoting anterior fusion with decreased risk of implant failure, as dynamic system protecting adjacent levels, or as hybrid system combining both advantages, with a stability comparable to Titanium rods. Further studies on larger populations and longer term follow-up are needed to confirm these data.

Accuracy of preoperative surgical planning software in predicting postoperative alignment in patients undergoing minimally invasive multilevel anterior column reconstruction for positive sagittal balance deformity

BACKGROUND CONTEXT: Sagittal realignment in adult deformity surgery is crucial. Patients can present with an obvious increase in sagittal vertical axis (SVA) or have a hidden sagittal balance problem with a normal SVA but high pelvic tilt (PT) (compensated balance). Software is available to measure patient alignment parameters and to simulate the operation. Anterior column reconstruction using multiple anterior cages inserted via a minimally invasive lateral or anterior technique may provide a reliable way of executing the preoperative plan.

Biomechanical comparison of transfacet screws to lateral mass screw-rod constructs in the lower cervical spine

Transfacet screws have been used as an alternative posterior fixation in the cervical spine. There is lack of spinal stability of the transfacet screws either as stand-along constructs or combined with anterior plate. This study was designed to evaluate spinal stability of transfacet screws following posterior ligamentous injury and combined with anterior plate, respectively, and compare transfacet screws to lateral mass screw-rod constructs. Flexibility tests were conducted on eight cadaveric specimens in an intact and injury, and instrumented with the transfacet screw fixation and lateral mass screw-rod construct at C5-C7 levels either after section of the posterior ligamentous complex or combined with an anterior plate and a mesh cage for C6 corpectomy reconstruction. A pure moment of±2.0 Nm was applied to the specimen in flexion-extension, lateral bending, and axial rotation. Ranges of motion (ROM) were calculated for the C5-C7 segment. ROM with the transfacet screws was 22% of intact in flexion-extension, 9% in lateral bending and 11% in axial rotation, while ROM with the lateral mass screw-rod construct was 9% in flexion-extension, 8% in lateral bending and 22% in axial rotation. The only significant difference between two constructs was seen in flexion-extension (5.8±4.2° vs. 2.4±1.2°, P=0.002). When combined with an anterior plate and mesh cage, the transfacet screw fixation reduced ROM to 3.0° in flexion-extension, 1.2° in lateral bending, and 1.1° in axial rotation, which was similar to the lateral mass screw-rod construct. This study identified the transfacet screw fixation, as stand-alone posterior fixation, was equivalent to the lateral mass screw-rod constructs in axial rotation and lateral bending except in flexion-extension. When combined with an anterior plate, the transfacet screw fixation was similar to the lateral mass screw-rod construct in motion constraint. The results suggested the transfacet screw fixation a biomechanically effective way as supplementation of anterior fixation.

Assessment and classification of subsidence after lateral interbody fusion using serial computed tomography.

OBJECT Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF. METHODS A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores. RESULTS Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049). CONCLUSIONS The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

Biomechanical Evaluation of a New Posterior Stabilization Device

Introduction Over the last two decades, different techniques to stabilize the spine have been developed. The gold standard in spinal stabilization today is the pedicle screw. However, different techniques like different types of facet fixation devices are available. Based on different principles of facet fixation, a new implant is available, the so called “Facet Wedge.” The purpose of this study is to evaluate the primary stability of this new approach for facet fixation in comparison with established posterior fixation techniques such as pedicle screws and translaminar screws with and without anterior cage interposition. Materials and Methods In a two-arm biomechanical study using a robot-based spine tester, 24 monosegmental fresh frozen nonosteoporotic human motion segments (L2–L3 and L4–L5) were tested. Facet Wedge stand-alone and in combination with an anterior fusion cage was compared with pedicle screws and translaminar screws. Results All tested techniques could stabilize an intact motion segment effectively. In the used setup, Facet Wedge was comparable to pedicle screws for lateral bending, extension, and flexion and slightly superior for axial rotation. Facet Wedge showed a superior kinematic capacity compared with translaminar screws. Conclusion Facet Wedge offers a novel posterior approach in achieving primary stability in lumbar spinal fixation. In the used model, Facet Wedge has a comparable primary stability to pedicle screws and potential advantages over translaminar screws.

Minimally Invasive Transpsoas L2 Corpectomy and Percutaneous Pedicle Screw Fixation for Osteoporotic Burst Fracture in the Elderly

Osteoporotic vertebral burst fractures are an increasingly common cause of pain and severe functional disability in the elderly. Although anterior-posterior surgical stabilization offers an efficacious and durable treatment, the associated high blood loss, long durations of surgery, and prolonged hospitalization are often not tolerable for elderly patients, who are most often medically frail with multiple comorbidities. We report a case of an L2 osteoporotic burst fracture in an elderly patient with significant comorbidities treated with a minimally invasive tubular direct lateral transpsoas approach for L2 vertebrectomy and anterior cage placement. The construct was supplemented by a percutaneous pedicle screw construct and adjacent level vertebroplasty. Duration of surgery was 3.5 hours with a total of 35 mL blood loss. The patient was discharged ambulating 36 hours after surgery and reported marked improvement in pain, disability, and quality of life measures at 6 weeks postoperatively. L2 vertebrectomy by direct lateral transpsoas tube systems supplemented by percutaneous pedicle screws can be performed safely and may allow for anterior column decompression and reconstruction in elderly or comorbid patients not otherwise able to tolerate traditional stabilization procedures.

Is anterior plating of the cervical spine associated with increased incidence of adjacent segment disease compared with anterior cage fusion alone?

Is anterior plating of the cervical spine associated with increased incidence of adjacent segment disease compared with anterior cage fusion alone?

Facet Wedge Fixation in Lumbar Spine Degenerative Pathology: A New Option for Minimally-Invasive Posterior Approach?

In recent years spinal surgery has undergone a drastic change of course, mainly due to the increasing use of minimally invasive and percutaneous techniques for the treatment of lumbar spine degenerative pathology. This has led to the development of techniques more effective (for the pathology) and less invasive (for the patient). Recently the technological progress focused on a very specific vertebral fusion technique: the facet joint fixation. This technique has already been described in past as available with the assistance of autologous bone chips into the facet joint; nowadays it has been brought up to date by the development and use of an implantable device that promotes the bone fusion of the joint complex: the Facet-Wedge®. The employment of this device seems to offer a minimally invasive choice to the standard posterior screws fixation techniques for the treatment of selected cases of lumbar degenerative pathologies. Obviously their application has to be evaluated on the basis of a careful preoperative radiological planning. Up to date there aren’t in literature clinical trials about the effective of this device and this technique. The biomechanical meaning of this device, the possibility of implanting in percutaneous technique and in combined instrumentation with anterior cages or different posterior techniques, could reveal that this technique might be an effective and feasible alternative, which needs to be addressed in further studies.

Circumferential management of unstable thoracolumbar fractures using an anterior expandable cage, as an alternative to an iliac crest graft, combined with a posterior screw fixation: results of a series of 85 patients.

The optimal management of unstable thoracolumbar fractures remains unclear. The objective of the present study was to evaluate the results of using an expandable prosthetic vertebral body cage (EPVBC) in the management of unstable thoracolumbar fractures. Eighty-five patients with unstable T7-L4 thoracolumbar fractures underwent implantation of an EPVBC via an anterior approach combined with posterior fixation. Long-term functional outcomes, including visual analog scale and Oswestry disability index scores, were evaluated. In a mean follow-up period of 16 months, anterior fixation led to a significant increase in vertebral body height, with an average gain of 19%. However, the vertebral regional kyphosis angle was not significantly increased by anterior fixation alone. No significant difference was found between early postoperative, 3-month, and 1-year postoperative regional kyphosis angle and vertebral body height. Postoperative impaction of the prosthetic cage in adjacent endplates was observed in 35% of the cases, without worsening at last follow-up. Complete fusion was observed at 1 year postoperatively and no cases of infections or revisions were observed in relation to the anterior approach. The use of EPVBCs for unstable thoracolumbar fractures is safe and effective in providing long-term vertebral body height restoration and kyphosis correction, with a moderate surgical and sepsis risk. Anterior cage implantation is an alternative to iliac bone graft fusion and is a viable option in association with a posterior approach, in a single operation without additional risks.

Biomechanical evaluation of a biomimetic spinal construct

BackgroundLaboratory spinal biomechanical tests using human cadaveric or animal spines have limitations in terms of disease transmission, high sample variability, decay and fatigue during extended testing protocols. Therefore, a synthetic biomimetic spine model may be an acceptable substitute. The goal of current study is to evaluate the properties of a synthetic biomimetic spine model; also to assess the mechanical performance of lateral plating following lateral interbody fusion.MethodsThree L3/4 synthetic spinal motion segments were examined using a validated pure moment testing system. Moments (±7.5 Nm) were applied in flexion-extension (FE), lateral bending (LB) and axial rotation (AR) at 1Hz for total 10000 cycles in MTS Bionix. An additional test was performed 12 hours after 10000 cycles. A ±10 Nm cycle was also performed to allow provide comparison to the literature. For implantation evaluation, each model was tested in the 4 following conditions: 1) intact, 2) lateral cage alone, 3) lateral cage and plate 4) anterior cage and plate. Results were analysed using ANOVA with post-hoc Tukey’s HSD test.ResultsRange of motion (ROM) exhibited logarithmic growth with cycle number (increases of 16%, 37.5% and 24.3% in AR, FE and LB respectively). No signification difference (p > 0.1) was detected between 4 cycles, 10000 cycles and 12 hour rest stages. All measured parameters were comparable to that of reported cadaveric values. The ROM for a lateral cage and plate construct was not significantly different to the anterior lumbar interbody construct for FE (p = 1.00), LB (p = 0.995) and AR (p = 0.837).ConclusionsBased on anatomical and biomechanical similarities, the synthetic spine tested here provides a reasonable model to represent the human lumbar spine. Repeated testing did not dramatically alter biomechanics which may allow non-destructive testing between many different procedures and devices without the worry of carry over effects. Small intra-specimen variability and lack of biohazard makes this an attractive alternative for in vitro spine biomechanical testing. It also proved an acceptable surrogate for biomechanical testing, confirming that a lateral lumbar interbody cage and plate construct reduces ROM to a similar degree as anterior lumbar interbody cage and plate constructs.

Traumatic L5–S1 spondylolisthesis in a 15-year-old

Traumatic spondylolisthesis is a rare injury resulting from complex trauma and high-energy mechanisms. We present a case report of traumatic spondylolisthesis at the L5-S1 disc space of a patient who was buried after a wall fell on his back. In the physical examination, bilaterally decreased muscle strength was observed. Examination images indicated a 90% slip at L5-S1. Surgical treatment was provided with a posterior and anterior approach using pedicle fixation and an anterior cage. After 4 months, there was significant recovery of muscle strength in the lower limbs.

En bloc resection of a multilevel high-cervical chordoma involving C-2: new operative modalities

En bloc resection of cervical chordomas has led to longer survival rates but has resulted in significant morbidities from the procedure, especially when the tumor is multilevel and located in the high-cervical (C1-3) region. To date, there have been only 5 reported cases of multilevel en bloc resection of chordomas in the high-cervical spine. In this technical report the authors describe a sixth case. A complete spondylectomy was performed at C-2 and C-3 with spinal reconstruction and stabilization, using several new modalities that were not used in the previous cases. The use of 1) preoperative endovascular sacrificing of the vertebral artery, 2) CT image-guidance, 3) an ultrasonic aspirator for skeletonizing the vertebral artery, and 4) the custom design of an anterior cage all contributed to absence of intraoperative or long-term (20 months) hardware failure and pseudarthrosis.

Analysis on the causes of dysphagia after multilevel anterior cervical discectomy and fusion

Objective To investigate incidence and related factors of dysphagia after fusion with an anterior cervical plate plus cage or a stand-alone cage (Zero-p cage) following anterior cervical discectomy procedure for treating multilevel cervical spondylotic myelopathy (MCSM).Methods From September 2008to September 2011,226 patients with MCSM underwent anterior cervical discectomy and fusion using an anterior cervical plate plus cage (118 patients,P&C group) or a stand-alone cage (108 patients,Zero-p group).Neurological function was evaluated by Japan orthopedic association (JOA) scores before and after operation.Cervical X-rays were taken to assess the graft fusion,internal fixation related complications and the thickness of the prevertebral soft tissue.The Bazaz dysphagia score and Swallowing Quality of Life questionnaire were used to assess the incidence and degree of dysphagia.Results The average follow-up time was 2.4years (range,1.0 to 3.5 years).The incidence of dysphagia was 41.53％ in P&C group,while 33.33％ in Zero-p group at 2 days after operation.The thickness of the prevertebral soft tissue in P&C group was significantly thicker than that in Zero-p group at 2 days and 2 months after surgery.In Zero-p group,the incidence of dysphagia was 43.1％ in patients who underwent operation from C3 to C6,while 22％ in patients who underwent operation from C4 to C7.Conclusion Dysphagia is common after multilevel anterior cervical discectomy and fusion.The choice of implants and the extent of operation are important influencing factors of postoperative dysphagia.The use of stand-alone cage can decrease the incidence of dysphagia.The operation at higher levels has a higher incidence of dysphagia. Key words: Cervical vertebrae; Spinal cord compression; Spinal fusion; Deglutition disorders