Facets Of Space Research Articles

Atlantoaxial facet fixation using cervical facet cage: technical case report and review of the literature.

In 1994, the use of interfacet spacer placement was for joint distraction, reduction, and fusion to supplement atlantoaxial or occipitocervical fixation. Here, we present a unique case of bilateral atlantoaxial interfacet fixation using cervical facet cages (CFC) in a pediatric patient with basilar invagination. In addition, we review the literature on atlantoaxial facet fixation. We present a 12-year-old boy with Wiedemann-Steiner syndrome who presented with multiple episodes of sudden neck jerking, described as in response to a sensation of being shocked, and guarding against neck motion, found to have basilar invagination with cervicomedullary compression. He underwent an occiput to C3 fusion with C1-C2 CFC fixation. We also conducted a literature review identifying all publications using the following keywords: "C1" AND "C2" OR "atlantoaxial" AND "facet spacer" OR "DTRAX." The patient demonstrated postoperative radiographic reduction of his basilar invagination from 6.4 to 4.1mm of superior displacement above the McRae line. There was a 4.5mm decrease in the atlantodental interval secondary to decreased dens retroflexion. His postoperative course was complicated by worsening of his existing dysphagia but was otherwise unremarkable. His neck symptoms completely resolved. We illustrate the safe use of CFC for atlantoaxial facet distraction, reduction, and instrumented fixation in a pediatric patient with basilar invagination. Review of the literature demonstrates that numerous materials can be safely placed as a C1-C2 interfacet spacer including bone grafts, titanium spacers, and anterior cervical discectomy and fusion cages. We argue that CFC may be included in this arsenal even in pediatric patients.

Confirming a C5 Palsy with a Motor Evoked Potential Trending Algorithm during Insertion of Cervical Facet Spacers: A Case Study

ABSTRACT The use of cervical facet spacers has shown favorable clinical results in the treatment of cervical spondylotic disease; however, there are limited data regarding neurological complications associated with the procedure. This case report demonstrates the specificity of multi-myotomal motor evoked potentials (MEPs) in detecting acute postoperative C5 palsy following placement of facet spacers. A posterior cervical fusion with decompression and instrumentation involving DTRAX (Providence Medical Technology; Lafayette, CA) was used to treat a patient with cervical stenosis and myelopathy. Intraoperative neurophysiological monitoring (IONM) consisting of MEPs, somatosensory evoked potentials (SSEPs), and free-run electromyography (EMG), was used throughout the procedure. Immediately following the placement of the DTRAX spacers at C4-5, a decrease in amplitudes from the right deltoid and biceps MEP recordings (>65%) was detected. All other IONM modalities remained stable; it is noteworthy that there was an absence of mechanically elicited EMG. A novel post-alert regression analysis trending algorithm of MEP amplitudes confirmed the visual alert. This warning along with an intraoperative computed tomography (CT) scan of the cervical spine subsequently resulted in the decision to remove one of the facet spacers. Surgical intervention did not result in recovery of the aforementioned MEP recordings, which remained attenuated at the time of wound closure. Postoperatively, the patient exhibited an immediate right C5 palsy (2/5). A post-surgery application of the trending algorithm demonstrated that it correlated to the visual alert until the end of monitoring.

Comparison of the Biomechanical Effect of the FFX Device Compared With Other Lumbar Fusion Devices: A Finite Element Study.

Lumbar decompression can result in postsurgical instability and spondylolisthesis in patients with lumbar spinal stenosis (LSS). While pedicle screw (PS) constructs improve stability and support fusion, their use can lead to adjacent level degeneration due to rigidity and resultant overload of anatomical structures. The FFX device is a facet spacer designed to be a less invasive alternative for obtaining fusion compared with PS. The present study aimed to compare biomechanical performance of the FFX device to different lumbar spine procedures using the finite element (FE) method. Comparative biomechanical study by FE method. An FE model for the lumbar spine was developed and validated to assess vertebral displacement and stress variations in the facet joints and discs following surgery. Modeled scenarios included a healthy spine as a reference model, laminectomy (LAM), and prior to/following L4-L5 fusion for LAM + FFX and LAM + PS. LAM increased displacement compared with the healthy spine and both instrumented spine procedures. Facet joint stress at adjacent levels for LAM + PS was significantly higher than with LAM + FFX prior to fusion (+13.5% for L3-L4; +15.7% for L5-S1). Adjacent level disc stress at L5-S1 was 7.7% higher for LAM + PS vs LAM + FFX. Adjacent level facet joint and disc stresses for LAM + FFX were equivalent to LAM + PS once fusion occurred. Instrumented spine fixation prevents the risk of lumbar instability associated with LAM alone. Compared with PS, the FFX device is a less invasive alternative for the treatment of LSS, which potentially lowers the risk of adjacent segment degeneration prior to fusion that provides equivalent stability once fusion is achieved.

Biomechanical Comparison of Lumbar Motion Unit Stability Following Posterior Instrumentation with Facet Spacers and Facet Screws

PurposeLumbar posterior instrumentation for facet stabilization has become popular for the treatment of lumbar instability. The present study investigated and compared facet stabilization following lumbar posterior instrumentation with facet spacers and facet screws using porcine lumbar spines.MethodsEighteen L5–L6 lumbar motion units (LMUs) of the porcine spines were randomly divided into three groups (un-instrumented, facet-spacer and facet-screw). In the un-instrumented group (control), all ligamentous structures were preserved. In the facet-spacer group, two facet spacers were inserted into the joint spaces of the bilateral upper and lower facets. In the facet-screw group, two cannulated screws were used to transfix the bilateral upper and lower facets. With the use of a material testing machine, a gradually increasing moment of up to 6000 N-mm was generated in flexion, extension, lateral bending and torsion motions to compare facet stabilization among the groups.ResultsThe facet-spacer group was significantly stiffer than the facet-screw group in extension (p = 0.013), whereas the facet-screw group was significantly stiffer than the facet-spacer group in axial rotation (p = 0.004). No statistically significant differences were observed between the two fixation techniques in flexion (p = 0.284) and lateral bending (p = 0.085).ConclusionBoth facet-spacer and facet-screw fixation techniques significantly improve stability in a single LMU. Facet-spacer fixation provided better stabilization in extension, while facet-screw fixation provided better stabilization in axial rotation.

Posterior revision surgery using an intraarticular distraction technique with cage grafting to treat atlantoaxial dislocation associated with basilar invagination.

The treatment of atlantoaxial dislocation (AAD) and basilar invagination (BI) is challenging, especially in symptomatic patients with a history of previous surgery. Although seldom reported, posterior revision surgery to revise prior constructs can be advantageous over an anterior or combined approach. The authors describe their experience in performing posterior revision surgery using Goel's technique. The authors reviewed patients with AAD and BI who had undergone previous posterior surgery at the cranio-cervical junction between January 2016 and September 2017. All of these patients underwent revision surgery from a posterior approach. The Japanese Orthopaedic Association (JOA) score was used to assess clinical symptoms before and after surgery. The distance from the tip of the odontoid to Chamberlain's line, atlantodental interval (ADI), and clivus-canal angle (CCA) were used for radiographic assessment before and after surgery. Twelve consecutive patients were reviewed. Prior surgeries were as follows: 4 patients (4/12) with posterior osseous decompression without fusion, 7 (7/12) with reduction and fusion without decompression, and 1 (1/12) with posterior osseous decompression and reduction and fusion. With the use of Goel's technique for revision in these cases, distraction using facet spacers afforded release of the anterior soft tissue from a posterior approach. The occiput was fixated to C2 using a cantilever technique, and autologous cancellous bone was grafted into the intraarticular joints. In all 12 patients, complete reduction of BI and AAD were achieved without injury to nerves or vessels. All patients had evidence of bony fusion on CT scans within 18 months of follow-up. Posterior revision surgery using Goel's technique is an effective and safe revision salvage surgery for symptomatic patients with AAD and BI.

Only spinal fixation as treatment of prolapsed cervical intervertebral disc in patients presenting with myelopathy.

Aim:An alternative form of surgical treatment of prolapsed cervical intervertebral disc in patients presenting with symptoms related to myelopathy is discussed. The treatment involved fixation of the affected spinal segments and aimed at arthrodesis. No direct manipulation or handling of the disc was done.Materials and Methods:During the period August 2010 to June 2017, 16 patients presenting with symptoms attributed to myelopathy and diagnosed to have prolapsed cervical intervertebral disc were surgically treated by spinal stabilization. There were 11 males and 5 females and their ages ranged from 20 to 66 years (average: 40.6 years). Apart from clinical and radiological indicators, the number of spinal segments that were stabilized depended on direct observation of facetal morphology, alignment, and stability. Surgery involved distraction-fixation of facets using Goel facet spacer (8 patients), transarticular facetal fixation (5 patients) using screws or a combination of both facetal spacer, and transarticular screws (3 patients).Results:All patients had “remarkable” clinical improvement in the immediate postoperative period as assessed by visual analog scale, Goel's clinical grading, and Japanese Orthopedic Association scores. Follow-up ranged from 3 to 84 months (average: 50 months). The herniated disc regressed or disappeared at follow-up radiological assessment that ranged from 24 h to 3 months after surgery.Conclusions:Spinal segmental fixation aiming at arthrodesis with or without distraction of facets and without any direct surgical manipulation in the disc space or removal of the prolapsed portion of the disc can be considered in the armamentarium of the surgeon.

Cortical bone facet spacers for cervical spine decompression: effects on intervertebral kinetics and foraminal area.

Nerve root decompression to relieve pain and radiculopathy remains one of the main goals of fusion-promoting procedures in the subaxial cervical spine. The use of allograft facet spacers has been suggested as a potential alternative for performing foraminotomies to increase the space available for the cervical nerve roots while providing segmental stiffening. Therefore, the goal of this cadaveric biomechanical study was to determine the acute changes in kinetics and foraminal area after the insertion of cortical bone facet spacers into the subaxial cervical spine. Allograft spacers (2 mm in height) were placed bilaterally into cadaveric cervical spine specimens (C2-T1, age of donors 57.5 ± 9.5 years, n = 7) at 1 (C4-5) and 3 (C3-6) levels with and without laminectomies and posterior lateral mass screw fixation. Standard stereophotogrammetry under pure moment loading was used to assess spinal kinetics. In addition, the authors performed 3D principal component analysis of CT scans to determine changes in foraminal cross-sectional area (FCSA) available for the spinal nerve roots. Generally, the introduction of 2-mm-height facet spacers to the cervical spine produced mild, statistically insignificant reductions in motion with particular exceptions at the levels of implantation. No significant adjacent-level motion effects in any bending plane were observed. The addition of the posterior instrumentation (PI) to the intact spines resulted in statistically significant reductions in motion at all cervical levels and bending planes. The same kinetic results were obtained when PI was added to spines that also had facet spacers at 3 levels and spines that had been destabilized by en bloc laminectomy. The addition of 2-mm facet spacers at C3-4, C4-5, and C5-6 did produce statistically significant increases in FCSA at those levels. The addition of allograft cervical facet spacers should be considered a potential option to accomplish indirect foraminal decompression as measured in this cadaveric biomechanical study. However, 2-mm spacers without supplemental instrumentation do not provide significantly increased spinal segmental stability.

Quantitative morphometric analysis of the lumbar vertebral facets and evaluation of feasibility of lumbar spinal nerve root and spinal canal decompression using the Goel intraarticular facetal spacer distraction technique: A lumbar/cervical facet comparison.

Objective:The authors evaluate the anatomic subtleties of lumbar facets and assess the feasibility and effectiveness of use of ‘Goel facet spacer’ in the treatment of degenerative spinal canal stenosis.Materials and Methods:Twenty-five lumbar vertebral cadaveric dried bones were used for the purpose. A number of morphometric parameters were evaluated both before and after the introduction of Goel facet spacers within the confines of the facet joint.Results:The spacers achieved distraction of facets that was more pronounced in the vertical perspective. Introduction of spacers on both sides resulted in an increase in the intervertebral foraminal height and a circumferential increase in the spinal canal dimensions. Additionally, there was an increase in the disc space or intervertebral body height. The lumbar facets are more vertically and anteroposteriorly oriented when compared to cervical facets that are obliquely and transversely oriented.Conclusions:Understanding the anatomical peculiarities of the lumbar and cervical facets can lead to an optimum utilization of the potential of Goel facet distraction arthrodesis technique in the treatment of spinal degenerative canal stenosis.

Facetal distraction as treatment for single- and multilevel cervical spondylotic radiculopathy and myelopathy: a preliminary report

The authors discuss their successful preliminary experience with 36 cases of cervical spondylotic disease by performing facetal distraction using specially designed Goel cervical facet spacers. The clinical and radiological results of treatment are analyzed. The mechanism of action of the proposed spacers and the rationale for their use are evaluated. Between 2006 and February 2010, 36 patients were treated using the proposed technique. Of these patients, 18 had multilevel and 18 had single-level cervical spondylotic radiculopathy and/or myelopathy. The average follow-up period was 17 months with a minimum of 6 months. The Japanese Orthopaedic Association classification system, visual analog scale (neck pain and radiculopathy), and Odom criteria were used to monitor the clinical status of the patient. The patients were prospectively analyzed. The technique of surgery involved wide opening of the facet joints, denuding of articular cartilage, distraction of facets, and forced impaction of Goel cervical facet spacers into the articular cavity. Additionally, the interspinous process ligaments were resected, and corticocancellous bone graft from the iliac crest was placed and was stabilized over the adjoining laminae and facets after adequately preparing the host bone. Eighteen patients underwent single-level, 6 patients underwent 2-level, and 12 patients underwent 3-level treatment. The alterations in the physical architecture of spine and canal dimensions were evaluated before and after the placement of intrafacet joint spacers and after at least 6 months of follow-up. All patients had varying degrees of relief from symptoms of pain, radiculopathy, and myelopathy. Analysis of radiological features suggested that the distraction of facets with the spacers resulted in an increase in the intervertebral foraminal dimension (mean 2.2 mm), an increase in the height of the intervertebral disc space (range 0.4-1.2 mm), and an increase in the interspinous distance (mean 2.2 mm). The circumferential distraction resulted in reduction in the buckling of the posterior longitudinal ligament and ligamentum flavum. The procedure ultimately resulted in segmental bone fusion. No patient worsened after treatment. There was no noticeable implant malfunction. During the follow-up period, all patients had evidence of segmental bone fusion. No patient underwent reexploration or further surgery of the neck. Distraction of the facets of the cervical vertebra can lead to remarkable and immediate stabilization-fixation of the spinal segment and increase in space for the spinal cord and roots. The procedure results in reversal of several pathological events related to spondylotic disease. The safe, firm, and secure stabilization at the fulcrum of cervical spinal movements provided a ground for segmental spinal arthrodesis. The immediate postoperative improvement and lasting recovery from symptoms suggest the validity of the procedure.

Facet distraction spacers for treatment of degenerative disease of the spine: Rationale and an alternative hypothesis of spinal degeneration

Facet distraction spacers for treatment of degenerative disease of the spine: Rationale and an alternative hypothesis of spinal degeneration