Biomechanical evaluation of DTRAX(®) posterior cervical cage stabilization with and without lateral mass fixation

Physiotherapeutic Approach Towards Sensory and Motor Recovery in a Patient With Lateral Mass Fixation: A Report of a Rare Case

Atlantoaxial dislocations (AAD) are a diverse set of C1-C2 rotatory subluxations that include the inferior and superior axial facet articulations. C1-C2 segments are both covered by cranial-cervical ligaments, indicating that AAD would damage both joints. Whenever the posterior elements are missing or impaired, lateral mass screw fixation has replaced alternative posterior cervical fixation procedures as the preferred treatment for securing the sub-axial cervical spine. An increase in muscle tone, hyperreflexia, pathological reflexes, digit/hand clumsiness, and gait deviations caused by spinal cord compression at the cervical level are the most common clinical features. A 23-year-old female patient came with the chief complaint of weakness, tingling sensation, and numbness in both upper and lower limbs along with imbalance while walking. She had a history of falls which was managed conservatively. As the symptoms progressed, an MRI, a CT scan, and an X-ray of the neck were done to rule out the level of injury which revealed AAD, and the patient was operated on for C1-C2 lateral mass fixation. Post-operatively, the patient was referred to the physiotherapy department for further management. The patient's quality of life and daily functioning were positively affected after undergoing early intervention as measured by the Functional Independence Measure, Neck Disability Index, Berg Balance Scale, and Dynamic Gait Index.

Intrafacet Spacer Placement as a Mobility-Sparing Bailout Option in Atlantoaxial Fusion Construct Salvage

Background: Salvage revisions of atlantoaxial (AA) joint complex posterior segmental instrumented fusion constructs require careful individualized planning to prevent occipital extension. In this case report, we describe the use of bilateral intrafacet spacer placement as a mobility-sparing bailout option for the revision surgery. Case Report: A 64-year-old male with a history of diffuse idiopathic skeletal hyperostosis, extremely limited baseline cervical mobility, and prior AA posterior segmental instrumented fusion presented with increasing pain at his 6-month follow-up. Imaging showed fusion and hardware failures and dynamic instability. To prevent occipitocervical fixation, AA intra-articular fusion via a DTRAX spinal system (Providence Medical Technology, Inc) was used as an adjunct to a navigated C1 lateral mass and C2 pars screw posterior segmental instrumented fusion construct. The patient had an uneventful postoperative course and was discharged with resolution of symptoms. Three-month postoperative follow-up confirmed persistent resolution of symptoms and absence of complaints, along with successful arthrodesis on imaging. Conclusion: AA posterior segmental instrumented fusion revision is technically challenging, particularly when partial preservation of craniovertebral junction mobility is required. Bilateral intra-articular cages may be used as an adjunct to hardware revision in construct salvage when sturdy arthrodesis is desired without occipital extension and may represent a major potential strength of intra-articular cages.

Minimally Invasive Posterior Cervical Fusion: A Handsome Option

Cervical spondylosis is the leading cause of cervical myelopathy. When surgery is indicated, it is commonly addressed through an anterior or posterior cervical approach, such as cervical discectomy and fusion (ACDF) or laminectomy and fusion (LMF). Besides their own merits, each one has specific approach- or device-related complications, such as dysphagia, significant postoperative pain, wound infection, adjacent segment degeneration (ASD), and pseudoarthrosis. Through a tissue-sparing minimally invasive technique, posterior cervical fusion (PCF) has shown unfolding compelling evidence of biomechanical stability, good clinical outcomes, and high fusion rates, with fewer complications and better econometrics. On the basis of our own experience, we discuss here the indications, advantages, and drawbacks of minimally invasive PCF.

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

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.

Biomechanics of Circumferential Cervical Fixation Using Posterior Facet Cages: A Cadaveric Study

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) is a common procedure for the treatment of cervical disease. Circumferential procedures are options for multilevel pathology. Potential complications of multilevel anterior procedures are dysphagia and pseudarthrosis, whereas potential complications of posterior surgery include development of cervical kyphosis and postoperative chronic neck pain. The addition of posterior cervical cages (PCCs) to multilevel ACDF is a minimally invasive option to perform circumferential fusion. This study evaluated the biomechanical performance of 3-level circumferential fusion with PCCs as supplemental fixation to anteriorly placed allografts, with and without anterior plate fixation.

METHODS

Nondestructive flexibility tests (1.5 Nm) performed on 6 cervical C2-7 cadaveric specimens intact and after discectomy (C3-6) in 3 instrumented conditions: allograft with anterior plate (G+P), PCC with allograft and plate (PCC+G+P), and PCC with allograft alone (PCC+G). Range of motion (ROM) data were analyzed using 1-way repeated-measures analysis of variance.

RESULTS

All instrumented conditions resulted in significantly reduced ROM at the 3 instrumented levels (C3-6) compared to intact spinal segments in flexion, extension, lateral bending, and axial rotation (p < 0.001). No significant difference in ROM was found between G+P and PCC+G+P conditions or between G+P and PCC+G conditions, indicating similar stability between these conditions in all directions of motion.

CONCLUSION

All instrumented conditions resulted in considerable reduction in ROM. The added reduction in ROM through the addition of PCCs did not reach statistical significance. Circumferential fusion with anterior allograft, without plate and with PCCs, has comparable stability to ACDF with allograft and plate.

Intraoperative image guidance for cervical spine surgery

Intraoperative image-guidance in spinal surgery has been influenced by various technological developments in imaging science since the early 1990s. The technology has evolved from simple fluoroscopic-based guidance to state-of-art intraoperative computed tomography (iCT)-based navigation systems. Although the intraoperative navigation is more commonly used in thoracolumbar spine surgery, this newer imaging platform has rapidly gained popularity in cervical approaches. The purpose of this manuscript is to address the applications of advanced image-guidance in cervical spine surgery and to describe the use of intraoperative neuro-navigation in surgical planning and execution. In this review, we aim to cover the following surgical techniques: anterior cervical approaches, atlanto-axial fixation, subaxial instrumentation, percutaneous interfacet cage implantation as well as minimally invasive posterior cervical foraminotomy (PCF) and unilateral laminotomy for bilateral decompression. The currently available data suggested that the use of 3D navigation significantly reduces the screw malposition, operative time, mean blood loss, radiation exposure, and complication rates in comparison to the conventional fluoroscopic-guidance. With the advancements in technology and surgical techniques, 3D navigation has potential to replace conventional fluoroscopy completely.

A novel classification and algorithmic-based management of craniovertebral junction osteoarthrosis

Introduction:

The objective of this study is to propose a novel classification and algorithmic-based management plan for craniovertebral junction osteoarthrosis (CVJOA).

Materials and Methods:

A retrospective study was done based on prospective database of radiological studies and clinical history. Twenty symptomatic patients (12 females and 8 males) with a mean age of 54.8 years were identified with CVJOA. These patients underwent either nonsurgical treatment only or surgical intervention and had follow-up of at least 14 months. Classification of CVJOA is based on coronal deformity, rigidity, stability, and two modifiers. The main surgical procedures done in the surgical arm of these patients included C1–C2 fusion, C1–C2 facet distraction and fusion, and unilateral subaxial facet distraction, and posterior column osteotomy.

Results:

All the twenty patients included in this study complained of either sub-occipital or upper neck pain and had radiological evidence of CVJOA. Seven patients improved with nonsurgical management and 13 underwent surgical intervention. Surgical recommendations for each type of CVJOA have been described with case examples, and algorithm for the management of CVJOA has been developed based on this study. Interobserver agreement on CVJOA classification was measured using kappa value statistics which showed moderate strength of agreement (0.467).

Conclusion:

This study describes a novel classification and management of CVJOA based on algorithm and current surgical recommendations for each type of CVJOA.

Overview of Minimally Invasive Spine Surgery

Minimally invasive spine surgery (MISS) has continued to evolve over the past few decades, with significant advancements in technology and technical skills. From endonasal cervical approaches to extreme lateral lumbar interbody fusions, MISS has showcased its usefulness across all practice areas of the spine, with unique points of access to avoid pertinent neurovascular structures. Adult spine deformity has also recognized the importance of minimally invasive techniques in its ability to limit complications and to provide adequate sagittal alignment correction and improvements in patients' functional status. Although MISS has continued to make significant progress clinically, consideration must also be given to its economic impact and the learning curve surgeons experience in adding these procedures to their armamentarium. This review examines current innovations in MISS, as well as the economic impact and future directions of the field.

Minimally Invasive Posterior Cervical Fusion With Facet Cages to Augment High-Risk Anterior Cervical Arthrodesis: A Case Series

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To evaluate the efficacy and results of minimally invasive posterior cervical fusion with facet cages as an augment to high-risk patients and patients status post multilevel anterior cervical decompression and fusion.

METHODS

Thirty-five patients with symptomatic cervical stenosis with high risk for pseudoarthrosis underwent circumferential cervical decompression and fusion via staged anterior and posterior approach. Anterior cervical decompression and fusion was performed first by means of the standard anterior approach, with the patient supine on the operating table. The patients were subsequently flipped into a prone position and minimally invasive posterior cervical facet fusion with DTRAX was performed. The patients were then followed in the outpatient clinic for an average of 312.71 days. Postoperative patient satisfaction scores were obtained via the visual analogue scale (VAS). Preoperative VAS scores were compared with postoperative VAS scores in order to evaluate patient outcomes.

RESULTS

Of the 35 patients evaluated, minimum follow-up was 102 days, with a maximum follow-up of 839 days. Average preoperative and postoperative VAS scores were 7.6 and 2.8, respectively (P < .0001), with an average improvement of 4.86 points. This was an average improvement of 64.70% from preoperative to postoperative. Seventeen patients had excellent outcomes, with a postoperative VAS score ≤2. Seven patients achieved a postoperative VAS score of 0, with 100% improvement of preoperative pain and symptoms. Average blood loss was 70.38 mL. Average length of stay was 1.03 days.

CONCLUSIONS

The results indicate that minimally invasive posterior cervical decompression and fusion with facet cages, when combined with standard anterior cervical decompression and fusion, is an effective means of obtaining circumferential cervical fusion while simultaneously improving patient outcomes.

Tissue-Sparing Posterior Cervical Fusion With Interfacet Cages: A Systematic Review of the Literature

STUDY DESIGN

Literature review.

OBJECTIVES

Posterior cervical interfacet cages are an alternative to lateral mass fixation in patients undergoing cervical spine surgery. Recently, a percutaneous, tissue-sparing system for interfacet cage placement has been developed, however, there is limited clinical evidence supporting its widespread use. The aim was to review studies published on this system for patient reported outcomes, radiographic outcomes, intraoperative outcomes, and complications.

METHODS

Four electronic databases (PubMed, EMBASE, Scopus, and MEDLINE) were queried for original published studies that evaluated the percutaneous, tissue-sparing technique for posterior cervical fusion with interfacet cage placement. All studies reporting on open techniques and purely biomechanical studies were excluded.

RESULTS

The extensive literature search returned 7852 studies. After systematic review, a total of 7 studies met inclusion criteria. Studies were independently classified as retrospective or prospective cohort studies and each assessed by the GRADE criteria. Patient reported outcomes, radiographic outcomes, intraoperative outcomes, and complications were extracted from each study and presented.

CONCLUSIONS

Tissue-sparing, posterior cervical fusion with interfacet cages may be considered a safe and effective surgical intervention in patients failing conservative management for cervical spondylotic disease. However, the quality of evidence in the literature is lacking, and controlled, comparative studies are needed for definitive assessment.

MIS approaches in the cervical spine

Minimally invasive surgical approaches for the treatment of spinal pathologies have accelerated over the past three decades and resulted in superior functional outcomes with less complications. Yet cervical pathologies have been slower to gain traction for multiple anatomical factors and its "high-risk" profile. Various minimally invasive techniques for cervical disease have now been described and validated in long-term studies with comparable outcomes to traditional open approaches and concomitant reduction in morbidity and socioeconomic costs. Transnasal operations can be used to treat ventral upper cervical disease, circumventing traditional and morbid transoral approaches. Posterior-based focused treatments for radiculopathy and myelopathy such as tubular-guided foraminotomies and unilateral laminotomies for bilateral cord decompression have also been described and becoming increasingly less invasive. Cervical fusions can now be performed percutaneously through modified, stand-alone facet joint cages that can be packed with allogeneic bone graft. These advances have been facilitated by the development of intraoperative imaging technologies (intraoperative CT) and 3-dimensional stereotactic navigation software. While this review focuses on these procedures and evidence-based outcomes data, the future for MIS applications in cervical spine surgery will continue to evolve over the coming years with wider indications and technological adjuncts.

Length of stay associated with posterior cervical fusion with intervertebral cages: experience from a device registry

Background

Using a multi-center medical device registry, we prospectively collected a set of perioperative and clinical outcomes among patients treated with tissue-sparing, posteriorly-placed intervertebral cage fusion used in the management of symptomatic, degenerative neural compressive disorders of the cervical spine.

Methods

Cervical fusion utilizing posteriorly-placed intervertebral cages offers a tissue-sparing alternative to traditional instrumentation for the treatment of symptomatic cervical radiculopathy. A registry was established to prospectively collect perioperative and clinical data in a real-world clinical practice setting for patients treated via this approach. This study evaluated length of stay as well as estimated blood loss and procedural time in 271 registry patients.

Results

The median length of stay was 1.1, 1.1 and 1.2 days for patients having a stand-alone arthrodesis, revision of a pseudoarthrosis, and circumferential fusion (360°), respectively, and was not related to number of levels treated. Historical comparison to published literature demonstrated that average lengths of stay associated with open, posterior lateral mass fixation were consistently ≥4 days. Average blood loss (range, 32-75 mL) and procedural time (range, 51-88 min) were also diminished in patients having tissue-sparing, cervical intervertebral cage fusion compared to open posterior lateral mass fixation.

Conclusions

Adoption of this tissue-sparing procedure may offer substantial cost-constraining benefits by reducing the length of post-operative hospitalization by, at least, 3 days compared to traditional lateral mass fixation.

Multilevel cervical laminectomy and fusion with posterior cervical cages

Context:

Cervical spondylotic myelopathy (CSM) is a progressive disease that can result in significant disability. Single-level stenosis can be effectively decompressed through either anterior or posterior techniques. However, multilevel pathology can be challenging, especially in the presence of significant spinal stenosis. Three-level anterior decompression and fusion are associated with higher nonunion rates and prolonged dysphagia. Posterior multilevel laminectomies with foraminotomies jeopardize the bone stock required for stable fixation with lateral mass screws (LMSs).

Aims:

This is the first case series of multilevel laminectomy and fusion for CSM instrumented with posterior cervical cages.

Settings and Design:

Three patients presented with a history of worsening neck pain, numbness in bilateral upper extremities and gait disturbance, and examination findings consistent with myeloradiculopathy. Cervical magnetic resonance imaging demonstrated multilevel spondylosis resulting in moderate to severe bilateral foraminal stenosis at three cervical levels.

Materials and Methods:

The patients underwent a multilevel posterior cervical laminectomy and instrumented fusion with intervertebral cages placed between bilateral facet joints over three levels. Oswestry disability index and visual analog scores were collected preoperatively and at each follow-up. Pre- and post-operative images were analyzed for changes in cervical alignment and presence of arthrodesis.

Results:

Postoperatively, all patients showed marked improvement in neurological symptoms and neck pain. They had full resolution of radicular symptoms by 6 weeks postoperatively. At 12-month follow-up, they demonstrated solid arthrodesis on X-rays and computed tomography scan.

Conclusions:

Posterior cervical cages may be an alternative option to LMSs in multilevel cervical laminectomy and fusion for cervical spondylotic myeloradiculopathy.

Perioperative complications in patients treated with posterior cervical fusion and bilateral cages

Context:

Posterior cervical cages have recently become available as an alternative to lateral mass fixation in patients undergoing cervical spine surgery.

Aims:

The purpose of this study was to quantify the perioperative complications associated with cervical decompression and fusion in patients treated with a posterior cervical fusion (PCF) and bilateral cages.

Settings and Design:

A retrospective, multicenter review of prospectively collected data was performed at 11 US centers.

Subjects and Methods:

The charts of 89 consecutive patients with cervical radiculopathy treated surgically at one level with PCF and cages were reviewed. Three cohorts of patients were included standalone primary PCF with cages, circumferential surgery, and patients with postanterior cervical discectomy and fusion pseudarthrosis. Follow-up evaluation included clinical status and pain scale (visual analog scale).

Statistical Analysis Used:

The Wilcoxon test was used to test the differences for the data. The P level of 0.05 was considered significant.

Results:

The mean follow-up interval was 7 months (range: 62 weeks - 2 years). The overall postsurgery complication rate was 4.3%. There were two patients with neurological complications (C5 palsy, spinal cord irritation). Two patients had postoperative complications after discharge including one with atrial fibrillation and one with a parietal stroke. After accounting for relatedness to the PCF, the overall complication rate was 3.4%. The average (median) hospital stay for all three groups was 29 h.

Conclusions:

The results of our study show that PCF with cages can be considered a safe alternative for patients undergoing cervical spine surgery. The procedure has a favorable overall complication profile, short length of stay, and negligible blood loss.