Implantation of C2 prosthesis with dorsal fusion C0-C4 due to pathologic C2 fracture. Case report and literature review.

INTRODUCTION: Pathological destruction of the axis vertebra leads to a highly unstable condition in an upper cervical spine. As surgical resection and anatomical reconstruction of the second cervical vertebrae represents a life threatening procedure, less radical approaches are preferred and only few cases of C2 prosthesis are described in literature. CASE DESCRIPTION: The focus of this case report is a 21-year-old man with a pathological fracture of C2 managed primarily surgically with the C1-C3 dorsal fusion. Due to the progression of giant cell tumor and destruction of the axis vertebra, C2 prosthesis through anterior approach and dorsal occipito-cervical fusion C0-C4 were performed. Postoperative infection was managed surgically with a 2-staged dorsal debridement, ostheosynthesis material change and autologous bone graft. After a 4 week-intravenous therapy with the ceftriaxone in combination with the amoxicillin/clavulanate, followed by 12 week per oral therapy with amoxicillin/clavulanate in combination with ciprofloxacin, the complete recovery of the infection was achieved. Radiotherapy was initiated 2 months after the last revision surgery and the patient showed a good clinical outcome with stable construct at a 1 year follow-up. A review of literature of all reported C2 prosthesis cases was performed CONCLUSION: C2 prosthesis allows a more radical resection in pathological processes involving the axis vertebra. Combined with the posterior fusion, immediate stability is achieved. Anterior surgical approach is through a highly unsterile oral environment which presents a high-risk of postoperative infection.

What is the C2 pedicle, pars interarticularis, and isthmus? Anatomical study and review of the literature regarding these confusing terms with proposal of new nomenclature.

INTRODUCTION: The atypical anatomy of the C2 vertebra has led to terminological discrepancies within reports and studies in the literature regarding the location of its pedicle, pars interarticularis, and isthmus. These discrepancies not only limit the power of morphometric analyses, but they also confuse technical reports regarding operations involving C2, and thus confuse our ability to properly communicate this anatomy. Herein, we examine the variations in nomenclature regarding the pedicle, pars interarticularis, and isthmus of C2, and via an anatomical study, propose new terminology. METHODS: The articular surface and underlying superior and inferior articular processes and adjacent transverse processes were removed from 15 C2 vertebrae (30 sides). Specifically, the areas regarded as the pedicle, pars interarticularis, and isthmus were evaluated. Morphometrics were performed. RESULTS: Our results indicate that, anatomically, C2 has no "isthmus" and that a pars interarticularis for C2, when present, is very short. Deconstruction of the attached parts allowed for visualization of a bony arch extending from the anterior most aspect of the lamina to the body of C2. The arch is composed almost entirely of trabecular bone and without its attached parts, e.g., transverse process, really has no cortical bone laterally. CONCLUSIONS: We propose a more accurate terminology, the pedicle, for pars/pedicle screw placement of C2. Such a term more accurately describes this unique structure of the C2 vertebra and would alleviate terminological confusion in the future literature on this topic.

Two-Surgeon Multidisciplinary Approach to Pediatric Cervical Spinal Fusion: A Single-Institution Series and Review of the Literature.

BACKGROUND: A collaborative 2-surgeon approach is becoming increasingly popular in surgery but is not widely used for pediatric cervical spine fusions. The goal of this study is to present a large single-institution experience with pediatric cervical spinal fusion using a multidisciplinary 2-surgeon team, including a neurosurgeon and an orthopedic surgeon. This team-based approach has not been previously reported in the pediatric cervical spine literature. METHODS: A single-institution review of pediatric cervical spine instrumentation and fusion performed by a surgical team composed of neurosurgery and orthopedics during 2002-2020 was performed. Demographics, presenting symptoms and indications, surgical characteristics, and outcomes were recorded. Particular focus was given to describe the primary surgical responsibility of the orthopedic surgeon and the neurosurgeon. RESULTS: A total of 112 patients (54% male) with an average age of 12.1 (range 2-26) years met the inclusion criteria. The most common indications for surgery were os odontoideum with instability (n=21) and trauma (n=18). Syndromes were present in 44 (39%) cases. Fifty-five (49%) patients presented with preoperative neurological deficits (26 motor, 12 sensory, and 17 combined deficits). At the time of the last clinical follow-up, 44 (80%) of these patients had stabilization or resolution of their neurological deficit. There was 1 new postoperative neural deficit (1%). The average time between surgery and successful radiologic arthrodesis was 13.2±10.6 mo. A total of 15 (13%) patients experienced complications within 90 days of surgery (2 intraoperative, 6 during admission, and 7 after discharge). CONCLUSIONS: A multidisciplinary 2-surgeon approach to pediatric cervical spine instrumentation and fusion provides a safe treatment option for complex pediatric cervical cases. It is hoped that this study could provide a model for other pediatric spine groups interested in implementing a multi-specialty 2-surgeon team to perform complex pediatric cervical spine fusions. LEVEL OF EVIDENCE: Level IV-case series.

Traumatic spondylolisthesis of axis: clinical and imaging experience at a level one trauma center.

PURPOSE: Traumatic spondylolisthesis of the axis (TSA) with bilateral pars interarticularis fracture (a pattern also known as Hangman's fractures) accounts for 4-5% of all cervical fractures. Various classification systems have been described to assist therapeutic decision-making. The goal is to reassess the utility of these classifications for treatment strategy and evaluate additional imaging associations. METHODS: This is an IRB approved, retrospective analysis of patients with imaging diagnosis of TSA from 2016 to 2019. Consensus reads were performed classifying TSA into various Levine and Edwards subtypes and typical vs. atypical fractures. Other imaging findings such as additional cervical fractures, traumatic brain injury, spinal cord injury, and vertebral artery injury were recorded. Treatment strategy and outcome were reviewed from clinical charts. Fisher exact test was used for statistical analysis. RESULTS: A total of 58 patients were included, with a mean age of 62.7 ± 25 years, and male to female ratio of 1:1.2. Motor vehicle collision was the most common cause of TSA. Type I and III injuries were the most and the least common injuries, respectively. Patients with type I injuries were found to have good healing rates with conservative management (p < 0.001) while type IIa and III injuries were managed with surgical stabilization (p = 0.04 and p = 0.01, respectively). No statistical difference was observed in the treatment strategy for type II fractures (p = 0.12) and its prediction of the associated injuries. Atypical fractures were not found to have a higher incidence of SCI (p = 0.31). A further analysis revealed significantly higher-grade vertebral artery injuries (grades III and IV according to Biffl grading) in patients with type IIa and III injuries (p = 0.001) and an 11-fold increased risk of TBI compared to type I and type II fractures (p = 0.013). CONCLUSION: TSA fracture types were not associated with any clinical outcome. Levine and Edwards type II classification itself is not enough to guide the treatment plan and does not account for associated injuries. Additional imaging markers may be needed.

Asymmetry of the C2 pars interarticularis: a clinical anatomical study with relevance to screw placement.

PURPOSE: Potential asymmetries of the C2 posterior elements pose a problem for the spine surgeon seeking to make the best choice for spinal stabilization while reducing morbidity. METHODS: A digital caliper was used to measure the pars interarticularis height and length on left and right sides of 25 adult C2 vertebrae. The pars interarticularis was defined as the bone between the posterior most aspect of the superior articular process and the anterior most aspect of the inferior articular process of C2. Also, the C2 vertebrae from 49 patients were scanned by CT. Parasagittal images were reviewed and using the same definitions as were used for the skeletal specimens, the length and the height of the C2 pars interarticularis from both the left and right sides were measured using CT. The image slices were acquired at 3 mm intervals. The pars interarticularis height was determined on sagittal CT reconstruction, while the pars interarticularis length was calculated on the basis of the axial images. RESULTS: The lengths and the heights of the left and right pars interarticularis were compared using CTs of patients and skeletal specimens. No significant differences were found in the length and height measurements of the CT images on both sides. However, in the skeletal specimens, the left and right pars interarticularis did not differ significantly in length but differed significantly in height (p = 0.003). The mean height of the left pars interarticularis was approximately two times larger than the right in the skeletal specimens. Absolute differences were calculated between the side with the greater length and height and the side with the lesser length and height irrespective of their left-right orientations. For CT measurements, most differences in length and height between the greater pars interarticularis and lesser pars interarticularis occurred between 0 and 1 mm with each successive disparity interval yielding lower numbers. Skeletal measurements revealed a similar length disparity distribution to the CT measurements. However, height measurements in the skeletal specimens varied widely. Eight pars interarticularis specimens demonstrated a height difference between 0 and 1 mm. No dry bone pars interarticularis specimens demonstrated a height difference between 1 and 2 mm. The pars interarticularis of nine specimens demonstrated a height difference between 2 and 3 mm. Two demonstrated a height difference between 3 and 4 mm. Four demonstrated a height difference between 4 and 5 mm and two demonstrated a height difference greater than 5 mm. The greater pars interarticularis lengths and heights were combined and compared to their lesser counterparts on CT and skeletal measurements. In all measurements of this type, significant differences were found in the pars interarticularis length and height, whether measured through CT or via digital calipers. CONCLUSION: Asymmetry between the left and right C2 pars interarticularis as shown in the present study can alter surgical planning. Therefore, knowledge of this anatomical finding might be useful to spine surgeons.

Minimally invasive posterior percutaneous transarticular C1-C2 screws: how I do it.

BACKGROUND: Transarticular C1-C2 screw fixation, first described by Magerl, is a widely accepted used technique for C1-C2 instability with a good biomechanical stability and fusion rate. METHOD: We present a 69-year-old woman, who was diagnosed with a C2 Odontoid fracture type III and primarily treated with conservative treatment and collar. During first 2 weeks of follow-up, the patient developed cervical pain associated with C1-C2 instability. A minimally invasive posterior C1-C2 transarticular screw instrumentation with a percutaneus approach was performed. RESULTS AND CONCLUSION: Minimally invasive approach with tubular transmuscular approach for C1-C2 transarticular screws instrumentation is safe and effective for C1-C2 instability.

C1-C2 Pedicle Screw Fixation for Pediatric Atlantoaxial Dislocation: Initial Results and Long-term Follow-up.

BACKGROUND: There are few studies reporting the use of atlantoaxial pedicle screws and the long-term effects of C1-C2 posterior fusion in children. Our study is to investigate the initial results of C1-C2 pedicle screw fixation for pediatric atlantoaxial dislocation (AAD) and assessed spontaneous change of postoperative radiography after a long-term follow-up period. METHODS: Posterior pedicle screw fixations were performed in 21 pediatric patients with AAD. All the patients underwent implant removal 1 year after their initial surgery and had regular follow-up with an average duration of 76.4 months (range, 52 to 117 mo). Clinical and radiographic data were then collected and compared. RESULTS: Frankel Grade was significantly improved at 3 months follow-up compared with pretreatment values. All patients had good bony fusion at a mean of 4.2±0.9 months (range, 3 to 6 mo) after treatment. None of the patients experienced worsening neurological symptoms or injury to the vertebral artery. However, 2 cases experienced minor complications. Following removal of the implants, no spinal deformities or subaxial instabilities were found. The mean angle of sagittal curvature increased from 12.1±2.4 degrees (range, 0 to 22 degrees) immediately postoperatively to 19.1±2.7 degrees (range, 6 to 31 degrees) at the final follow-up (P>0.05). CONCLUSIONS: The results demonstrated that C1-C2 pedicle screw fixation could achieve satisfactory initial results for the management of the pediatric AAD. Moreover, removal of the metal implant after bony fusion did not increase the risk of spinal deformity or subaxial instability at long-term follow-up.

Occipital Plate Fixation in the Pediatric Population.

BACKGROUND: Occipital plate fixation has been shown to improve outcomes in cervical spine fusion. There is a paucity of literature describing occipital plate fixation, especially in the pediatric population. The authors reviewed a case series of 34 patients at a pediatric hospital who underwent cervical spine fusion with occipital plate fixation between 2003 and 2016. This study describes how occipital plates aid the cervical spine union in a case series of diverse, complex pediatric patients. METHODS: Our orthopaedic database at our institution was queried for patients undergoing an instrumented cervical spine procedure between 2003 and 2016. Medical records were used to collect diagnoses, fusion levels, surgical technique, and length of hospitalization, neurophysiological monitoring, complications, and revision procedures. RESULTS: Thirty-four patients met the inclusion criteria. The mean age was 10.9 years (range, 3-21 y). Indications for surgery included cervical instability, basilar invagination, and os odontoideum. These indications were often secondary to a variety of diagnoses, including trisomy 21, Klippel-Feil syndrome, and rheumatoid arthritis. The mean length of hospitalization was 10 days (range, 2 to 80 d). There were no cases of intraoperative dural leak, venous sinus bleeding from occipital screw placement, or implant-related complications. Postoperative complications included 2 cases of nonunion. Eight patients (24%) had follow-up surgery, only 3 (9%) of which were instrumentation revisions. Both patients with nonunion had repeat occipitocervical fixation procedures and achieved union with revision. CONCLUSIONS: Occipital plate fixation was successful for pediatric cervical spine fusion in this diverse cohort. The only procedure-related complication demonstrated was delayed union or nonunion and implant loosening (4/34, 12%) and there were no plate-related complications. This novel case series shows that occipital plate fixation is safe and effective for pediatric patients with complex diagnoses. LEVEL OF EVIDENCE: Level IV-case series.

Os odontoideum: diagnosis and role of imaging.

OBJECTIVE: To elucidate the imaging manifestations of os odontoideum, establish the diagnosis and guide surgical therapy. METHODS: Clinical and imaging data, including X-ray, CT and MR of 24 patients with os odontoideum, were retrieved and reviewed retrospectively. RESULTS: Os odontoideum with intact cortex was divided into round, conical and blunt tooth types. Four cases of orthotopic and 20 cases of dystopic os odontoideum were included. There was anterior displacement of the base of the dens in six cases, posterior displacement in nine cases and no displacement in nine cases. A widening of anterior atlanto-axial space was shown in 14 patients with varying degrees. Thickening of the soft tissue posterior to the dens was observed in 19 patients, spinal canal stenosis in 21 patients, cervical myelopathy in 10 patients and craniocervical junction malformation in 9 patients. Posterior C1-C2 pedicle screw fixation and fusion was performed in 12 patients and 4 patients underwent posterior occipito-cervical fixation and fusion. CONCLUSION: Radiographically, os odontoideum is defined as an independent ossicle of variable size with smooth circumferential cortical margins separated from the axis. Imaging can be used to assess atlanto-axial instability, associated normal or abnormal anatomical structures and guide surgical therapy.

Chondrosarcoma in the body of the C2 vertebral axis.

Chondrosarcoma, a malignant bone tumor, is rarely encountered in the cervical spine. This article describes a patient whose neck pain and dysphagia were caused by an expansive, destructive lesion with calcification that was located in the body of the axis (C2 vertebra), the first time a chondrosarcoma has been reported in this location.

Low energy chronic traumatic spondylolisthesis of the axis.

OBJECTIVE: The aim of this study is to present a unique case of a patient who presented to our Emergency Department with evidence of a chronic traumatic spondylolisthesis of the axis with severe displacement treated with anterior cervical discectomy and fusion (ACDF) of C2-C3 as well as and posterior cervical fusion (PCF) of C1-C3. METHODS: One patient with an untreated traumatic spondylolisthesis of the axis with Levine type II injury pattern and 1.2 cm of anterior subluxation underwent ACDF C2-C3 and PCF C1-C3. RESULTS: The patient recovered well, radiographs demonstrated reduction of the anterior subluxation, and the patient reported a neck disability index (NDI) score of 20 at 6-month follow-up with full neurologic function intact. The patient was then lost to follow-up. CONCLUSION: In this report, we present an alcoholic patient with a history of many falls who presented with a Levine type II traumatic spondylolisthesis of the axis with signs of chronicity seen on magnetic resonance imaging (MRI). We were able to partially reduce the anterior displacement with traction, but needed both anterior and posterior cervical approaches to achieve adequate reduction and stabilization of the injury.

Why the Craniovertebral Junction?

The craniovertebral junction (CVJ) has unique anatomical bone and neurovascular structure architecture. It not only separates the skull base from the subaxial cervical spine but also provides a special cranial flexion, extension and axial rotation pattern. Stability is provided by a complex combination of osseous and ligamentous supports, which allow a large degree of motion. Perfect knowledge of CVJ anatomy and physiology allows us to better understand instrumentation procedures of the occiput, atlas and axis, and the specific diseases that affect the region. Therefore, a review of the vascular, ligamentous and bony anatomy of the region, in relation to all possible surgical approaches to this anatomically unique segment of the cervical spine, appears to be absolutely mandatory in order to preview and to overcome possible anatomy-related complications of CVJ surgery; moreover, knowledge of the basic principles of instrumentation and of the kinematics of the region, since they interact with the anatomy, seems to be strategic in preoperative planning.Historically considered a no man's land, CVJ surgery, or the CVJ specialty, has recently attracted strong consideration as a symbol of challenging surgery as well as selective top-level qualifying surgery.Although many years have passed since the beginning of this pioneering surgery, managing lesions situated in the anterior aspect of the CVJ still remains a challenging neurosurgical problem. Many studies are available in the literature, aiming to examine the microsurgical anatomy of both the anterior and posterior extradural and intradural aspects of the CVJ, as well as the differences in all possible surgical exposures obtained by the 360° approach philosophy. In this paper the author provides a short but quite complete at-a-glance tour of personal experience and publications and the more recent literature available.

Wiring or Screwing at the Craniovertebral Junction in Childhood: Past and Present Personal Experience.

BACKGROUND: Craniovertebral junction (CVJ) instrumentation and fusion in childhood are frequently performed with either sublaminar wires or screws in lateral masses, and both are considered quite safe procedures. METHODS: Our experience deals with 12 children: six (mean age 9.5 years) harbouring a congenital instability associated with Down's or Morquio's syndromes and primary os odontoideum; and six (mean age 11.5 years) with acquired iatrogenic instability due to transoral anterior decompression for different reasons (inferior clivectomy, anterior arch removal and odontoidectomy). All patients in the 'congenital group', except for one, had preoperative dynamic x-rays and underwent surgical correction by means of posterior wiring, fusion and an external orthosis. All patients in the 'iatrogenic group' had no preoperative dynamic x-rays and underwent a screwing technique with fusion and an external orthosis. RESULTS: The postoperative clinical picture had improved in all patients at the latest follow-up (observation range 63-202 months [mean 118.5 months]), with neuroradiological confirmation of satisfactory bony fusion and with neural decompression in all patients. CONCLUSION: Although it requires a more accurate preoperative neuroradiological setting, the screwing technique takes less time and is characterized by less blood loss and less postoperative discomfort than the wiring technique. The latter features confirm the simplicity, safety (continuous fluoroscopic assistance is not necessary, and there is no risk of neurovascular injuries) and lower expense (neither complex hardware devices nor neuronavigation systems are required) of the screwing technique.

Retro-odontoid Degenerative Pseudotumour Causing Spinal Cord Compression and Myelopathy: Current Evidence on the Role of Posterior C1-C2 Fixation in Treatment.

BACKGROUND: A retro-odontoid pseudotumour compressing the spinal cord and causing myelopathy is often associated with an inflammatory condition such as rheumatoid arthritis. A degenerative non-inflammatory retro-odontoid pseudotumour responsible for clinically relevant spinal cord compression is a rare condition described in small clinical series and is likely associated with craniovertebral junction hypermobility or instability-like conditions. For several years, direct removal of the lesion through an anterior or lateral approach has been advocated as the best surgical option. However, in the last decade the posterior approach to the craniovertebral junction, to perform C1-C2 fixation and C1 laminectomy without removal of the retro-odontoid tissue, has demonstrated its efficacy in reducing retro-odontoid pannus as well as in obtaining improvement of myelopathy. METHODS: In this paper we analyse the clinical and radiological outcomes of seven patients (five males and two females) treated with posterior C1-C2 fixation and C1 laminectomy for a degenerative non-inflammatory retro-odontoid pseudotumour responsible for spinal cord compression. C1 laminectomy provided immediate spinal cord decompression. We also review the relevant literature focusing on associated cervical degenerative conditions that may contribute to triggering or acceleration of atlantoaxial hypermobility or 'instability', causing formation of the retro-odontoid tissue. RESULTS: The mean follow-up period (of six followed-up patients) was 55.8 months (range 10-96 months). In all cases the Nurick score at the latest follow-up visit demonstrated clinical improvement; magnetic resonance imaging during follow-up demonstrated progressive reduction of the retro-odontoid pseudotumour in all but one patient, who died of surgery-unrelated disease in the early postoperative period. No vascular or neural damage secondary to C1-C2 fixation was observed. CONCLUSION: C1-C2 fixation associated with C1 laminectomy is an effective surgical option to treat myelopathy secondary to a degenerative retro-odontoid pseudotumour. In these cases, direct removal of intracanalar tissue compressing the spinal cord is not required, as C1-C2 fixation is sufficient to cause its disappearance.

The Decision-Making Process in Traumatic Lesions of the Craniovertebral Junction: An Evidence-Based Approach? Part II.

This paper is Part II of a two-part report. Part I of the report covered atlanto-occipital dislocation or dissociation, and isolated condylar fractures. This part of the report covers isolated and combination fractures of the atlas and axis.

Realignment of Basilar Invagination by C1-C2 Joint Distraction: A Modified Approach to a Paradigm Shift.

BACKGROUND: Distraction of the C1-C2 joint and maintenance thereof by introduction of spacers into the articular cavity can successfully and durably reduce basilar invagination (BI). Thus, with the adjunct of instrumented fusion and decompression, BI-induced myelopathy can be efficiently treated with a one-stage posterior approach. This intervention is technically challenging, and in this paper we describe a procedural variation to facilitate the approach. METHODS AND RESULTS: Through a description of a case of BI, the main anatomopathological alteration underlying and perpetrating the condition of BI is elucidated. A technique of realignment of BI is then described in which this alteration is specifically targeted and neutralized. The result is a single-stage posterior-only approach with decompression, C1-C2 distraction and introduction of poly(methyl methacrylate) (PMMA) into the joint cavity. Instrumented occipitocervical fusion completes the procedure. CONCLUSION: C1-C2 joint distraction is a technically demanding procedure. By providing a modification of the original technique and a detailed description of the crucial steps necessary to successfully and safely carry it out, we hope to make this excellent procedure more approachable.

Insights into the Past and Future of Atlantoaxial Stabilization Techniques.

Over the past century, atlantoaxial stabilization techniques have improved considerably. To our knowledge there has been a scarcity of articles published that focus specifically on the history of atlantoaxial stabilization. Examining the history of instrumentation allows us to evaluate the impact of early influences on current modern stabilization techniques. It also provides inspiration to further develop the techniques and prevents repetition of mistakes. This paper reviews the evolution of C1-C2 instrumentation techniques over time and provides insights into the future of these practices.We did an extensive literature search in PubMed, Embase and Google Scholar, using the following search terms: 'medical history', 'atlantoaxial', 'C1/C2', 'stabilization', 'instrumentation', 'fusion', 'arthrodesis', 'grafting', 'neuroimaging', 'biomechanical testing', 'anatomical considerations' and 'future'.Many different entry zones have been tested, as well as different constructs, from initial attempts with use of silk threads to use of hooks and rod-wire techniques, and handling of bone grafts, which eventually led to the development of the advanced screw-rod constructs that are currently in use. Much of this evolution is attributable to advancements in neuroimaging, a wide range of new materials available and an improvement in biomechanical understanding in relation to anatomical structures.

Atlantoaxial dislocation and os odontoideum in two identical twins: perspectives on etiology.

PURPOSE: There are two theories about the origin of os odontoideum: traumatic or congenital. However, most studies favor the hypothesis of traumatic theory. To emphasize the congenital theory, we report a pair of identical twins both with atlantoaxial dislocation and os odontoideum, which is believed to be a congenital defect. METHODS: We present two 14-year-old identical twins with atlantoaxial dislocation and os odontoideum. Neither of the twins had history of trauma in head nor cervical spine. We reviewed and compared the cervical radiographs of the identical twins. Posterior atlantoaxial reduction, pedicle screw fixation and atlantoaxial fusion were performed for the two twins. RESULTS: Radiological examination showed the identical twins had typical atlantoaxial dislocation and os odontoideum. The twins had high similarity in the appearance of atlantoaxial dislocation and os odontoideum. The etiology of the os odontoideum in the twins is believed to be congenital. Both the twins had improvement in neurological function after surgery. CONCLUSION: Although a great number of cases with os odontoideum have been reported to be traumatic, there are some cases believed to be congenital.

Posterior decompression and occipitocervical fixation followed by intraoperative vertebroplasty for metastatic involvement of the axis.

BACKGROUND: Metastases to the upper cervical spine were rarely reported in the literature. However, metastases to this area may cause spinal instability and cord compression, which in turn can result in respiratory failure and neurological dysfunction. The present study investigated the efficacy and safety of posterior decompression and occipitocervical fixation followed by intraoperative vertebroplasty for this disease. METHODS: This was a retrospective study that included 10 patients with metastatic involvement of the axis from March 2002 to May 2014. All cases presented with occipitocervical pain: 5 patients with compressive myelopathy and 6 patients with radiculopathy. Japanese Orthopedic Association (JOA) scores and Visual Analogue Scale (VAS) were used to evaluate the improvement of neurological function and pain intensity, respectively. RESULTS: All patients underwent posterior decompression and occipitocervical fixation followed by intraoperative vertebroplasty. The VAS scores and JOA scores both improved postoperatively, from 8.2 ± 0.4 to 2.3 ± 0.2 and from 10.1 ± 2.2 to 14.2 ± 2.9, respectively. Additionally, the improvement rate of JOA was 52.4 ± 1.8%. The mean overall survival was 12.8 months. The median survival time was 7 months. The 6-month and 12-month survival rates were 70% and 40%, respectively. The mean duration of operation was 182 min and blood loss was 450 mL. The mean volume of bone cement injected was 4.0 mL. The cement extravasation was observed in only 1 patient without clinical symptoms. One patient developed tumour recurrence and died 1 month later. CONCLUSIONS: Posterior decompression and occipitocervical fixation followed by intraoperative vertebroplasty was a safe and valuable palliative method with relatively less invasion to treat metastatic involvement of the axis.

C2 Translaminar Screw Fixation in Children.

BACKGROUND: Axis (C2) screw fixation has been shown to be effective in treating disorders that necessitate cervical stabilization. Although translaminar C2 screws have demonstrated clinical efficacy in adults, this technique has not yet been thoroughly investigated in children. This study describes the indications, technique, and results of translaminar C2 screw fixation in a case series of pediatric cervical spine disorders. METHODS: We searched the orthopaedic database at our institution for patients who had undergone a cervical spinal fusion that encompassed C2 between 2007 and 2017. Operative records were reviewed to determine if C2 screw fixation was performed and, if so, the type of C2 screw fixation. Clinical data with regard to patient age at surgery, diagnosis, procedure details, intraoperative complications, and postoperative complications were recorded. Preoperative and postoperative computer tomographic scans were reviewed to determine laminar measurements and containment, respectively. RESULTS: In total, 39 C2 translaminar screws were placed in 23 patients that met our inclusion criteria. The mean age was 12.6 years (range, 5.2 to 17.8 y) with a mean of 2 levels fused (range, 1 to 6). Diagnoses included 7 patients with instability related to skeletal dysplasia, 6 os odontoideum, 4 congenital deformities, 3 basilar invaginations, 2 cervical spine tumors, and 1 fracture. Indications for C2 translaminar screws included 14 cases with distorted anatomy favoring C2 translaminar screws, 6 cases without explicit reasoning for translaminar screw usage in the patient records, and 3 cases with intraoperative vertebral artery injury (1 sacrificed secondary to tumor load and 2 others injured during exposure because of anomalous anatomy). The vertebral artery injuries were not due to placement of any instrumentation. There were no screw-related intraoperative or postoperative complications and no neurological injuries. All patients demonstrated clinical union or healing on follow-up with no episodes of nonunion. CONCLUSIONS: Translaminar C2 screw fixation can be reliably used in the pediatric population. Our series contained no screw-related complications, no neurological injuries, and all patients demonstrated clinical union or healing. LEVEL OF EVIDENCE: Level IV-Case series.