Single stage reduction and stabilization of basilar invagination after failed prior fusion surgery in children with Down's syndrome

Traumatic posterior dislocation of atlanto-axial joint with anterior arch fracture in the patient of atlanto-occipital assimilation: A case report

INTRODUCTION AND IMPORTANCE

Traumatic atlanto-axial dislocation (AAD) is relatively uncommon and can pose life-threatening risks. In this case, we describe a patient with a combination of AAD, an anterior arch fracture of the atlas, and a rare congenital anomaly known as atlanto-occipital assimilation (AOA).

CASE PRESENTATION

A 70-year-old man presented with posterior neck pain and right-sided torticollis following an accident that collision with a car while riding an electric scooter. Radiographic findings confirmed posterior AAD with anterior arch fracture of C1 in the inherent setting of AOA. The patient showed no neurologic deficit, so a closed reduction technique using Gardner-Wells tongs was attempted in an awakened state, and successful reduction could achieve without a neurologic deficit. After about three months of rigid brace application, head and neck motion was allowed, and no recurrence of dislocation or cervical pain occurred during the follow-up period of about one year.

CLINICAL DISCUSSION

Because the posterior AAD is usually accompanied by anterior arch fracture of atlas, the transverse atlantal ligament remained intact. So nonoperative management after manual reduction was possible. The presence of a C1 anterior arch fracture observed in our case can be regarded as an indicator predicting the success of closed reduction of AAD.

CONCLUSION

Our case highlighted the successful nonoperative management of traumatic posterior AAD with an accompanying anterior arch fracture of the atlas in a peculiar inherent combination of AOA through the closed reduction technique and rigid cervical brace application.

[Analysis of cervical instability and clinical characteristics in treatment-naive rheumatoid arthritis patients]

OBJECTIVE

To study the proportion of cervical spine instability in treatment-naive rheumatoid arthritis (RA) patients, to investigate the associated neck symptoms, and to analyze the clinical characteristics in treatment-naive RA patients and treated RA patients.

METHODS

RA patients who underwent cervical spine X-ray imaging from the Department of Rheumatology and Immunology of Peking University Third Hospital and Peking University Shenzhen Hospital from August 2015 to October 2019 and had clinical records of medication administration were included. Clinical and laboratory data including cervical symptoms and X-ray imaging data of cervical spine were collected. The constituent ratio of cervical spine instability in treatment-naive RA patients was statistically analyzed. The clinical data and laboratory data were analyzed by t-test, u-test and chi square to explore the clinical characteristics of the treatment-naive RA patients with cervical instability.

RESULTS

Of the 408 RA patients, 105 patients were treatment-naive. Of the 105 treatment-naive patients, 82.9% (87/105) were female, with an average age of (52±14) years, the median duration of the disease was 24 months, the shortest history was 2 weeks, and the longest history was 30 years. 28.6% (30/105) of the treatment-naive RA patients showed cervical spine instability. The prevalence of cervical instability was 13.6% in the treatment-naive RA patients with disease duration less than 24 months. Among them, there were no significant differences in neck symptoms between cervical spine instability group and none cervical spine instability group. The patients with cervical spine instability had a longer duration of disease [60 (18, 180) months vs.16 (8, 51) months], a higher proportion of peripheral joint deformity (63.3%vs.21.3%), and a lower hemoglobin [(106.90±21.61) g/L vs. (115.77±14.69) g/L]. There was no significant difference in the occurrence of cervical instability in the treatment-naive RA patients compared with treated RA patients. Among the RA patients with cervical instability, there was no statistically significant difference in the composition of each type between the patients with treatment-naive RA and patients with treated RA, except for a shorter duration of disease [120.0 (72.0, 240.0) months vs. 60.0 (27.0, 167.5) months].

CONCLUSION

28.6% of treatment-naive RA patients showed cervical spine instability. Cervical instability was also common in RA patients with a duration less than 24 months. There was no significant correlation between cervical instability and neck symptoms. Patients with cervical spine instability had a long-term disease, a higher proportion of peripheral joint deformity and a lower hemoglobin. Controlling the condition of RA early may help to control the progression of cervical involvement in patients with RA.

Transoral release to realign postoperative loss of reduction following occipitocervical fixation for congenital basilar invagination

PURPOSE

Revision surgery in an irreducible atlantoaxial dislocation (IAAD) previously operated with a posterior approach is challenging. Multiple modalities using anterior, posterior, and dual approaches have been described. We report a so far unreported technique of revision surgery by posterior implant removal and decompression with anterior transoral release followed by posterior instrumentation.

METHODS

14-year male with basilar invagination (BI) with IAAD, previously operated with posterior decompression and instrumented occipitocervical fusion presented three months later with post-traumatic recurrence of myelopathy with quadriparesis with Di Lorenzo grade 4 and loss of reduction. He was operated with a posterior implant and early fusion mass removal with extended foramen magnum decompression (FMD), followed by anterior transoral release with a satisfactory reduction on traction, and finally, a posterior revision instrumented occipitocervical fusion.

RESULTS

At 2-year follow-up, the patient was symptom-free with Di Lorenzo grade 1 and cervicomedullary angle improvement from 97.4° to 141.2°; achieving bony fusion.

CONCLUSION

Single-stage posterior-anterior transoral-posterior approach can be used to achieve satisfactory reduction for a revision BI with IAAD with prior posterior instrumentation.

Clinical Outcomes of Atlantoaxial Dislocation Combined with Osteoporosis Using Posterior Atlantoaxial Rod, Screw Fixation, and Posterior Interfacet Fusion: A Retrospective Study of 21 Cases

Background

Surgical procedures on atlantoaxial dislocation combined with osteoporosis remain controversial. This study was established to assess the mid-term clinical outcomes of atlantoaxial dislocation combined with osteoporosis using posterior atlantoaxial rod, screw fixation and posterior interfacet fusion.

Material/Methods

From January 2017 to January 2020, 21 patients (4 males and 17 females) with coexisting atlantoaxial dislocation and osteoporosis who underwent posterior atlantoaxial rod and screw fixation were included in our study with an average age of 64±8.1 years (range, 57–74 years). The subjective and objective symptoms, together with the neurological function of the patients were measured. Radiography and magnetic resonance imaging (MRI) were performed, Japanese Orthopaedic Association (JOA) score for spinal cord function and VAS score for pain recovery was assessed.

Results

JOA and visual analog scale (VAS) score were significantly improved at 14±5.9 month follow-up compared with pretreatment values. Complete or almost complete anatomical reduction was observed in all 21 patients. All patients had good bony fusion at the final follow-up. No screw-loosening or atlantoaxial redislocation occurred in 21 cases. The only complication was mild numbness in the C2 innervation area of the posterior occipital region in 6 cases, which had no effect on life.

Conclusions

The results suggested that posterior atlantoaxial rod, screw fixation system, and posterior interfacet fusion could achieve satisfactory initial results for the treatment of atlantoaxial dislocation combined with osteoporosis.

Atlanto-axial rotary instability (Fielding type 1): characteristic clinical and radiological findings, and treatment outcomes following alignment, fusion, and stabilization

Atlanto-axial instability (AAI) is common in the connective tissue disorders, such as rheumatoid arthritis, and increasingly recognized in the heritable disorders of Stickler, Loeys-Dietz, Marfan, Morquio, and Ehlers-Danlos (EDS) syndromes, where it typically presents as a rotary subluxation due to incompetence of the alar ligament. This retrospective, IRB-approved study examines 20 subjects with Fielding type 1 rotary subluxation, characterized by anterior subluxation of the facet on one side, with a normal atlanto-dental interval. Subjects diagnosed with a heritable connective tissue disorder, and AAI had failed non-operative treatment and presented with severe headache, neck pain, and characteristic neurological findings. Subjects underwent a modified Goel-Harms posterior C1-C2 screw fixation and fusion without complication. At 15 months, two subjects underwent reoperation following a fall (one) and occipito-atlantal instability (one). Patients reported improvement in the frequency or severity of neck pain (P < 0.001), numbness in the hands and lower extremities (P = 0.001), headaches, pre-syncope, and lightheadedness (all P < 0.01), vertigo and arm weakness (both P = 0.01), and syncope, nausea, joint pain, and exercise tolerance (all P < 0.05). The diagnosis of Fielding type 1 AAI requires directed investigation with dynamic imaging. Alignment and stabilization is associated with improvement of pain, syncopal and near-syncopal episodes, sensorimotor function, and exercise tolerance.

Three-Dimensional-Printed Model-Assisted Management of Craniovertebral Junction Abnormalities: An Institutional Experience with Literature Review

Study Design

Prospective study.

Purpose

To evaluate the utility and limitations of using three-dimensional (3D)-printed models for the management of craniovertebral (CV) junction abnormalities.

Overview of Literature

In comparison to other bony and vascular anomalies, CV junction abnormalities are difficult to treat. For cases of irreducible atlantoaxial dislocation (AAD), posterior reduction and stabilization have replaced anterior decompression as the standard management protocol. The use of 3D models, such as those described herein, can provide surgeons with in-depth knowledge of the vertebral artery course and bony anomalies associated with CV junction abnormalities.

Methods

Clinical and radiological features of 18 patients with CV junction abnormalities were analyzed between March 2017 and February 2019 at Sawai Man Singh Medical College, Jaipur, India. Dynamic computed tomography (CT) of the CV junction and CT angiographies of the neck with respect to the vertebral artery course at the C1–C2 joints were obtained and studied. Customized 3D models of the CV junction were then made based on the CT data, and rehearsal of the surgical procedure was performed using the 3D model one day prior to performing the actual procedure.

Results

Seventeen patients had congenital-type AAD, whereas one patient had posttraumatic AAD. Improvements in neck pain and myelopathy were seen in all patients at the follow-up, as analyzed using the Visual Analog Scale and the Japanese Orthopedic Association Scale score, respectively. There were no cases of malpositioning of screws or any direct vertebral artery injury, although in one patient, the distal flow in the dominant vertebral artery was cut off as it got compressed between the bony arch and the screw head.

Conclusions

Compared to computer-generated images, 3D-printed models are a more practical approach for dealing with complex CV junction abnormalities. They provide surgeons with deep insights into the complex bony anomalies as well as variations in the vertebral artery courses, thereby improving surgical outcomes.

The Value and Limitation of Cervical Traction in the Evaluation of the Reducibility of Atlantoaxial Dislocation and Basilar Invagination Using the Intraoperative O-Arm

OBJECTIVE

To assess the value and limitation of cervical traction in the evaluation of the reducibility of atlantoaxial dislocation (AAD) and basilar invagination (BI) using the intraoperative O-arm.

METHODS

A total of 22 patients with hyperextensive, irreducible AAD were included. The cervical traction test under general anesthesia was performed, and the degree of reduction was evaluated using the O-arm before the operation started. The traction effects both vertically and horizontally were evaluated. All cases then underwent modified direct posterior reduction and fixation. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scale. Radiologic measurements included the anterior atlantodental interval, the distance of odontoid tip above Chamberlain line, and the clivus-canal angle. Magnetic resonance imaging signal changes, size of syringomyelia, and the space ventral to medulla also were used to evaluate the postoperative reduction result.

RESULTS

After the cervical traction test, 7 patients achieved incomplete reduction, 5 achieved only vertical reduction, 6 achieved only horizontal reduction, and 4 achieved complete reduction in both horizontal and vertical orientations as assessed by the O-arm. All patients underwent a direct reduction technique. The mean JOA score increased from 11.1 to 14.5. Complete reduction of AAD and BI were achieved in 19 patients (86.4%), with partial reduction achieved in 3 (13.6%). Sufficient cerebrospinal fluid space anterior to the medulla with improved JOA score was achieved in the 3 partially reduced patients.

CONCLUSIONS

With the innovations of direct posterior reduction techniques, cervical traction under anesthesia may not sufficiently predict the reducibility of BI and AAD. Cervical traction still plays an important role during the direct posterior reduction procedure.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Posterior revision surgery using Goel's technique is an effective and safe revision salvage surgery for symptomatic patients with AAD and BI.

Outcomes of Surgical Correction of Atlantoaxial Instability in Patients with Down Syndrome: Systematic Review and Meta-Analysis

BACKGROUND

Atlantoaxial instability (AAI) is a common cause of neurologic dysfunction and pain in patients with Down syndrome (DS), frequently requiring instrumented fusion of the upper cervical spine. Despite this, optimal treatment strategy is controversial.

METHODS

A systematic review of the literature was performed according to the Preferred Reporting Items for Systemic Reviews and Meta-Analysis statement to identify patients with AAI and DS were treated with upper cervical spine fusion. Patient demographics, preoperative symptoms, fixation type, and outcome measures including complications, neurologic outcomes, and bony fusion status were gathered for patients in the included publications. Meta-analysis was performed to compare outcomes of different types of fixation constructs.

RESULTS

Of the 1191 publications retrieved, 51 met inclusion criteria, yielding 137 patients. Six fixation strategies were identified: noninstrumented (n = 6), wiring (n = 77), wiring with rods (n = 14), screw fixation (n = 33), hook and rod fixation (n = 2), and screw and wire fixation (n = 5). Constructs with screws and rods had greater bony union (P = 0.003) and a lower rate of revision surgery (P = 0.047), loss of reduction or pseudoarthrosis (P = 0.009), halo utilization (P < 0.001), and early neurologic decline (P = 0.004) compared with wiring alone. Constructs with wires and rods had greater bony union (P = 0.036) than wiring alone.

CONCLUSIONS

Numerous fixation strategies exist for AAI in patients with DS. Using a combination of screws, rods, and wiring in appropriately selected patients may help reduce the high rate of surgical complications in these patients.

Japanese patient with Cole-carpenter syndrome with compound heterozygous variants of SEC24D

Cole-Carpenter syndrome is a rare skeletal dysplasia associated with low-bone mass or an osteogenesis imperfecta (OI)-like syndrome. Only 3 and 6 variants in SEC24D have been reported in patients with Cole-Carpenter syndrome type 2 and autosomal recessive OI, respectively. We describe a 15-year-old Japanese boy with short stature of the short-trunk type and craniofacial abnormalities including ocular proptosis, marked frontal bossing, midface hypoplasia, and micrognathia. These features were consistent with a diagnosis of Cole-Carpenter syndrome. He had low-bone mineral density and basilar impression. Whole exome sequencing analysis identified biallelic variants in SEC24D (p.Arg484* and p.Arg313His) in the patient. We will report a patient with compound heterozygous variants of SEC24D causing Cole-Carpenter syndrome type 2.

An infantile alantoaxial dislocation with patent foramen ovale managed with titanium cabling and allogenic bone grafts

Atlantoaxial dislocation is a disorder that is characterized with loss of stability of the atlas and axis (C1-C2) with consequential loss of usual articulation. Although this condition is very common, no one has reported a case as young as our patients. We present a 7-month infant with bilateral paralysis of the lower limbs for four (4) months with no history of trauma. Computer tomographic (CT-scan) imaging revealed alantoaxial dislocation with severe cervical spinal cord compression. The odontoid process is displaced outwardly with no bone destruction. Doppler echocardiogram done revealed patent foramen ovale. Thorough physical examination as well as radiological evaluation revealed no feather malformations. Electrophysio - logical studies reveal normal compound muscle action potentials (CMAP) and sensory nerve action potentials (SNAPs) in all the limbs. Electromyography (EMG) also revealed normal nerves in the limbs and the trunk. We attained a stable fusion and anatomical reduction using a posterior titanium wire and an iliac bone graft harvested from his mother. This is the youngest patient reported in literature. Infantile alantoaxial dislocation should be managed at early stage to prevent long-term neurologic disorders.

Combined preoperative traction with instrumented posterior occipitocervical fusion for severe ventral brainstem compression secondary to displaced os odontoideum: technical report of 2 cases

Severe os odontoideum causing ventral brainstem compression is a rare and difficult entity to treat. It is generally accepted that severe os odontoideum causing ventral brainstem compression and neurological deficits warrants surgical treatment. This often requires both anterior and posterior procedures. Anterior approaches to the craniocervical junction are fraught with complications, including infection and risk of injury to neurovascular structures. External traction systems traditionally require long-term bedrest. The authors report 2 cases of severe ventral brainstem compression secondary to displaced os odontoideum and describe their use of extended preoperative halo vest traction to reduce the severe kyphosis and improve neurological function, followed by posterior occipitocervical fusion. Postoperatively both patients showed remarkable improvements in their neurological function and kyphotic deformity. Preoperative halo vest traction combined with posterior occipitocervical fusion appears to be a safe and effective method to treat brainstem compression by severe os odontoideum. It allows for adequate decompression of ventral neural structures and improvement of neurological function, but it is not hindered by the risks of anterior surgical approaches and does not restrict patients to strict bedrest as traditional traction systems. This method of halo vest traction and posterior-only approaches may be transferable to other cervical instability issues with both anterior and posterior pathologies.

Allograft versus autograft for pediatric posterior cervical and occipito-cervical fusion: a systematic review of factors affecting fusion rates

OBJECT Fusion rates are high for children undergoing posterior cervical fusion (PCF) and occipito-cervical fusion (OCF). Autologous bone has been widely used as the graft material of choice, despite the risk of donor-site morbidity associated with harvesting the bone, possibly because very low fusion rates were reported with posterior allograft cervical fusions in children several decades ago. Higher overall fusion rates using allograft in adults, associated with improvements in internal fixation techniques and the availability of osteoinductive substances such as bone morphogenetic protein (BMP), have led to heightened enthusiasm for the use of bank bone during pediatric PCF. A systematic review was performed to study factors associated with successful bone fusion, including the type of bone graft used. METHODS The authors performed a comprehensive PubMed search of English-language articles pertaining to PCF and OCF in patients less than 18 years old. Of the 561 abstracts selected, 148 articles were reviewed, resulting in 60 articles that had sufficient detail to be included in the analysis. A meta-regression analysis was performed to determine if and how age, fusion technique, levels fused, fusion substrate, BMP use, postoperative bracing, and radiographic fusion criteria were related to the pooled prevalence estimates. A systematic review of the literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. RESULTS A total of 604 patients met the specific inclusion and exclusion criteria. The overall fusion rate was 93%, with a mean age of 9.3 years and mean follow-up of 38.7 months. A total of 539 patients had fusion with autograft (94% fusion rate) and 65 patients with allograft (80% fusion rate). Multivariate meta-regression analysis showed that higher fusion rates were associated with OCF compared with fusions that excluded the occiput (p < 0.001), with the use of autograft instead of allograft (p < 0.001), and with the use of CT to define fusion instead of plain radiography alone. The type of internal fixation, the use of BMP, patient age, and the duration of follow-up were not found to be associated with fusion rates in the multivariate analysis. CONCLUSIONS Fusion rates for PCF are high, with higher rates of fusion seen when autograft is used as the bone substrate and when the occiput is included in the fusion construct. Further study of the use of allograft as a viable alternative to autograft bone fusion is warranted because limited data are available regarding the use of allograft in combination with more rigid internal fixation techniques and osteoinductive substances, both of which may enhance fusion rates with allograft.

Modern instrumentation of the pediatric occiput and upper cervical spine: review article

BACKGROUND

Rigid screw rod techniques for cervical stabilization are widely used in adults. The benefits of rigid internal fixation include increased fusion rates, improvements in deformity correction, and diminished immobilization requirements. Applications of these techniques in children are challenging due to size constraints and the pathologic conditions encountered which require instrumented cervical fusions. Preparation as well as thorough understanding of the anatomy and surgical techniques is paramount to surgical safety in pediatric patients.

QUESTIONS/PURPOSES

This review article serves as an educational tool regarding the use of modern posterior instrumentation techniques for pediatric cervical deformity.

METHODS

Expert review based on clinical expertise and literature review.

RESULTS

The use of rigid screw rod instrumentation for the pediatric occiput and upper cervical spine is discussed. Preoperative imaging requirements for pediatric patients undergoing cervical spine surgery are reviewed. Anatomy, morphologic studies, and surgical techniques are discussed for each area of instrumentation.

CONCLUSIONS

Modern posterior cervical instrumentation techniques can be safely applied to the majority of pediatric patients who require an instrumented posterior cervical fusion. Patient safety revolves around thorough preoperative imaging tests, understanding of upper cervical anatomy, and meticulous surgical technique. Modern instrumentation leads to an improvement in fusion rates and a diminishment in immobilization requirements.

A review of the diagnosis and treatment of atlantoaxial dislocations

Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning "atlantoaxial dislocation" or "atlantoaxial subluxation" on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.

Posterior realignment of irreducible atlantoaxial dislocation with C1-C2 screw and rod system: a technique of direct reduction and fixation

BACKGROUND CONTEXT

Treatment of chronic and irreducible atlantoaxial dislocation (AAD) with ventral compression is challenging for surgeons. The main procedures are occipitocervical/C1-C2 fusion after transoral odontoidectomy or release of the periodontoid tissues. These surgical procedures, which are performed simultaneously or intermittently, have many disadvantages that may discount their effectiveness. Therefore, a more effective way to achieve surgical reduction and to keep solid stability with only a single procedure is needed.

PURPOSE

We describe a technique to reduce chronic and irreducible AAD with C1 lateral mass and C2 pedicle screw and rod system.

STUDY DESIGN

This was a retrospective case series.

PATIENT SAMPLE

Our sample comprised 26 patients (9 men and 17 women) with irreducible AAD who ranged in age from 15 to 54 years (mean, 35 years).

OUTCOME MEASURES

Patients' neurologic status was evaluated with the Japanese Orthopedic Association (JOA) scale.

METHODS

Twenty-six symptomatic patients underwent posterior realignment and reduction through the C1 lateral mass and C2 pedicle screw and rod system. The proposed mechanism of reduction is that the implanted screws and rods between C1 and C2 acting as a lever system drew C1 backward and pushed C2 downward and forward after removing circumambient obstruction and scars and thoroughly releasing the facet joints. The preoperative and postoperative JOA score, the extent of reduction, and the conditions of C1-C2 bony fusion were examined.

RESULTS

No neurovascular injury occurred during surgery. Follow-up ranged from 6 to 40 months (mean 20.7 months). Radiographic evaluation showed that solid bony fusion was achieved in all patients, and that complete reduction was attained in 18 patients and partial reduction (>60% reduction) in 8 patients. The mean postoperative JOA score at last follow-up was 15.7, compared with the preoperative score of 12.1 (p<.01).

CONCLUSIONS

This C1-C2 screw and rod system provides reliable stability and sufficient reduction of the anatomic malalignment at the craniovertebral junction and meanwhile retains the mobility of atlanto-occipital joints in the treatment of chronic and irreducible AAD. Sophisticated skills, thorough release of the facet joints, and intraoperative protection of the vertebral artery are key points to accomplish this technique.

Novel surgical classification and treatment strategy for atlantoaxial dislocations

STUDY DESIGN

Retrospective study of 904 patients with a diagnosis of atlantoaxial dislocation (AAD), using a novel surgical classification and treatment strategy.

OBJECTIVE

To describe a novel surgical classification and treatment strategy for AADs.

SUMMARY OF BACKGROUND DATA

AADs can result from a variety of etiologies, yet no comprehensive classification has been accepted that guides treatment. Because of the rarity of the cases, however, the treatment strategy has also been debated.

METHODS

During a period of 12 years, a total of 904 patients with a diagnosis of AAD were recruited from a single academic institution. According to the treatment algorithm that included preoperative evaluation using dynamic radiograph, reconstructive computed tomography, and skeletal traction test, the cases were classified into 4 types: I to IV. Types I and II were fused in the reduced position from a posterior approach. Type III, which were irreducible dislocations, were converted to reducible dislocations using a transoral atlantoaxial release, followed by a posterior fusion. Type IV presented with bony dislocations and required transoral osseous decompressions prior to posterior fusion.

RESULTS

Four hundred seventy-two cases were classified as type I, 160 as type II, 268 as type III, and 4 cases as type IV. Follow-up was in the range of 2 to 12 years (average: 60.5 mo). Eight hundred and ninety-nine cases (99.4%) achieved a solid atlantoaxial fusion. Anatomic atlantoaxial reduction was achieved in 892 cases (98.7%), whereas 12 cases had a partial reduction. Neurological improvement was seen in 84.1% (512/609) of the patients with myelopathy. The overall complication rate was 9.1% (82/949).

CONCLUSION

Our surgical classification and treatment strategy for AADs was applied in those 904 cases and associated with excellent clinical results with a minimal risk of complications.

LEVEL OF EVIDENCE

4.

Endoscopic image-guided transcervical odontoidectomy: outcomes of 15 patients with basilar invagination

BACKGROUND

Ventral decompression with posterior stabilization is the preferred treatment for symptomatic irreducible basilar invagination. Endoscopic image-guided transcervical odontoidectomy (ETO) may allow for decompression with limited morbidity.

OBJECTIVE

To describe the perioperative outcomes of patients undergoing anterior decompression of basilar invagination with the use of ETO.

METHODS

Fifteen patients who had a follow-up of at least 16 months were retrospectively reviewed. Intraoperatively, the vertebral body of C2 was removed and the odontoid was resected in a "top-down" manner using endoscopic visualization and frameless stereotactic navigation. Posterior instrumented stabilization was subsequently performed.

RESULTS

The average (± standard deviation) age of the patients was 42.6 ± 24.5 (range, 11-72) years. Postoperative complications occurred in 6 patients, including a urinary tract infection (n = 2), upper airway swelling (n = 2), dysphagia (n = 2), gastrostomy tube placement (n = 1), and an asymptomatic pseudomeningocele (n = 1). No patients required a tracheostomy, had bacterial meningitis, or developed a venous thromboembolic event; only 1 patient was intubated for more than 48 hours postoperatively. With a mean follow-up of 41.9 ± 14.4 (range, 16-59) months, myelopathy improved in all patients and no patient experienced late neurological deterioration. The mean modified Japanese Orthopedic Association (JOA) score increased from 11.2 ± 4.2 to 15.9 ± 1.4 (P = .002). Patients with a diagnosis other than rheumatoid arthritis or who had a higher preoperative JOA score had a significantly better postoperative neurological recovery (P = .005).

CONCLUSION

ETO may be a valid treatment for patients with symptomatic irreducible basilar invagination that avoids some of the morbidity of transoral surgery and leads to long-term improvement in myelopathy.

Placement of occipital condyle screws for occipitocervical fixation in a pediatric patient with occipitocervical instability after decompression for Chiari malformation

In cadaveric studies and recently in one adult patient the occipital condyle has been studied as an option to allow bone purchase by fixation devices. In the current case the authors describe the use of occipital condyle screws in a child undergoing occipitocervical fixation. To the best of the authors' knowledge this case is the first reported instance of this technique in a pediatric patient. This girl had a history of posterior fossa decompression for Chiari malformation Type I when she was 22 months of age. When she was 6 years old she presented with neck pain on flexion and extension of her head. Magnetic resonance imaging in flexion and extension revealed occipitocervical instability. She underwent an occiput to C-2 posterior arthrodesis with bilateral screw placement in the occipital condyles, C-2 lamina, and C-1 lateral masses. Postoperatively, she was neurologically intact. Computed tomography demonstrated a stable construct, and her cervical pain had resolved on follow-up.