Sagittal slope angle of lateral atlantoaxial articulation is associated with the severity of basilar invagination with atlantoaxial dislocation and predicts reduction degree after surgery.

OBJECTIVE: To investigate (1) lateral atlantoaxial articulation (LAA) morphology in patients with basilar invagination (BI) with atlantoaxial dislocation (AAD) and healthy individuals and its relationship with the severity of dislocation and (2) the effect of the LAA morphology on reduction degree (RD) after surgery. METHODS: In this retrospective propensity score matching case-control study, imaging and baseline data of 62 patients with BI and AAD from 2011 to 2022 were collected. Six hundred thirteen  participants without occipitocervical junctional deformity served as controls. Logistic regression and receiver operating characteristic (ROC) curve were used for analysis. RESULTS: The age, BMI and sex did not differ significantly between the two groups after propensity score matching. Sagittal slope angle (SSA) and coronal slope angle (CSA) was lower and greater, respectively, in the patient group than in the control group. A negative SSA value usually indicates anteverted LAA. Regression analysis revealed a significant negative correlation between SSA and severity of dislocation. However, no relationship was found between CSA and the severity of dislocation. The multivariate logistic regression analysis revealed that minimum-SSA emerged as an independent predictor of satisfactory reduction (RD ≥ 90%). The ROC curve demonstrated an area under the curve of 0.844, with a cut-off value set at -40.2. CONCLUSION: SSA in patients group was significantly smaller and more asymmetric than that in the control group. Dislocation severity was related to SSA but not to CSA. Minimum-SSA can be used as a predictor of horizontal RD after surgery.

Augmented Reality in Spine Surgery: A Case Study of Atlantoaxial Instrumentation in Os Odontoideum.

Despite advancement in surgical innovation, C1-C2 fixation remains challenging due to risks of screw malposition and vertebral artery (VA) injuries. Traditional image-based navigation, while useful, often demands that surgeons frequently shift their attention to external monitors, potentially causing distractions. In this article, we introduce a microscope-based augmented reality (AR) navigation system that projects both anatomical information and real-time navigation images directly onto the surgical field. In the present case report, we discuss a 37-year-old female who suffered from os odontoideum with C1-C2 subluxation. Employing AR-assisted navigation, the patient underwent the successful posterior instrumentation of C1-C2. The integrated AR system offers direct visualization, potentially minimizing surgical distractions. In our opinion, as AR technology advances, its adoption in surgical practices and education is anticipated to expand.

Autologous rib grafts for craniocervical junction surgery in children: a clinical application.

OBJECTIVE: Autologous iliac bone is commonly used as a bone graft material to achieve solid fusion in craniocervical junction (CVJ) surgery. However, the developing iliac bone of children is less than ideal as a bone graft material. The matured rib bone of children presents a potential substitute material for iliac bone. The aim of this study was to evaluate the efficacy of autologous rib grafts for craniocervical junction surgery in children. METHODS: The outcomes of 10 children with abnormalities of the craniocervical junction who underwent craniocervical junction surgery between January 2020 and December 2022 were retrospectively reviewed. All patients underwent posterior fusion and internal fixation surgery with autologous rib grafts. Pre- and post-operative images were obtained and clinical follow-ups were conducted to evaluate neurological function, pain level, donor site complications, and bone fusion rates. RESULTS: All surgeries were successful. During the 8- to 24-month follow-up period, all patients achieved satisfactory clinical results. Computed tomography at 3-6 months confirmed successful bone fusion and regeneration of the rib defect in all patients with no neurological or donor site complications. CONCLUSION: Autologous rib bone is a safe and effective material for bone grafting in craniocervical junction fusion surgery for children that can reduce the risks of donor site complications and increase the amount of bone graft, thereby achieving a higher bone fusion rate.

Intraoperative Ultrasonography for the Surgical Treatment of Grisel Syndrome of the Adult: Management of A Rare Condition.

STUDY DESIGN: This is a narrative review and case report. OBJECTIVE: To review the literature concerning Grisel syndrome physiopathology, diagnosis, and surgical reports, highlighting the decision-making for treatment and its timing. We describe the role of intraoperative US in the management of 2 cases of GS of the adult. SUMMARY OF BACKGROUND DATA: GS is a rare nontraumatic post inflammatory C1-C2 rotatory instability usually affecting children; adult cases are even rarer, and the role of surgical treatment is not well defined. CASE DISCUSSION: Case 1: A 72-year-old man with upper cervical pain and no neurological deficit; radiologic examination revealed C1-C2 spondylitis and epidural abscess. After antibiotic therapy, the patient developed cervical instability. Hence, surgical decompression and C1-C2 stabilization were performed. Case 2: An 82-year-old woman with progressive right hemiparesis. CT and MRI showed C1-C2 spondylitis with retro-odontoid epidural abscess. Atlanto-axial rotatory instability was evident so surgery was achieved. In both cases, intraoperative US was useful for localizing retro-odontoid abscess and allowing safe puncture of the collection, leading to its remarkable radiologic reduction. CONCLUSION: GS in adults remains a challenge: Patients should be closely monitored concerning neurological and inflammatory status. We describe the successful use of intraoperative US for draining retro-odontoid abscess for the first time, with satisfactory postoperative outcome without need of circumferential approach.

[Expert consensus on posterior facet distraction and fusion technique for the treatment of atlantoaxial dislocation(2024)].

Atlantoaxial dislocation is a common bony structural deformity in the craniovertebral junction area. It can cause severe neurological defects, seriously affect the patient's life quality, and even threaten the patient's life. The most effective treatment for patients with apparent clinically symptoms is surgical treatment. In recent years, with the development of surgical techniques, posterior facet distraction and fusion (PFDF) technique has gradually become an important technique for the treatment of atlantoaxial dislocation. In order to better standardize the diagnosis and treatment of patients with atlantoaxial dislocation and the application of PFDF technique, based on the existing evidence, the Spine and Spinal Cord Group in Neurosurgical Society of Chinese Medical Association and the Chinese Craniovertebral Junction Malformation Research Alliance and Craniovertebral Junction Malformation Alliance of National Center for Neurological Disorders organized experts in relevant fields to fully discuss and formulated the "Expert consensus on posterior facet distraction and fusion technique for the treatment of atlantoaxial dislocation（2024）". This consensus elaborates and recommends the preoperative evaluation, surgical techniques, and management of complications using PFDF technique for the treatment of atlantoaxial dislocation. It is intended to provide guidance for surgeons who encounter problems in the treatment of atlantoaxial dislocation using PFDF technique.

Successful recovery from cardiac arrest due to atlantoaxial subluxation in Down syndrome: a case report.

INTRODUCTION: Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain difficulties in clarifying the cause of death because the manifestations may be quite diverse and involve many organ systems. Atlantoaxial subluxation is a dangerous complication of Down syndrome, as it may lead to cervical cord-medullary compression. CASE PRESENTATION: Herein, we present a case of Down syndrome in a patient who completely recovered from cardiac arrest due to atlantoaxial subluxation. The neck was immobilized during post-cardiac arrest care, and the patient underwent surgery after 14 days. The patient could walk independently and was discharged 3 months later. At the last follow-up 5 years after surgery, the patient's general condition was good. DISCUSSION: Physicians should be aware that atlantoaxial instability can cause cardiac arrest in patients with genetic syndromes.

The C2 isthmus screw provided sufficient biomechanical stability in the setting of atlantoaxial dislocation-a finite element study.

BACKGROUND: The emerging of the C2 isthmus screw fixation technique is gaining popularity in the setting of atlantoaxial dislocation or other conditions requiring fixation of C2. However, the biomechanical stability of this fixation is poorly understood. PURPOSE: To compare and elucidate the biomechanical stability of C2 pedicle screw (C2PS), C2 isthmus screw (C2IS) and C2 short isthmus screw (C2SIS) fixation techniques in atlantoaxial dislocation (AAD). METHOD: A three-dimensional finite element model (FEM) from occiput to C3 was established and validated from a healthy male volunteer. Three FEMs, C1 pedicle screw (PS)-C2PS, C1PS-C2IS, C1PS-C2SIS were also constructed. The range of motion (ROM) and the maximum von Mises stress under flexion, extension, lateral bending and axial rotation loading were analyzed and compared. The pullout strength of the three fixations for C2 was also evaluated. RESULT: C1PS-C2IS model showed the greatest decrease in ROM with flexion, extension, lateral bending and axial rotation. C1PS-C2PS model showed the least ROM reduction under all loading conditions than both C2IS and C2SIS. The C1PS-C2PS model had the largest von Mises stress on the screw under all directions followed by C1PS-C2SIS, and lastly the C1PS-C2IS. Under axial rotation and lateral bending loading, the three models showed the maximum and minimum von Mises stress on the screw respectively. The stress of the three models was mainly located in the connection of the screw and rod. Overall, the maximum screw pullout strength for C2PS, C2IS and C2SIS were 729.41N, 816.62N, 640.54N respectively. CONCLUSION: In patients with atlantoaxial dislocations, the C2IS fixation provided comparable stability, with no significant stress concentration. Furthermore, the C2IS had sufficient pullout strength when compared with C2PS and C2SIS. C2 isthmus screw fixation may be a biomechanically favourable option in cases with AAD. However, future clinical trials are necessary for the evaluation of the clinical outcomes of this technique.

Post-Traumatic Central or Axial Atlantoaxial Dislocation Presenting with "Atypical" Symptoms-Analyzing the Role of Dynamic Imaging on the Basis of Experience with 14 Patients Treated by Atlantoaxial Fixation surgery.

BACKGROUND: This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed. METHODS: Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facet alignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery. RESULT: A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms. CONCLUSIONS: Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma.

Two-level Anterior Cervical Corpectomy and Fusion versus Posterior Open-door Laminoplasty for the Treatment of Cervical Ossification of Posterior Longitudinal Ligament: A Comparison of the Clinical Impact on the Occipito-Atlantoaxial Complex.

OBJECTIVE: Both two-level anterior cervical corpectomy and fusion (t-ACCF) and posterior open-door laminoplasty (ODLP) are effective surgical procedures for the treatment of ossification of the posterior longitudinal ligament (OPLL). Previous studies have identified different effects of different surgical procedures on the upper and subaxial cervical spine (UCS, SCS), however, there are no studies on the effects of t-ACCF and ODLP on the occipito-atlantoaxial complex. Therefore, the purpose of this study is to compare the changes in sagittal parameters and range of motion (ROM) of the occipito-atlantoaxial complex in OPLL patients treated with t-ACCF and ODLP. METHODS: This was a retrospective study that included 74 patients who underwent t-ACCF or ODLP for the treatment of OPLL from January 2012 to August 2022 at our institution. Preoperative, 3-month, and 1-year postoperative cervical neutral, flexion-extension, and lateral flexion radiographs were taken. Sagittal parameters including Cobb angle of C2-7, C0-2, C0-1, C1-2, C2 slope, and the ROM were measured. The clinical outcome was assessed using the JOA, VAS, and NDI scores preoperatively and at 3 and 12 months postoperatively. Multiple linear regression was employed to identify factors influencing changes in UCS. RESULTS: In the ODLP group, the SCS (C2-7) Cobb angle was significantly reduced (12.85 ± 10.0 to 7.68 ± 11.27; p < 0.05), and the UCS (C0-2) Cobb angle was significantly compensated for at 1 year postoperatively compared with the t-ACCF group (3.05 ± 4.09 vs 0.79 ± 2.62; p < 0.01). The SCS and lateral flexion ROM of the ODLP group was better maintained than t-ACCF (14.51 ± 6.00 vs 10.72 ± 3.79; 6.87 ± 4.56 vs 3.81 ± 1.67; p < 0.01). The compensatory increase in C0-2, C0-1, and C1-2 ROM was pronounced in both groups, especially in the ODLP group. The results of multiple linear regression showed that only the surgical procedure was a significant factor influencing UCS. CONCLUSION: The loss of the SCS Cobb angle was more pronounced in ODLP relative to t-ACCF, resulting in a significant compensatory increase in UCS and atlantoaxial Cobb angle. The ROM of the UCS, atlantooccipital, and atlantoaxial joints was significantly increased in both groups, this may accelerate degenerative changes in the occipital-atlantoaxial complex, may leading to poorer outcomes in the long-term; of these, ODLP should receive more attention. In contrast, t-ACCF better maintains normal curvature of the SCS and occipito-atlantoaxial complex but loses more ROM.

[Traumatic posterior atlantoaxial dislocation without fracture of the upper cervical spine in a female geriatric patient : Case report and literature search]. / Traumatische posteriore atlantoaxiale Dislokation ohne Fraktur der oberen Halswirbelsäule bei einer geriatrischen Patientin : Fallbericht und Literaturrecherche.

Traumatic posterior atlantoaxial dislocation (PAAD) without detection of a fracture of the upper cervical spine is a very rare injury that usually occurs in younger patients and in most cases leads to immediate death due to distraction of the spinal cord. In contrast, the present case describes this injury in a female geriatric patient at the age of 75 years. In the literature there are also clinical case reports, where traumatic PAAD without a fracture did not result in neurological deficits and where initially existing neurological deficits were completely reversible through closed or open reduction and internal fixation.

Comparison of iCT-based navigation and fluoroscopic-guidance for atlantoaxial screw placement in 78 patients with traumatic cervical spine injuries.

BACKGROUND CONTEXT: Studies have shown biomechanical superiority of cervical pedicle screw placement over other techniques. However, accurate placement is challenging due to the inherent risk of neurovascular complications. Navigation technology based on intraoperative 3D imaging allows highly accurate screw placement, yet studies specifically investigating screw placement in patients with traumatic atlantoaxial injuries are scarce. The aim of this study was to compare atlantoaxial screw placement as treatment of traumatic instabilities using iCT-based navigation or fluoroscopic-guidance with intraoperative 3D control scans. METHODS: This was a retrospective review of patients with traumatic atlantoaxial injuries treated operatively with dorsal stabilization of C1 and C2. Patients were either assigned to the intraoperative navigation or fluoroscopic-guidance group. Screw accuracy, procedure time, and revisions were compared. RESULTS: Seventy-eight patients were included in this study with 51 patients in the navigation group and 27 patients in the fluoroscopic-guidance group. In total, 312 screws were placed in C1 and C2. Screw accuracy was high in both groups; however, pedicle perforations > 1 mm occurred significantly more often in the fluoroscopic-guidance group (P = 0.02). Procedure time was on average 23 min shorter in the navigation group (P = 0.02). CONCLUSIONS: This study contributes to the available data showing that navigated atlantoaxial screw placement proves to be feasible as well as highly accurate compared to the fluoroscopic-guidance technique without prolonging the time needed for surgery. When comparing these data with other studies, the application of different classification systems for assessment of screw accuracy should be considered.

Posterior atlantoaxial fixation of osteoporotic odontoid fracture: biomechanical analysis of the Magerl versus harms techniques in a cadaver model.

BACKGROUND CONTEXT: Odontoid fractures are among the most common cervical spine fractures in the elderly and are associated with increased morbidity and mortality. Clinical evidence suggests improved survival and quality of life after operative intervention compared to nonoperative treatment. PURPOSE: This study seeks to examine the stability of an osteoporotic Type II odontoid fracture following posterior atlantoaxial fixation with either the Magerl transarticular fixation technique or the Harms C1 lateral mass screws C2 pedicle screw rod fixation. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Eighteen cadaveric specimens extending from the cephalus to C7 were used in this study. Reflective marker arrays were attached to C1 and C2 and a single marker on the dens to measure movement of each during loading with C2-C3 and occiput-C1 being allowed to move freely. A biomechanical testing protocol imparted moments in flexion-extension, axial rotation, and lateral bending while a motion capture system recorded the motions of C1, C2, and the dens. The spines were instrumented with either the Harms fixation (n=9) or Magerl fixation (n=9) techniques, and a simulated Type II odontoid fracture was created. Motions of each instrumented spine were recorded for all moments, and then again after the instrumentation was removed to model the injured, noninstrumented state. RESULTS: Both Harms and Magerl posterior C1-C2 fixation allowed for C1, C2, and the dens to move as a relative unit. Without fixation the dens motion was coupled with C1. No significant differences were found in X, Y, Z translation motion of the dens, C1 or C2 during neutral zone motions between the Magerl and Harms fixation techniques. There were no significant differences found in Euler angle motion between the two techniques in either flexion-extension, axial rotation, or lateral bending motion. CONCLUSIONS: Our findings suggest that both Harms and Magerl fixation can significantly reduce dens motion in Type II odontoid fractures in an osteoporotic cadaveric bone model. CLINICAL SIGNIFICANCE: Both Harms and Magerl posterior atlantoaxial fixation techniques allowed for C1, C2, and the dens to move as a relative unit following odontoid fracture, establishing more anatomic stability to the upper cervical spine.

Atlantoaxial joint stabilization using patient-specific 3-D-printed drill guides and 3-D-printed titanium plates or polymethyl methacrylate is effective in toy-breed dogs.

OBJECTIVE: To report the clinical outcomes in toy-breed dogs with atlantoaxial instability (AAI) stabilized with patient-specific 3-D-printed titanium plates or polymethyl methacrylate (PMMA), both with the assistance of 3-D-printed drill guides. ANIMALS: 15 client-owned dogs undergoing surgical treatment for AAI between January 1, 2020, and October 31, 2022. METHODS: The clinical characteristics, diagnostic images, and neurological outcomes of 15 dogs treated for AAI using 3-D-printing technology were reviewed. Postoperative CT images were examined to evaluate the screw placement accuracy in the atlas and axis. Clinical outcomes, including postoperative neurological improvement and screw loosening, were evaluated in dogs treated with a patient-specific titanium plate and those treated with PMMA. RESULTS: Patient-specific titanium plates (7 dogs) and PMMA (8 dogs) were used for AAI stabilization. The mean follow-up period was 15.2 months (range 7 to 22 months). A reduction of the axis without vertebral canal violation was confirmed on postoperative CT in 14 dogs. The mean deviation from the preoperative planning ranged from 0.30 to 1.27 mm at the insertion and exit points of 84 screws using this method. The neurological grade had improved in each dog postoperatively and at the final follow-up. Screw loosening was noted in 4 dogs in the titanium plates groups without neurological deterioration. CLINICAL RELEVANCE: Patient-specific 3-D-printed drill guides and titanium plates or PMMA are effective for AAI stabilization in toy-breed dogs, providing accurate guidance.

A new etiology of nontraumatic C0-C1-C2-Complex instability - abnormality of musculus rectus capitis posterior minor: a case report.

PURPOSE: This study presents an abnormality of the musculus rectus capitis posterior minor (RCPmi) as a new etiological factor for nontraumatic sagittal plane instability in the C0-C1-C2-complex, with a focus on identifying the absence or atrophy of RCPmi on both sides. METHODS: A 36-year-old male patient presented with recurring neck pain (VAS 8/10) and tingling paresthesia in the entire left hand over a six-month period, without significant neurological deficits. Radiated arm pain was not reported. Imaging examinations revealed sagittal plane instability in the C0-C1-C2-complex, spinal canal stenosis (SCS), and myelopathy at the C1 level. Subsequently, a dorsal C0-1 reposition and fusion with laminectomy were performed. RESULTS: The congenital absence or atrophy of RCPmi, leading to the lack of cephalad-rearward traction on the C1-tuberculum-posterius, induced a developmental failure of the C1 posterior arch. Consequently, the oblate-shaped C1 posterior arch lost support from the underlying C2 posterior arch and the necessary cephalad-rearward traction throughout the patient's 36-year life. This gradual loss of support and traction caused the C1 posterior arch to shift gradually to the anterior side of the C2 posterior arch, resulting in a rotational subluxation centered on the C0/1 joints in the sagittal plane. Ultimately, this led to SCS and myelopathy. Traumatic factors were ruled out from birth to the present, and typical degenerative changes were not found in the upper cervical spine, neck muscles, and ligaments. CONCLUSION: In this case, we not only report the atrophy or absence of RCPmi as a new etiological factor for nontraumatic sagittal plane instability in the C0-C1-C2-complex but also discovered a new function of RCPmi. The cephalad-rearward traction exerted by RCPmi on the C1 posterior arch is essential for the development of a normal C1 anterior-posterior diameter.

Posterior intra-articular distraction technique to treat pediatric atlantoaxial instability.

PURPOSE: Surgical treatment for atlantoaxial instability in pediatric patients is challenging. We report our experience with posterior intra-articular distraction technique in treating this disorder. METHODS: This is a retrospective descriptive study which included 15 patients of atlantoaxial instability whose age was less than 16 years at the time of clinical presentation. All patients underwent anterior soft tissue released through a posterior-only approach, followed by intra-facet cage implantation, cantilever correction, and instrumentation. Clinical results were measured using the Japanese Orthopedic Association (JOA) scale and radiographic measurements including the atlantodental interval (ADI), posterior atlantodental interval (pADI), the distance of odontoid tip above Chamberlain's line, clivuscanal angle (CCA), and triangular area (TA) of craniovertebral junction. RESULTS: The follow-up period ranged from 18 to 72 months, with an average of 41.2 ± 15.2 months. The JOA score increased from 13.6 ± 2.3 to 16.6 ± 0.8. ADI decreased from 4.31 ± 2.37 to 1.85 ± 1.09 mm, and TA decreased from 261.96 ± 107.99 to 197.12 ± 72.37 mm2. pADI increased from 12.89 ± 3.52 to 18.25 ± 3.89 mm, and CCA improved from 132.19 ± 16.34 to 144.35 ± 13.91°. All changes in measurements showed statistically significant. There were no evidence of surgery-related complications or iatrogenic secondary cervical deformity during follow-up. Radiological evaluation showed satisfactory corrections and bony fusions of C1-2 facet joint in all cases. CONCLUSION: Posterior intra-articular distraction followed by cage implantation and cantilever correction can be one of the safe and effective ways to solve atlantoaxial instability in pediatric patients.

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

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

Unilateral Biplanar Screw-Rod Fixation Technique for the Treatment of Odontoid Fractures in Patients with Atlantoaxial Bone or Vascular Abnormalities.

OBJETIVE: This study aims to introduce the unilateral biplanar screw-rod fixation (UBSF) technique (a hybrid fixation technique: 2 sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures. METHODS: Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and computerized tomography scans were conducted and reviewed at 1 day, and patients were asked to return for computerized tomography reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index presurgery and at 1 week and 12 months postsurgery. RESULTS: Between January 2016 and December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck Visual Analog Scale and Neck Disability Index scores improved significantly at 1 week and 12 months postoperative (P < 0.01). CONCLUSIONS: The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation.