Odontoid Fracture with Locked Posterolateral Atlantoaxial Dislocation: A Case Report and Review of Literature.

CASE: Odontoid fractures with atlantoaxial dislocations are rare injuries. We report a case of a 41-year-old man with a Type 2 odontoid fracture with locket facet and posterolateral dislocation. He underwent single-stage C1-C4 posterior fixation and fusion, and at 2-year follow-up, he is symptom-free without any residual pain. Follow-up radiograph and CT scan show healed odontoid fracture with posterior fusion. CONCLUSION: This case highlights successful management of a complex odontoid fracture by a single-stage posterior surgery. Closed reduction is usually unsuccessful, and open reduction using posterior approach is preferable.

Acute Neck Pain from Crowned Dens Syndrome: A Case Report and Clinical Insights.

BACKGROUND Crowned dens syndrome (CDS) is a rare condition characterized by deposition of calcium pyrophosphate crystals on the odontoid process of the second cervical vertebra, forming a calcified 'crown', with neck pain being a common symptom. The disorder exhibits unique clinical and radiological features, resembling manifestations of meningitis, such as acute headaches and cervical stiffness. There are few case reports and case series related to CDS. Patients generally respond well to treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), although there is a certain rate of recurrence. Since there are few reports of CDS, we sought to publish this case report, aiming of increasing clinicians' awareness and reducing misdiagnosis rates. CASE REPORT A 62-year-old man presented to the Emergency Department with "cutting-like" headaches and neck pain for 2 days, and was subsequently diagnosed with CDS by cervical computed tomography (CT) scan, and hematological tests revealed inflammatory manifestations. He was advised to take oral nonsteroidal anti-inflammatory drugs and to rest; his symptoms improved after 3 days and his neck pain had almost resolved after 2 months. CONCLUSIONS In older patients experiencing new headaches and neck pain, along with increased inflammatory markers, particularly those with a history of pseudogout, the possibility of CDS should be considered. Case reports suggest that oral NSAIDs and short courses of corticosteroids can generally alleviate symptoms. Further research is needed on CDS diagnosis and treatment.

Surgical versus conservative treatment for odontoid fractures in older people: an international prospective comparative study.

BACKGROUND: The optimal treatment for odontoid fractures in older people remains debated. Odontoid fractures are increasingly relevant to clinical practice due to ageing of the population. METHODS: An international prospective comparative study was conducted in fifteen European centres, involving patients aged ≥55 years with type II/III odontoid fractures. The surgeon and patient jointly decided on the applied treatment. Surgical and conservative treatments were compared. Primary outcomes were Neck Disability Index (NDI) improvement, fracture union and stability at 52 weeks. Secondary outcomes were Visual Analogue Scale neck pain, Likert patient-perceived recovery and EuroQol-5D-3L at 52 weeks. Subgroup analyses considered age, type II and displaced fractures. Multivariable regression analyses adjusted for age, gender and fracture characteristics. RESULTS: The study included 276 patients, of which 144 (52%) were treated surgically and 132 (48%) conservatively (mean (SD) age 77.3 (9.1) vs. 76.6 (9.7), P = 0.56). NDI improvement was largely similar between surgical and conservative treatments (mean (SE) -11 (2.4) vs. -14 (1.8), P = 0.08), as were union (86% vs. 78%, aOR 2.3, 95% CI 0.97-5.7) and stability (99% vs. 98%, aOR NA). NDI improvement did not differ between patients with union and persistent non-union (mean (SE) -13 (2.0) vs. -12 (2.8), P = 0.78). There was no difference for any of the secondary outcomes or subgroups. CONCLUSIONS: Clinical outcome and fracture healing at 52 weeks were similar between treatments. Clinical outcome and fracture union were not associated. Treatments should prioritize favourable clinical over radiological outcomes.

Redefining Diagnostic Criteria for Basilar Invagination Using Linear Craniometric Parameters.

AIM: To establish the diagnosis of basilar invagination (BI) on the basis of specific bony landmarks Klaus' index (KI), perpendicular distance between the tip of the odontoid process and palato internal occipital protuberance (PI) line. MATERIAL AND METHODS: Forty-nine patients were analysed, who underwent surgery for BI, between July 2020 and June 2023. Radiological assessment was done in all the patients using reconstructed midsagittal images on computed tomography scans . RESULTS: Mean age was 34.82 ± 10.52 years with male preponderance (67.35%) in patients with BI. We also analysed randomly selected 120 control subjects (male: female = 59:61) with mean age 43.5 ± 14.08 years. The mean distance of tip of the odontoid process from PI line in patients with BI was 3.39 ± 3.09 mm. The mean value of KI in the patients with BI was 28.57 ± 1.68 mm. Receiver operating characteristic (ROC)curve was used for analysing the distance of the tip of the odontoid process from PI line in the patients with BI which produced area under curve( AUC) of 0.97 (confidence interval [CI] -0.931 to 0.990, p < 0.0001). Cut-off point of 7.5 mm was identified for the distance of tip of odontoid process from PI line with sensitivity of 89.8% and specificity of 97.5% having 95.27% diagnostic accuracy for BI. ROC curve analysis of value of KI for the diagnosis of BI produced AUC of 1( CI: 0.978 to 1.000, p < 0.0001). Cut-off value of 33.2 mm for KI was identified for diagnosing BI with 100% accuracy. CONCLUSION: The distance of tip of the odontoid process from PI line < 7.5 mm and value of KI < 33.2 mm, both of these parameters can diagnose BI with comparable accuracy to most widely used conventional radiological methods.

Crowned Dens Syndrome-Pseudogout of the Neck.

This is a case report of a patient who presented with neck pain and intermittent pyrexia as a manifestation of pseudogout of the neck.

A Staged Approach for Surgical Management of Basilar Invagination.

BACKGROUND AND OBJECTIVES: Patients with basilar invagination (BI) can be treated with several surgical options, ranging from simple posterior decompression to circumferential decompression and fusion. Here, we aimed at examining the indications and outcomes associated with these surgical strategies to devise a staged algorithm for managing BI. METHODS: We conducted a retrospective cohort study in 2 neurosurgical centers and included patients with a BI, as defined by a position of the dens tip at least 5 mm above the Chamberlain line. Other craniovertebral junction anomalies, such as atlas assimilation, platybasia, and Chiari malformations, were documented. C1-C2 stability was assessed with a dynamic computed tomography scan. RESULTS: We included 30 patients with BI with a mean follow-up of 56 months (min = 12, max = 166). Posterior decompression and fusion (n = 8) was only performed in cases of obvious atlanto-axial instability (eg, increased atlanto-dental interval or hypermobility on flexion/extension), while anterior decompression (transoral or transnasal) was reserved to patients with lower cranial nerves deficits (eg, swallowing dysfunction) and irreducible anterior compression (n = 9). Patients with posterior signs (eg, Valsalva headaches) or myelopathy but without C1-C2 instability nor anterior signs were managed with an isolated foramen magnum decompression, with or without duraplasty (n = 13). Complications were more frequent for combined procedures, including neurological deterioriation (n = 4) and tracheostomy (n = 2), but reinterventions were more likely in patients undergoing posterior decompression alone (n = 3). CONCLUSION: Patient selection is key to determine the appropriate surgical strategy for BI: In our experience, combined approaches are only needed for patients with irreducible and symptomatic anterior compression, while fusion should be restricted to patient with obvious signs of atlanto-axial instability. Other BI patients can be managed by foramen magnum decompression alone to minimize surgical morbidity.

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.

Circumferential Pannus at C1-C2 Causing Spinal Cord Compression.

Periodontoid pannus formation is a pathologic condition caused by a multitude of different etiologies, however, it is most commonly due to rheumatoid arthritis. In these cases, the pannus is typically located in the retro-odontoid space ventral to the spinal cord, leading to progressive neural compression. We describe in this report, a patient who presented with progressive high cervical myelopathy, who on imaging revealed both a retro-odontoid pannus and a posterior C1-C2 mass causing severe circumferential compression of the spinal cord. The patient was successfully treated with a C1-C2 laminectomy and occipitocervical fusion. Periodontoid pannus is a common entity; however, the presence of a C1-C2 posterior pannus is a unique finding. To our knowledge, circumferential pannus at C1-C2 causing neural compression is a clinical entity that has not been previously reported.

Short-term and long-term results of odontoid screw fixation in patients with Type II and rostral Type III dens fractures.

OBJECTIVES: To evaluate both the short-term and long-term outcomes of odontoid screw fixation (OSF), identifying potential risk factors for implant-related complications in patients with odontoid fractures. METHODS: This is a retrospective observational cohort study. Inclusion criteria were as follows: 1) Type II fractures and rostral Type III fractures, according to the Anderson and D'Alonzo classification; 2) patients older than 15 years. Exclusion criteria were: 1) other Type III injuries; 2) osteoporosis confirmed by densitometry or a CT bone density score below 100 Hounsfield units; 3) odontoid fractures related to tumors or aneurysmal bone cysts. RESULTS: In total, 56 patients were considered for the analysis of short-term results, and 26 patients were evaluated for long-term outcomes. No significant differences were observed in the preoperative imaging data and intraoperative features of OSF between patients with Type II and rostral Type III fractures. The mean operative duration was 63.9 ± 20.9 min, and the mean intraoperative blood loss was 22.1 ± 22.9 ml. Screw cut-out was identified in four patients with rostral Type III fractures (p = 0.04). The rate of screw cut-out was found to correlate with the degree of dens fragment displacement. The bone fusion rate was 95.7%. CT scans identified stable pseudarthrosis in two cases. We observed C2-C3 ankylosis in all cases following partial disc resection. One third of patients with screws placed through the anterior lip of C2 showed no C2-C3 ankylosis. A strong trend towards lateral joint ankylosis formation in patients with a median lateral mass dislocation of 11.9 mm was observed. Most SF-36 scores either matched or exceeded the corresponding normal median values in the published reference database. CONCLUSIONS: OSF is a reliable treatment method of Type II and rostral Type III odontoid fractures with fragment displacement of 4 mm or less. The minimally invasive OSF through the anterior-inferior lip of C2, using monocortical screw placement and cannulated instruments, without rigid intraoperative head immobilization, is sufficient to achieve favorable clinical and fusion results. This technique reduces the risk of ankylosis in the C2-C3 segment. OSF restore the quality of life for patients with odontoid fractures to levels comparable to those of the general population norm.

Posterolateral Paramass Approach to Lesions Located at the Anterior C1-2 Level: A Cadaver Study.

OBJECTIVE: A novel posteriolateral surgical approach is described that will provide safe access to intradural and extradural lesions located in the anterior part of the spinal cord (SC) at the C1-2 level and to the odontoid in single session. METHODS: A total of five cadavers and two dry C1 vertebrae were used in this study. The study involved obtaining computed tomography magnetic resonance imaging scans and magnetic resonance imaging of all cadaver groups before and after the procedures. Group 1: Control; Group 2: Unilateral C1 posterior arch was removed, the inferomedial part of C1 lateral mass was removed, and access the anterior and lateral aspects of the SC. Group 3: In addition, odontoid was removed, Group 4: In addition, unilateral C1- C2 screw was placed. Group 5: In addition, bilateral C1-C2 screw was placed. RESULTS: The median distance from the midpoint of C1 posterior tubercle to vertebral groove which was removed in groups is 21.4 ± 2.88 mm. The average width of C1 lateral mass was 13.4±2.4 mm. After the lateral mass was drilled, its width decreased to 10,2 mm.This area was sufficient to open a surgical corridor and reach the anterior of SC and odontoid. After the procedure, no instability was found in group 2 without instrumentation on computed tomography and magnetic resonance imaging scans. CONCLUSIONS: It is possible to access the anterior C1-C2 via a posterolateral paramass approach by drilling 20%-30% of the lateral mass, providing an open pathway for easy intervention in C1-C2 intradural lesions. It is also possible to perform odontoid resection using this approach.

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.

Evaluation of Craniometric Parameters and Efficacy of Posterior Surgical Intervention Types in Basilar Invagination Patients.

OBJECTIVE: Basilar invagination is one of the most frequently observed abnormalities at the craniovertebral junction, in which the odontoid process of C2 prolapses into the foramen magnum. METHODS: The current study included 27 patients who underwent surgery for basilar invagination between October 2013 and January 2023. The study group was divided into 2 groups according to basilar invagination types; type I (the presence of type A atlantoaxial instability and instability is the main pathology) and type II (the presence of type B and C atlantoaxial instability and skull base dysgenesis is the main pathology). Craniometric parameters included in the study were atlantodental interval, posterior atlantodental interval, Chamberlain's line violation, clivus-canal angle, Welcher's basal angle, and Boogaard angle. RESULTS: The mean age of the patients was 24.30 ± 14.36 years (5-57 years). Fourteen patients (51.9%) were female, and 13 patients (48.1%) were male. Ten patients (37%) had type I basilar invagination, and 17 patients (63%) had type II basilar invagination. Preoperative and postoperative atlantodental interval and Boogaard angle were significantly higher in type I basilar invagination, as preoperative and postoperative posterior atlantodental interval and clivus-canal angle were significantly higher in type II basilar invagination. There was a positive strong correlation between Chamberlain's line violation and Boogaard angle. Postoperative Chamberlain's line violation was significantly higher in occipitocervical fixation (P = 0.035). C1 lateral mass screw fixation was found more successful in Chamberlain's line violation correction than occipital plates. Occipitocervical fixation was found to be associated with higher postoperative Nurick scores (P = 0.015) and complication rates (P = 0.020). Cages applied to the C1-C2 joint space were found to be associated with higher fusion rates (P = 0.023) and lower complication rates (P = 0.024). CONCLUSIONS: In the present study, it was found that C1-C2 fixation was more successful in correcting craniometric parameters and had lower complication rates than occipitocervical fixation. In appropriate patients, it was determined that cage application increased the success rates of the operations.

Dens Growth After Surgical Fixation in Children with Morquio-Brailsford Disease.

Mucopolysaccharidosis type IVA is a lysosomal storage disorder caused by a deficiency of the enzyme N-acetyl-galactosamine-6-sulphate sulphatase. Mucopolysaccharidosis type IVA is multisystemic disease with significant spinal involvement and atlantoaxial instability leading to neural compression and significant morbidity. Dens hypoplasia is a common feature of this condition. In this study we demonstrate that after spinal fixation, there is new growth of dens in significant proportion of patients, suggesting atlantoaxial instability as one of the major driving forces of lack of development of dens in this condition.

Odontoid/Dens Fractures.

Odontoid fractures remain the most common C2 fracture and of those individuals older than 65 years. The type of optimal management remains in question given comorbidities, risk of nonunion, and limitations in mobility when surgical fusion is the treatment selected. These fractures are of particular importance, given the high incident of morbidity and mortality following an odontoid fracture. Overall quality of life remains a significant consideration when selecting the best intervention following careful examination and confirmation with radiographic imaging. The literature continues with controversies in the best treatment interventions for these fractures, resulting in a case-by-case decision-making process.

Odontoid incidence: a constant cervical anatomical feature evident in standing plain radiographs and supine magnetic resonance images.

OBJECTIVE: To assess whether there is a difference between measurements of odontoid incidence (OI) and other cervical sagittal parameters by X-ray radiography and those by supine magnetic resonance imaging (MRI). METHODS: Standing X-ray and supine MRI images of 42 healthy subjects were retrospectively analyzed. Surgimap software was employed to measure cervical sagittal parameters including OI, odontoid tilt (OT), C2 slope (C2S), C0-2 angle, C2-7 angle, T1 slope (T1S) and T1S-cervical lordosis (CL). Paired samples t-test was applied to determine the difference between parameters measured by standing X-ray and those by supine MRI. In addition, the statistical correlation between the parameters were compared. The prediction of CL was performed and validated using the formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S. RESULTS: Significant correlations and differences were found between cervical sagittal parameters determined by X-ray and those by MRI. OI was verified to be a constant anatomic parameter and the formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S can be used to predict CL in cervical sagittal parameters. CONCLUSIONS: OI is verified as a constant anatomic parameter, demonstrating the necessity of a combined assessment of cervical sagittal balance by using standing X-ray and supine MRI. The formula CL = 0.36 × OI - 0.67 × OT - 0.69 × T1S can be applied to predict CL in cervical sagittal parameters.

Imaging Characteristics of Nonrheumatoid Arthritis Patients With Retro-odontoid Pseudotumor: A Multicenter Case-control Study.

STUDY DESIGN: Multicenter case-control study. OBJECTIVE: To identify imaging characteristics of the cervical spine in patients with retro-odontoid pseudotumor (ROP) without rheumatoid arthritis (RA) and determine the pathogenesis of ROP. BACKGROUND: ROP results from proliferative changes in the soft tissue of the atlantoaxial junction surrounding the region of the transverse ligament, and is commonly seen in RA patients. However, the pathogenesis of ROP caused by mechanical instability of the upper cervical spine in patients without RA is yet to be explained. MATERIALS AND METHODS: We collected imaging data [preoperative radiographs, magnetic resonance imaging (MRI), and computed tomography (CT)] of patients who underwent surgery between April 2011 and March 2022 at the three university hospitals for ROP (cases) and cervical spondylotic myelopathy (as age, sex, and institution matched controls). The two groups were compared for different parameters on cervical dynamic radiographs, MRI, and CT. RESULTS: The ROP group consisted of 42 patients, and the control group comprised 168 patients. C2-C7 range of motion was significantly smaller in the ROP group (25.8 ± 2.6°) compared with the control group (33.0 ± 1.0°). C2-C7 sagittal vertical axis was significantly larger in the ROP group than the control group (39.3 ± 3.6 vs. 32.2 ± 1.3 mm). MRI and CT assessment showed progressive degeneration at all intervertebral levels in the ROP group. A significant positive correlation was observed between the thickness of the soft tissue posterior to the dental process and the atlantodental interval in the flexion position ( r = 0.501). CONCLUSIONS: The development of ROP was associated with degeneration of facet joints and intervertebral disks in the middle and lower cervical spine. Our findings suggest that decreased mobility of the middle and lower cervical spine may cause instability in the upper cervical spine, leading to the formation of ROP.

Combined Anterior Odontoid Screw Fixation and C1-C2 Jefferson Fracture Anterior Fixation: A Step-by-Step Technical Note.

BACKGROUND: Combined triple atlas (C1)-axis (C2) fixation has been described in previous literature as a safe, effective, and minimally invasive procedure for complex atlas and odontoid fractures that allows for a greater range of motion compared with posterior approaches and atlanto-occipital fusion. However, it is rarely performed due to the occipital-cervical diastasis resulting from often-fractured C1 joint masses. No evidence-based consensus has been reached regarding the treatment of complex atlantoaxial fractures, and the choice of surgical strategy is based only on clinical experience. METHODS: We report the combined triple C1-C2 fixation technique with manual reduction of the joint masses during patient positioning on the operating table, which allowed for effective stabilization during a single surgical session. We describe our experience in the management of a 75-year-old patient presenting with an acute complex type II fracture of C1, which also involved 1 lateral mass, combined with a type II odontoid fracture and occipital-cervical diastasis. RESULTS: We provide a step-by-step guide for combined triple C1-C2 anterior fixation with manual fracture reduction and describe the clinical case of an acute complex type II fracture of C1, which also involved 1 lateral mass, combined with a type II odontoid fracture and occipital-cervical diastasis. CONCLUSIONS: Combined triple C1-C2 fixation represents a safe and efficient minimally invasive anterior approach for complex type II fractures of C1 with type II odontoid fractures. Manual reduction of the joint masses during patient positioning allows for effective stabilization in a single surgical session.