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.

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.

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.

Os odontoideum and craniovertebral junction instability secondary to dystonia: case series and review of the literature.

INTRODUCTION: Os odontoideum refers to a rounded ossicle detached from a hypoplastic odontoid process at the body of the axis. The aetiology has been debated and believed to be either congenital or acquired (resulting from trauma). Os odontoideum results in incompetence of the transverse ligament and thus predisposes to atlantoaxial instability and spinal cord injury. METHODS/RESULTS: Three cases of children with severe dystonic cerebral palsy presenting with myelopathic deterioration secondary to atlantoaxial instability due to os odontoideum are presented. This observation supports the hypothesis of os odontoideum being an acquired phenomenon, secondary to chronic excessive movement with damage to the developing odontoid process. CONCLUSION: In children with cerebral palsy and dystonia, pre-existing motor deficits may conceal an evolving myelopathy and result in delayed diagnosis of clinically significant atlantoaxial subluxation.

Development of a Predictive Model for Persistent Instability Following Conservative Management of Type II Odontoid Fractures.

BACKGROUND: Odontoid fractures are common cervical spine fractures; however, significant controversy exists regarding their treatment. Risk factors for failure of conservative therapy have been identified, although no predictive risk score has been developed to aid in decision-making. METHODS: A retrospective review was conducted of all patients evaluated at a level 1 trauma center. Patients identified with type II odontoid fractures as classified by the D'Alonzo Classification system who were treated with external orthosis were included in analysis. Patients were considered to have failed conservative therapy if they were offered surgical intervention. A machine learning method (Risk-SLIM) was then utilized to create a risk stratification score based on risk factors to identify patients at high risk for requiring surgical intervention due to persistent instability. RESULTS: A total of 138 patients were identified as presenting with type II odontoid fractures that were treated conservatively; 38 patients were offered surgery for persistent instability. The Odontoid Fracture Predictive Model (OFPM) was created using a machine learning algorithm with a 5-fold cross validation area under the curve of 0.7389 (95% CI: 0.671 to 0.808). Predictive factors were found to include fracture displacement, displacement greater than 5 mm, comminution at the fracture base, and history of smoking. The probability of persistent instability was <5% with a score of 0 and 88% with a score of 5. CONCLUSIONS: The OFPM model is a unique, quick, and accurate tool to assist in clinical decision-making in patients with type II odontoid fractures. External validation is necessary to evaluate the validity of these findings.

Feasibility of Two-Screw Anterior Fixation for Odontoid Fractures in a Chinese Population: A Morphometric Study Based on Computed Tomography.

Background: To evaluate the feasibility of treating odontoid fractures in the Chinese population with two cortical screws based on computed tomography (CT) scans and describe a new measurement strategy to guide screw insertion in treating these fractures. Methods: A retrospective review of cervical computed tomographic scans of 128 patients (aged 18-76 years; men, 55 [43.0%]) was performed. The minimum external transverse diameter (METD), minimum external anteroposterior diameter (MEAD), maximum screw length (MSL), and screw projection back angle (SPBA) of the odontoid process were measured on coronal and sagittal CT images. Results: The mean values of METD and MEAD were 10.0 ± 1.1 mm and 12.0 ± 1.0 mm, respectively, in men and 9.2 ± 1.0 mm and 11.0 ± 1.0 mm, respectively, in women. Both measurements were significantly higher in men (p < 0.001). In total, 87 individuals (68%) had METD > 9.0 mm that could accommodate two 3.5-mm cortical screws. The mean MSL value and SPBA range were 34.4 ± 2.9 mm and 13.5°-24.2°, respectively, with no statistically significant difference between men and women. Conclusions: The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fractures in 87 patients (68%) in our study, and there was a statistically significant difference between men and women.

Neuronavigated Retropharyngeal Anterior Screw Fixation of the Odontoid for the Treatment of C2 Type II Fractures: Case Report.

Odontoid fractures, frequently observed in patients over the age of 70, often involve the base of the axis (Anderson-D'Alonzo type 2). For surgical treatment, posterior C1-C2 fixation is the traditional method, whose fusion rates range between 93 and 100%. However, morbidity and mortality rates are high. In addition, cervical motion, especially axial rotation, is postoperatively reduced. Nakanishi and Bohler introduced the anterior screw fixation approach for the surgical treatment of odontoid fracture type II. This procedure preserves the atlantoaxial complex motion, provides immediate stability and high fracture healing rates, and, most importantly, has a low incidence of complications with good fusion rates. The surgical strategy must take into account the patient's anatomy, the morphological characteristics of the fracture, the quality of the bone, and any concomitant injuries. In this chapter, we describe a C2 type II fracture treated via a neuronavigated anterior retropharyngeal approach.

Odontoid fracture in geriatric patients - analysis of complications and outcome following conservative treatment vs. ventral and dorsal surgery.

BACKGROUND: Different treatment options are discussed for geriatric odontoid fracture. The aim of this study was to compare the treatment options for geriatric odontoid fractures. METHODS: Included were patients with the following criteria: age ≥ 65 years, identification of seniors at risk (ISAR score ≥ 2), and odontoid fracture type A/B according to Eysel and Roosen. Three groups were compared: conservative treatment, surgical therapy with ventral screw osteosynthesis or dorsal instrumentation. At a follow-up examination, the range of motion and the trabecular bone fracture healing rate were evaluated. Furthermore, demographic patient data, neurological status, length of stay at the hospital and at the intensive care unit (ICU) as well as the duration of surgery and occurring complications were analyzed. RESULTS: A total of 72 patients were included and 43 patients could be re-examined (range: 2.7 ± 2.1 months). Patients with dorsal instrumentation had a better rotation. Other directions of motion were not significantly different. The trabecular bone fracture healing rate was 78.6%. The patients with dorsal instrumentation were hospitalized significantly longer; however, their duration at the ICU was shortest. There was no significant difference in complications. CONCLUSION: Geriatric patients with odontoid fracture require individual treatment planning. Dorsal instrumentation may offer some advantages.

C2 Odontoid Fracture Associated with C1-C2 Rotatory Dislocation: A Retrospective Analysis of 2 Surgical Techniques.

BACKGROUND: Odontoid fractures in association with a C1-C2 rotatory luxation reports are seldom found in the literature. The fusion between the lateral mass of C1 and C2 could be of interest to ensure adequate treatment in these particular cases. We report 23 cases where there was coexistence of an odontoid fracture and rotatory subluxation, which were treated surgically using cages between C1 and C2 or just traditional Goel-Harms technique. We evaluated the radiologic fusion rate, reoperation rate, and complications. METHODS: This was a single-center, retrospective, cohort study of patients with C2 fractures (mixed type and C1-C2 rotatory luxation according to the Fielding classification) who were treated surgically. Radiologic computed tomography scans were used to assess fusion (presence of bridging trabecular bone end plate or pseudoarthrosis) between 6 months and 1.5 years after the surgery. RESULTS: Twenty-three patients were diagnosed with C2 fractures and C1-C2 rotatory luxation that were treated surgically and were suitable for the analysis; 11 patients underwent C1-C2 fusion with intra-articular cages, and 12 underwent a classical Goel-Harms technique. The fusion rate at the C1-C2 joint was higher in the cages group. Only 12 patients exhibited fusion at the level of the odontoid fracture. CONCLUSIONS: C2 fractures associated with C1-C2 rotatory dislocation are rare. The fusion rate at the level of the odontoid in these patients appears to be lower than that reported in patients without rotatory dislocation. It may be of special interest to obtain a clear fusion at the C1-C2 joint, where this type of implant seems to offer an advantage.

Comparative Study of Surgical Outcomes of Occipitocervical and Atlantoaxial Fusion for Retro-Odontoid Pseudotumor.

OBJECTIVE: To compare the surgical and radiographic outcomes of occipitocervical fusion (OCF) with those of atlantoaxial fusion (AAF) in patients with cervical myelopathy caused by retroodontoid pseudotumors (ROPs). METHODS: This retrospective, comparative study included 26 patients; 12 underwent occipitocervical fusion (OCF) (group O) and 14 retroodontoid pseudotumor (AAF) (group A) with a minimum 2-year follow-up. Neurologic outcomes were evaluated using the Japanese Orthopedic Association (JOA) score. Radiologic assessment included the maximum anteroposterior (AP) diameter of the anteroposterior-retroodontoid pseudotumor (AP-ROP), C2-7 angle, O-C2 angle, C1-2 angle, atlantodental interval (ADI), range of motion (ROM) of the ADI, C2-C7 sagittal vertical axis (C2-7 SVA), and T1 slope. Global spinal alignments (pelvic incidence [PI] minus lumbar lordosis [LL] [PI-LL], pelvic tilt, sacral slope, and C7 sagittal vertical axis) were also compared between the groups. RESULTS: Both groups had equally good clinical outcomes with equal complication rates. Three patients had a three-level fusion, 5 cases had a four-level fusion, and 4 cases had more than five-level fusion in group O. All cases had a single-level fusion in group A. Surgical time was significantly shorter in group A. AP-ROP was significantly downsized postoperatively in both groups and was more prominent in group O. C2-7 SVA was significantly increased and C2-7A ROM was significantly reduced in group O at the final follow-up. The PI-LL showed a significant increase in group O at the final follow-up. CONCLUSIONS: Although OCF and AAF were similarly effective for cervical myelopathy with ROP, AAF was less invasive, and spinal alignment was better maintained postoperatively in AAF than OCF.

Type II Odontoid Fractures: Is the Anterior Screw a Good Solution for all Patients? A Case Series of 60 Consecutive Patients.

OBJECTIVE: Type II odontoid fracture is the most common fracture type, and its treatment remains challenging. The objective of this study was to evaluate the results of anterior screw fixation for type II odontoid fractures in patients aged over and below 60 years. METHODS: A retrospective analysis of consecutive patients diagnosed with type II odontoid fractures who were surgically treated using the anterior approach by a single surgeon was conducted. Demographic characteristics, including age, sex, type of fracture, time from trauma to surgery, length of stay (LoS), fusion rate, complications, and reoperation, were evaluated. Surgical outcomes were compared between patients over and below 60 years of age. RESULTS: Sixty consecutive patients underwent odontoid anterior fixation during the analysis period. The mean age of patients was 49.58 ± 23.22 years. Twenty-three (38.3%) patients were aged over 60 years, and the minimum follow-up period was two years. Of the patients, 93.3% developed bone fusion, which was observed in 86.9% of patients over 60 years. Complications related to hardware failure occurred in six (10%) patients. Transient dysphagia was observed in 10% of the cases. Three (5%) patients required reoperation. Patients over 60 years had a significantly increased risk of dysphagia compared with those below 60 years (P = 0.0248). There was no significant difference between the groups regarding nonfusion rate, reoperation rate, or LoS. CONCLUSIONS: Anterior fixation of the odontoid showed high fusion rates with a low rate of complications. It is a technique to be considered for treating type II odontoid fractures in selected cases.

[Minimally invasive surgery for invaginated CII odontoid process]. / Miniinvazivnaya khirurgiya invaginirovannogo zubovidnogo otrostka CII pozvonka.

Odontoidectomy is indicated for anterior compression of the brainstem by invaginated odontoid process. This procedure can currently be performed via transoral microsurgical and transnasal endoscopic access. OBJECTIVE: To analyze the results of endoscopic transnasal odontoidectomy. MATERIAL AND METHODS: We assessed treatment outcomes in 10 patients with anterior compression of the brainstem by invaginated odontoid process. All patients underwent endoscopic transnasal odontoidectomy. RESULTS: Brainstem decompression was achieved in all cases. CONCLUSION: Currently, endoscopic transnasal approach is gradually replacing the transoral one in some patients requiring anterior odontoidectomy. Analysis of literature data reflects the development of this technique taking into account various features of surgical treatment including optimization of dimensions of surgical field, attempts to perform C1-sparing surgeries and analysis of sufficient size of trepanation. Nasopalatine and nasoclival lines are used to select optimal access. Nevertheless, the choice of access depends on equipment of the hospital and surgical experience in most cases.

Morphometric analysis of odontoid process among Arab population: a retrospective cone beam CT study.

Objective: This study aims to evaluate the feasibility of using cone beam computed tomography (CBCT) scans to assess the odontoid process diameter in the Arab population and to determine whether one or two cortical screws can be used for treating odontoid fractures. Methods: The odontoid process of 142 individuals aged 12-75 years, including 72 males (mean age: 35.5) and 70 females (mean age: 36.2), were analyzed using CBCT scans. The sagittal and coronal CBCT views were used to evaluate the antero-posterior (AP) and transverse diameters of the odontoid process. Results: Males had substantially bigger transverse and AP diameters of the odontoid process than females (p < 0.05 & P < 0.01 respectively). Among the sample, 97 individuals (67.4%) had external transverse diameter (METD) of less than 9 mm which is slightly bigger than that of Indians and 48 individuals (31.83%) had enough room for two 3.5 mm or two 2.7 mm screws as their METD was more than 9 mm like that of Greek and Turkish. Age had no significant impact on the morphometric measurements of the odontoid process. Conclusion: More than sixty percent of the sample had METDs of less than 9 millimeters, indicating that a single 4.5-mm Herbert screw may be suggested for fixing fractured odontoid processes in the Arab population.

Endoscopic odontoidectomy for brainstem compression in association with posterior fossa decompression and occipitocervical fusion.

OBJECTIVE: Endonasal endoscopic odontoidectomy (EEO) is an alternative to transoral surgery for symptomatic ventral compression of the anterior cervicomedullary junction (CMJ), allowing for earlier extubation and feeding. Because the procedure destabilizes the C1-2 ligamentous complex, posterior cervical fusion is often performed concomitantly. The authors' institutional experience was reviewed to describe the indications, outcomes, and complications in a large series of EEO surgical procedures in which EEO was combined with posterior decompression and fusion. METHODS: A consecutive, prospective series of patients who underwent EEO between 2011 and 2021 was studied. Demographic and outcome metrics, radiographic parameters, extent of ventral compression, extent of dens removal, and increase in CSF space ventral to the brainstem were measured on the preoperative and postoperative scans (first and most recent scans). RESULTS: Forty-two patients (26.2% pediatric) underwent EEO: 78.6% had basilar invagination, and 76.2% had Chiari type I malformation. The mean ± SD age was 33.6 ± 3.0 years, with a mean follow-up of 32.3 ± 4.0 months. The majority of patients (95.2%) underwent posterior decompression and fusion immediately before EEO. Two patients underwent prior fusion. There were 7 intraoperative CSF leaks but no postoperative CSF leaks. The inferior limit of decompression fell between the nasoaxial and rhinopalatine lines. The mean ± SD vertical height of dens resection was 11.98 ± 0.45 mm, equivalent to a mean ± SD resection of 74.18% ± 2.56%. The mean increase in ventral CSF space immediately postoperatively was 1.68 ± 0.17 mm (p < 0.0001), which increased to 2.75 ± 0.23 mm (p < 0.0001) at the most recent follow-up (p < 0.0001). The median (range) length of stay was 5 (2-33) days. The median time to extubation was 0 (0-3) days. The median time to oral feeding (defined as, at minimum, toleration of a clear liquid diet) was 1 (0-3) day. Symptoms improved in 97.6% of patients. Complications were rare and mostly associated with the cervical fusion portion of the combined surgical procedures. CONCLUSIONS: EEO is safe and effective for achieving anterior CMJ decompression and is often accompanied by posterior cervical stabilization. Ventral decompression improves over time. EEO should be considered for patients with appropriate indications.