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Introduction Fractures of the odontoid process are associated with high non-union rates, challenging treatment, and high incidence of screw-related complications. The aim of this study was to compare the biomechanical competence of a single biointegrative bone allograft screw versus two conventional cannulated screws for odontoid fracture fixation. Materials and methods The odontoid process of intact C2 vertebral specimens was subjected to quasi-static loading until fracture. Specimens with an Anderson and d’Alonzo type II or III fracture ( n  = 47) were fixated with either two conventional cannulated screws or with a single bone allograft screw. The constructs were biomechanically tested to failure in the same fashion as in their intact state. Stiffness, yield, and ultimate load were evaluated. The results were adjusted by age, sex, volumetric bone mineral density (vBMD), and the cross-sectional area ratio of cortical bone to total bone measured at the junction of the odontoid process with the vertebral body (Ct.Ar/Tt.Ar). Results Stiffness, yield and ultimate load were restored in the cannulated screws group by 44 ± 10%, 46 ± 7%, and 46 ± 5% and in the bone allograft group by 50 ± 12%, 30 ± 9%, and 34 ± 6% (mean ± SE). There were no significant differences between the groups regarding the three mechanical outcomes (0.104 ≤  p  ≤ 0.223). Positive significant relation was found between vBMD and stiffness in each group (0.248 ≤ R²≤0.273, 0.018 ≤  p  ≤ 0.038), as well as between Ct.Ar/Tt.Ar and stiffness (R²=0.218, p  = 0.033), vBMD and ultimate load (R²=0.430, p  = 0.001) and ultimate loadand vBMD (R²=0.315, p  = 0.010) in the cannulated screws group. Conclusions The primary stability of odontoid fracture fixation is determined mainly by the quality of the local bone and independent of the fixation technique. From the biomechanical perspective, the lower mean values for the yield and ultimate load restored in the bone allograft group compared to the cannulated screws group should be compensated by lower peak load during the patient’s rehabilitation process.

Key Clinical Message Traumatic posterior atlantoaxial dislocation combined with Jefferson fracture and odontoid process fracture with vertebral artery injury is rare. The management of such injury raises controversial issues and is still open to debate. A 74‐year‐old Chinese male presented with sustained neck pain and stiffness after falling from height. The patient was neurologically intact. Preoperative radiographs demonstrated a Jefferson burst fracture with a posterior dislocation of the atlantoaxial joints and odontoid process Anderson and D'alonzo type II fracture. A computed tomography angiography (CTA) showed an occluded left vertebral artery. Coil embolization in the proximal portion of the occluded vertebral artery was performed to prevent further cerebral infarction due to distal embolization of the thrombus. Then a second stage occipito‐cervical fusion was performed to reconstruct cervical spine stability. A systematic screening of blunt trauma vertebral artery injuries through CTA is required when dealing with upper cervical fracture. For cases with vertebral artery occlusion secondary to cervical spine injury, endovascular treatment preceding cervical spine surgery is a feasible and a safe treatment.

Aim A morphometric analysis of the odontoid process of the A2 vertebra, in the Greek population, was conducted using CT scan. We aimed to determine the feasibility to use one or two screws when treating fractures of this anatomic element. Patients and methods One hundred and fifteen patients (57 men) of a mean age of 48 years (16–95 years) underwent a cervical spine CT scan examination. The anterior–posterior and transverse diameters of the odontoid process were measured from the base, at 1-mm interval upward on axial CT images. The length from the tip of the odontoid process to the anterior–inferior angle of the body of the axis was calculated. Data concerning the height and weight of the examined patients were collected. Results The mean transverse and anterior–posterior distances were found to be 11.46 and 10.45 mm, respectively, for the upper end of the odontoid process. At the neck level of the odontoid process, the equivalent mean values were 11.12 and 8.73 mm, respectively, while at the base, these distances were found to be 13.84 and 12.3 mm, respectively. The mean distance from the tip of the odontoid to its base was 17.25 and 17.28 mm, respectively, while the mean distance from the tip of the dens to the anterior–inferior corner of the axis’ body was 39.2 mm. Men showed greater values than women. Conclusions In this study, it was shown that in the Greek population there is enough room for one 4.5-mm or one 3.5-mm cannulated screw to be used. The application of two 3.5-mm screws is feasible in 58.6 % of the male and 26.3 % of the female population. This confirms that the knowledge of the true dimensions of the odontoid process is of paramount importance before the proper management of fractured dens using the anterior screw technique.

We wished to investigate the role of the cervical ligaments in maintaining atlantoaxial stability after fracture of the odontoid process. We dissected eight fresh-frozen cadaveric cervical spines to prepare the C1 and C2 vertebrae for biomechanical analysis. The C1 and C2 blocks were mounted and biomechanical analysis was performed to test the stability of the C1-C2 complex after cutting the odontoid process to create an Anderson and D'Alonzo type II fracture then successive division of the atlantoaxial ligaments. Biomechanical analysis of stiffness, expressed as Young's modulus, was performed under right rotation, left rotation and anterior displacement. The mean Young's modulus in anterior displacement decreased by 37% when the odontoid process was fractured (p = 0.038, 95% confidence interval 0.04-1.07). The mean Young's modulus in anterior displacement decreased proportionally (compared to the previous dissection) by the following percentages when the structures were divided: facet joint capsules (bilateral) 16%, ligamentum flavum 27%, anterior longitudinal ligament 10%. These differences did not reach statistical significance (p > 0.05). We have found that the odontoid process itself may account for up to 37% of the stiffness of the C1-C2 complex and that soft tissue structures account for further resistance to movement. We suggest magnetic resonance imaging (MRI) of the soft tissues in the acute setting of a minimally displaced odontoid process fracture to plan management of the injury. If the MRI determines that there is associated ligament injury it is likely that the fracture is unstable and we would suggest operative management.

The necessity of routinely placing closed suction wound drainage in spinal surgery has been questioned. This study aims to assess if closed suction wound drainage is necessary for posterior atlantoaxial fixation via intermuscular approach. The functional outcomes of these 40 patients who underwent posterior atlantoaxial fixation via intermuscular approach without drainage tube (Group A) were compared with that of a control group, which consisted of 68 randomly enrolled cases with posterior atlantoaxial fixation via intermuscular approach with drainage tube (Group B). Outcome assessments included American Spinal Injury Association (ASIA) scoring grade and Visual Analog Scale Score for Neck Pain (VASSNP). The postoperative analgesic consumption, the incidence of subcutaneous and surrounding ecchymosis and the time of ambulation were compared between two groups. Bone fusion was evaluated through computed tomography (CT) reconstruction. Postoperative paravertebral tissue edema was evaluated by the edema coefficient. The use of drainage tube had no significant influence on the postoperative analgesic consumption, wound ecchymosis, the time of ambulation and paravertebral tissue edema ( P  > 0.05). There were no statistically significant differences in the VASSNP and bone fusion rates during the follow-up period between the two groups ( P  > 0.05). All patients achieved ASIA grade E 3 months after surgery. No complications such as wound infection occurred in either group. Posterior atlantoaxial fixation via intermuscular approach does not necessitate postoperative drainage tube placement if there is no accidental vascular injury or excessive muscle bleeding occurs intraoperatively.

Background Displaced odontoid fractures in the elderly are treated non-surgically with a cervical collar or surgically with C1–C2 fusion. Due to the paucity of evidence, the treatment decision is often left to the discretion of the expert surgeon. Methods The Uppsala Study on Odontoid Fracture Treatment (USOFT) is a multicentre, open-label, randomised controlled superiority trial evaluating the clinical superiority of the surgical treatment of type-2 odontoid fractures, with a 1-year Neck Disability Index (NDI) as the primary endpoint. Fifty consecutive patients aged ≥ 75 years, with displaced type-2 odontoid fracture, are randomised to non-surgical or surgical treatment. Excluded are patients with an American Society of Anaesthesiologists (ASA) score ≥ 4, dementia nursing care or anatomical cervical anomalies. The minimal clinically important difference of the NDI is 3.5 points. A minimum of 16 patients are needed in each group to test the superiority with 80% power. By considering a 1-year mortality forecast of 29%, up to 25 participants are recruited in each group. The non-surgical group is fitted with a rigid cervical collar for 12 weeks. The surgical group is treated with a posterior C1–C2 fusion. All participants are monitored with regard to the NDI, EuroQol score (EQ-5D), socio-demographics and computed tomography (CT) at the time of injury, at 6 weeks, 3 months and 12 months. At 12 months, a dynamic radiographical investigation of upper cervical stability is performed. The secondary endpoints are: EQ-5D score, activities of daily living (ADL), bony union, upper cervical stability and mortality. Discussion USOFT is the first randomised controlled trial comparing non-surgical and surgical management of type-2 odontoid fractures in the elderly. Using the NDI and EQ-5D as endpoints, future value-based decisions may consider quality-adjusted life years gained. Major limitations are (1) the allocation bias of the open-label study design, (2) that only higher training levels of all core specialties of spine surgery are included in the surgical treatment arm and (3) that only one type of surgical stabilisation is investigated (posterior C1–C2 fusion), while other methods are not included in this study. Trial registration ClinicalTrials.gov , NCT02789774 . Registered retrospectively on 25 August 2015.

Odontoid fractures of the second cervical vertebra commonly affect elderly patients due to osteoporosis and low-energy trauma. Treatment is controversial, with prolonged cervical collar immobilization risking non-union and complications, and surgical C1-C2 stabilization involving higher upfront surgical risks. High-level evidence from randomized controlled trials to guide optimal treatment decisions is lacking. The SCORE study aims to determine whether surgical stabilization is non-inferior to conservative collar management in maintaining functional independence for elderly patients with unstable odontoid fractures. SCORE is a multicenter, parallel-group, randomized controlled non-inferiority trial enrolling 322 patients aged ≥70 years with acute (≤2 weeks) unstable odontoid Type II, III, or atypical fractures. Participants will be randomized 1:1, stratified by center, to receive surgical stabilization via posterior C1-C2 fixation or conservative management with a rigid cervical collar. The primary outcome measure is the change in Barthel Index (BI) from baseline to 12 weeks. Secondary outcomes include quality of life (EQ-5D), neck pain (Visual Analog Scale, VAS), neck disability (Neck Disability Index, NDI), radiographic fusion, treatment compliance, cross-over rates to surgery, and incidence of adverse and serious adverse events up to 6 months. Follow-ups will take place at 12 weeks and 6 months post-injury, with an additional visit at approximately 2 weeks post-surgery for surgical patients. Analysis will use mixed models for repeated measures, targeting 90% power to detect non-inferiority within a 5-point margin on the BI (one-sided α = 0.025), accounting for 15% attrition. This trial addresses a critical evidence gap by directly comparing surgical and conservative treatments, aiming to guide clinical decision-making and improve functional outcomes and quality of life in elderly patients. ClinicalTrials.gov, ID: NCT06961578.

Background Anterior screw fixation has been widely adopted for the treatment of Type II dens fractures. However, there is still controversy regarding whether one- or two-screw fixation is more appropriate. Questions/Purposes We addressed three questions: (1) Do one- and two-screw fixation techniques differ regarding shear stiffness and rotational stiffness? (2) Can shear stiffness and rotational stiffness after screw fixation be restored to normal? (3) Does stiffness after screw fixation correlate with bone mineral density (BMD)? Methods We randomly assigned 14 fresh axes into two groups (seven axes each): one receiving one-screw fixation and another receiving two-screw fixation. Shear and torsional stiffness were measured using a nondestructive low-load test in six directions. A transverse osteotomy then was created at the base of the dens and fixed using one or two screws. Shear and torsional stiffness were tested again under the same testing conditions. Results Mean stiffness in all directions after screw fixation was similar in both groups. The stiffness after one- and two-screw fixation was not restored to normal: the mean shear stiffness restored ratio was less than 50% and the mean torsional stiffness restored ratio was less than 6% in both groups. BMD did not correlate with mean stiffness after screw fixation in both groups. Conclusions One- and two-screw fixation for Type II dens fractures provide similar stability but neither restores normal shear or torsional stiffness. Clinical Relevance One-screw fixation might be used as an alternative to two-screw fixation. Assumed BMD should not influence surgical decision making.

Abstract Anterior odontoid screw fixation is a simple and safe surgical technique. It is performed routinely for adult patients, resulting in an abundance of literature on the subject. On the other hand, the use of an anterior odontoid screw in pediatric patients for the management of type 2 odontoid fractures is scarcely reported. Although the surgical strategy is the same as in adult patients, it is essential to be aware of a few distinct perioperative nuances in pediatric patients. These nuances have been highlighted. In order to prevent irreversible loss of head rotatory motion for pediatric type II odontoid fractures, anterior screw fixation should be attempted whenever feasible. This provides adequate fixation while maintaining the range of cervical rotatory motion.

PurposeTo examine the clinical features and post-treatment complications in patients with isolated C2 odontoid fractures.MethodsWe extracted data for all patients who were admitted with C2 odontoid fractures from the Japanese Diagnosis Procedure Combination database between July 2010 and March 2017. We then compared the post-treatment complications during hospitalization according to treatment types: conservative treatment (with or without use of halo-vest) and surgery (anterior or posterior spinal fixation).ResultsA total of 3167 patients (1533 men, 1634 women; mean age, 70 years) with isolated C2 odontoid fractures were identified, including 1124 patients (35%) aged ≥ 80 years. Among the total patients, 2476 (78%) received conservative treatment (with halo-vest, 728; without halo-vest, 1748). The remaining 691 patients (22%) underwent surgery (anterior surgery, 129; posterior surgery, 556; combined surgery, 6). There were no differences between the conservative treatment and surgery groups in baseline characteristics and preexisting comorbid conditions except for age (71 vs. 69 years, p = 0.042). In-hospital death occurred in 136 patients (4.3%). There was no significant difference in in-hospital mortality between the two groups (overall, conservative treatment 4.6% vs. surgery 3.0%, p = 0.066; age ≥ 80 years, conservative treatment 7.2% vs. surgery 5.4%, p = 0.34). Use of halo-vest was not associated with increased mortality (with halo-vest 3.7% vs. without halo-vest 5.0%, p = 0.15).ConclusionThe great majority of isolated odontoid fractures occurred in elderly patients. Conservative treatment and surgery had similarly low in-hospital mortality. Use of halo-vest was not associated with an increase in mortality.