Biomechanical Analysis of Atlas Fractures

Gebauer, Matthias; Goetzen, Nils; Barvencik, Florian; Beil, Frank Timo; Rupprecht, Martin; Rueger, Johannes M.; Püschel, Klaus; Morlock, Michael M.; Amling, Michael

doi:10.1097/brs.0b013e31816956de

Cited by 25 publications

(5 citation statements)

References 23 publications

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“…The maximum stress value of the atlas plate was 0.176 × 10 9 N / m 2 and the stress was mainly focused on screw holes and the contact with the artificial dens (above the left lateral wall of dens hole). The maximum stress value at axis plate was 0.345 × 10 9 N / m 2 which was concentrated on the anterior arch and posterior arch (9). Our study demonstrated that after the AAOJ replacement, stress increased on the screw holes and the junction of lateral mass -posterior arch, the stress at a hole was gradually transferred to its periphery, while the stress at the junction of lateral mass -posterior arch passed to posterior arch.…”

Section: Fe Analysis On the Biomechanical Properties Of Aaoj Componenmentioning

confidence: 55%

Construction of finite element model for an artificial atlanto-odontoid joint replacement and analysis of its biomechanical properties

Hu¹,

Dong²,

Hann³

et al. 2014

Turkish Neurosurgery

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However, intraoperative flipping of a patient may aggravate cervical spinal cord injury. To solve this problem, some (1,28) have adopted the transoropharyngeal atlantoaxial reduction plate (TARP); however, this fusion technique restricts normal physiological range of motion (ROM) of the upper cervical spine. Several prospective studies of artificial atlantoodontoid joint (AAOJ) replacement have been reported (11-13,18) but finite element biomechanical analysis of AAOJ has not yet been reported to the authors knowledge. We reported a design of an AAOJ that can not only rebuild the stability of the atlanto-axial joint, but also reserve the rotation function █ INTRODUCTIONThe anterior high cervical spine fusion technique is often performed to relieve ventral compression and to improve the stability of the craniovertebral junction (CVJ) (8,10,17,24). Some of the indications include congenital atlanto-occipital fusion induced C1-C2 joint laxity and chronic dislocation; basilar invagination; congenital odontoid malformation caused C1-C2 dislocation; rheumatoid arthritis induced compression and C1-C2 dislocation; and brainstem and cord compression from CVJ tumors. These are typically treated by transoral decompression combined with posterior fusion (1,2,5). AIM:To investigate the stress distribution on artificial atlantoaxial-odontoid joint (AAOJ) components during flexion, extension, lateral bending and rotation of AAOJ model constructed with the finite element (FE) method. MATERIAL and METHODS:Human cadaver specimens of normal AAOJ were CT scanned with 1 mm -thickness and transferred into Mimics software to reconstruct the three-dimensional models of AAOJ. These data were imported into Freeform software to place a AAOJ into a atlantoaxial model. With Ansys software, a geometric model of AAOJ was built. Perpendicular downward pressure of 40 N was applied to simulate gravity of a skull, then 1.53 N• m torque was exerted separately to simulate the range of motion of the model. RESULTS:An FE model of atlantoaxial joint after AAOJ replacement was constructed with a total of 103 053 units and 26 324 nodes. In flexion, extension, right lateral bending and right rotation, the AAOJ displacement was 1.109 mm, 3.31 mm, 0.528 mm, and 9.678 mm, respectively, and the range of motion was 1.6°, 5.1°, 4.6° and 22°.CONCLUSION: During all ROM, stress distribution of atlas-axis changed after AAOJ replacement indicating that AAOJ can offload stress. The stress distribution in the AAOJ can be successfully analyzed with the FE method.

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Section: Fe Analysis On the Biomechanical Properties Of Aaoj Componenmentioning

confidence: 55%

Construction of finite element model for an artificial atlanto-odontoid joint replacement and analysis of its biomechanical properties

Hu¹,

Dong²,

Hann³

et al. 2014

Turkish Neurosurgery

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“…The normal range of axial rotation of the atlas on the axis is from 43 to 56° [ 10 ]. Based on an average atlas transverse diameter of 79.6 mm [ 11 ], lateral rotation to a displacement of 10 mm, corresponding to 15° of rotation, is well within the normal limits of rotation. This was deemed important as the purpose of this study was to assess the relative contributions of the bony and soft tissue structures within the C1-C2 complex and thus we wanted the mechanical analysis to evaluate the effect of our dissections, rather than disrupt the complex in any way.…”

Section: Methodsmentioning

confidence: 99%

Odontoid process fractures: the role of the ligaments in maintaining stability. A biomechanical, cadaveric study

Boughton

Bernard

Szarko

2015

SICOT-J

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Aims: We wished to investigate the role of the cervical ligaments in maintaining atlantoaxial stability after fracture of the odontoid process. Methods: 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. Results: 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). Discussion: 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.

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“…1 ) due to the sloping surface of the atlantoaxial articulation. 1 9 Isolated posterior arch fractures of the atlas may result from the pinching of the posterior arch between a hyperextended occiput and C2 spinous process. 1 10 High-speed impact leads to classic burst fracture and slow speed trauma leads to LM fractures.…”

Section: Injury Mechanism and Pathological Anatomymentioning

confidence: 99%

“…These fractures correlate directly to osteoporosis. 9 The atlantoaxial joint contributes nearly 50% to the observed range of neck rotation. 11 Due to the contrasting demands posed by requirements of rotational freedom and resilience of craniocervical articulation, ligaments have a disproportionate role in stabilizing this region of the cervical spine as compared with the shape of articular surfaces.…”

Section: Injury Mechanism and Pathological Anatomymentioning

confidence: 99%

Technical Considerations in Surgical Fixation of Jefferson Fracture

Gurjar

Singh

Mishra

et al. 2022

Indian Journal of Neurotrauma

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Jefferson fracture is defined as the simultaneous disruption of the continuity of the anterior and posterior arches of the atlas vertebra. It generally results from an axial impact to the head. Most of these fractures are amenable to nonoperative management. Significant disruption of the transverse atlantal ligament that is the main stabilizing ligament of the atlantoaxial articulation and contiguous spinal injuries often form the indications for operative intervention in these fractures. The outward and caudal displacement of the C1 lateral masses observed in these fractures often requires significant deviation from the standard operative technique of atlantoaxial fixation when the osseous elements are intact. Accordingly, we have described the surgical nuances relevant to the exposure and instrumentation of the atlantoaxial region in the setting of Jefferson fracture, through our experience in two cases.

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Biomechanical Analysis of Atlas Fractures

Cited by 25 publications

References 23 publications

Construction of finite element model for an artificial atlanto-odontoid joint replacement and analysis of its biomechanical properties

Construction of finite element model for an artificial atlanto-odontoid joint replacement and analysis of its biomechanical properties

Odontoid process fractures: the role of the ligaments in maintaining stability. A biomechanical, cadaveric study

Technical Considerations in Surgical Fixation of Jefferson Fracture

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