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Biomechanical comparison of five different atlantoaxial posterior fixation techhniques
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Orthopaedics.
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2000 (English)In: Spine, ISSN 0362-2436, E-ISSN 1528-1159, Vol. 25, no 22, 2877-2883 p.Article in journal (Refereed) Published
Abstract [en]


Five different reconstructions of the atlantoaxial complex were biomechanically compared in vitro in a nondestructive test.


To determine whether non-bone graft-dependent one-point fixation affords stability levels equivalent to three-point reconstructions.


Previous investigations have demonstrated that three-point fixation, using bilateral transarticular screws in combination with posterior wiring, provide the most effective resistance to minimize motion around C1-C2. However, placement of transarticular screws is technically demanding. Posterior wiring techniques affording one-point fixation have failure rates of approximately 15%, with failure considered to be secondary to structural bone graft failures. One-point, non-bone graft-dependent fixations have not been tested.


Eight human cervical specimens, C0-C3 were loaded nondestructively. Unconstrained three-dimensional segmental motion was measured. The reconstructions tested were two one-point fixations, one two-point fixation, and two three-point fixations.


Under axial rotation two and three-point reconstructions provided better stiffness than the one-point reconstructions (P < 0.05). During flexion-extension, higher stiffness levels were observed in one- and three-point fixations when compared with the intact spine (P < 0.05). In lateral bending no significant differences were observed among the six groups, although the trend was that reconstructions including transarticular screws provided greater stability than one-point fixations.


The current findings substantiate the use of three-point fixation as the treatment of choice for C1-C2 instability. [l: atlantoaxial fixation, biomechanics, cervical spine, instability, spinal instrumentation, transarticular screws]

Place, publisher, year, edition, pages
2000. Vol. 25, no 22, 2877-2883 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-90827PubMedID: 11074673OAI: oai:DiVA.org:uu-90827DiVA: diva2:163311
Available from: 2003-09-11 Created: 2003-09-11 Last updated: 2014-09-26Bibliographically approved
In thesis
1. Biomechanical and Clinical Aspects on Fixation Techniques in the Cervical Spine
Open this publication in new window or tab >>Biomechanical and Clinical Aspects on Fixation Techniques in the Cervical Spine
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present work is analyzing the general biomechanical aspects of fixation techniques in the upper and lower cervical spine along with clinical implications.

The in vitro biomechanical properties of five different posterior atlanto-axial fixation techniques are compared. They provided for either a one, two or three-point fixation between atlas and axes. A new device, the C1 claw was biomechanically tested, which allow for fixation without the need for a structural bone graft. The three-point reconstructions indicated superior biomechanical properties compared to all others.

The new C1 claw device was clinically evaluated in a series of 26 patients treated with a posterior C1-C2 fusion. There were no clinical or radiological failures in the series, Twenty-one patients out of twenty-three with any length of follow up either showed a solidly healed fusion or a healed fracture.

Distractive flexion (DF) injuries in the lower cervical spine treated with anterior plate alone were analyzed with respect to healing rate and complications in a consecutive series of 36 patients. Results indicated that DF injury stage 1 and 2 according to Allen and Ferguson healed without complication, whereas DF injuries stage 3 had a high frequency of failure, needing an additional posterior fixation.

The in vitro biomechanical properties of four different fixation techniques for a distractive flexion injury stage 3 were analyzed. The result indicated that anterior plate alone for fixation of a DF injury stage 3 is insufficient supporting the clinical finding in the previous study.

Adjacent level motion was analyzed following a one segment fusion in the lower cervical spine. Motion was found to increase in adjacent levels possibly contributing to accelerated degeneration.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 37 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1286
Medicine, Biomechanics, Atlanto-axial fusion, Distractive flexion injuries, cervical spine, adjacent level motion, Medicin
National Category
Dermatology and Venereal Diseases
urn:nbn:se:uu:diva-3574 (URN)91-554-5735-5 (ISBN)
Public defence
2003-10-17, Rosénsalen, ingång 95/96, Uppsala, 09:15
Available from: 2003-09-11 Created: 2003-09-11Bibliographically approved

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