Biomechanical characteristics of posterior fixation for repairing atlantoaxial instability / 中国组织工程研究

ABSTRACT

BACKGROUND:With the development of atlantoaxial morphology, applied anatomy and biomechanics, pathogenesis, diagnosis and treatment of atlantoaxial instability have attracted more and more attention. However, the development of effective fixation for atlantoaxial instability is relatively late, so scholars al over the world have made numerous studies. OBJECTIVE:To compare biomechanical functions of different fixations through atlantoaxial posterior approach, and to assess its stability. METHODS:We retrieved recent studies on comparative biomechanical evaluation and its primary clinical application of different posterior approaches in repair of atlantoaxial instability, and conducted a retrospective analysis by measuring the three-dimensional range of movement in normal atlantoaxial complex and atlantoaxial instability models. This analysis evaluated the stability of different fixations under normal three-dimensional atlantoaxial movement, and provided a biomechanical basis for reasonable fixator selection. RESULTS AND CONCLUSION:Atlantoaxial posterior fixation included Gal ie wire fixation, Brooks fixation, Apofix and Halifax vertebral plate hook fixation, screw fixation through joint and atlantoaxial pedicle nail/rod fixation. Gal ie technique contributes to the reduction of anterior semiluxation, but its mechanical stability is poor. Brooks technique has strong rotation and stretch forces. Apofix and Halifix vertebral plate hook device provides strong anti-rotation and anti-antelocation strength, and is more stable than Gal ie technique in mechanics. The biomechanics of screw fixation through joint was better than wire technique and Halifax. The screw fixation avoids occipitocervical fusion, and has a high requirement to instal ation. When an internal fixator was selected, immediate cervical vertebra stability should be provided to protect spinal cord functions. Upper neck functions should be maintained to reach reduction and maintenance of occipital bone, atlas and axis. A suitable fixation method should be selected for each patient.