The Biomechanical Research Of Transoral Anterior Atlantoaxial Locking Anatomic Plate(TLAP)

Objective: By comparing the range of the three-dimensional motion of differentfixation state and screw pull-out force test to evaluate the biomechanical performanceof transoral anterior atlantoaxial locking anatomic plate(TLAP),so as to provide newfixation techniques for the irreducible atlantoaxial dislocation.Method:1.6fresh human occipitocervical specimens were prepared for the test ofrange of the three-dimensional motion(ROM) of atlantoaxial joint with differentfixation;2.6fresh human occipitocervical specimens were prepared for screwpull-out strength by diameter3.5mm tapered single cortical screw.3. Theexperimental results were statistically analyzed.Results:1. The range of three-dimension motion of atlantoaxial joint:1) Thebiomechanical comprision showed that there was significant difference inthree-dimensional motion(ROM) between injured group and intact group (p<0.05).2）There was significant difference in three-dimensional motion(ROM) between fourinternal fixation with injured group or intact group (p<0.05) and the value of fourinternal fixation were less than the later two groups.3) By comparing the range of theflexion of four internal fixation, there was no significant difference between TLAPand Brooks+Magerl (p<0.05),additional,the two group’s value were better thanBrooks and Magerl.Secondly,there was significant difference between Brooks andMagerl (p<0.05),the value of Magerl is better.4) The range of lateral bending of fourinternal fixation showed that there was no significant difference between TLAP andBrooks+Magerl (p>0.05),and the two groups were better than those of other methodsof internal fixation.In addition to, there was no significant difference betweenBrooks and Magerl (p>0.05).5） The range of rotation of four internal fixationshowed that there was no significant difference between TLAP, Brooks+Magerl and Magerl (p>0.05).And the three groups were better than Brooks group.2.1)Bycomprision showed that there was significant difference between atlas screw pulloutforce with third cervical (p<0.05),additional, there was no significant differencebetween axial screw pullout force with third cervical(p>0.05).2) By the length of thescrew channel showed that there was significant difference between atlas with thirdcervical(p<0.05), additional, there was no significant difference between axialwith third cervical(p>0.05).3) From pearson Linear Analysis,we can see that positivelinear correlation between screw pullout force with the length of the screw channel.Conclusions:1.The design of TLAP system has excellent biomechanical performancewhich is equivalence with Magerl+Brooks as the gold standard of internal fixation ofatlantoaxial joint.2.TLAP’s atlas and axial screws were strong enough foratlantoaxial arthrodesis and there anti-pullout force performance was excellent.3.inorder to get excellent performance of anti-pullout force,we can choose a longer screwchannel by using TLAP’s multi-angle locking mechanism.