Lateral Joint Morphological Changes In The Atlantoaxial Joint Study On The Biomechanical Significance Of Dislocation

ObjectiveTo elucidate the influence of morphological changes of the lateral joint of the atlantoaxial joint on the range and stability of the atlantoaxial joint motion and the biomechanical significance of the structural support bone graft between the atlantoaxial joints.MethodsSix fresh human cadaveric neck specimens(CO-C3 of the occipital epiphysis)were selected from the Department of Anatomy of Southern Medical University.Each specimen was sequentially made into a complete state,unstable state,lateral vertebral osteotomy,posterior C1+C2 pedicle screw fixation,posterior C1+C2 pedicle screw fixation and lateral joint bone grafting,flexion/post extension,left/right lateral bending,left/right rotation biomechanical study,measuring the three-dimensional range of motion of the atlantoaxial joint,statistical processing and analysis of the data obtained,objectively evaluate the stability of different cervical vertebrae models,and guide clinical practice.Results1.Comparison of stability of flexion flexion:posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group=posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant difference(F=1669.860,P<0.05),among them,the lateral vertebral osteotomy group had the largest activity,and the difference between the two groups was significant(P<0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group was slightly less active than posterior C1+C2 pedicle screw fixation group,the difference between the two groups was not significant(P>0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group,posterior C1+C2 pedicle screw fixation group compared with orther groups having significant significance(P<0.05).2.Comparison of posterior extension stability:posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group=posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant significant(P=2839.045,P<0.05),among them,the lateral vertebral osteotomy group had the largest activity,and the difference between the two groups was significant(P<0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group was slightly less active than posterior C1+C2 pedicle screw fixation group,the difference between the two groups was not significant(P>0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group,posterior C1+C2 pedicle screw fixation group compared with orther groups having significant significance(P<0.05).3.Comparison of stability of left lateral bending motion:post.erior C1+C2 pedicle screw fixation and lateral joint bone grafting group=posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant difference(F=880.728,P<0.05).Among them,the lateral vertebral osteotomy group had the largest activity,and the difference between the two groups was significant(P<0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group was slightly less active than posterior C1+C2 pedicle screw fixation group,the difference between the two groups was not significant(P>0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group,posterior C1+C2 pedicle screw fixation group compared with orther groups having significant significance(P<0.05).4.Comparison of stability of right lateral bending motion:posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group=posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant difference(F=2728.070,P<0.05).Among them,the lateral vertebral osteotomy group had the largest activity,and the difference between the two groups was significant(P<0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group was slightly less active than posterior C1+C2 pedicle screw fixation group,the difference between the two groups was not significant(P>0.05),posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group,posterior C1+C2 pedicle screw fixation group compared with orther groups having significant significance(P<0.05).5.Comparison of stability of left rotation motion:posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group>posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant difference(P=14967.886,P<0.05).Among them,the lateral vertebral osteotomy group had the largest activity,the posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group had the smallest activity,and the difference between each two groups was significant(P<0.05).6.Comparison of stability of right rotation motion:posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group>posterior C1+C2 pedicle screw fixation group>complete group>instability group>lateral vertebral osteotomy group,the comparison between the six groups was significant difference(F=12494.946,P<0.05).Among them,the lateral vertebral osteotomy group had the largest activity,the posterior C1+C2 pedicle screw fixation and lateral joint bone grafting group had the smallest activity,and the difference between each two groups was significant(P<0.05).ConclusionPosterior C1+C2 pedicle screw fixation and lateral joint bone grafting can maintain the stability of the atlantoaxial three-dimensional motion.Comparing with the posterior C1+C2 pedicle screw fixation,there is an advantage in the stability of the left/right rotation of the vertebrae,and the stability is comparable in terms of flexion/extension and left/right bending.In clinical work,patients with atlantoaxial dislocation,especially at the atlantoaxial anterior dislocation,should be supported by bone grafting in lateral joints to improve their rotation stability.