The Design Of Artifical Bone Lamella In Craniovertebral Junction

Background and ObjectiveThe craniocervical junction which is consist of occipital, atlas, axis, and its sur-rounding ligament, is considered as transition zone between occipital bone and the upper cervical, and contained the medulla oblongata. Because of the importance of position, The Lesions such as vessels and nerves often cause significant clinical symptoms, Even life threatening.Clinically, Surgical decompression and internal fixation system such as occipitocervical fusion or atlanto-axial fusion is used for craniocervical junction deformity, however the technique requires sufficient bone graft area to improve the fusion rate and enhance the stability in this area. Currently the graft materials basically contained autogeneous bone, allograft bone,heterogeneous bone, Bioactive materials and bone growth factors, however all kinds of materials has its advantages and disadvantages.On the basis of imaging anatomical parameters of the craniocervical junction, we designed the artifical bone lamella accord with craniocervical junction anatomy asbone graft material of posterior surgery. Materials and methods1 Imaging anatomy measurementAfter collecting the imaging data of 63 patients with clinical craniocervical malformation, we measured the related parameters of anatomical atlas and axis. The five relevant parameters are following: the length of the axis pedicle screw point, the central angle corresponds to the arc of connecting rods, the distance between two points of the arc,the upper oblique angle of axis vertebral pedicle, the inside oblique angle of axis vertebral pedicle; furthermore, we also collected and measured the imaging data of 50 normal people, the two parameters are the length of the axis pedicle screw point and the distance from spinal cord to the anterior margin of spinal canal in atlas plane.2 The design of artifical bone lamella in craniovertebral junctionWe design the bone graft lamella accord with craniocervical junction anatomy on the basis of imaging anatomical parameters.we call it the artifical bone lamella.Results1 Imaging anatomy parametersFor group of patients, the length of the axis pedicle screw point, the central angle corresponds to the arc of connecting rods, the distance between two points of the arc,the upper oblique angle of axis vertebral pedicle, the inside oblique angle of axis vertebral pedicle were 35.36±3.12 (29.0-41.6) mm,,41.74±7.21 (23.2-57.2)。,33.22±6.05 (20.6～43.4)。,109.94±8.33 (98.7-128.1)。,47.1±7.35 (35.3-66.3) mm, respectively. For normal group, the length of the axis pedicle screw point and the distance from spinal cord to the anterior margin of spinal canal in atlas plane were 34.03±3.49 (28.0-38.5) mm,4.74±0.94 (3.1-6.6) mm, respectively.2 The structural features of the artifical bone lamellaThe artifical bone lamella has smart geometrical shape and structure design, favourable biological performance, and it is convenient to install and observe after operation.Conclusion1 The artifical bone lamella which can beautifully cover the bone graft bed of surgical decompression, avoid oppressing cervical spinal cord, and the follow-up is convenient, is a excellent bone graft material in posterior surgery of the craniocervical junction.2 The artifical bone lamella can be designed for multiple models that can satisfy the demand of individual differences.