Surgical Anatomy And Early Clinical Application Of Anterior Atlantoaxial Transarticular Screw Fixation

Objective To investigate anatomic parameters of the occipitoatlantoaxial complex soas to provide anatomic clues for anterior atlantoaxial transarticular screw fixation(AATSF) and discuss the feasibility of AATSF and evaluate early clinical outcome of the AATSF.Methods1 Anatomical Measurement Anatomic data that are clinically significant were obtained by measuring the atlas and the axial specimens from 30 normal Chinese cadavers, and anatomic observation was conducted in the occipitoatlantoaxial complex from 5 cadaveric occipitocervical specimens.2.Surgical Model 5 formalin preserved human specimen were obtained for simulating operation, and 5 fresh human cadaveric occipitocervical specimens were performed under visual control with anterior atlantoaxial transarticular screws. Lateral views were filmed by X-ray, on which the trajectory parameters of the screws were measured. The shortest distances between screws and vertebral artery, between screws and the spine and between screws and atlanto-occipital transarticular were measured in the specimen sections.3.Clinlic Outcome 11 patients with atlantoaxial instability underwent reconstructive surgery including anterior atlantoaxial transarticular screw fixation and fusion.Results1 Anatomical Measurement The inside and outside height of normal atlas lateral mass was 9.76±0.22mm and 18.84±0.23mm respectively. The length and width of atlas lateral mass was 10.09+0.14 mm and 11.03+0.23 mm respectively. The width of axis was 22.4±1.2 mm. The appropriate angulation of screw insertion were 18°-32°upper tilting in sagittal plane and 21°-30° outward tilting in coronary plane.