Application of transoral atlantoaxial reduction plateⅢin treatment of complicated atlantoaxial dislocation

尹慶水(Yin Qingshui，Dept Orthop，Guangzhou Gen Hosp Guangzhou Mil Command，Guangzhou 510010)…∥Chin J Trauma.－2011，27(2).－106 ～109

Application of transoral atlantoaxial reduction plateⅢin treatment of complicated atlantoaxial dislocation

尹慶水(Yin Qingshui，Dept Orthop，Guangzhou Gen Hosp Guangzhou Mil Command，Guangzhou 510010)…∥Chin J Trauma.－2011，27(2).－106 ～109

ObjectiveTo evaluate the biomechanical characteristies and the clinical advantage of transoral atlantoaxial reduction plate(TARP)Ⅲ.MethodsDesign of TARP-Ⅲ was based on TARP-Ⅱ.The screw hole in the axis was moved 1～2 mm upwards and inwards in a plate which turned a vertebral screw into a pedicle screw or an artiecular process screw.A polyaxial self-lock ring and polyaxial guiding drill were added to the crew hole of the plate.Finally，the withdrawal resist ence force of the three axis screws was tested and TARP-Ⅲwas used in 44 patients with complicated irreducible atlantoaxial dislocation.The axis was fixed with the pedicle screw or the articular process screw.ResultsThe maximum withdrawal resist ence force of the anterior pedicle screw，the articular process screw and the vertebral screw in the axis was(593.1 ±97.8)N，(469.9 ±73.3)N and(395.2 ±75.1)N respectively，with statistical difference between groups among three fixation methods(P ＜0.05).All 44 patients were followed up for 5～38 months(average 18 months)，which showed complete anatomic reduction in 36 patients and appropriate anatomic reduction in eight，with basic correction of the angles between the brain stem and the spinal cord and sufficient decompression of the spinal cord.The decompression rate of the cervical spinal cord was 88.2%on avarage according to the Yin evaluating method of cervical cord decompression.The improvement rate of spinal cord function was 76.6%on avarage according to Japanese Orthopaedic Accociation(JOA)score.ConclusionWith the design of polyaxia self-lock mechanism，TARP-Ⅲ with the pedicle screw or the articular process screw surpasses TARP-Ⅱwith vertebral screw in aspect of biomechanics.8 refs，6 figs.

(Authors)