Evaluation Of The Diagnosis And Treatment Value Of Sagittal Atlantoaxial Joint Inclination And Reduction Index In Irreducible Atlantoaxial Dislocation

Objective:To evaluate Sagittal atlantoaxial joint Inclination and reduction index that provided the surgeon with objective data for surgical planning and selecting surgical approachMethods: A retrospective analysis was carried out on 24 patients(11 females and 13 males;ranged 20 to 62 years,mean 43 years) with irreducible atlantoaxial dislocation from January 2008 to July 2014. According to the difference of the operation method,the patients were divided into two groups: the anterior loosening with posterior atlanto-axial fusion group,the alone posterior atlanto-axial fusion group, besides, 12 healthy individuals as control group.We utilized the statistics software to analysis clinical dates and proposed objective imaging indexes,including sagittal atlantoaxial joint Inclination and reduction index, which could reflect the atlantoaxial dislocation’ reversibility.Result: In the control group,the mean sagittal atlantoaxial joint angles were(5.6±1.9)°and(5.1±2.1)°on the left and right sides,respectively.In the patient,the mean angles were(38.8±5.8)° and(39.5±6.0)°on the right and left sides, respectively, for the A group. They were(23.9±6.1)°and(23.1±7.0)°on the right and left sides, respectively, for the B group.Sagittal atlantoaxial joint angles significantly correlated with among the control group A group and B group(Ρ<0.05). The mean reduction indexes in A、B group were(17.6±9.3)%,and(34.4±5.2)%,respectively.The differences of reduction indexes in A、B group were significant(Ρ< 0.05).Besides,there is obvious negative correlation between A、B group for the sagittal atlantoaxial joint angle and the reduction index.Conclusion :The Sagittal atlantoaxial joint Inclination and the reduction index were the great imaging indicators which could reflect the reversibility before the surgery. We could merely choice the posterior atlanto-axial fusion to treat the dislocation, if the reduction index>27.9%, the sagittal atlanto-axial joint slope angle<32.5°, otherwise we need the further anterior loosening.