The Clinical Efficacy Analysis Of Nail Plate System For Atlantoaxial Instability

Objective: Analysis the efficacy of Posterior Atlantoaxial Fixation of nail plate system for atlantoaxial dislocation.Materials and methods:A retrospective study was performed in 21 patients from August 2010 to December 2016 with atlantoaxial dislocation in our Hospital operated Posterior Atlantoaxial Fixation sugery.Which 12 males and 9 females aged between 20-65.There were 1 case with Jefferson fracture caused by acute injury,5cases with fresh odontoid fracture and one of them was pathological fracture.3 case with congenital dysplasia of odontoid process and 1 with arthritis pauperum and 2case with spontaneous atlantoaxial dislocation.Use Japaneses Orthopedic Association(JOA)compare the clinical and radiologic outcomes of preoperative,postoperative and follow-up to evaluate the efficacy.ASIA grade were checked for neurological outcome,VAS for pain assessment in clinical outcome assessment.Atlantodental intervals,the space available for cord,C1-C2 angle,and fusion rate were checked in radiologic outcome assessment.Results: The mean follow-up period was 12 months(range from 6 months ~24months).The neurological function was improved in unequal degree after operation in all 21 patients and there were no complications such as vertebral artery injury,infection of bone extraction area and incision,and so on.The mean postoperative JOA score at last follow-up was 15.09±1.7,compared with the preoperative score of 11.27±3.55(p<0.01).VAS score at last follow-up was 1.36±0.50 compared with the preoperative score of 1.36±0.50(p<0.05).According to ASIA classification of spinal cord function there were 16 cases of spinal cord dysfunction before operation,which 12 cases were grade D and 4 case were grade C developed to1 case with grade D and 15 cases with grade E.The cervical rotation was partially limited but the flexion and extension function recovered well after operation.X-ray showed bone graft fusion rate was 100% of all 21 patients after 6 months of underwent surgery.Imaging examinations showed completly decompr-ession.Theatlantodens interval(ADI)was reduced from 6.6 ±38 mm before operation to 1.5 ±0.5mm postoperatively,and the Spinal effective space(SAC)was increased from 11.6±4.2 mm to 19 ±2.2 mm after operation(P < 0.05).The angle of C1-2 recovered from14.4 ±5.94 degrees before operation to 25.8 ±3.35 degrees.All these patients achieved satisfactory with atlantoaxial reduction and no internal fixation failure was found.Conclusions:It was reliable to treat atlantoaxial instability with the Posterior Atlantoaxial Fixation technique with posterior pedicle screw plate fixation system.It has a excellent intraoperative reduction function and can achieve strong internal fixation,the biomechanical stability was well,and the fusion rate was high.