摘要To the Editor:Os odontoideum (OO) is a rare congenital anomaly of the second cervical vertebra that is defined as occurring when an independent ossicle is separated from the base of the odontoid process.[1] In general,it requires surgeries for the patients who suffer from OO-associated atlantoaxial dislocation (AAD),especially for young patients due to their immature bones and the unavoidable tumbles and physical impacts in their daily lives.[2] In clinical practice,the use of posterior screw-rod fixation systems enables unique three-dimensional fixation.The use of these systems can provide effective correction and bone fusion for OO-associated AAD.[3] For the treatment of irreducible atlantoaxial dislocation (IrAAD),posterior stabilization,and the use of additional transoral decompression were thought to be necessary,as reported in the literature.[4] To our knowledge,few procedures have been proven to be simple and effective treatments for IrAAD.In our study,we enrolled 15 adolescents with OO-associated AAD that was treated with modified C1-C2 pedicle screw fixation,and for the patients who failed to benefit from pre-operation skull traction,we administered a direct posterior compound reduction technique.