Deflective placement of anterior odontoid cannulated screw for treatment of odontoid fracture combined with atlantoaxial posterior dislocation

Abstract

Objective To investigate deflective placement of anterior odontoid cannulated screw for treatment of odontoid fracture combined with atlantoaxial posterior dislocation.Method From August 2002 to December 2011,18 cases of fresh odontoid fracture combined with atlantoaxial posterior dislocation were treated with deflective placement of anterior odontoid cannulated screw in our hospital.They were 10 males and 8 females,aged from 20 to 50 years (mean,41 years).According to the classification of Anderson-D'Alonzon,12 cases were type Ⅱ and 6 type Ⅲ; according to the classification of American Spinal Injury Association (ASIA),3 cases were grade C,10 grade D and 5 grade E.All patients underwent skull traction pre-operation to reduce dislocation.During the operation,the head was bent close to the chest in order to maintain atlantoaxial restoration and odontoid reduction.Because in this posture the jawbone blocked Kirschner wire and made the placement challenging,the anterior odontoid cannulated screw was deflected in all cases.Results In this series,the operation time ranged from 1.0 to 1.5 hours and the blood loss 50 to 100 mL (mean,75 mL).The mean time of follow-up was 15 months (range,12 to 18 months).All cases got bony union 3 to 4 months postoperation without screw failure.According to the ASIA grading for neural function,one case improved from grade C to grade E,one from grade C to grade D,9 cases from grade D to grade E,and no improvement was noted in the other cases.The difference in atlantoaxial shift distance between preoperation and postoperation was statistically significant (P ＜ 0.05).Conclusion In the treatment of odontoid fracture combined with atlantoaxial posterior dislocation,deflective placement of anterior odontoid cannulated screw may preserve the rotation function of the atlas and axis and lead to positive outcomes. Key words: Fascia dentate; Atlanto-axial joint; Fracture, bone; Dislocation ; Fracture fixation, internal