The primary outcome of posterior nonfusion screw-rod fixation for preserving the atlantoaxial rotary function due to fresh type II odontoid fracture

Objectives: To introduce the primary outcome of posterior nonfusion screw-rod fixation for preserving the atlantoaxial rotary function due to fresh type Ⅱ odontoid fracture.Methods: From January 2010 to July 2011,8 cases suffering from fresh type Ⅱ odontoid fracture and unsuitable for anterior odontoid screw fixation were included in this study,of them,anterior-inferior to posterior-superior incline fracture line was noted in 5 cases,poor fracture reduction after traction in 3 cases.There were 6 males and 2 females,with an average age of 38 years(range,21-56 years).Under the general anesthesia,all 8 cases underwent C1-C2 screw-rod fixation without bony graft.When a solid bony union of the dens was confirmed by CT scan,instruments were removed,and the recovery of atlantoaxial rotation function was observed.Results: All 8 cases got an odontoid fracture reduction and a successful posterior C1-C2 screw-rods fixation,and no neurovascular injury was noted.A total of 16 3.5mm diameter screws including 13 pedicle screws and 3 partial trans-pedicle screws was placed in C1;and 16 3.5mm diameter screws including 11 pedicle screws and 5 translaminar screws were placed in C2.All cases were followed up from 12 to 24 months(average,16 months) after the first stage operation,that all patients had a solid bony fusion on radiographs and CT scans,and the cervical rotation ROM was from 35° to 55°(average,45°).After the second stage operation,the atlantoaxial rotation ROM partially recovered instantly,with the cervical rotation ROM from 50° to 70°(average 60°),and almost recovered to normal 6 to 12 months later,with the cervical ROM from 80° to 90°(average 85°) finally.Conclusions: For patients with fresh type Ⅱ odontoid fracture and unsuitable for anterior odontoid screw fixation,posterior screw-rod fixation followed by second-stage instruments removing can preserve the C1-2 rotation function.