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

English Keywords:Axis  Odontoid fracture  Fresh fracture  Screw-rod fixation  Nonfusion

English Abstract:

  【Abstract】 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.