Anatomic research on atlantoaxial reduction and plate fixation via transoral approach in children

Abstract

Objective To investigate the feasibility of using transoral anterior reduction plate (TARP) for the atlantoaxial reduction and fixation in pediatric patients.Methods 30 complete sets of cervical CT scan images were obtained from the pediatric patients who had been treated in our department from January 2010 to December 2012.They were 15 boys and 15 girls,with an age range of 5 to 15 years (mean,8.9 ±3.6 years).The children were divided into group A (15 cases,from 5 years old to 9 years old) and group B (15 cases,from 10 years old to 15 years old).The following parameters were measured using tools in the PACS software:transverse and longitudinal diameters,inner and outer heights and width of atlas lateral mass,length of virtual atlas screw path,outward angle of atlas screw,length of axis screw,length of reverse axis pedicle screw,and outward angle of axis reverse pedicle screw.Results The size of lateral mass in both groups could accommodate a 3.5 mm screw.The length of screw path in group A (13.9 ±2.8 mm) was significantly shorter than that in group B (15.9 ± 2.8 mm) (t =2.487,P =0.033).The outward angle of atlas screw in group A (12.4° ± 2.9°) was not significantly different from that in group B (12.0° ± 3.9°) (t =1.546,P =0.136).Group A exhibited a significantly smaller proportion of pedicle width ＞ 3.5 mm [46.7 ％ (7 / 15)],a significantly shorter length of pedicle screw (10.8 ± 2.5 mm) and a significantly shorter length of reverse axis pedicle screw (17.0 ± 2.0 mm) than group B [73.3％ (11/15),11.9 ± 2.7 mm and 20.9 ± 2.3 mm,respectively] (P ＜ 0.05).Conclusions It is basically feasible to use TARP for atlantoaxial reduction and fixation in pediatric patients from 5 to 15 years old,but older children allow for a longer screw path than younger ones.An individualized screw placement is advised when placing screws via transoral approach in pediatric patients. Key words: Children; Anatomy; Atlanto-axial joint; Internal fixators