RESUMO
BACKGROUND:At present,there is a lack of an internal fixation system with good reduction and simple operation for the treatment of atlas burst fracture by posterior single-segment fixation. OBJECTIVE:Based on the atlas CT measurement data,a new posterior atlas fracture reduction and internal fixation system was designed and optimized,which was in line with the characteristics of human local anatomical structure,easy to operate and with good reduction. METHODS:CT images of 347 adults were analyzed retrospectively.In the images,the length of pedicle screw track with a medial inclination of 0°,the angle of the maximum medial inclination angle and the length of pedicle screw track at this time,the height of vertebral artery groove,the distance between the entry points of bilateral pedicle screws and the midline,the radius of the posterior arch of atlas,the distance between the posterior tubercle of the atlas and the posterior edge of the foramen magnum,and the distance between the posterior tubercle of the atlas and the upper surface of the axial arch were measured.The imaging data were analyzed and a reduction and internal fixation system was designed and optimized for atlas fracture in line with human anatomical characteristics. RESULTS AND CONCLUSION:(1)There was no statistically significant difference in the the length of pedicle screw track with a medial inclination of 0°,the maximum medial inclination angle and the length of pedicle screw track at this time,the height of vertebral artery groove,the distance between the entry points of bilateral pedicle screws and the midline,the radius of the posterior arch of atlas,the distance between the posterior tubercle of the atlas and the posterior edge of the foramen magnum,and the distance between the posterior tubercle of the atlas and the upper surface of the axial arch measured on the left and right sides of all subjects(P>0.05).There were statistically significant differences in each index measured between the male and female groups(P<0.05).(2)The new posterior atlas fracture reduction and internal fixation system has been successfully designed and obtained the national patent.The internal fixation system is suitable for the anatomical characteristics of the posterior arch of the atlas.It can not only effectively treat the atlas burst fracture,but also retain the movement function of the occipital atlantoaxial joint.
RESUMO
STUDY DESIGN: A retrospective computed tomography (CT)-based morphometric study of 84 C1pedicles in an Indian population focusing on critical morphometric dimensions vis-a-vis C1 pedicle screw placement. PURPOSE: To determine the feasibility of C1 pedicle screw placement in an Indian population and propose a novel classification system for the same. OVERVIEW OF LITERATURE: At present, C1 pedicle screws are rarely used, and very few studies have focused on the feasibility of pedicle screw placement in terms of racial, gender, and ethnic variations in anatomical structures. There are no CT-based data on C1 pedicles that assess the feasibility of pedicle screw placement in the Indian population. METHODS: We measured C1 pedicle diameter on CT coronal scan images of 42 adult patients. Extramedullary height (EMH) and intramedullary height (IMH) were measured. We examined the differences between the right and left atlas pedicles and compared measures between males and females. These data were analyzed using significance tests. Based on the results, we propose a novel classification system, which we believe will help in determining the feasibility of C1 pedicle screw placement. RESULTS: Forty-two adult patients (84 pedicles) were examined. Average EMH and IMH were 4.48±0.91 and 0.86±0.77, respectively. Approximately, 32% of the C1 pedicles had bone thicknesses of <4 mm, 49% had IMH of <1 mm, and 38% had no pedicles. The average thickness in women was 4.21±0.93 mm, which was significantly thinner than that in men (4.73±0.81 mm, p=0.004). Right and left pedicles were not significantly different. CONCLUSIONS: Our data indicate that approximately one-third of the Indian population may not be suitable candidates for C1 pedicle screw placement. Caution should be exercised while placing type 1B and type 2 pedicles based on our proposed classification system.