The X-ray Measurement And Clinical Application Of Head And Neck Relative Position In Natural Head Position

【abstract】Objective:To measure normal anatomic angles of healthy people,which can reflect the relative position of head and neck in natural head position, and applying these angles to determine the appropriate fixing position of head and neck in occipitocervical fusion and evaluate the therapeutic effect of the surgery.Methods:Lateral radiographs of cervical spine of 60 healthy people were taken in natural head position, with 29 male and 31 female, respectively. VER represents true vertical line, HOR represents true horizontal line. The following angles were measured: posterior-inferior angle between anterior cranial fossa plan (S-N plane) and vertical plane (NSL/VER), anterior-superior angle between S-N plane and dorsal tangent line of the second cervical vertebra (craniocervical angle NSL/OPT), anterior-superior angle between S-N plane and cervical vertebra tangent line (NSL/CVT), anterior- superior angle between dorsal tangent line of the second cervical vertebra and true horizontal line (OPT/HOR), anterior-superior angle between cervical vertebra tangent line and true horizontal line (CVT/HOR), the superior angle between dorsal tangent line of the second cervical vertebral and cervical vertebra tangent line (OPT/CVT), and posterior-inferior angle between atlas plane and vertical plane (AP/VER). The repeatability of these angles was confirmed and showed no differences between male and female, and the average number of each angle was calculated. After that, these angles were applied to determine the appropriate fixing position in ten patients received occipitocervical fusion in our hospital, and the pre-operation and postop measurements of all these angles were compared.Results:The planes outside the skull (VER,HOR) were used as reference plan in the lateral radiograph of cervical spine in natural head position, which are stable and repeatable and not affected by the anatomical landmarks of inner skull. The measurements of each angles of healthy people are: NSL/VER: 75.7±6.7, NSL/OPT: 109.0±7.3, NSL/CVT: 113.8±8.0, OPT/HOR: 81.2±4.7, CVT/HOR: 80.3±6.0, OPT/CVT: 4.6±3.3. These angles were applied to determine the appropriate fixing position of head and neck in occipitocervical fusion. After surgery, these angles were measured in the lateral radiograph of cervical spine of all patients, which are: NSL/VER: 81.4±3.8, NSL/OPT: 76.7±5.0, NSL/CVT: 75.6±5.3, OPT/HOR: 86.1±3.0, CVT/HOR: 81.0±2.9, OPT/CVT: 5.1±2.0,AP/VER: 81.6±4.9, and there is no statistically significant difference between healthy people and postop measurements.Conclusion:The angles measured from lateral radiograph of cervical spine in natural head position can reflect the normal position of head and neck, which also a good reference for determining the appropriate fixing position of head and neck in occipitocervical fusion, and for evaluating the therapeutic effect and satisfactory of the surgery.