Morphological Study of Subaxial Cervical Pedicles by Using Three-Dimensional Computed Tomography Reconstruction Image

Abstract

Malpositioning of cervical screws risks neurovascular injury. A cervical screw fixation system can provide proper rigidity, alignment correction, and high rates of fusion afforded by high pullout biomechanical strength. The objective is to assess the dimensions and axis of the C3–C7 cervical pedicles. A 1-mm slice thickness computed tomography (CT) scan of the cervical spine of 30 patients (15 males, 15 females) were analyzed and reconstructed in three-dimensions using Mimics® 10.01 software. We measured pedicle axis length (PAL), pedicle and lateral mass length (PL-LM), pedicle length (PL), outer pedicle width (OPW), and pedicle transverse angle (PTA) from the axial image and outer pedicle height (OPH) and pedicle sagittal angle (PSA) from the sagittal image. The OPH and OPW at all subaxial cervical spines were suitable for insertion of 3.5 mm cervical pedicle screws. PSA was directed cranially at C3 to C5 (13.84, 7.09, and 2.71) and directed caudally at C6 and C7 (–4.55, –6.94). PTA was greatest at C5 and smallest at C7. The respective difference between the left and right side for nearly all parameters was not statistically significant (except for C6 PL and C7 OPH). Females had a significantly smaller OPH and OPW than males at nearly all levels. The PTA was not significantly different between the sexes. Cervical pedicle screw fixation in the Thai population can be safely performed and guidelines for insertion at each vertebra documented. Appropriate preoperative planning is necessary to achieve safe and accurate placement of the screws.

Computerized Tomography–Based Morphometric Analysis of Subaxial Cervical Spine Pedicle in Asymptomatic Indian Population

“…In our study we that found morphometric parameters were significantly larger in men compared with women, and no significant differences were noted between left-and right-sided measured pedicle parameters at any spinal levels, which was in accordance with previous studies in other ethnic groups. 12,13,23,24 PW, PH, and PTA values in our study were found to be smaller than those in European/American, Thai, and Chinese populations. 12,13,24 An optimum of 4.5 mm PW is required for safe CPS placement in order to have 0.5 mm of bone stock on each side.…”

“…Al-saeed et al 30 noted in an Arab population that PAL was 32.2 mm at C3, 32.3 mm at C4, 33 mm at C5, 33.5 mm at C6, and 34 mm at C7. Wasinpongwanich et al 23 noted in the Thai population that PAL was 29.10 mm at C3, 30.48 mm at C4, 32.05 mm at C5, 33.40 mm at C6, and 34.36 mm at C7.…”

“…Chanplakorn et al 13 found that overall mean PH in the Chinese population was 5.7 mm at C3, 6.01 mm at C4, 5.8 mm at C5, 5.9 mm at C6, and 6.8 mm at C7. Wasinpongwanich et al 23 noted that overall mean PH in the Thai population was 6.3 mm at C3, 6.5 mm at C4, 6.9 mm at C5, 6.9 mm at C6, and 7.4 mm at C7. They observed that PH significantly increased at each level from C3 to C7, and there was no statistically significant difference between left and right pedicle height, except at C4 where left was greater than right.…”

“…Rao et al 12 noted the overall mean PL in the American population was 5.25 mm at C3, 5.2 mm at C4, 5.6 mm at C5, 5.8 mm at C6, and 5.7 mm at C7. Wasinpongwanich et al 23 noted that mean PL in the Thai population was 5.55 mm at C3, 5.76 mm at C4, 6.07 mm at C5, 6.13 mm at C6, and 6.28 mm at C7.…”

“…Rao et al 12 found that overall mean PTA was 46.58 at C3, 478 at C4, 45.58 at C5, 41.58 at C6, and 338 at C7 in the American population. Wasinpongwanich et al 23 noted that overall PTA in the Thai population was 46.38 at C3, 48.58 at C4, 48.88 at C5, 44.38 at C6, and 38.78 at C7. Chanplakorn et al 13 observed that PTA in the Chinese population was 42.78 at C3, 44.28 at C4, 44.058 at C5, 42.218 at C6, and 39.048 at C7.…”