| Objective To use digital software for anatomical measurements of sacral pedicle and to investigate the digitized anatomical structure and application of the sacral fractures treatment using computer simulated sacral pedicle screw technology.Methods This study collected the Philips spiral CT scan data of pelvis from61patients, and the3-dimensonal pelvic models were reconstructed by the Mimics15.0software. We identified the screw feeding safety zone of S1-4pedicle screw, simulated the imbedding of sacral screw, measured the optimum direction of screw entry, the length of screw, diameter, horizontal and sagittal position of screw entry.Result In the male(27),The screw feeding site of S1sacral pedicle screw was located on the beneath of lamina terminalis9.15±1.24mm, above dorsal sacral foramina11.52±1.77mm,28.73±1.75mm outside of crista sacralis mediana, and it was similar to the screw feeding site recognized in domestic and overseas, that is, the midpoint of ligature between S1zygopophysis lateral border and sacrum superior border, and the maximum diameter of pedicle screw was12.12±1.20mm, the length of screw was41.20±3.90mm, the angle of screw road extraverted22.25±5.06°in horizontal plane, the angle of screw road in sagittal position was paralleled to S1upper lamina terminalis.The screw feeding site of S2sacral pedicle screw was located on the beneath of S1dorsal sacral foramina5.57±0.95mm, above S2dorsal sacral foramina7.21±1.80mm,22.88±1.58mm outside of crista sacralis mediana, and the maximum diameter of pedicle screw was6.10±0.98mm, the length of screw was28.49±2.21mm, the angle of screw road extraverted23.73±4.59°n horizontal plane, the angle between sagittal position and S2upper lamina terminalis was4.13±7.48°trim by stern. The screw feeding site of S3sacral pedicle screw was located on the beneath of S2dorsal sacral foramina5.31±0.72mm,above S3dorsal sacral foramina7.23±1.56mm,24.82±2.44mm outside of crista sacralis mediana, and the maximum diameter of pedicle screw was5.71±0.69mm, the length of screw was23.45±2.68mm, the angle of screw road extraverted46.72±4.37°n horizontal plane, the angle between sagittal position and S3upper lamina terminalis was3.91±6.00°trim by stern. The screw feeding site of S4sacral pedicle screw was located on the beneath of S3dorsal sacral foramina5.18±1.31mm,above S4dorsal sacral foramina6.11±1.54mm,21.26±2.55mm outside of crista sacralis mediana,and the maximum diameter of pedicle screw was5.71±0.83mm, the length of screw was17.89±2.29mm, the angle of screw road extraverted53.83±3.42°in horizontal plane, the angle between sagittal position and S4upper lamina terminalis was13.46±5.43°down by the bow.In the female(34),the screw feeding site of S1sacral pedicle screw was located on the beneath of lamina terminalis8.96±1.43mm, above dorsal sacral foramina11.06±1.81mm,29.55±2.34mm outside of crista sacralis mediana, and it was similar to the screw feeding site recognized in domestic and overseas, that is, the midpoint of ligature between S1zygopophysis lateral border and sacrum superior border, and the maximum diameter of pedicle screw was11.82±1.62mm, the length of screw was39.25±3.17mm, the angle of screw road extraverted26.90±4.22°in horizontal plane, the angle of screw road in sagittal position was paralleled to S1upper lamina terminalis.The screw feeding site of S2sacral pedicle screw was located on the beneath of S1dorsal sacral foramina5.56±1.04mm, above S2dorsal sacral foramina6.84±1.03mm,23.20±2.85mm outside of crista sacralis mediana, and the maximum diameter of pedicle screw was6.08±1.09mm, the length of screw was25.71±2.59mm, the angle of screw road extraverted30.60±7.24°in horizontal plane, the angle between sagittal position and S2upper lamina terminalis was4.57±6.50°trim by stern. The screw feeding site of S3sacral pedicle screw was located on the beneath of S2dorsal sacral foramina5.30±0.82mm, above S3dorsal sacral foramina6.63±1.41mm,24.59±3.27mm outside of crista sacralis mediana, and the maximum diameter of pedicle screw was5.51±0.91mm,the length of screw was22.04±2.69mm, the angle of screw road extraverted49.80±9.27°in horizontal plane, the angle between sagittal position and S3upper lamina terminalis was3.37±8.12°trim by stern. The screw feeding site of S4 sacral pedicle screw was located on the beneath of S3dorsal sacral foramina4.80±0.89mm,above S4dorsal sacral foramina5.32±1.17mm,20.46±2.00mm outside of crista sacralis mediana, and the maximum diameter of pedicle screw was5.34±0.93mm, the length of screw was16.89±2.11mm, the angle of screw road extraverted55.27±3.71°in horizontal plane, the angle between sagittal position and S4upper lamina terminalis was13.87±6.22°down by the bow.Compared male with female, the included angles between horizontal plane, vertical plane and S1-4screw had no significant difference (P>0.05). The distance (L1) between best screw feeding site of S1-4to sacral hole margo inferior tangent had no significant difference (P>0.05). The distance (L2) between best screw feeding site of S2to sacral hole margo inferior tangent had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The vertical dimension between screw feeding sites of S2and center of the sacral crest (L3) had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The largest diameter of S3screw had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The largest length of S1-4screw had no significant difference (P>0.05). Compared>50years and<50years old, the camber of S2screw feeding horizontal plane had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The sagittal position angel between upper vertebral endplate and S1-4sacral screw had no significant difference (P>0.05). The distance between best screw feeding sites of S1-4and upper sacral hole margo inferior tangent (L2), between best screw feeding sites and below sacral hole superior border tangent (L3) had no significant difference (P>0.05).The vertical dimension between screw feeding sites of S2and center of the sacral crest (L3) had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The largest diameter of S1screw (P<0.05) had a significant difference (P<0.05), while this ratio in other segments had no significant difference (P>0.05). The largest length of Sl-4screw had no significant difference (P>0.05).Conclusion We did anatomical measurements of sacral pedicle by Mimics digital software technology, simulated screw imbedding by sacral3D images, and carried out clinical screw imbedding experiment in the corpse specimens. The measured optimum direction of screw entry, the length of screw, diameter, horizontal and sagittal position of screw entry might be reference of clinical operation. The results which had small error and good repeatability could provide theoretical basis for sacral pedicle screw fixation techniques, meanwhile, provide safe anatomic basis for sacral fracture internal fixation reconstruction. |
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