Feasibility of a novel type of complex anterior cervical fixation by using Mimics software / 中国骨伤

OBJECTIVE@#To investigate the feasibility of mimics software in analyzing a new type of complex anterior cervical fixation -- anterior transpedicular screw fixation+zero notch internal fixation.@*METHODS@#From January 2021 to September 2022, 50 normal pedestrians who underwent cervical spine CT scanning were selected for C1-C7 segment scanning, including 27 males and 23 females, aged from 25 to 65 years old with an average of (46.0 ± 9.0) years old. The dicom format is exported and engraved into the CD, and use the mimics software to perform 3D reconstruction of each segment. A simulated screw is placed on the image according to the critical value of zero notch screw (head and tail angle 44°, internal angle 29°). The position of zero notch screw in each segment is observed to determine the feasibility of anterior transpedicular screw fixation plus zero notch internal fixation.@*RESULTS@#For the upper zero notch screws the three-dimensional images of the cervical spine across all 50 subjects within the C3-C7 segments demonstrated safe position, with no instances of intersection with ATPS. For the lower zero notch screw, in C3-C4 and C4-C5, 4 out of 50 subjects are in the safe position in the three-dimensional images of cervical vertebrae, and 46 cases could achieve secure screw placement when the maximum caudal angle is(32.3±1.9) ° and (36.1±2.2) °, respectively. In C5-C6 and C6-C7 segments, no lower zero notch screws intersected with ATPS, and all screws are in safe positions.@*CONCLUSION@#Lower cervical anterior pedicle screw fixation plus zero notch internal fixation can achieve successful nail placement through the selected entry point and position.

Biomechanical study of the stability of subaxial cervical anterior transpedicular screw fixation for three-column injury / 中国骨伤

<p><b>OBJECTIVE</b>To compare the stability of subaxial cervical anterior transpedicular screw(ATPS) fixation and three traditional fixations for three-column injury.</p><p><b>METHODS</b>Six specimens of cervical spine were prepared. After measurememt of the range of motion(ROM) in intact state, the specimens were made into three-column injury models. The models were reconstructed with an anterior cervical cage, and stabilized by ATPS, anterior plate(AP), anterior plate + lateral mass screw(AP+LMS) and posterior transpedicular screw(PTPS). The ROM of the models in the four states were measured, and the results of data were compared after standardization.</p><p><b>RESULTS</b>The normalized ROM of ATPS state in flexion-extension, lateral bending, axial rotation were(77.17±4.75)%, (82.00±2.61)%, (83.17±2.23)%, which were significant small than those in intact state(<0.05). The normalized ROM of AP state in flexion-extension, lateral bending, axial rotation were(119.67±7.42)%, (116.33±7.53)%, (112.67±5.99)% , which were significant larger than those in intact state(<0.05). The normalized ROM of AP in all directions were significant larger than those of ATPS(<0.05). There was no significant difference between normalized ROM of PTPS state and those of ATPS state in flexion-extension and lateral bending(>0.05). The normalized ROM of PTPS state in axial rotation was(6.83±2.48)% and was significant larger than that of ATPS state(=0.009). The normalized ROM of AP+LMS state in flexion-extension was(68.50±2.43)%, which was significant smaller than that of ATPS state(=0.003). There was no significant difference between the normalized ROM of AP+LMS state and those of ATPS state in lateral bending and axial rotation(>0.05).</p><p><b>CONCLUSIONS</b>Subaxial cervical three-column injury model reconstruction by ATPS can provide the adequate primary stability, of which biomechanics property is superior compared to AP and PTPS, and is similar to that of AP+LMS. It can be applied to the patients with no need to decompression and reduction through posterior approach.</p>

Experimental study on rigidity effect of 3 kinds of different internal fixation at upper thoracic spine / 重庆医学

Objective To compare the rigidity at upper thoracic spine among the anterior transpedicular screw-plate system (ATPSPS),posterior transpedicle screw-rod system (PTPSRS) and anterior vertebral body screw-plate system (AVBSPS).Methods Twelve embalmed cadaver specimens were divided into three groups.The specimens in each group were randomly allocated to use the above 3 different internal fixation devices for conducting fixation.The stiffness of each specimen on the directions of axial compression,flexion and extension,and left and right lateral bending was detected under original status.All specimens conducted the simulated corpectomy of T2 (damage status).Then the rigidity on various directions was re-detected on the damage status.The corresponding internal fixation system was selected for conducting the install and fixation according to the grouping results.The intra-group and inter-group rigiditieson different directions were compared amongoriginal status,damage status and after internal fixation.Results The rigidities on different directions under original and damage statushad no statistical difference among various groups (P＜0.05).After conducting fixation in each group,the rigidity after fixation on different directions had statistically significant difference among groups(P＜0.05).The stiffness of anterior flexion in the ATPSPS group was greater than that in the other two groups (P＜0.05).The rigidity of axial compression and extension in the PTPSRS group was greater than that in the other two groups,the difference among groups was statistically significant (P＜0.05).The stiffness of lateral bending in the AVBSPS group was smaller than that in the other two groups,the difference was significant (P＜0.05),but the difference between the other two groups had no statistical significance (P＞0.05).Conclusion The rigidity of ATPSPS in all directions is higher than that of AVBSPS.The anterior flexion rigidity is greater than PTPSRS,and the axial compression and extension rigidity are less than PTPSRS,but the lateral bending rigidity is equivalent to PTPSRS.