Artikel
Biomechanical comparison of anterior cervical spine instrumentation techniques with and without supplemental posterior instrumentation after different corpectomy/discectomy combinations
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Veröffentlicht: | 4. Juni 2012 |
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Gliederung
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Objective: To compare the stiffness and range of motion (ROM) of four cervical spine constructs and the intact condition.
Methods: Eight human cadaveric fresh-frozen cervical spines from C2–T2 were utilized. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods: 1) intact, 2) segmental construct with discectomies at C4–C5, C5–C6, C6–C7, PEEK interbody cage, and anterior plate, 3) segmental construct with discectomy at C6–C7, corpectomy of C5, with PEEK interbody graft at discectomy level and titanium cage at corpectomy level, 4) corpectomy at C5 and C6 with titanium cage and an anterior cervical plate and, 5) corpectomy at C5 and C6 with titanium cage and an anterior cervical plate and posterior lateral mass screws/rod system from C4 to C7. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation.
Results: In all tested motions the statistical comparison between intact and the two-level corpectomy with anterior plate and posterior fixation construct was significant. All other statistical comparisons between the instrumented constructs were not statistically significant except between the three-level discectomy with anterior plate and the two-level corpectomy with anterior plate in axial rotation. There were no statistically significant differences between the group of one-level discectomy and one-level corpectomy with anterior plate and the group of two-level corpectomy with anterior plate in any tested motion. There was also no statistical significance between the three-level discectomy with anterior plate and the two-level corpectomy with anterior plate and posterior fixation.
Conclusions: Posterior segmental instrumentation confers significant stability to two level corpectomy, therefore the surgeon should strongly consider the placement of segmental posterior instrumentation to improve the overall stability of the fusion construct in cases which requires a two level corpectomy for adequate anterior decompression. Additionally, segmental plate fixation three-level discectomy affords the same stiffness and range of motion as circumferential fusion in two-level cervical spine corpectomies. This obviates the need for staged circumferential procedures in cases of multilevel cervical spondylotic myelopathy in which an adequate anterior decompression can be achieved by multilevel discectomies.