Biomechanical comparison of anterior cervical spine instrumentation techniques with and without supplemental posterior fusion after different corpectomy and discectomy combinations

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The objective of this study was to compare the stiffness and range of motion (ROM) of 4 cervical spine constructs and the intact condition. The 4 constructs consisted of 3-level anterior cervical discectomy with anterior plating, 1-level discectomy and 1-level corpectomy with anterior plating, 2-level corpectomy with anterior plating, and 2-level corpectomy with anterior plating and posterior fixation.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Eight human cadaveric fresh-frozen cervical spines from C2–T2 were used. Three-dimensional motion analysis with an optical tracking device was used to determine motion following various reconstruction methods. The specimens were tested in the following conditions: 1) intact; 2) segmental construct with discectomies at C4–5, C5–6, and C6–7, with polyetheretherketone (PEEK) interbody cage and anterior plate; 3) segmental construct with discectomy at C6–7 and corpectomy of C-5, with PEEK interbody graft at the discectomy level and a titanium cage at the corpectomy level; 4) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate; and 5) corpectomy at C-5 and C-6, with titanium cage and an anterior cervical plate, and posterior lateral mass screw-rod system from C-4 to C-7. All specimens underwent a pure moment application of 2 Nm with regards to flexion-extension, lateral bending, and axial rotation.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In all tested motions the statistical comparison was significant between the intact condition and the 2-level corpectomy with anterior plating and posterior fixation construct. All other statistical comparisons between the instrumented constructs were not statistically significant except between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating in axial rotation. There were no statistically significant differences between the 1-level discectomy and 1-level corpectomy with anterior plating and the 2-level corpectomy with anterior plating in any tested motion. There was also no statistical significance between the 3-level discectomy with anterior plating and the 2-level corpectomy with anterior plating and posterior fixation.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>This study demonstrates that segmental plate fixation (3-level discectomy) affords the same stiffness and ROM as circumferential fusion in 2-level cervical spine corpectomy in the immediate postoperative setting. This obviates the need for staged circumferential procedures for multilevel cervical spondylotic myelopathy. Given that the posterior segmental instrumentation confers significant stability to a multilevel cervical corpectomy, the surgeon should strongly consider the placement of segmental posterior instrumentation to significantly improve the overall stability of the fusion construct after a 2-level cervical corpectomy.</jats:p></jats:sec>

Adjacent-level biomechanics after single-level anterior cervical interbody fusion with anchored zero-profile spacer versus cage-plate construct: a finite element study

“…As indicated in the present finite element study, ACDF impairs normal cervical biomechanics, alters mechanics at adjacent segments, resulting in higher stress and hypermobility in adjacent segments. Our results are in line with the reported data of the biomechanical studies on the behavior of the adjacent segments in the setting of different operation procedures [49][50][51][52][53]. Both the present and all of the reported results suggested that ASD might be related to iatrogenic biomechanics.…”

Construct stability of an instrumented 2-level cervical corpectomy model following fatigue testing: biomechanical comparison of circumferential antero-posterior instrumentation versus a novel anterior-only transpedicular screw–plate fixation technique

“…Comparison of our results with those in the literature is difficult because few biomechanical studies have analyzed 2-level corpectomies [18,19,41,44]. The number of biomechanical studies on multilevel constructs including cyclic loading tests is even fewer [27,45,46].…”

“…It was available with 2 mm increments and entailed 2 cephalad and 2 caudad screw holes for rigid fixation of 1 unilateral anterior transpedicular screw (28 mm length, 3.5 mm diameter) and 1 contralateral VBS (16 mm length, 3.5 mm diameter). For insertion of anterior transpedicular screws, the freehand manual technique with radiographic control according to Yukawa et al [18] was done. In addition, visual inspection of specimens and pedicles for screw placement accuracy was done.…”

“…Accordingly, anterior decompression and cage stabilization with antero-posterior instrumentation ('360°') are increasingly recognized as the mechanical standard of reference for multilevel corpectomies, due to its excellent biomechanical characteristics [18,19].…”

Is "mini-invasive" technique for iliac crest harvesting an alternative to cervical cage implant? An overview of a large personal experience

“…[2633] This has allowed achievement of satisfactory results in the vast majority of patients. However, great debate has always existed as to whether or not fusion would be necessary,[138132431323437] and in the case fusion was considered necessary, which would be the best material for obtaining interbody fusion, whether autografts or allografts. [561819212732]…”