Can an Endplate-conformed Cervical Cage Provide a Better Biomechanical Environment than a Typical Non-conformed Cage?: A Finite Element Model and Cadaver Study

被引：15

作者：

Zhang, Fan ^{[1
]}

Xu, Hao-cheng ^{[1
]}

Yin, Bo ^{[2
]}

Xia, Xin-lei ^{[1
]}

Ma, Xiao-sheng ^{[1
]}

Wang, Hong-li ^{[1
]}

Yin, Jun ^{[1
]}

Shao, Ming-hao ^{[1
]}

Lyu, Fei-zhou ^{[1
,3
]}

Jiang, Jian-yuan ^{[1
]}

机构：

[1] Huashan Hosp, Dept Orthopaed, Shanghai, Peoples R China

[2] Shanghai Med Coll, Dept Clin Med, Shanghai, Peoples R China

[3] Fudan Univ, Peoples Hosp Shanghai 5, Dept Orthopaed, Shanghai, Peoples R China

来源：

ORTHOPAEDIC SURGERY | 2016年 / 8卷 / 03期

基金：

中国国家自然科学基金;

关键词：

Biomechanical; Cadaver study; Cage; Endplate-conformed; Finite element method; ADJACENT SEGMENT DEGENERATION; INTERBODY FUSION; INTRADISCAL PRESSURE; TITANIUM CAGE; SPINE FUSION; SUBSIDENCE; DISKECTOMY; MOTION; IMPLANT; LEVEL;

D O I：

10.1111/os.12261

中图分类号：

R826.8 [整形外科学]; R782.2 [口腔颌面部整形外科学]; R726.2 [小儿整形外科学]; R62 [整形外科学（修复外科学）];

学科分类号：

摘要：

ObjectivesTo evaluate the biomechanical characteristics of endplate-conformed cervical cages by finite element method (FEM) analysis and cadaver study. MethodsTwelve specimens (C-2-C-7) and a finite element model (C-3-C-7) were subjected to biomechanical evaluations. In the cadaver study, specimens were randomly assigned to intact (I), endplate-conformed (C) and non-conformed (N) groups with C4-5 discs as the treated segments. The morphologies of the endplate-conformed cages were individualized according to CT images of group C and the cages fabricated with a 3-D printer. The non-conformed cages were wedge-shaped and similar to commercially available grafts. Axial pre-compression loads of 73.6 N and moment of 1.8 Nm were used to simulate flexion (FLE), extension (EXT), lateral bending (LB) and axial rotation (AR). Range of motion (ROM) at C4-5 of each specimen was recorded and film sensors fixed between the cages and C-5 superior endplates were used to detect interface stress. A finite element model was built based on the CT data of a healthy male volunteer. The morphologies of the endplate-conformed and wedge-shaped, non-conformed cervical cages were both simulated by a reverse engineering technique and implanted at the segment of C4-5 in the finite element model for biomechanical evaluation. Force loading and grouping were similar to those applied in the cadaver study. ROM of C4-5 in group I were recorded to validate the finite element model. Additionally, maximum cage-endplate interface stresses, stress distribution contours on adjoining endplates, intra-disc stresses and facet loadings at adjacent segments were measured and compared between groups. ResultsIn the cadaver study, Group C showed a much lower interface stress in all directions of motion (all P < 0.05) and the ROM of C4-5 was smaller in FLE-EXT (P = 0.001) but larger in AR (P = 0.017). FEM analysis produced similar results: the model implanted with an endplate-conformed cage presented a lower interface stress with a more uniform stress distribution than that implanted with a non-conformed cage. Additionally, intra-disc stress and facet loading at the adjacent segments were obviously increased in both groups C and N, especially those at the supra-jacent segments. However, stress increase was milder in group C than in group N for all directions of motion. ConclusionsEndplate-conformed cages can decrease cage-endplate interface stress in all directions of motion and increase cervical stability in FLE-EXT. Additionally, adjacent segments are possibly protected because intra-disc stress and facet loading are smaller after endplate-conformed cage implantation. However, axial stability was reduced in group C, indicating that endplate-conformed cage should not be used alone and an anterior plate system is still important in anterior cervical discectomy and fusion.

引用

页码：367 / 376

页数：10