Abstract: BACKGROUND: When performing percutaneous minimally invasive transforaminal lumbar interbody fusion to implant an intervertebral cage, due to the narrow operating range of the approach, there is a risk of nerve root injury or poor position of cage. To solve the above problems, a novel mechanical deformable press-fit cage (YP-cage) was invented.
OBJECTIVE: To preliminarily evaluate the mechanical strength characteristics of this new lumbar fusion device YP-cage.
METHODS: Static axial compression and torsion tests were conducted on 9, 11, and 13 mm YP-cages (n=9) and poly (ether ether ketone) (PEEK)-cages (n=9). The force-displacement curves were collected to calculate yield displacement and load, ultimate load displacement and stiffness, yield angular displacement and torque, ultimate load and angle displacement torque and stiffness for comparative analysis. 
RESULTS AND CONCLUSION: (1) In the static axial compression test, YP-cage was superior to PEEK-cage in terms of stiffness, yield load, ultimate displacement, and load limit in three groups of tests (9, 11, 13 mm) (P < 0.01), but the yield displacement of YP-cage was smaller than that of PEEK-cage (P < 0.05). (2) In the static torsion test, there was no significant difference in the ultimate torsion angle between YP-cage and PEEK-cage in 9 mm group. YP-cage was lower than PEEK-cage in yield torque, yield torsion angle, and ultimate torque (P < 0.01), while YP-cage torsional stiffness was greater than PEEK-cage in 9 mm group and 11 mm group (P < 0.01). (3) The results show that the novel press-fit mechanical lumbar cage has higher compressive strength than PEEK cage, but the torsional strength is not as good as PEEK-cage.

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

Key words: intervertebral fusion cage, transforaminal lumbar interbody fusion, spinal fusion, mechanical performance, physical property