Biomechanical comparison of polyetheretherketone rods and titanium alloy rods in transforaminal lumbar interbody fusion: a finite element analysis

Table 1 Definition of materials properties in the finite element models

Materials	Element type	Young’s modulus (MPa)	Poisson’s ratio (µ)	Cross-Sectional Area (mm2)
Bone
Cortical bone	C3D4	12,000	0.3
Cancellous bone	C3D4	100	0.2
Bony endplate	C3D8I	1 200	0.29
Cartilage endplate	C3D8I	24	0.4
Intervertebral disc
Nucleus pulposus	C3D8I	1	0.49
Annulus ground	C3D8H	Hyperelastic C10 = 0.18 C01 = 0.045
Annulus fiber	T3D2	Hypoelastic (360–550 MPa)
Ligaments	T3D2	Hypoelastic
Anterior longitudinal		7.8 (< 12%), 20 (> 12%)		63.7
Posterior longitudinal		10 (< 11%), 20 (> 11%)		20
Ligamentum flavum		15 (< 6.2%), 19.5 (> 6.2%)		40
Supraspinous		8.0 (< 20%), 15 (> 20%)		30
Interspinous		10 (< 14%), 11.6 (> 14%)		40
Intertransverse		10 (< 18%), 58.7 (> 18%)		1.8
Capsular		7.5 (< 25%), 32.9 (> 25%)		66
Screws	C3D4	110,000	0.3
Rods
Ti-6Al-4 V	C3D4	110,000	0.3
PEEK	C3D4	3600	0.25
Cage	C3D4	3600	0.25
Bone grafts	C3D4	100	0.2

Ti: Titanium; Al: Aluminum; V: Vanadium; PEEK: polyetheretherketone; C3D4: 4-node tetrahedral elements; C3D8: 8-node hexahedral elements; T3D2: 2-node truss elements

ISSN: 1471-2482