Application of dual-trajectory screws in revision surgery for lumbar adjacent segment disease: a finite element study

Table 1 Material properties used by the finite element model

Component	Young’s modulus (MPa)	Poisson’s ratio	Cross-sectional area (mm²)
Vertebra
Cortical bone	12,000	0.3
Cancellous bone	100	0.2
Posterior element	3500	0.25
Sacrum	5000	0.2
Facet	11	0.2
Disc
Endplate	24	0.4
Nucleus pulpous	1	0.49
Annulus ground substance	4	0.4
Annulus fibres	360–550		0.15
Ligaments
ALL	7.8		63.7
PLL	10		20
LF	15		40
CL	7.5		30
ISL	10		40
SSL	8		30
ITL	10		1.8
Implants
Cage	3600	0.25
Screws and rods	110,000	0.28

ALL Anterior longitudinal ligament; PLL posterior longitudinal ligament; LF ligamentum flavum; CL capsular ligament; ISL interspinous ligament; SSL supraspinal ligament; ITL intertransverse ligament

ISSN: 1749-799X