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ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

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0<br />

-15 -10 -5 0 5 10 15<br />

3.3 Modeling of the ligaments<br />

-20<br />

-40<br />

-60<br />

Fig.2 Characteristic curves of the intervertebral disc L4-L5<br />

for flexion/extension, lateral bending and axial rotation<br />

The several vertebral bodies are not only connected by intervertebral discs but also by<br />

surrounding ligaments. The model the lumbar spine includes, in every functional spine<br />

unit, the ligaments: lig. longitudinale posterius, lig. longitudinale anterius, lig. flavum,<br />

lig. interspinale as well as the lig. supraspinale, lig. intertransversarium, and lig.<br />

iliolumbale. All ligaments have a characteristic initial length. If ligaments are stretched<br />

due to movement of the vertebrae they produce a reaction force corresponding to the<br />

extension l following their characteristic curves in Fig.3.<br />

ISL<br />

LF<br />

SSL<br />

PLL<br />

Torque [Nm]<br />

extension<br />

lateral<br />

bending<br />

ALL<br />

Force [N]<br />

60<br />

40<br />

20<br />

Angle [°]<br />

PLL<br />

axial rotation<br />

ALL<br />

ISL<br />

Deformation [mm]<br />

flexion<br />

Fig.3 Characteristic curves of the ligaments according to Panjabi [2]<br />

LF<br />

SSL

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