Biomedical Engineering Reference
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Fig. 5.43 Simulated motions of a FE-spine model: a dorsal-and ventral flexion and neutral mid
position, b lateral flexion and mid position, c combined motion from flexion and rotation
5.3.3.4 Angle Displacement between Vertebrae
The relative displacement of adjacent vertebrae differs and strongly depends on
biological variability, i.e. gender, age and physical condition. To assign realistic
joint characteristics, a feasible approach was to adopt literature values,
(Prometheus 2005) and (Kampandji 2001) which however, differ substantially.
Mean values were therefore established, cf. Fig. 5.42 .
In Fig. 5.43 and based on the values of Fig. 5.42 , the simulated motions of the
FE-spine model are depicted in the dorsal, ventral and neutral mid position as well
as laterally flexed with neutral mid position and a combined motion from both
flexion and a rotation (cf. Fig. 5.40 ).
5.3.3.5 Hip and Knee Joints
During loading in the recumbent or seated body position, the kinematic modelling
of the joint connections of the spine, as well as of the knee and hip joints, is
simplified by modelling the hinge joints with only one rotational degree of free-
dom. The dynamic modelling of the knee and hip joints is analogue to that of the
spine, employing moment-angle characteristics.
5.3.4 B OSS -Models for Recumbent Posture
Percentile: The percentile definition as a special case of the quantile (also
fractile), as used in statistics, plays in important role in human modelling in the
seated or recumbent body position in automotive or airplane seating. By the use of
percentile (lat. ''hundredth value''), also percentage rating, a distribution is divided
into 100 equal parts. Percentile thus divides a unit in segments of 1 %, such that
below the 95th percentile, 95 % of all cases will be encountered.
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