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1.
J Math Biol ; 48(6): 623-46, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15164226

ABSTRACT

Alignment of joints with respect to the leg axis reduces the moment arm of external forces and therefore joint torques. Moreover, it affects the gearing of muscle forces and displacements. Thus, it influences tissue stress, cost of support and locomotion, and stability. Assuming that alignment is of general advantage we propose a mathematical criterion quantifying the axial alignment using the static torque equilibrium of a three-segment leg. Using this criterion derived from joint torque minimisation we asked for optimal leg designs (segment lengths and joint angles) at varied leg lengths. The trivial "straight is best" solution is excluded and the configuration space is restricted by geometrical constraints such as the ground contact. For different total leg lengths we could identify different optimal segment length combinations and appropriately adjusted joint angles. The extended human leg configuration characterised by a short foot and a combination of unequal ankle and knee angles emerges as a global optimum from our analysis. For crouched configurations allowing for larger leg extensions an angle symmetrical 1:1:1 segment length combination is best. The plantigrade optimum is enforced by the requirement of the distal segment (foot) being shorter than the opposite outer segment (thigh), as well as by the ground contact constraint. Different (e.g. digitigrade) geometries might be of advantage in different biological contexts with different constraints. The fact that small mammals use a crouched equal segment design implies that other locomotor requirements such as stability, strain rates, and acceleration distance per step might dominate.


Subject(s)
Leg/anatomy & histology , Models, Anatomic , Biomechanical Phenomena , Foot/anatomy & histology , Foot/physiology , Humans , Knee/anatomy & histology , Knee/physiology , Leg/physiology
2.
Arch Kriminol ; 213(1-2): 32-40, 2004.
Article in German | MEDLINE | ID: mdl-15012041

ABSTRACT

The aim of forensic biomechanics is the reconstruction of traumatic events based on the pathological findings in the victim's morphology, the accident traces and the car damages. The use of forensic documentation tools (e.g. Streifenlichttopometrie) enables 3-dimensional and proportional accurate documentation of the victim's body, of its injuries and of the car damages with submillimeter precision. The generated topographic image serves as input for a multi-body system model of the victim. It allows further to determine exactly the contact points between car and victim for a computer simulated dynamical reconstruction of the impact situation. In the case of an accident involving a car and a pedestrian the generation and application of computer aided 3-dimensional reconstruction models are shown.


Subject(s)
Accidents, Traffic/legislation & jurisprudence , Computer Graphics , Computer Simulation , Homicide/legislation & jurisprudence , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Multiple Trauma/physiopathology , Photography , Athletic Injuries/pathology , Athletic Injuries/physiopathology , Autopsy/legislation & jurisprudence , Humans , Jogging/injuries , Male , Models, Anatomic , Multiple Trauma/pathology , Software
3.
Arch Kriminol ; 213(1-2): 41-52, 2004.
Article in German | MEDLINE | ID: mdl-15012042

ABSTRACT

A real pedestrian-car-crash was reconstructed by use of a multi-body simulation. The main aspect was the use of an individual body surface for the human body model and the car. The simulation allowed a plausible reconstruction of the accident. A good correlation of the contact-pairs in the model and the real forensic data was achieved by variation of the hypothetical szenario.


Subject(s)
Accidents, Traffic/legislation & jurisprudence , Computer Graphics , Computer Simulation , Homicide/legislation & jurisprudence , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Multiple Trauma/physiopathology , Photography , Acceleration , Athletic Injuries/pathology , Athletic Injuries/physiopathology , Autopsy/legislation & jurisprudence , Humans , Jogging/injuries , Male , Models, Anatomic , Multiple Trauma/pathology , Software
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