Biomechanics II Lecture 5 PDF

‫السالم عليكم و رحمه الله و بركاته‬  Ahmed Torad, PhD, PT, Cairo university, 2020 Presente lecturer, Basic Science department, d by Faculty of Physical Therapy, Kafrelsheik Week Lecture Practical Gait 3...

‫السالم عليكم و رحمه الله و بركاته‬  Ahmed Torad, PhD, PT, Cairo university, 2020 Presente lecturer, Basic Science department, d by Faculty of Physical Therapy, Kafrelsheik Week Lecture Practical Gait 3 Applications on gait Week 4 Determinants of gait determinants Week Gait 4 Applications on kinetic analysis 5 Basics of kinetic analysis of gait of gait Gait 5 Week Muscular activities during gait Applications on muscular cycle activities during gait cycle 6 Gait 6 Applications on Week pathomechanics of gait Pathomechanics of gait 7  start talking about kinetic analysis of gait Describe different forces acting on the body Determine the interaction between internal and external forces Kinetic Analysis: the analysis of the forces acting on the body during gait. Gait forces are internal Inertia, andany external forces external resistance or Extern assistance, friction gravity al ground reaction force (GRF). ligaments, tendons, joint capsules, Muscles Intern bony components by resisting, al transmitting and absorbing forces. Joint reaction force  (A) External forces The force of gravity acts directly downward through the center of gravity (COG) of the body. It is represented by the line of gravity (LOG). LOG: It is vertical line which passes perpendicularly in the body connecting the COG of the segment above to the COG of the from lateral view: LOG during standing passes via: 1- Vertex. 2- Mastoid process behind the ear. 3- Anterior to atlanto- 5- At the junction of the cervico-dorsal vertebrae. 6- Anterior to the body of dorsal vertebrae. 7- At the junction of dorso- lumbar vertebrae. 8- Posterior to the body of the lumbar vertebrae. 9- Anterior to the 2nd sacral vertebrae. 10- Via the axis of the hip joint. 11- Anterior to the axis of LOG from front or back view: The vertical LOG passes through the body`s COG which bisects the body into two equal halves, with the body weight is equally distributed between the two  The effect of forces on body segments is determined by the location of LOG relative to the axis of motion of the body segment.  If the LOG passes directly through a joint axis, no gravitational torque is created around that joint. If the LOG passes at a distance away from the joint axis, (i.e. anterior or posterior to the joint axis) a gravitational torque is created. This torque will cause motion to  Torque (moment )= f *d So, the magnitude of the gravitational moment increases as the distance between LOG and the joint axis increases. Example 1: if the LOG passes anterior to the ankle axis, the gravitational torque will tend to rotate the tibia anteriorly resulting in ankle dorsiflexion. The Example 2: if the LOG passes anterior to the axis of the knee joint, the gravitational torque will tend to rotate the femur anteriorly causing extension of the knee.  What about this ??example The gravitational torque is opposed by a counterbalancing torque created in the opposite direction. This counterbalancing torque is done mainly by active muscular tension, passive  Do you still remember about the determinants of ??force Can you apply on gravitational ?force  Ground reaction force The GRF represents the force of the ground on the foot and it is equal in magnitude and opposite in direction to the force of gravity. The GRF is the most important external force during walking.  Center of Pressure The point of application of GRF is at the body`s center of pressure (COP) which is located in the foot in unilateral stance and between the feet in bilateral standing postures. COP moves along a path during gait COP moves along a path during gait: At the beginning of stance phase it starts at the posterolateral edge of the heel. Then it moves in a linear fashion through midfoot laterally then moves medially then moves to second and first toes during terminal  Ground Reaction Force Vector The GRGFV represents the forces that act on the body as a result of interaction with the ground, are composed of three forces: vertical force and two horizontal forces ( medial-lateral and anterior-posterior). The resultant of these three forces, the GRFV is equal in magnitude but opposite in direction to  When GRFV pass on a distance from joint axis, it tends to create torque toward its direction. This torque is opposed by a counterbalancing torque created by the muscles in the opposite direction. Ex: When GRFV pass  Pathway of GRFV during stance phase of gait ANK KNE HIP LE E P A A IC P P A LR A A P MS A A P TS A P P PS  Pathway of GRFV during stance phase of gait ANK KNE HIP LE E P A A IC P P A LR A A P MS A A P TS A P P PS ANK KN HIP LE EE P A A IC P P A LR A A P MS A A P TS A P P PS  Frontal plane analysis The relationship of the GRFV to the joint axes of the hip, knee, ankle and subtalar joints in the frontal plane may lie lateral or medial or neutral and that determines the type of moment either abduction or adduction ( or eversion and inversion) moments acting around the joints.  Frontal plane analysis Passage of the GRFV medial to the hip or knee creates adduction moment, while its location laterally creates abduction moment. Location of GRFV lateral to the subtalar joint creates eversion moment while its location medially creates inversion moment. Preswing Terminal Midstanc Loading Initial stance e response contact L M M M L Hip N M M M L Knee N M L L N Subtala r