Biomechanics is a branch of science which employs mechanical and engineering principles to study bio

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What is Biomechanics

• Biomechanics is a branch of science which employs
  mechanical and engineering principles to study
  biological systems
• The objectives of Biomechanics are
• To understand human physical performance how do
  we perform movement and apply forces? how is
  human motion controlled and how can it be
  refined
• To understand how the biological tissues
  (materials) such as muscles, bones, cartilage,
  tendons and other soft tissues participate in
  such performance

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Objectives of Biomechanics Cont.

• To determine what kind of forces are acting on
  musculoskeletal tissue elements during physical
  activity
• To find out what are the mechanical properties of
  the relevant biological tissues how do they
  deform and endure the application of forces and
  how do they remodel
• To understand the mechanisms of injury what kind
  of loads cause tissues to fail (lose their
  structural integrity)

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Examples of Questions that Biomechanics can Answer

• Truck drivers are known to develop chronic lower
  back pain. Is there a critical vibration spectrum
  which will cause injury?
• Running can produce injuries to the joints of the
  lower limbs. Can athletic shoes help prevent
  injury by improving dynamic foot-ground
  interaction?
• Leg amputation and a continuous use of prosthesis
  is likely to produce lower back pain in later
  life. Can such arthritic development be prevented
  via control of the limb structural parameters?

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Examples of Biomechanical Applications

• Plastic surgeon needs to perform skin graft to
  cover an affected area of burned skin. What is
  the best way to prepare skin for grafting?
• Plastic surgeon needs to perform reconstructive
  surgery by transplanting cartilage from the
  sternum to the nose. How can he prevent stress
  related deformity
• How does one control an overuse syndrome in
  articular cartilage such as in osteoarthritis of
  the knee or hip

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Examples Cont.

• An orthopedic surgeon is presented with a case of
  a child where the hip joint is abnormally
  overloaded such that it causes degeneration of
  the joint cartilage. What kind of solution can be
  applied and what are the consequences
• Degenerative changes in a joint (Ankle, knee,
  hip, spine) may cause unbearable pain. The
  surgeon may consider fusion of the bony elements
  of the joint. What are the benefits and the
  shortcomings of the procedure.

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Examples Cont.

• An alternative solution to the same problem could
  be to resurface the joint with prosthetic
  components, what kind of loads need to be
  considered? how should the prosthetic component
  be interfaced to the bony tissue? what kind of
  geometry need to be reproduced?
• Runners often suffer joint injuries as a result
  of the frequent and extensive loading. Are shoes
  contributory to the alleviation of such stresses?
  Which shoe characteristics need to be considered?

• A child broke his tibia. Is plaster casting a
  good solution?

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Examples Cont.

• In the design of high acceleration equipment,
  such as airplanes, space rockets, roller
  coasters and road vehicles, how does one decide
  what kind of accelerations can the body sustain
  without being injured?
• In the design of off road equipment and vehicles,
  exposure to vibrations considers frequencies
  amplitudes duty cycle exposure time, etc.?
• In the design of seat belts for automotive
  application, what would be an optimal
  configuration to prevent rib fractures?

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Human Performance Biomech.

• Biomechanics in Rehabilitation
• Biomechanics in Sport
• Occupational Biomechanics

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Performance of Movement

• 1. How do we perform movement and/or apply
  forces

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The Musculoskeletal System
Anatomy Physiology
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Musculoskeletal Biomechanics

• Modeling of the MSK system with the objective of
  identifying forces exerted/acting on the Bones,
  Joints, Muscles and other soft tissues
• Application to Trauma, Prosthetics and Orthopedic
  Implant Design.

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Tissue Biomechanics

• The study of the mechanical behavior of
  biological tissues
• Force
• Deformation
• Growth and Remodeling
• Failure

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Bone Mechanics Remodeling
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Knowledge Required to deal with Biomechanical
Problems

• Anatomy understanding body structural
  composition
• Physiology understanding the body operational
  principles
• Applied Engineering-Mechanics The modeling tools

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The Principles of Biomechanical Analysis

• We approach the biomechanical analysis similarly
  to the mechanical analysis
• Determine the external forces either by static
  modeling or by dynamic modeling
• Determine the internal forces via fragmentation
  and free body diagrams
• Attribute the internal forces and moments to the
  corresponding tissues
• Perform Tissue Mechanics analysis

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Performance Analysis is the way to Determine the
External Loading

• Document the motion (kinematics)
• Measure the applied forces
• Assess muscular activity (EMG)
• Analyze trajectories of motion
• Develop a dynamic model to determine the forces
• Suggest ways to ptimize the performance
• Alternatively, analyze the motions of an elite
  athlete and adopt his/her criteria

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A Typical Protocol For Tissue Mechanics Study

• Determine the performance characteristics
• Motion, External Forces (measurable)
• Focus on a particular body part/tissue of
  interest and determine the forces acting on it
• Typically a model is required
• Subject the specific part/tissue to the applied
  forces and obtain its mechanical behavior
  comparing loads and deformations
• Compare the forces to the tissue endurance values

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1. Document the motion (kinematics)
Data Presentation
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2. Measure the applied forces
Ground Forces acting during locomotion
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Analyze Trajectories of Motion
Determine velocities and accelerations