Biomechanics Education Module

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Biomechanics Education Module

• David Gracia
• Kristen Kelley
• Vinit Prabhu

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Presentation Outline

• Definition of Biomechanics
• History of Biomechanics
• Basic Terms
• Lever Classes
• Types of Joints
• Gait Information
• Balance Information
• Posture Information
• How to use and measure for crutches.

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Biomechanics is

• The science concerned with the actions of
  forces, internal or external on the living body.

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Historical People and Biomechanics

• Aristotle might be considered the first
  biomechanician.
• Da Vinci also gained some insight into
  biomechanics. He analyzed muscle forces as acting
  along lines connecting origins and insertions and
  studied joint function.

• Galileo because he also made important
  contributions to biomechanics. He was
  particularly aware of the mechanical aspects of
  bone structure and the basic principles of
  allometry.

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Some Basic Information

• Coronal Plane Frontal
• Sagittal Plane Lateral
• Axial Plane Transverse

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Anatomical Directional Terminology

• Anterior In front of, front.
• Posterior After, behind, following, toward the
  rear.
• Distal Away from, father from the original.
• Proximal Near, closer to the origin.
• Dorsal Near the upper surface, towards the
  back.
• Ventral Toward the bottom, towards the belly.

• Inferior Below, under.
• Superior Above, over.
• Lateral Toward the side, away from the midline.
• Medial Toward the midline,
• middle, away from the side.
• Rostral Toward the front.
• Caudal Toward the back, toward the tail.

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Three Lever Classes
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Lever Classes in the Body
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Types of Joints

• Fibrous
• Fibrous joints connect bones without allowing any
  movement. The bones of your skull and pelvis are
  held together by fibrous joints. The union of the
  spinous processes and vertebrae are fibrous
  joints.
• Cartilaginous
• Cartilaginous joints are joints in which the
  bones are attached by cartilage. These joints
  allow for only a little movement, such as in the
  spine or ribs.
• Synovial
• Synovial joints allow for much more movement than
  cartilaginous joints. Cavities between bones in
  synovial joints are filled with synovial fluid.
  This fluid helps lubricate and protect the bones.
  Bursa sacks contain the synovial fluid.

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Joints

• Hinge A hinge joint allows extension and
  retraction of an appendage.
• Saddle A saddle joint allows movement back and
  forth and up and down, bot does not allow for
  rotation like a ball and socket joint.

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Joints

• Ball and Socket A ball and socket joint allows
  for radial movement in almost any direction. They
  are found in the hips and shoulders.
• Pivot
• Pivot joints allow rotation around an axis. The
  neck and forearms have pivot joints. In the neck
  the occipital bone spins over the top of the
  axis. In the forearms the radius and ulna twist
  around each other.

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Gait

• The phases of normal gait.

• Pain, Paralysis and Tissue Damage cause abnormal
  Gait.
• Abnormal Gait
• Ataxic unsteady
• Antalgic limp
• Apraxic loss of ability

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• What is Gait Analysis? Gait analysis is the
  study of walking. More specifically it is
  detailed observation of the movements of the arms
  and legs and the actions of the muscles when
  someone walks.
• Normal gait requires the correct functioning of
  the musculoskeletal system and nervous system.
• The basic divisions of the gait cycle are stance
  and swing.
• Stance is when the foot is on the ground.
• Swing begins when the foots is lifted from the
  floor until the heel is placed down.

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Balance is

• the ability to maintain equilibrium and
  orientation in a gravitational environment.
• The behavior that we call balance results from an
  interaction of many systems and subsystems. In
  dynamical systems terms, balance is a collective
  variable, a measure of the way a system or
  organism reduces a huge number of potential
  postural responses to a finite set of
  possibilities.

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Standing Bio-Mechanics

• To understand and assess balance, it is important
  to become familiar with some basic bio-mechanical
  terminology.
• First, like any other object, the body has a
  centre of gravity (CG) or center of mass (COM),
  which acts vertically downwards (towards the
  centre of the earth). In order for an object to
  remain stable this line from the CG to the ground
  must fall within the base of support. For the
  body, this base of support is composed of the two
  feet and the area between them.

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Balance Continued

• Postural reflexes are continually used to
  maintain stability. The three main sensory
  systems contribute inputs to these reflexes
•    visual
•    vestibular
•    somatosensory

• Somatosensory
• System

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Posture

• Posture
• "the position or bearing of the body"
• refers to the overall alignment of the various
  body parts to each other when the person is
  standing in a relaxed stance.
• Posture is the result of many underlying
  processes and tensional relationships throughout
  the body.
• As such posture becomes a measure of the overall
  balances in the body and can be used as a tool to
  assess if interventions have resulted in a change
  in overall body balance.
• The ideal posture is assumed to be when the
  earlobe, tip of the shoulder, hip joint and
  outside bump of the ankle all lined up on a plumb
  line.

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Optimal Posture vs. Faulty Posture

• Optimal posture
• State of muscular and skeletal balance that
  protects the supporting structures of the body
  against injury or progressive deformity
• Involves the positioning of the joints to provide
  minimum stress on the joints of the body.
• Faulty Posture
• Increases stress on the joints.

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Posture
Bad Posture
Good Posture
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Causes of Poor posture

• Structural Causes
• Permanent anatomical deformities not amenable to
  correction by conservative treatments
• Positional Causes
• Poor postural habit--for whatever reason, the
  individual does not maintain a correct posture
• Psychological factors, especially self-esteem.
• Respiratory conditions
• General weakness
• Loss of the ability to perceive the position of
  your body

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Tests for Postural Faults

• The Mirror Test- (Anterior View)
• Stand facing as full length mirror and check to
  see if
• your shoulders are level
• your head is straight no chin deviation ears
  are level
• the spaces between your arms and sides are
  equally spaced
• your iliac crests and hips are level
• kneecaps face straight ahead
• a 5 foot flare is shown
• arches are not flat
• no evidence of scrunching of the toes

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Orthotics and Posture

• Orthotic devices are employed to correct and
  support posture.
• An orthosis is an external appliance worn to
  restrict or assist motion or to transfer the load
  from one area to another.
• Adjustments allow all joints to function under a
  proportionate weight distribution.

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Crutches
Auxillary Crutches For temporary use (ex.
injury). Forearm Crutches For long term use
(ex. disability).
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Fitting Crutches

• The height should be 2 below the patients
  armpit.
• Nerve damage can be caused if the crutches extend
  all the way.
• Crutches must be rest against the ribs just below
  the armpit.

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Walking With Crutches

• Start by placing both crutches in front of you.
• Next step forward with the affected leg. The
  foot should line up with the crutches.
• Next step forward with the unaffected leg.
• Repeat.
• If both legs are affected the crutches can be
  used as canes. Move the opposite leg and
  opposite arm at the same time.

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Questions?