2. OBJECTIVES
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After completion of this lecture the
student should be able;
1. To know the basic definition of
biomechanics
2. To know the types of biomechanics
3. To know the basic terms of biomechanics
4. To know that why biomechanics is
important to study?
5. To know about the brief clinical
applications of biomechanics
4. WHAT IS
BIOMECHANICS?
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❖ Biomechanics;
❖ “ The application of mechanical principles in the study of
living organisms ”
Involves the principles of anatomy and physics in the
descriptions and analysis of movement.
The study of biological structures, processes and
functions by applying the methods and principles of
mechanics
Bio = Living
Mechanics = Forces & Effects
5. WHY STUDY
BIOMECHANICS?
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The purpose of studying Biomechanics is;
❖ To understand the forces acting on the human
body
❖ To manipulate these forces in treatment
procedures so that human performance may be
improved and further injury may be prevented.
6. WHY STUDY
BIOMECHANICS?
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❖ Better understanding of both joint function and
dysfunction
❖ Design improvements in devices e.g. joint
arthroplasty systems and orthotic devices
❖ To understand how the musculoskeletal system
functions
❖ Useful in patient evaluations and treatments
❖ Important for clinicians such as orthopaedic
surgeons and physical and occupational
therapists
7. KINEMATICS
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❖ Kinematics …
●Description of motion (e.g. how fast, how high, etc.)
without consideration given to its mass or the forces
acting on it.
❖ This may include …
✓ The movement of a single point on the body (e.g.
COG)
✓ Position of several segments (e.g. the Upper
Extremity)
✓ Position of a single joint
✓ Motions that occur between adjacent joint surfaces
❖ Kinematics examines how, when, and where a body
moves
8. TYPES OF
KINEMATICS
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❖ Arthrokinematics ……
✓ The movements occurring
between joint surfaces in
relation to the direction of
movement of the distal
extremity of the bone
❖ Osteokinematics …….
✓ Concerned with the movements
of the bones
9. KINETICS
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❖ Kinetics …..
✓ The study of forces that lead to produce, stop or modify
motions of the body
❖ It examines ……
✓ The causes of motion
✓ The internal and external forces that cause motion or
cause a body to remain at rest
✓ The interactions between these forces
❖ Forces affecting motion …..
✓ Gravity
✓ Muscle tension
✓ External resistance
✓ Friction
10. TYPES OF KINETICS
• Statics
• Refers to situations where the body or object remains at rest, or is moving
at a constant speed in a state of equilibrium.
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✓ Equilibrium is a balanced state in which there is no
acceleration
❖ Dynamics...
✓ Deals with the changes in motion (acceleration)
brought on by unbalanced forces
11. ARTHROKINEMAT
ICS
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❖ When a joint moves, three types of
motion can occur between the two
articulating surfaces
✓
✓
✓
Rolling or Rocking
Sliding or Gliding
Turning or Spinning
12. ARTHROKINEMAT
ICS
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❖ In a pure rolling motion
✓ Each subsequent point on one surface contacts a
new point on the other surface
❖ In sliding and spinning
✓ the same point on one surface contacts new
points on the mating surface
❖ Most normal joint movement has some
combination of rolling, sliding and spinning
13. ❖ The knee joint ……
✓ Shows the combination of
these movements most
clearly
✓ If there were only a rolling
of the condyles of the femur
on the tibial plateau, the
femur would roll off the tibia
and the knee would dislocate
ARTHROKINEMATICS
13
14. ARTHROKINEMATICS IN SIT TO
STAND
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❖ Rising from a Seated to a
Standing Position ……..
✓ the femur is extended on the
fixed tibia, the femoral
condyles roll and slide so that
they are always in contact with
the tibial condyles
✓ In the last part of knee
extension, the femur spins
(internally rotates on the tibia)
15. CLINICAL
IMPORTANCE OF
ARTHROKINEMA
TICS
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❖ Arthrokinematics (combination of Roll, Slide
and Spin) ……
✓ Permits a Large ROM while using a Small
Articular Surface
❖ If joints possessed only one of these motions
✓ The ROM would be limited
✓ The Larger joint surfaces would be
needed to accomplish the same ROM
16. KINEMATIC
CHAINS
A kinematic chain refers to a series
of articulated segmented links,
such as the connected pelvis,
thigh, leg, and foot of the lower
extremity (Lower Kinematic Chains )
❖ Open Kinematic Chain
✓ the distal segment of the chain moves
in space while the proximal segment is
fixed or stable
❖ Closed Kinematic Chain
✓ the distal segment is fixed, and
09/29p
/16roximal parts move 16
17. A SQUAT IS AN
EXAMPLE OF AN
CLOSE-CHAIN
MOTION
09/29/16
A leg curl from sitting
in a chair is an example
of an open-chain motion17
18. KINEMATIC CHAINS
ACTIVITIES
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❖
❖
❖
❖
✓
✓
✓
Reaching or bringing the hand to the mouth …….
Open - Chain Motion
Performing a chin-up …….. Closed - Chain Motion
Standing to Sit …….. Closed - Chain Motion
Sitting down in a Chair …… Closed - Chain Motion
The leg moves forward on the fixed foot (dorsiflexion)
The thigh approaches the leg (knee flexion)
The thigh approaches the pelvis (hip flexion)
19. ❖ Walking and Stair Climbing alternation of closed-
chain motion and open-chain motion
❖ Standing from a Chair When a person uses the
armrest of a chair to assist in coming to the standing
position, the hand is fixed and the forearm moves in
relation to the hand, the arm moves away from the
forearm, and the arm moves toward the trunk
❖ Crutch-walking the arms are fixed and the body
moves in relation to the arms ( Close – Chain
activity )
KINEMATIC CHAINS
ACTIVITIES
09/29/16 19
21. ARTHROKINEMATIC
RELATIVE TO THE
OSTEOKINEMATICS
❖ Convex-Concave Relationships ………..
✓ If the bone with the convex joint surface moves on the
bone with the concavity, the convex joint surfaces move
in the opposite direction to the bone segment ………….
Shoulder Movements
✓ If the bone with the concavity moves on the convex
surface, the concave Articular surfaces moves in the same
direction as the bone segment ………………………….
Knee Movements
22. EXAMPLES
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❖ Shoulder Abduction …….
✓ A downward motion of the humeral head on the Glenoid
Cavity occurs when the humerus is moving upward
❖ Knee Extension ……..
✓ An anterior movement of the concave tibial plateau on
the femur occurs during anterior movement of tibia
23. Convex - Concave Principle
Example
Normal
Interphalangeal
Joint Movements
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24. BIBLIOGRAPHY
• Susan-hall (2011 6th -edition) basic-biomechanics 2-5
• Pamela K Levangie ,Cynthia C Norkin (2006 4th edition) Joint
structure & Function 99-102
•
