Transcript KNEE LIGAMENTS - Amirkabir University of Technology

KNEE
LIGAMENTS
By KAREN MINASSIAN
8533080
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Knee Anatomy
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What is ligament ?
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Knee ligaments function
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Knee ligaments injuries
Knee Anatomy
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Bony Anatomy
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Upper Leg
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Lower Leg
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Femur
Tibia
Fibula
Patella
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Lower Leg Musculature
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Anterior
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Medial
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Tibialis Posterior
Extensor Digitorum Longus
Extensor Hallicus Longus
Lateral
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Tibialis Anterior
Peroneals
Posterior
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Gastrocnemius
Soleus
Tibialis Anterior
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Thigh Musculature
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Anterior
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Quadriceps Femoris
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Vastus Lateralis
Vastus Medialis
Vastus Intermedius
Rectus Femoris
Posterior
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Biceps Femoris
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Long Head
Short Head
Semi-tendonosis
Semi-membranosis
Gracilis
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Ligaments
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Medial Collateral
Lateral Collateral
Anterior Cruciate
Posterior Cruciate
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Cartilage
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Medial Meniscus
Lateral Meniscus
Articular Cartilage
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Nerve Supply
Blood Supply
WHAT IS LIGAMENT ?
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Any set of collagen fibres
joining one bone of an
articulating pair to the
other is called a ligament.
Thus, the articular bursal
wall is a ligament, called
either the fibrous capsule
or the joint capsule.
KINDS OF LIGAMENTS
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Capsular ligaments
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Noncapsular ligaments
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Internal
External
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proximate
remote
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Contrary to the opinion of earlier anatomists, ligaments
are not normally responsible for holding joint surfaces
together. This is because a set of collagen fibres, like a
string, can exert a reactive force only if stretched and
tightened by some tensile stress. Normally, the bones at
a joint are pressed together (when at rest) by the action
of muscles or by gravity. An individual ligament can stop
a movement that tightens it. Such a movement will
loosen the ligaments that would be tightened by the
opposite movement. The one exception to this case is
the movement that brings a joint into the close-packed
position. This movement is brought about by a
combination of a swing with a spin of the moving bone.
Experiments show that the combination of movement
screws the articular surfaces firmly together so that they
cannot be separated by traction and that the capsule and
most of the ligaments are in simultaneous maximal
tautness.
BIOMECHANICS OF THE KNEE
JOINT
tibio-femoral
AXIS
MOTION
lateral
flexion/extension
longitudinal tibial rotation
CLOSEPACKED
POSITION
extension
Ligaments function to limit joint motion
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Certain motions elongate certain ligaments.
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When they elongate, ligaments develop force.
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The force resists further lengthening of the
ligament, and resists or limits further joint
motion.
Knee ligaments function
MCL
LCL
PCL
ACL
MCL
LCL
PCL
ACL
MCL
LCL
Resist/Limit extension
Resist/Limit rotation
Resist valgus stress/force
Resist varus stress/force
TIBIAL GLIDE IS CAUSED BY LIGAMENTOUS
FORCES.
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during knee flexion:
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tibia rolls posteriorly, elongating ACL.
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ACL's pull on tibia causes it to glide posteriorly.
during knee extension:
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tibia rolls anteriorly, elongating PCL.
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PCL's pull on tibia causes it to glide anteriorly.
Development of passive (viscoelastic)
force
HUMAN TISSUES,
INCLUDING MUSCLES,
BEHAVE LIKE SPRINGS; THEY
ARE ELASTIC.
At lengths greater than their
resting length (l0), they
develop tension or force. This
force is passive, since it exists
whether or not the muscle is
active.
Passive force, like active
force, acts in a direction from
the muscle’s points of
attachment toward its center.
Development of active force
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Active muscle force is proportional to number of active
actin/myosin binding sites.
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The number of sites available for actin/myosin binding
depends on the muscle's length.
Length-tension properties of muscle
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A muscle's length-tension curve illustrates how its
force comes from two sources:
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Actice tension derives from the interaction between myosin
and actin active tension.
Passive tension can develop in the muscle's complex
connective tissue.
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The distinctive stiffness
properties of any soft
tissue are illustrated by
its length-tension curve.
The knee's anterior
cruciate ligament has a
distinct length-tension
curve.
knee motion simulator jig
Injuries
The knee is a commonly injured joint, Within recent
years, the increase in ACL, anterior cruciate
ligament, injuries has been remarkable, as it is one
of the most commonly injured ligaments of the
knee. Trauma to this ligament within the knee can
be serious, and injuries to it usually occur during
high-risk athletic activities such as basketball,
football, skiing, and soccer etc. This injury is so
common that it is currently estimated that
approximately 200,000 ACL’s are injured annually,
with 100,000 ACL reconstructions performed each
year.
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A 1st degree sprain involves damage to few ligament fibres.
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A 2nd degree injury means damage to a larger muscle group with
the ligaments still intact
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A 3rd degree sprain involves rupture of the whole ligament. Other
structures such as the knee, cartilage and the anterior cruciate
ligament can also be damaged due to the force applied to it.
Mechanism of Injury
Direct blow to
Anterior tibia
Hyperextension injury
Dashboard injury
Fall onto a flexed knee with foot
In plantarflexion
Knee Injuries in
Basketball
Knee Injuries in football
Skiing Injuries
Sergical Repair
Questions???