Transcript Knee Injuries

The Knee Joint
The Knee Joint
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Hinge joint?
Double-condyloid joint
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The locking of the knee into full extension is often
referred to as the “screw home” movement
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Flexion and Extension
Internal and External Rotation
Tibia externally rotates 10 degrees
Biceps femoris
Initial flexion of the knee, the knee “unlocks”
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Tibia internally rotates
Popliteus, semitendonosus, semimembranosus
Two-Joint Muscles
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Uniarticulate
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A muscle that crosses one joint
Biarticulate
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A muscle that crosses two joints
Two-Joint Muscles
Two-joint muscles are most effective when
either the origin or insertion is stabilized.
 Why?
 Explain the benefit of leaning backwards
while kicking a ball.
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Two-Joint Muscles
A muscle's ability to contract dependent upon its
length, or degree of contraction.
 A muscle can contract more forcefully when it is
slightly stretched.
 Muscle generates maximal concentric tension at
a length 1.2 times its resting length.
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Two-Joint Muscles
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During knee FLEXION, what muscle group is being
stretched?
What affect will this have on that muscle groups ability to
contract?
During knee EXTENSION, what muscle group is being
stretched?
What affect will this have on that muscle groups ability to
contract?
How do these relationships help during running?
Quadriceps
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The quadriceps function as a
decelerator when it is necessary to
decrease speed for changing
direction or running downhill or to
prevent falling when landing.
What type of contraction does
deceleration require?
What ultimate affect does this type
of contraction have on muscle
strength?
What ultimate affect does this type
of contraction have on muscle
soreness?
Quadriceps
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What is a typical test that
measures the strength of the
quadriceps muscles?
Strong quadriceps muscles
are essential for maintenance
of patellofemoral stability
The vastus medialis muscle is
not emphasized until the last
10-20 degrees of knee
extension
Acute Knee Injuries
Causes of ACL Injuries
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Cutting (rotation)
Hyperextension
 Straight knee landing
 When the knee is
extended, the ACL is at
it’s maximal length
putting it at an
increased risk of
tearing
Unhappy Triad
1.
2.
3.
ACL
Medial collateral
ligament
Medial meniscus
Lachman Test and Anterior Drawer Test
Normal knees have
2-4 mm of anterior
translation and a solid
end point
 ACL injury will have
increased translation
and a soft end point
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Chronic Injuries
1.
2.
3.
4.
5.
6.
Patellar Tendonitis
Patellofemoral Pain Syndrome
Subluxation of Patella
Chondromalacia
Osgood-Schlatters Disease
IT Band Syndrome
Patellar Tendonitist
Patellar Tendonitist
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Due to high deceleration or eccentric forces of the quadriceps at
the knee during landing
As you land the hamstrings cause your knee to flex to absorb the
shock of impact
In order to control or decelerate the flexion produced by the
hamstrings, the quadriceps muscles contract eccentricly
Eccentric contractions occur as the muscle is being lengthened or
stretch
Eccentric contractions produces high amounts of force, and
therefore stress to the patellar tendon
Patellar Tendonitist
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Prevention: strong quadriceps muscles
Squats
Lunges
More Quadriceps Exercises
Leg Extension
Leg Press
More Quadriceps Exercises
Plyometric or Jump Training
Uphill Running
Hamstring Exercises
Hamstring Exercises
Chondromalacia
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This is a Latin term meaning “bad cartilage” or breakdown or
softening of the articular cartilage of the patella
The cartilage surface on the underside of the patella becomes
soft. Part of the cartilage can become stringy and flake off at
times. Part of the surface may become roughened.
Causes (FYI)
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Training errors
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Weak vastus medialis muscle
Large Q angle
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6.
Increasing intensity too soon
Greater than 25 for women and 20 for men
Pronation of the foot causing the tibia to medial rotate
Gender - more common in women
Poor footwear and/or surface
Patellofemoral Stability
Osgood- Schlatter Disease
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Overuse, not a diesease.
Inflammation to the patellar tendon at the tibial
tuberoscity
Most common in adolescents (8-13 year olds girls
and 10-15 year old boys); age of rapid bone
growth
Osgood- Schlatter Disease
Anterior pain about 2-3 inches below the
patella
 Avulsion fracture
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IT Band Syndrome
Excess duration or
time exercising
 Hip abductor
weakness
 Tight hip abductors
and/or IT band
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