Transcript Knee Anatomy and Evaluation

Knee Anatomy and Evaluation
By
Dr. Sue Shapiro
Osseous Structures


Formed by the articulations of femur, tibia,
and patella.
They form 2 articulations
• Tibiofemoral joint
• Patellofemural joint

These two articulation are not independent
of each other but have a biomechanical
relationship
Femur Anatomy

Distal Aspect
• Condyles
• Articulate with patella
and tibia.
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Posterior Aspect
• Epicondyles
Tibial Anatomy

Tibial Plateus
• Medial plateau
• Lateral plateau

Anterior Portion
• Tibial tuberosity
Tibiofemoral & Femoral Joints

Motion in 2 planes
• Flexion/Extension &
IR/ER
• Motion of the tibia on
the femur
• Femoral Rotation
• Flex/Ext above
meniscus
• IR/ER below meniscus
• The Screw Home
Mechanism
• Results in ER of the
femur at terminal Ext.
Patellofemoral Joint

The patella a
triangular in both
sagital and frontal
plane
 The superior portion
ins wider than it distal
part
 5 distinct facets
• super., infer., lateral,
medial and odd
Osseous Abnormalities

Genus Varus and Valgus
• Knock Knee - excessive valgus
• Bowleg - excessive varus
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Genus Recurvatum - excessive extension
Shallow Trochlear Groove - redisposed to
ACL problems
Patella Abnormalities - camel sign
Osseous Abnormalities
Extra Articular Structures

Extensor Mechanism
• Function
• to provide deceleration of the patellofemoral
articulation at different points along
flexion/extension motion.
• Lateral retinaculum- static stabilizer
• Vastus Lateralis & IT band - dynamic stabilizers
• Medial retinaculum- static stabilizer
• Vastus Medialis & Adductor Magnus- dynamic
stabilizers
Extensor Mechanism

Extensor Mechanism
• Function
• to provide deceleration of
the patellofemoral
articulation at different
points
• Lateral retinaculum- static
stabilizer
• Vastus Lateralis & IT band
- dynamic stabilizers
• Medial retinaculum- static
stabilizer
• Vastus Medialis &
Adductor Magnus- dynamic
stabilizers
Extensor Mechanism

Superior of the patella
is supported by the
lateral and medial
patellofemoral
ligament, and inferior
by the patello-tibial
ligament
Q-Angle

The relationship b/t
line of pull of the
quadriceps and the line
of the tendon from the
midpoint on the patella
to its insertion on the
tibial tuberosity.
 Normal ranges
• Male - 13 degrees
• Female - 18 degrees
Patella Plica

A fold in the synovial
lining of the knee
 Signs
• Aggravated by
quadriceps exercise
• + Moviegoer’s sign
• Pop or snap as the knee
is flexed and extended
• Point tenderness at
medial and lateral
retinacular regions
Joint Capsule

Characteritics
• Medial, lateral and anterior aspects arises superior to
the femoral condyles and fixates distal to the tibial
condyle
• Posteriorly the capsule attaches to the posterior margins
of the femoral condyles above the Jt. Line & inferiorly,
to the posterior tibial condyle
• Strength of the capsule is reinforced by the collateral
lig. Medially & laterally, the retinaculum medially &
laterally, the oblique popliteal lig. and the patella
tendon
• Capsular attachment of the menisci along the peipheral
Collateral Ligament

Medial Collateral Lig.
• Deep & Superficial
Layers
• Primary Function is to
protect the knee against
valgus

Lateral Collateral Lig.
• No attachment to the
capsule or meniscus
• Primary restrain
against varus forces
Medial Knee Anatomy

Medial Knee muscle
Insertion
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•
Semimembranosus
Medial Gastroc
VMO
Adductor Magnus
Pes Anerine Group
Lateral Knee Anatomy

Posteriorlateral
Structures
• Arcuate Lig. Complex
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Popliteous Muscle
Lateral Grastroc Head
Arcuate Lig.
Posterior third of the
capsular lig.
Middle Third
• LCL
• Mid-lat capsular lig
• Bicep Femoris Muscle
Lateral Knee Anatomy

Anteriorlateral Aspect
• Joint Line
• Lateral patellar
restrainsts
• Ilitibial Tract &
insertion
• Fibular head
• Common peroneal
nerve

Posterior
Compartment
• Bicep Femoris
• Semimmembranosis
• Medial & lateral head
gastroc
• Popliteal fossa
• Popliteal pulse
Intra Articular Structures

Menisci
• Functions
• Distributed WB load
over a large surface area
• To increase stability
• Increase joint
congruency by
deepening the tibia
plateau
• Limits abnormal
movements
Menisci

Peripheral Meniscus
• The outer perimeter is
vascular & has the
ability to heal itself if
torn.
• Coronary ligament
attach outer perimeter
to tibial plateau

Medial Meniscus
• Avascular & can not
heal if torn
• Semimbranosus
attaches to the
posterior horn
• C-shaped & attaches to
the MCL and medial
capsule
Lateral Meniscus

O-shaped
 Popliteus tendon
attaches to the
posterior horn & this
causes pot. Translation
during knee flexion
Meniscus

Biomechanics
• Total Excursion
(ant/post)
• Medial - 6 mm
• Lateral - 12 mm
• Knee Extension
• Kaplan’s Lig. Pulls
menisci anteriorly
• Knee Flexion
• Semimembranosus
pulls medial menisci
• Popliteus pulls lateral
menisci

Mechanism of Injury
• Flexion/ Rotation
Injury
• In flexed position
(w/wt) trying to extend
the post. Horns get trap
and create a bucket
handle tear which
create pseudo-locking
Types of Menisci
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Most commonly torn in
the posterior horn
Unusual for a anterior
meniscal tear
Second most common in
middle
Names of meniscus tear
• Medial- Longitudinal,
complex, horizontal.
Cleavage
• Lateral - Radial,
longitudinal, bucket-handle
Cruciate Ligaments

Anterior Cruciate Lig.
• Anatomy of ACL
• Three Bundles
– Anteromedial
– Intermediate
– Posterolateral
• Special Teest
– Anterior Drawer
– Lachman’s Test
• Functions of ACL
– anterior displacement
of tibia to the femur
– Stabilizer of rotation
Anterior Cruciate Lig

Ligament Restrains
• Anterior Stability
• Provides 89% of
restraint to anterior
displacement
• Secondary restraints 15%
• Stress on ACL
• Greatest stress (30-0
deg,)

Factors affecting ACL
rupture
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•
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Equipment Design
Technique
Fitness
Anatomy
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•
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Intercodylar Notch
Narrow Notch
Quick Rotation (ER)
Notchplasty
• Braces
• Prophylactic &
Functional
Anterior Cruciate Lig
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Signs and Symptoms
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Pivot: deceleration + valgus stress + ER tibia
Hyperextension
Direct contact
80-90% hear/feel “pop/click”
Perception of the knee going out of place
Accumulation of effusion over 2-24 hours
Posterior Cruciate Lig.
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Anatomy

• Two bundles
• Blow to proximal tibia,
or fall on flexed knee
with plantar flexion
• Posteromedial
• Anteromedial

Stability
• Provides 95% of
restraint to posterior
displacement

Function
• Prevents posterior
displacement of the
tibia on femur
Mechanism of Injury
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PCL Testing
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Recurvatum
Sag Test
Clancy’s Step Up
Posterior Drawer
Bursas
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Intracapsular
• Suprapatellar
• Subpopliteal
• Semimembranosus

Extracapsular
• Prepatellar
• Superficial
infrapatellar
• Deep infrapatellar
Bursas

Functions
• During motion of flexion and extension
synovial fluid moves throughout the bursal
recesses to lubricate the articular surface and
the bursas compress compressing fluid in many
directions.
• Give protection to articular surfaces at the sites
of tendon attachment
Reflexes and Cutaneous
Distribution
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Reflexes
• Patellar reflex ( L3 - L4)
• Medial Hamstrings reflex (L5 - S1)
Reflexes and Cutaneous
Distribution
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Nerves
• Tibial Nerve
(L4-S3)
• Common
Peroneal Nerve
(L4-S2)
• Femoral Nerve
(L2-L4)
• Saphenous
Nerve (L3-L4)
Reflexes and Cutaneous
Distribution

Blood Supply
• Popliteal Artery
• Located in popliteal
fossa