Download classification of knee joint

KNEE JOINT
LEARNING OBJECTIVES
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Discuss the classification of knee joint
Describe the articular surfaces of this joint
Discuss the articular capsule
Learn about the synovial membrane and the synovial cavity
Enumerate the ligaments of knee joint
Describe the bursa around the knee joint
Describe the blood and nerve supply of the knee joint
CLASSIFICATION OF KNEE
JOINT
• The knee or Genual Joint is formed between lower
end of femur, the upper end of tibia and the
posterior surface of patella.
• Between anterior surface of lower end of femur and
posterior surface of patella is Gliding Synovial
variety
• Between inferior surface of condyles of femur and
superior surface of condyles of tibia is hinge variety
of synovial joint.
ARTICULAR SURFACES OF THE
KNEE JOINT
 The bones involved are the femur, tibia, and patella.
 The articular surfaces are the large curved condyles of the
femur, the flattened condyles of the tibia, and the facets of
the patella.
 On the superior surface of each tibial condyle, there is an
articular area for the corresponding femoral condyle.
 These areas, commonly referred to as the medial and
lateral tibial plateau, are separated from each other by a narrow, nonarticular
area, which widens anteriorly and posteriorly into anterior and posterior
intercondylar areas, respectively.
LIGAMENTS
1. Fibrous capsule
2. Ligamentum patellae
3. Tibial colletral or medial ligament
4. Fibular collateral or Lateral ligament
5. Oblique popliteal ligament
6. Arcuate popliteal ligament
7. Anterior cruciate ligament
8. Posterior cruciate ligament
9. Medial meniscus
10. Lateral meniscus
11. Transverse ligament
ARTICULAR CAPSULE OF THE
KNEE
• The fibrous capsule is strong, especially where
local thickenings of it forms ligaments.
• Superiorly, the fibrous capsule is attached to the
femur, just proximal to the articular margins of the
condyles
• Posteriorly, it is attached to the intercondylar line.
• It is deficient on the lateral condyle, which allows the
tendon of the popliteus muscle to pass out of the
joint and insert into the tibia.
• Inferiorly the fibrous capsule is attached to the
articular margin of the tibia, except where the
tendon of the popliteus muscle crosses the bone.
• Here the fibrous capsule is prolonged inferolaterally over the
popliteus to the head of the fibula, forming the arcuate
popliteal ligament.
• The fibrous capsule is supplemented and strengthened by five
intrinsic ligaments;
1. patellar ligament
2. fibular collateral ligament
3. tibial collateral ligament
4. oblique popliteal ligament
5. arcuate popliteal ligament
SYNOVIAL MEMBRANE
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The synovial membrane of the knee-joint is the largest and most extensive
in the body.
• Commencing at the upper border
of the patella, it forms a large culde-sac beneath the Quadriceps
femoris on the lower part of the
front of the femur
• Frequently communicates with a
bursa interposed between the
tendon and the front of the femur.
• The pouch of synovial membrane
between the Quadriceps and front
of the femur is supported, during
the movements of the knee, by a
small muscle, the Articularis genu,
which is inserted into it.
PATELLAR LIGAMENT OR
LIGAMENTUM PATELLAE
• This very strong, thick band is the continuation of the
tendon of the quadriceps femoris muscle.
• The patella is a sesamoid bone in this tendon.
• The patella is continuous with the fibrous capsule of the
knee joint and is most easily felt when the leg is
extended.
• The superior part of its deep surface is separated from
the synovial membrane of the knee joint by a mass of
loose fatty tissue called the infrapatellar fatpad.
• The inferior part of the patellar ligament is separated
from the anterior surface of the tibia by the deep
infrapatellar bursa.
TIBIAL COLLATERAL LIGAMENT
• This ligament (also known as the medial ligament) is a
strong, flat band, 8 to 9 cm long, which extends from the
medial epicondyle of the femur to the medial condyle
and superior part of the medial surface of the tibia.
• It is a thickening of the fibrous capsule of the knee joint
and is partly continuous with the tendon of the adductor
magnus muscle.
• The deep fibers of the tibial collateral ligament are firmly
attached to the medial meniscus and the fibrous
capsule of the knee.
FIBULAR COLLATERAL
LIGAMENT
• The fibular collateral ligament (lateral ligament) is a
round cord about 5 cm long.
• It extends inferiorly from the lateral epicondyle of
the femur to the lateral surface of the head of the
fibula.
• The tendon of the popliteus muscle passes deep
to the fibular collateral ligament, separating it from
the lateral meniscus.
OBLIQUE POPLITEAL LIGAMENT
• The broad band is an expansion of the tendon of the
semimembranosus muscle. The oblique popliteal
ligament strengthens the fibrous capsule of the knee
joint posteriorly.
• It arises posterior to the medial epicondyle of the tibia
and passes superolaterally to attach to the central part
of the posterior aspect of the fibrous capsule of the
knee joint.
ARCUATE POPLITEAL LIGAMENT
• This Y-shaped band of fibres also strengthens the fibrous
capsule posteriorly.
• The stem of the ligament arises from the posterior
aspect of the head of the fibula.
• As it passes superomedially over the tendon of the
popliteus muscle, the arcuate popliteal ligament spreads
out over the posterior surface of the knee joint.
• It inserts into the intercondylar area of the tibia and the
posterior aspect of the lateral epicondyle of the
femur.
CRUCIATE LIGAMENTS
• The cruciate ligaments are strong, rounded
bands that cross each other obliquely in a
manner similar to an X.
• They are named anterior and posterior
according to their site of attachment to the tibia,
i.e., the anterior cruciate ligament attaches to the
tibia anteriorly and the posterior cruciate ligament
attaches to it posteriorly.
• These ligaments are essential to the
anteroposterior stability of the knee joint,
especially when it is flexed.
• These are very strong ligaments within the
capsule of the joint but are outside the synovial
cavity.
• Joining the femur and tibia, they are located
between the medial and lateral condyles and are
separated from the joint cavity by the synovial membrane.
• The synovial capsule lines the fibrous capsule, except posteriorly where it is
reflected anteriorly around the cruciate ligaments.
ANTERIOR CRUCIATE LIGAMENT
• The weaker of the two ligaments, the anterior cruciate
ligament arises from the anterior part of the
intercondylar area of the tibia, just posterior to the
attachment of the medial meniscus.
• It extends superiorly, posteriorly, and laterally to attach
to the posterior part of the medial side of the lateral
condyle of the femur.
• The anterior cruciate ligament, is slack when the knee
is flexed and taut when it is fully extended
• Prevents posterior
displacement of the femur on
the tibia on hyperextension of
the knee joint.
• When the joint is flexed at a
right angle, the tibia cannot
be pulled anteriorly because
it is held by the anterior
cruciate ligament.
POSTERIOR CRUCIATE LIGAMENT
• This is the stronger of the two ligaments.
• It arises from the posterior part of the intercondylar area of
the tibia and passes superiorly and anteriorly on the medial
side of the anterior cruciate ligament to attach to the anterior
part of the lateral surface of the medial condyle of the femur.
• The posterior cruciate ligament is the first structure
observed when the knee joint is surgically opened
posteriorly.
• The posterior cruciate ligament, which tightens during flexion
of the knee joint, prevents anterior displacement of the
femur on the tibia or posterior displacement of the tibia.
• It also helps to prevent hyperflexion of the knee joint.
In the weight bearing flexed knee, it is the main
stabilizing factor for the femur, e.g., when walking
downhill or downstairs.
MENISCI OF KNEE JOINT
• The medial and lateral menisci (G. crescents) are
crescentic plates of fibrocartilage on the articular surface
of the tibia.
• These act like shock absorbers.
• Because they are basically C-shaped, they were formally
called semilunar cartilages.
• They are wedge-shaped in the transverse section.
• The menisci are firmly attached at their ends to the intercondylar area of
the tibia.
• The menisci deepen the articular surfaces of the tibia where they
articulate with the femoral condyles.
 Their superior surfaces are slightly concave for reception of
their condyles, whereas their inferior surfaces rest on the
tibial condyles and are flatter.
 The menisci are thick at their peripheral attached
margins and thin at their internal unattached edges.
 Being smooth and slightly movable, the menisci fill the
gaps between the femur and tibia that would otherwise be
present during movements of the knee joint.
 Their external margins are attached to the fibrous
capsule of the knee joint and through it to the edges of the
articular surfaces of the tibia.
 The capsular fibers that attach the thick, convex margins of
the menisci to the tibial condyles are called coronary
ligaments.
 A slender fibrous band, called the transverse ligament of the knee, joins
the anterior edges of the two menisci.
 This connection allows them to move together during
movements of the femur on the tibia.
 The thickness of this ligament varies in different people;
sometimes it is absent.
 The thick peripheral margins of the menisci are vascularised by
genicular branches of the popliteal artery, but the thin
unattached edges of the interior of the joint are avascular.
MEDIAL MENISCUS
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This C-shaped cartilage is broader
posteriorly than anteriorly.
Its anterior end or horn (L. cornu) is
attached to the anterior intercondylar area of
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the tibia, anterior to the attachment of the anterior cruciate ligament.
The posterior end or horn is attached to the posterior intercondylar area,
anterior to the attachment of the posterior cruciate ligament and between
the attachments of the lateral meniscus and the posterior cruciate ligament.
The medial meniscus is firmly attached to the deep surface of the tibial
collateral ligament.
LATERAL MENISCUS
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This C-shaped cartilage is nearly circular and
conforms to the rather circular lateral tibial condyle.
The lateral meniscus is smaller and more freely
movable than the medial meniscus, but it covers a
larger area of articular surface than does the medial
meniscus.
The tendon of the popliteus muscle and bursa
separate the lateral meniscus from the fibular collateral
ligaments.
The anterior and posterior horns of the lateral
meniscus are attached close together in the anterior and
posterior intercondylar areas.
A strong tendinous slip, called the posterior
meniscofemoral ligament, joins the lateral meniscus to the
posterior cruciate ligament and the medial femoral condyle.
BURSAE AROUND KNEE
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Several bursa are present around the knee, to reduce
friction, because most tendons around the knee joint
run parallel to the bones and pull lengthwise across the
joint.
Four bursa communicate with the synovial cavity of the
knee joint; they lie deep to the tendons of :
o The quadriceps femoris
o The popliteus
o The medial head of the gastrocnemius
muscle.
There are around 13 bursae
Anterior: 4 bursae
 Subcutaneous prepatellar bursa
 Subcutaneous infra patellar bursa
 Deep infrapatellar bursa
 Suprapatellar bursa
Lateral: 4 bursae
Medial: 5 bursae
SUPRAPATELLAR (QUADRICEPS)
BURSA
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This large saccular extension of the synovial capsule passes
superiorly between the femur and the tendon of the quadriceps
femoris muscle.
The suprapatellar bursa permits free movement of the
quadriceps tendon over the distal end of the femur and
facilitates full extension and flexion of the knee joint.
The bursa is held in position by the part of the vastus intermedius muscle
called the articularis genu muscle.
PREPATELLAR BURSA
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This bursa lies between the skin and the anterior surface of
the patella.
It allows free movement of the skin over the patella during
flexion and extension of the leg.
Because of its superficial and exposed position, this bursa may
become inflamed after prolonged periods of weight bearing on
the hands and knees.
Inflammation of this is "housemaid's knee".
SUBCUTANEOUS INFRAPATELLAR
BURSA
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This bursa is located between the skin and the tibial
tuberosity.
It allows the skin to glide over the tibial tuberosity and withstand
pressure when kneeling with the trunk upright (e.g., when one kneels or
genuflects during praying).
Inflammation of this bursa is "clergyman's knee"
BLOOD SUPPLY
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Supplied by the anastomoses around it:
Five genicular branches of the popliteal artery
Descending genicular branch of the femoral artery
Descending branch of the lateral circumflex femoral artery
Two recurrent branches of the anterior tibial artery
Circumflex fibular branch of the posterior tibial artery
NERVE SUPPLY
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Femoral nerve, through its branches to the vasti.
Sciatic nerve, through its genicular branches of the tibial and commom
peroneal nerves.
Obturator nerve, through its post division.