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Knee Joint - PowerPoint PPT Presentation


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Knee Joint. actually 2 joints within the articular capsule tibio-femoral patello-femoral the superior fibulo-tibial joint is also near modified hinge joint flexion and extension is primary motion some rotation is possible when the knee is flexed. epicondyles. condyles. patella.

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knee joint
Knee Joint
  • actually 2 joints within the articular capsule
    • tibio-femoral
    • patello-femoral
    • the superior fibulo-tibial joint is also near
    • modified hinge joint
      • flexion and extension is primary motion
      • some rotation is possible when the knee is flexed
slide2

epicondyles

condyles

patella

tibial plateaus

intercondylar notch

tibial tuberosity

Anterior

Posterior

Transverse

Anterior

ligamentous support
Ligamentous Support

Menisci

Cruciate

Ligaments

Other

Ligaments

Collateral

Ligaments

menisci
Menisci
  • The menisci are discs of fibrocartilage attached to tibial plateaus. They are thicker along the periphery.
slide5

The lateral meniscus is smaller and more mobile than the medial meniscus. The inner portion of the menisci are avascular. The outer portion has some blood supply, making healing of tears possible.

lateral

medial

menisci function
Menisci Function
  • increases stability by deepening tibial plateaus
  • decreases friction by 20%
  • increases contact area by 70%
  • absorbs shock
    • removal of menisci does NOT preclude normal motion, but
      • increase wear on articulating surfaces
      • increase chance of developing degenerative joint disease
slide7

Collateral Ligaments

lateral (fibular)

medial (tibial)

slide8

prevents abduction and

adduction movement

of the knee

Collateral Ligaments

slide9

Additional Ligamentous Support

  • iliotibial band
    • thick, strong band of tissue connecting tensor fascia latae to femur and tibia
slide10

Cruciate

Ligaments

cruciate -- ‘cross’

ligaments form an ‘X’

or cross within the joint

named for their TIBIAL

attachments

Anterior Cruciate (ACL)

slide11

Posterior Crucuate (PCL)

shorter and stronger than

ACL

slide12

The ACL prevents the femur from sliding posteriorly on the tibia or the tibia from sliding anteriorly on the femur.

The PCL prevents the femur from sliding anteriorly on the tibia or the tibia from sliding posteriorly on the femur.

FEMUR

PATELLA

TIBIA

cruciates during flexion extension
Cruciates During Flexion/Extension

Note: the cruciate ligaments also limit rotation

patello femoral joint
Patello-femoral Joint
  • articulation of the patella and femur
  • the patella is a true sesamoid bone
  • posterior surface of the patella is covered with thick hyaline cartilage
  • the patella slides within the trochlear groove
functions of patello femoral joint
Functions of Patello-femoral Joint

with patella

without patella

(1) increases angle of pull of quads on tibia, improves the ratio of motive:resistive torque by 50%

(2) centralizes divergent tension of quads into a single line of action

(3) some protection of anterior aspect of knee

q angle
Q-Angle

The Q-angle is the angle formed by a line from the anterior superior spine of the ilium to the middle of the patella and a line from the middle of the patella to the tibial tuberosity. Males typically have Q-angles between 10 to 14o, females between 15-17o.

atypical q angles
Atypical Q-angles

bowleggedness

knock-knees

knee rotation locking your knee

Extension

Flexion

External

Rotation

Internal

Rotation

Knee Rotation(Locking Your Knee)
  • Six to 30 degrees of internal rotation of the tibia on the femur occurs through 90 degrees of knee flexion.
    • The femoral condyles do not have the same diameters, this helps cause internal rotation when the knee is flexed and external rotation when the knee is extended.
    • The lateral condyle slides more than medial condyle.
    • The anterior cruciate ligament becomes taut just prior to the rotation, this may help force a rotation of the femur on the tibia.
slide20

Knee Musculature

many 2 joint muscles

primary movements

- flexion and extension

- hams & quads,

respectively

medial and lateral

rotation possible

necessary for screw-

home mechanism

slide21

Knee Flexion

Hamstrings

cross hip and knee

biceps femoris

semitendinosus

semimembranosus

gastrocnemius

cross knee and ankle

popliteus

slide22

Knee Extension - Quadriceps

rectus femoris

vastus lateralis

vastus medialis

vastus intermedius

quadriceps tendon

patellar ligament

slide23

Lateral Rotation

biceps femoris

attaches to lateral aspect of knee

slide24

Medial Rotation

semitendinosus

semimembranosus

popliteus

attach to medial aspect of knee

common knee injuries
Common Knee Injuries
  • one of the most commonly injured joints
    • lack of bony and muscular support
    • positioned between the 2 longest bones
    • weight bearing and locomotion functions
  • often tear or stretching of soft tissue
ligament injuries
Ligament Injuries
  • ACL
    • more prevalent than PCL injuries
    • forces directed from posterior side of leg
  • PCL
    • forces directed from anterior side of leg
    • forced flexion of knee w/external rotation
      • wrestling and football
slide27

Ruptured ACL Knee

Intact Knee with ACL

& PCL

slide28

Mechanisms of ACL injury

1) attempting a rapid cutting maneuver with foot in contact with the ground and knee flexed (problem exacerbated if an external force applied to knee during this movement)

2) knee hyperextension with internal tibial rotation

Example

backward falling skier - boot and skis accelerate forward creating an anterior drawer mechanism

slide29

Gender issues related to ACL injuries

females more likely to sustain an ACL injury than males

soccer - 2.6X

basketball - 5.75X

wider pelvis

greater flexibility

less-developed musculature

hypoplastic vastus medialis obliquus

narrow femoral notch

genu valgum

external tibial torsion

slide30

PCL Injuries

  • When the knee is forcefully twisted or hyperextended BUT other ligaments are usually injured or torn, before the posterior cruciate ligament (PCL) is torn
  • Most common mechanism for PCL alone to be injured is from a direct blow to the front of the knee while the knee is bent. 
  • Automobile accident
  • Automobile strikes another and stops suddenly
  • Front passenger or driver slides forward. 
  • Bent knee hits the dashboard just below the knee cap forcing tibia backwards on the femur tearing PCL.
  • The same force can occur during a fall on the bent knee, where the force of the fall on the tibia pushes it back against the femur and tears the posterior cruciate ligament (PCL).
slide31

Common mechanism of

PCL injury in football is being tackled while the knee is fully extended.

When the tibia is displaced too much in the posterior direction the PCL may rupture.

ligament injuries1

L

M

Ligament Injuries
  • injuries to MCL more prevalent than LCL
  • MCL
    • foot planted and force applied to the lateral side of knee
      • football
meniscus injuries
Meniscus Injuries
  • most common injury in the knee
  • tearing is most common
  • medial side injured more often
    • medial meniscus more secured
    • foot planted with excessive rotation
iliotibial band syndrome
Iliotibial Band Syndrome
  • IT-band
    • thick strong band of ligamentous tissue
    • connects tensor fascia latae to the lateral condyle of the femur and the lateral tuberosity of the tibia
  • IT-band rubs against the lateral femoral condyle when there is excessive tension
slide35
excessive pronation increases internal rotation of the tibia, which accentuates the friction of the IT band and femoral condyle
  • tibial alignment and size of femoral condyle may also contribute to the development of this condition