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Human Movement > Knee Joint Biomechanics > Flashcards

Knee Joint Biomechanics Flashcards

1
Q

Name the articulations composing the knee joint complex

A
  • tibiofemoral joint

- patellofemoral joint

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2
Q

Describe the tibiofemoral joint

A

It’s a double condyloid joint between convex medial and lateral condyles of the femur and concave tibial condyles.

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3
Q

What are the motions of the tibiofemoral joint ?

A

Flexion/extension:

  • sagittal plane
  • frontal axis

Internal/ external rotation when the knee is flexed and foot fixed

  • horizontal plane
  • longitudinal axis
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4
Q

What is the total range of rotation of the tibiofemoral joint

A

If knee flexed and fixed : 40° to 50° of rotation can occur

If knee is extended : no rotation

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5
Q

Describe the kinematics of knee flexion in open kinetic chain

A

The concave tibia glides on convex femoral condyles so the glide is anterio-posterior (sime direction as the movement)

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6
Q

Describe the kinematics of knee extension in open kinetic chain

A

The concave tibia glides on convex femoral condyles so the glide is posterio-anterior (same direction as the movement)

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7
Q

Describe the kinematics of knee flexion in closed kinetic chain

A

The convex femoral condyles glide on concave tibia so the glide is antero-posterior (opposite direction to the movement)

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8
Q

Describe the kinematics of knee extension in closed kinetic chain

A

The convex femoral condyles glide on convex tibia so the glide is antero-posterior (opposite to the movement)

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9
Q

Define the femoral mechanical axis

A

An imaginary line that passes through the femoral head and through the center of the knee.

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10
Q

Define the anatomical axis of the tibia

A

An imaginary line that goes along the mid-shaft of the tibia

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11
Q

Explain the relation between mechanical axis of the femur and anatomical axis of the tibia

A

In healthy knees, the mechanical axis of the femur coincides with the anatomical axis of the tibia.
The angle formed between the two axis is 170° to 175°.

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12
Q

Define Genu Valgum

A

Is the pathological abduction of the tibia relative to the femur in the frontal plane.
Angle between femoral mechanical axis and anatomical axis of the tibia is inferior or equal to 165°

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13
Q

Define Genu Varum

A

Is the pathological adduction of the tibia relative to the femur in a frontal plane.
The angle between the mechanical femoral axis and the anatomical tibial axis is superior or equal to 180°.

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14
Q

Define Genu Recurvatum

A

Is the condition in which the knee joint extends beyond 10° in the sagittal plane

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15
Q

Describe the ranges of motion of the tibiofemoral joint

A
  • knee flexion : sagittal plane - 150°
  • knee extension : sagittal plane -5°
  • knee external rotation (knee flexed) : horizontal plane - 30°
  • knee internal rotation (knee flexed) : horizontal plane - 15°

If knee is less flexed, ROM diminishes in knee rotations

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16
Q

Define the screw-home rotation of the knee

A

Locking the knee if full extension requires 10° of external rotation. This rotary locking action is called screw-home rotation based on the observable twisting of the knee for the last 30° or so of extension.
The combined knee extension and external rotation maximizes the overall area of contact, increase the joint congruence and favors stability.
This mechanism decreases the work of the quadriceps femoris muscle group

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17
Q

Name the agonists for knee flexion

A

1) biceps femoris
Origin : ischial tuberosity (long head), lateral head of linea aspera (short head)
Insertion : head of fibula

2) semimembranosus
Origin : ischial tuberosity
Insertion : posterior aspect of medial condyle of tibia

3) semitendinosus
Origin : ischial tuberosity
Insertion : pes anserinus tendon

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18
Q

Name the synergists of knee flexion

A

1) popliteus
Origin : lateral condyle of the femur
Insertion : proximal, posterior aspect of the tibia

2) gastrocnemius
Origin : posterior surfaces of the condyles of the femur
Insertion : calcaneus via calcaneus tendon

3) gracilis :
Origin : inferior ramus of the pubis
Insertion : pes anserinus tendon

4) sartorius
Origin : ASIS
Insertion : pes anserinus tendon

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19
Q

Name the antagonists of knee flexion

A

Quadriceps group

1) rectus femoris
Origin : AIIS
Insertion : tibial tuberosity

2) vastus medialis
Origin : medial lip of linea aspera
Insertion : tibial tuberosity

3) vastus lateralis
Origin : lateral lip of linea aspera, gluteal tuberosity and greater trochanter
Insertion : tibial tuberosity

4) vastus intermedius
Origin : anterior and lateral shaft of the femur
Insertion : tibial tuberosity

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20
Q

Why is it hard to keep the knee extended while flexing the hip ?

A

Tension in the hamstrings increases as the hip flexes

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21
Q

Name the agonists for knee extension

A

1) rectus femoris
Origin : AIIS
Insertion : ischial tuberosity

2) vastus lateralis
Origin : lateral lip of linea aspera, gluteal tuberosity and greater trochanter
Insertion : tibial tuberosity

3) vastus medialis
Origin : medial lip of linea aspera
Insertion : tibial tuberosity

4) vastus intermedius
Origin : anterior and lateral shaft of the femur
Insertion : tibial tuberosity

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22
Q

Name the synergists for knee extension

A

None

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23
Q

Name the antagonists of knee extension

A

1) biceps femoris
Origin : ischial tuberosity (long head), lateral lip of linea aspera (short head)
Insertion : head of fibula

2) semitendinosus
Origin : ischial tuberosity
Insertion : pes anserinus tendon

3) semimembranosus
Origin : ischial tuberosity
Insertion : posterior aspect of medial condyle of tibia

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24
Q

Name the agonists of knee external rotation

A

1) biceps femoris
Origin : ischial tuberosity (long head), lateral lip of linea aspera (short head)
Insertion : head of fibula

2) popliteus (in knee extension)
Origin : lateral condyle of the femur
Insertion : proximal, posterior aspect of the tibia

25
Q

Name the synergists of knee external rotation

A

1) tensor fascia latae
Origin : illiac crest, posterior to ASIS
Insertion : illiotibial tract

26
Q

Name the antagonists of knee external rotation

A

1) semitendinosus
Origin : ischial tuberosity
Insertion : pes anserinus tendon

2) semimembranosus
Origin : ischial tuberosity
Insertion : posterior aspect of medial condyle of tibia

27
Q

Name the agonists of knee internal rotation

A

1) semitendinosus
Origin : ischial tuberosity
Insertion : pes anserinus tendon

2) semimembranosus
Origin : ischial tuberosity
Insertion : posterior aspect of medial condyle of the tibia

28
Q

Name the synergists of knee internal rotation

A

1) gracilis
Origin : inferior ramus of the pubis
Insertion : pes anserinus tendon

2) sartorius
Origin : ASIS
Insertion : pes anserinus tendon

29
Q

Name the antagonists of knee internal rotation

A

1) biceps femoris
Origin : ischial tuberosity (long head), lateral lip of linea aspera (short head)
Insertion : head of fibula

30
Q

Describe the knee joint meniscus

A
  • medial meniscus is shaped like a C while the lateral meniscus is shaped like a O
  • medial meniscus is torn more frequently
  • the popliteus attaches to lateral meniscus
31
Q

Does the meniscus heal well ?

A

No, because outer rim has blood supply, mid rim has moderate blood supply and inner rim has no blood supply

32
Q

What are the functions of the meniscus ?

A
  • it absorbs the compressive forces caused by muscular contraction and body weight
  • it protects the articular cartilage
33
Q

Describe the load transmission provided by the meniscus

A
  • responsible of 50% of load transmission through the medial joint at full extension
  • responsible of 85% of load transmission through the medial joint if knee is flexed at 90°
  • responsible of 70% of load transmission through the lateral joint at full extension
  • responsible of 85% of load transmission through the lateral joint if knee is flexed at 90°
34
Q

Describe the meniscus “movements” during flexion and extension of the knee

A
  • during flexion the meniscus moves posteriorly
  • during extension the meniscus moves anteriorly
  • during flexion , the popliteus retracts the lateral meniscus posteriorly in order to avoid it being entrapped between the femur and the tibia
35
Q

Describe the meniscus movement during external/internal rotation

A
  • during external rotation, the medial meniscus moves anteriorly while the lateral meniscus moves posteriorly
  • during internal rotation, the medial meniscus moves posteriorly while the lateral meniscus moves anteriorly

Knowing that the lateral meniscus has a greater range of motion than medial meniscus

36
Q

Name the different ligaments of the knee joint complex

A
  • Anterior cruciate ligament
  • Posterior cruciate ligament
  • Medial collateral ligament
  • Lateral collateral ligament
37
Q

Describe the anterior cruciate ligament

A
  • attaches from the anterior intercondylar area on the tibial plateau and to the posteromedial aspect of the lateral condyle of the femur
  • it is divided into the anteromedial band and the posterolateral band
  • taut at the end range of extension of the knee
38
Q

What are the functions of the Anterior Cruciate ligament ?

A
  • limits the anterior translation of the tibia on a fixed femur : it provides 85% of total passive resistance
  • limits the posterior translation of the femur on fixed tibia
  • limits hyperextension of the tibiofemoral joint
  • resists valgus and varus deformations
  • resists excessive rotations
39
Q

How can a torn ACL be masked ?

A

Due to a protective spasm of the hamstrings

40
Q

Describe the Posterior cruciate ligament

A
  • it is thicker and stronger than the anterior cruciate ligament
  • it is attached to the posterior intercondylar surface of the tibia and to the anterior lateral surface of the medial condyle of the femur
  • it is divided into two bundles : anterolateral and posteromedial
  • it is taut at the extreme end range of knee flexion
41
Q

What are the functions of the posterior cruciate ligament ?

A
  • resists posterior translation of the tibia on fixed femur
  • resists anterior translation of the femur on fixed tibia
  • resists excessive knee flexion
  • resists to valgus/varus stress
  • resists excessive rotations
42
Q

Describe the Medial collateral ligament of the knee

A
  • attaches to medial epicondyle of the femur and to medial aspect of the proximal tibia
  • some fibers of the MCL attach to medial meniscus
43
Q

What are the functions of the medial collateral ligament ?

A
  • limits abduction of the leg at the tibiofemoral joint in the frontal plane
  • resists excessive knee extension
  • it resists valgus stress
44
Q

Describe the lateral collateral ligament of the knee

A
  • it attaches to the lateral condyle of the femur and runs down to the head of fibula
  • it blends with the tendon of the biceps femoris
  • (also known as fibular collateral ligament)
45
Q

What is the role of the lateral collateral ligament of the knee ?

A
  • it limits adduction of the leg at the tibiofemoral joint

- it resists varus stress

46
Q

Describe the knee extension kinematics

A
  • in closed kinetic chain : during extension the convex femoral condyles roll anteriorly and glide posteriorly on concave tibia while a medial rotation of the femur happens during the last 30° of extension
  • in open kinetic chain : during extension, the concave tibia rolls and glide anteriorly on the convex femoral condyles while a lateral rotation of the tibia happens during the last 30° of extension
47
Q

Describe the knee flexion kinematics

A
  • during closed kinetic chain flexion : the concave femoral condyles roll posteriorly and glides anteriorly on the convex tibial plateau while a lateral rotation of the femur happens at the beginning initiated by popliteus muscle
  • during open kinetic chain flexion : the concave tibia rolls and glides posteriorly on the convex femoral condyles while an internal rotation of the tibia happens during the initial 30° of flexion
48
Q

Describe the patella

A
  • it’s the only sesamoid bone in the body
  • it lies within the quadriceps tendon
  • catalyzes knee flexion/extension process
  • increase by 20% the quadriceps muscle group strength at knee joint
  • reduces friction between the quadriceps tendon and the femoral condyles
49
Q

Define the patellofemoral joint

A
  • joint between the articular surface of the patella and the intercondylar groove of the femur
50
Q

Describe the patella Alta

A

Patella lies superior to it’s usual location

Increase the patellofemoral forces during knee flexion

51
Q

Describe the patella Baja

A

Patella lies inferior to its usual location

Restricts the range of motion

52
Q

Define the sulcus angle

A
  • angle formed between the anterior aspects of lateral and medial condyles of the femur
  • usually around 138°
  • a greater angle cause patellar subluxation
53
Q

Describe the patellofemoral joint kinematics

A
  • at 135° of flexion the patella contacts its superior pole on the femur
  • extending toward 90° of flexion, the patella migrate towards its inferior pole.
  • migration to the inferior pole is completed within the last 20° of flexion
  • when the knee extends, the patella lies proximal to the intercondylar groove
  • as the knee extends the patella migrates from its superior pole to its inferior pole
  • during extension, patella glides superiorly
  • during flexion, patella glides inferiorly

-patellar contact area increases with knee flexion

54
Q

What is the role of the patella

A

It works as an anatomical pulley for the quadriceps.

It reduces the friction between quadriceps tendon and femoral condyles.

55
Q

What are the major motions of the patella ?

A
  • superior and inferior glide
  • medial facet moves along medial condyle
  • lateral facet moves along lateral condyle
56
Q

Which muscles control the patella ?

A

Medial motion of the patella is controlled by vastus medialis
Lateral motion of the patella is controlled by vastus lateralis

57
Q

Define the “Q-angle”

A

The Q-angle mesure the lateral angle of pull of the quadriceps group on the patella.
It lies between two line, one passing through the tibial tuberosity and the center of the patella, and the other one running from the center of the patella to the ASIS

  • in men : 10°-13°
  • in women : 15°-17° because women have wider hips
58
Q

What does an increase of Q-angle mean ?

A

Patella is pulled laterally, causing damage to the cartilage and can even lead to patellar lateral dislocation.

Human Movement (11 decks)

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