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Joint Anatomy > Knee Anatomy > Flashcards

Knee Anatomy Flashcards

1
Q

What are the three joints at the knee?

A

Patella femoral joint (PFJ)
Tibiofemoral joint (TFJ)
Superior tibiofibular joint (STFJ)

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2
Q

What are the key bony points of the knee?

A

Tibial tuberosity
Medial and lateral femoral condyles
Patella
Superior tibiofibular joint
Knee Joint line
Tibial plateau

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3
Q

What attaches to the tibial tuberosity?

A

Patella tendon

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4
Q

What is key about the tibiofemoral joint?

A

Modified synovial hinge joint

Can only get rotation at the tibiofemoral joint when the knee is at 90 degrees flexion

Rounded surface of the femur comes into contact with flatter surface of the tibia meaning it isn’ as stable because the two bones aren’t ‘overlapping’ each other.

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5
Q

What is key about the articular surface of the knee?

A

The lateral and medial femoral condyles are not symmetrical

Lateral side is deeper to stop the patella dislocating and moving out of the lateral side of the femur.

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6
Q

What is key about the proximal tibia?

A

Slightly flatter tibia and different size areas which allows the femur to fit properly.

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7
Q

What is the ROM of flexion and extension at the knee?

A

130-150 degree flexion (depending on the hip)

0-10 degrees extension

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8
Q

What is the ROM of medial and lateral rotation at the knee?

A

30-35 degrees medial rotation (less than lateral because of the bony structure)

40-45 degree lateral rotation

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9
Q

What is the close packed position of the knee? (when the bones are closest together/ joint is most stable)

A

Full extension

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10
Q

What is the open packed position of the knee? (when the bones are furthest apart/ joint is least stable)

A

30 degrees flexion

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11
Q

What is the stability like in the knee?

A

Due to the femoral condyles being round and the tibial plateau being flatish it causes the knee to be unstable.

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12
Q

What adds stability to the knee?

A

Passive and dynamic stabilisers

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13
Q

What is a passive stabiliser?

A

A joint capsule
Intra and extra capsular ligaments
extracapsular ligaments are thickenings of the capsule
Menisci inside the joint

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14
Q

What are the extracapsular ligaments of the knee?

A

MCL
LCL
Oblique popliteal ligament (posterior)
Arcuate ligament

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15
Q

What do the MCL and LCL do in movements?

A

Both are taught in extension & prevent rotation at the knee; however, in knee flexion they become lax allowing rotation to occur

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16
Q

Describe the MCL

A

Triangular in shape
Blends with the medial meniscus
Medial stability to the knee
Stabilises and secures the medial meniscus
Most effective in flexion
Comes from the medial femoral condyle

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17
Q

What is the mode of injury for the MCL?

A

Medial valgus stress (struck on the lateral side of the leg when the foot is fixed)

Kicking the foot laterally when going in for a tackle

18
Q

Describe the LCL

A

Thin and pencil like

Associated closely with the insertion of the tendon of biceps femoris

Prevents Varus stress of the knee (force coming from medial to laterally)

Much less common injury

Comes from the lateral femoral condyle onto the head of the fibula

19
Q

How do you tension the MCL & LCL

A

When extended the MCL and LCL are under max tension to contribute to the locking mechanism.

20
Q

When are the MCL and LCL slack?

A

Under flexion they both slacken to allow rotation

Flexion is much more unstable meaning more likely to get injures when flexed

21
Q

What does the shape of the MCL allow

A

Due to the MCL being triangular shape some fibres will be in action during both flexion and extension

22
Q

What are the functions of the LCL?

A

Resists adduction (varus) not strong

Helped by iliotibial band (IT band) and popliteus

Not a great deal in controlling rotary movements

23
Q

What are the intracapsular ligaments of the knee?

A

They cross over so are referred to as the ‘cruciates’

From front to back (ACL)

From back to front (PCL)

They attach in the intracondricular area, in between the medial and lateral condyle on the femur

Stability in the anterior and posterior direction

24
Q

Describe the ACL

A

Prevents anterior translation of the tibia on the femur

Checks external rotation of the tibia in flexion

Aids medial displacement of the tibia

Assists in controlling rolling and gliding in the knee

25
Q

What is the mode of injury of the ACL?

A

Forced internal rotation of the knee, the foot is usually fixed

Common in football and skiing

26
Q

What is the unhappy triad?

A

When you get force on the lateral side going medially which causes damage in the ACL, MCL and meniscal damage

27
Q

What is the rolling and gliding of the tibiofemoral joint?

A
  • From extension, popliteus unlocks the knee & the femoral condyles begin to roll (approx. 15-20 degrees)
  • Then they begin to slide posteriorly as well
  • By the end of knee flexion rolling has stopped and only gliding takes place
  • Visa versa with extension but at 20 degrees to end of range the tibia laterally rotates to ‘lock the knee’ (closed-pack position)
  • This complex mechanism is another example of joint accessory movements
28
Q

Describe the PCL

A

Strongest ligament in the knee

Checks posterior translation of the tibia on the femur

Also aids to prevent lateral tibial displacement

Prevents hyperextension

29
Q

Mode of injury of the PCL

A

Rarely injured

‘Dashboard ligament’

A positive sag may be seen - with the knees flexed you may see some posterior shift in the tibial tuberosity on the affected side - the horizon sign

30
Q

Describe the Menisci

A

Medial and lateral meniscus

Shock absorbers of the knee

Two ‘c’ shaped structures

Fixed at either end – otherwise free to move

Thicker at the external margins

Continuous with the capsule

Lateral more mobile than medial, translated backwards during flexion by popliteus

In the knee extension the menisci translate anteriorly

31
Q

What is the function of the menisci?

A

Deepen the articular surface

Shock absorbers - transmit 50-70% of the load

Provide stability - allows the rounded surface to fit to the flat surface

Proprioception

Nutrition

Removal may hasten arthritic changes

32
Q

Mode of meniscal injury

A

Twisting on a semi-flexed knee with the foot fixed on the floor

Medial meniscus tears occur 10 times more frequently than lateral ones

Medial tears more longitudinal, lateral more radial

33
Q

What is the blood supply like in the meniscus?

A

The outer rim of the meniscus has a good blood supply

This reduces as we move inwards

34
Q

What muscles cause flexion of the knee?

A

The hamstrings:
- Semimembranosus
- Semitendinosus
- Biceps Femoris

35
Q

What muscles cause extension of the knee?

A

The Quadriceps:
- Rectus Femoris
- Vastus lateralis
- Vastus medialis
- Vastus intermedius

36
Q

What muscle causes internal rotation of the knee?

A

Popliteus unlocks the knee

37
Q

What muscle causes external rotation of the knee?

A

Biceps femoris locks the knee

38
Q

Describe the patello-femoral joint

A

Modified synovial plane joint - patella (sesamoid bone)

Patellar tendon attaches the apex of patella to the tibial tuberosity

39
Q

What are the movements of the patella-femoral joint?

A

Shift - tilt - rotate
Moves up (caudad) on femur with knee extension
Moves down (cephalad) on femur with knee flexion

40
Q

What is patellar tracking?

A

During knee flexion and extension the patella is not static but undergoes a degree of shift, tilt and rotation on the patellar surface of the femur as well as supero-inferior movement.

Different parts of the patella will articulate with the femur at different parts of the flexion/extension range

The posterior surface of the patella has different facets for changing areas of articulation

Joint Anatomy (5 decks)

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