03-11: The Knee Joint

Question 1

Knee joint (3)

Answer 1

• Femur, tibia, patella
• Largest joint in body
• Hinge joint (uniaxial) with rotary component
• Does not move only on one plane; has to rotate with flexion/extension

Question 2

Rotation of knee joint

Answer 2

• Medial condyle larger than lateral side
• Cave on vex: In extension, lateral side stops short, medial continues because of control space
• Extension: Initiates rotation laterally
• Flexion: Rotates knee joint medially
• Tibia locks into place via lateral rotation during extension (happens with 10˚ of terminal extension)

Question 3

Meniscus (vascular/avascular)

Answer 3

• Outside 1/3 meniscus is vascular (can heal itself)
• Inner 2/3 meniscus is avascular (inability to heal)
• Encapsulated with synovial membrane

Question 4

Meniscus tears

Answer 4

Tears occur due to significant compression and shear forces during rotation while flexing or extending during quick directional chanes in running

Question 5

“Screw Home” Maneuver

Answer 5

• Knee “screws home” to fully extend due to shape of medial femoral condyles
• As knee approaches full extension, tibia must externally rotate 10˚ to achieve proper alignment of tibial and femoral condyles
• During flexion, knee “unlocks” by tibia rotating internally, to a degree, from its externally rotated position to achieve flexion

Question 6

Ligaments (5)

Answer 6

Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), Medial Collateral Ligament (MCL), Lateral Collateral Ligament (LCL), Anterior Lateral Ligament (ALL)

Question 7

Anterior Cruciate Ligament (ACL)

Answer 7

• Posterior-lateral femur to anterior medial tibia
• Prevents excessive anterior translation of tissue
• Puts knee in valgus position
• With foot planted, can laterally rotate body
• One of more serious knee injuries

Question 8

Posterior Cruciate Ligament (PCL)

Answer 8

• Anterior-medial femur to posterior lateral tibia
• Prevents excessive posterior rotation of tibia
• Not often injured

Question 9

Medial Collateral Ligament (MCL)

Answer 9

• Prevents excessive valgus
• Connects condyle to condyle
• Blends in with medial meniscus

Question 10

Lateral Collateral Ligament (LCL)

Answer 10

• Prevents excessive varus

- Connects condyle to fibular head

Question 11

Anterior Lateral Ligament (ALL)

Answer 11

Prevents excessive medial rotation

Question 12

Unhappy Triad

Answer 12

• MCL, Medial Meniscus, ACL

- Would reset in major surgery repair

Question 13

Plica

Answer 13

Insertion point for synovial folds of tissues

Inflammation and excessive fold

Question 14

Genu Recurvation

Answer 14

Hyperextension in knees (backward knees)

Question 15

Q Angle

Answer 15

• Central line of Pull for entire quadriceps
• LOP from patella tendon runs from center of patella to center of tibial tuberosity
• Angle formed by the intersection of these two lines at the patella is Q angle
• 12˚ and less for males, 18˚ and less for females

Question 16

Vastus Medialis

Answer 16

O: Medial to middle aspect of proximal femur along the linea aspera
I: Tibial Tuberosity via patellar tendon
A: Extension of the knee
N: Femoral Nerve

• Oblique pull: more active in final 20˚ if terminal knee extension

Question 17

Vastus Lateralis

Answer 17

O: Lateral lip of linea aspera
I: Tibial Tuberosity via patellar tendon
A: Extension of the knee
N: Femoral Nerve

• Largest of the Quadriceps Muscles

Question 18

Vastus Intermedius

Answer 18

O: Upper 2/3 of femur
I: Tibial Tuberosity via patellar tendon
A; Extension of the knee
N: Femoral Nerve

Question 19

Quadriceps muscles (Jumping)

Answer 19

• Vital in jumping
• Functions as a decelerator: coming down from a jump, decreasing to change direction
• Eccentric contraction during deceleration

Question 20

Quadriceps muscles (strength measurement)

Answer 20

• 25% to 33% stronger than hamstrings

- prone to atrophy when injuries occur`

Question 21

Golgi Tendon Organ

Answer 21

• During muscle tension, the muscle strands are stretched as the muscle length changes - concentrically or eccentrically
• Protects against excessive forces

Question 22

Biceps Femoris (Long Head)

Answer 22

O: Ischial tuberosity
I: Head of fibula
A: Knee flexion, external rotation of tibia, hip extension
N: Tibial portion of sciatic nerve

Question 23

Biceps Femoris (Short Head)

Answer 23

O: Mid-to-distal lateral lip of linea aspera, lying between adductor magnus and vastus lateralis
I: Head of fibula
A: Knee flexion, external rotation of tibia
N: Peroneal branch of sciatic nerve

Question 24

Semitendinosis

Answer 24

O: Ischial tuberosity
I: Anterior medial aspect of proximal tibia (pes anserine)
A: Knee flexion, medial rotation of tibia, hip extension
N: Tibial branch of sciatic nerve

Question 25

Semimembranosis

Answer 25

O: Ischial tuberosity
I: Posterior aspect of medial proximal tibia
A: Knee flexion, medial rotation of tibia, hip extension
N: Tibial branch of sciatic nerve

Question 26

Popliteus (“Key that unlocks the knee”)

Answer 26

O: Lateral posterior condyle of femur
I: Medial posterior condyle of tibia
A: Internal rotation of tibia, unlocks the knee
N: Tibial nerve

Question 27

Hamstrings (function

Answer 27

• Weak hamstrings allow hip to anteriorly tilt

- Work eccentrically to decelerate - faster I go, harder hams try to slow you down

Question 28

Pes Anserine

Answer 28

• “Goose Foot”
• Sartorius, Gracilis, Semitendinosis
• Assists with knee flexion

Question 29

Nerves of the Knee Joint

Answer 29

Sciatic Nerve branches into:

• Common Peroneal (Lateral): Deep, Superficial
• Tibial Nerve (Straight down)