lower extremity - the knee

Question 1

what is the Q-angle?

Answer 1

angle between the line of action of quadriceps & line of action of patellar tendon

Question 2

what are the joints of the knee?

Answer 2

• tibiofemoral joint
• patellofemoral joint
• proximal tibiofibular joint

Question 3

what kind of joint is the tibiofemoral?

Answer 3

biondyloid joint

Question 4

what kind of joint is the patellofemoral joint?

Answer 4

trochlear joint

Question 5

what kind of joint is the proximal tibiofibular joint?

Answer 5

planar joint

Question 6

what are the roles of the proximal tibiofibular joint?

Answer 6

• very small weight bearing role

- very small role in motion

Question 7

what are the functions of the patella?

Answer 7

• anterior knee protection

- provides better mechanical advantage for quadricep action on tibia

Question 8

importance of mechanical advantage in patella function?

Answer 8

• insertion angle would be near 0° in extension

- resulting it in being impossible to produce force

Question 9

what are the four ligaments in the knee?

Answer 9

1. medial collateral ligament (MCL)
2. lateral collateral ligament (LCL)
3. anterior cruciate ligament (ACL)
4. posterior cruciate ligament (PCL)

Question 10

what are the extra capsular & extra articular ligaments?

Answer 10

1. medial collateral ligament (MCL)

2. lateral collateral ligament (LCL) `

Question 11

what are the intra articular & extra synovial ligaments?

Answer 11

1. anterior cruciate ligament (ACL)

2. posterior cruciate ligament (PCL)

Question 12

general functions of anterior & posterior cruciate ligaments?

Answer 12

• provide multiple planar dynamic knee stability
• guides natural arthrokinematics
• contributes to proprioception in knee

Question 13

what ligament is the primary restraint for valgus force?

Answer 13

medial collateral ligament (MCL)

Question 14

what are the secondary restraints for valgus force?

Answer 14

• posterior medial capsule
• anterior & posterior cruciate ligaments
• lateral joint contact
• lateral meniscus compression
• medial retinacular fibres
• medial head of gastrocnemius
• tendons of sartorius, gracilis, & semitendinosus

Question 15

what ligament is the primary restraint for varsus force?

Answer 15

lateral collateral ligament (LCL)

Question 16

what are the secondary restraints for varus force?

Answer 16

• posterior-lateral corner of knee
• iliotibial band
• biceps femoris tendon
• medial joint contact
• medial menisus compression
• anterior & posterior cruciate ligaments
• lateral head of gastrocnemius

Question 17

what is included in the posterior-lateral corner of the knee?

Answer 17

• posterior-lateral capsule
• arcuate popliteal ligament
• lateral collateral ligament (LCL)
• popliteofibular ligament
• popliteus tendon

Question 18

functions of medial collateral ligament & posterior-medial capsule

Answer 18

• resists valgus (abduction)
• resists knee extension
• resists extremes of axial rotation (especially external knee rotation)

Question 19

common injury mechanisms of medial collateral ligament & posterior-medial capsule

Answer 19

• valgus producing force with planted foot

- severe knee hyperextension

Question 20

functions of lateral collateral ligament

Answer 20

• resists varus (adduction)
• resists knee extension
• resists extremes of axial rotation

Question 21

common injury mechanisms of lateral collateral ligament

Answer 21

• varus producing force with planted foot

- severe knee hyperextension

Question 22

functions of posterior capsule

Answer 22

• resists knee extension
• oblique popliteal ligament resists knee external rotation
• posterior-lateral capsule resists varus

Question 23

common injury mechanism of posterior capsule

Answer 23

hyperextension or combined hyperextension with external knee rotation

Question 24

functions of anterior cruciate ligament (ACL)

Answer 24

• most fibers resist extension

- resists extremes of varus, valgus, & axial rotation

Question 25

common injury mechanisms of anterior cruciate ligament (ACL)

Answer 25

- large valgus-producing force with firmly planted foot - large axial rotation torque applied to knee with firmly planted foot - severe knee hyperextension

Question 26

functions of posterior cruciate ligament (PCL)

Answer 26

- most fibers resist knee extension | - resists extemes of varus, valgus, & axial rotation

Question 27

common injury mechanisms of of posterior cruciate ligament (PCL)

Answer 27

- falling on a fully flexed knee resulting in proximal tibia striking the ground first - any event causing forceful posterior tibial translation or anterior femoral translation, especially with fully flexed knee - large axial rotation or valgus-varus applied torque to knee with firmly planted foot & flexed knee - severe knee hyperextension

Question 28

what does severe knee extension involving posterior cruciate ligament cause?

Answer 28

large gapping of posterior side of the joint

Question 29

how do most fibers resist knee flexion?

Answer 29

- excessive posterior translation of tibia | - excessive anterior translation of femur

Question 30

what kinds of risk factors increase risk of anterior collateral ligament (ACL) rupture?

Answer 30

- environmental factors - anatomical factors - biomechanical factors - physiological factors

Question 31

what environmental factors increase the risk for anterior collateral ligament (ACL) rupture?

Answer 31

- improper footwear - bracing - playing conditions - weather/climate

Question 32

what anatomical factors increase the risk for anterior collateral ligament (ACL) rupture?

Answer 32

- bone & joint alignment involving Q-angle & foot pronation - body mass index - femoral intercondylar notch width - posterior-inferior directed slope of lateral tibial plateau

Question 33

what biomechanical factors increase the risk for anterior collateral ligament (ACL) rupture?

Answer 33

- muscular strength, stiffness, & fatigue - hamstring-quadriceps strength ratio - neuromuscular control of the body during landing & cutting maneuvers - cross sectional area strength of ACL

Question 34

what physiological factors increase the risk for anterior collateral ligament (ACL) rupture?

Answer 34

- physical maturation - hormonal fluctuations - limb dominance - proprioception or kinesthesis - overall joint laxity - genetic predisposition

Question 35

what muscles are involved in for lower extremity muscular strength, stiffness, & fatigue?

Answer 35

- hamstring muscles - gluteus maximus - hip abductor muscles - external rotators

Question 36

functions of menisci

Answer 36

- shock absorption - stabilization of tibiofemoral joint - joint lubrification - proprioception - helps to guide knee motions

Question 37

describe the lateral meniscus

Answer 37

- almost O-shaped with a small opening - covers around 60% of lateral tibial plateau - loosely attached

Question 38

describe the medial meniscus

Answer 38

- C-shaped with greater opening - covers about 50% of medial tibial plateau - firmly attached - medial collateral ligament has fibers attaching to medial meniscus

Question 39

what are the movements that can occur at the knee?

Answer 39

- flexion/extension | - internal/external rotation

Question 40

structural/functional causes of lateral tracking

Answer 40

- body dysplasia/ other anomaly - excessive laxity in periarticular connective tissue - excessive stiffness in periarticular connective tissue & muscle - extremes of bony/joint alignment - muscle weakness

Question 41

specific examples of body dysplasia/other anomaly

Answer 41

- dysplastic lateral facet of trochlear groove of femur | - "high" patella

Question 42

specific examples of excessive laxity in periarticular connective tissue

Answer 42

- laxity of medial patellar retinacular fibers (medial patellofemoral ligament) - laxity of attrition of medial collateral ligament (MCL) - laxity & reduced height of medial longitudinal arch of foot (overpronation of subtalar joint)

Question 43

specific examples of excessive stiffness in periarticular connective tissue & muscle

Answer 43

- increased tightness in lateral patellar retinacular fibers/iliotibial band - increased tightness of internal rotator/adductor muscles of the hip

Question 44

specific examples of extreme bony/joint alignment

Answer 44

- coxa verus - excessive anteversion of femur - external tibial torsion - large Q-angle - excessive genu valgum

Question 45

specific examples of muscle weakness

Answer 45

weakness or poor control over: - hip external rotator/abductor muscles - vastus medialis (oblique fibers) - tibialis posterior muscle (related to foot overpronation)