Biomechanics of Knee

Question 1

Type of Joint

Answer 1

Modified hinge Synovial
2 degrees of freedom

Question 2

joint articulations of knee joint

Answer 2

femorotibial
Pallelofemoral

Question 3

How is the femur aligned?

Answer 3

oblique angle inferiorly and medially from proximal to distal

Question 4

Angle b/w lateral aspect of femur and tibia is approximately

Answer 4

170-175
Due to the size and shape of evenly distributed b/w the medial and lateral surfaces of knee joint

Question 5

Genu Valgus Knock knees

Answer 5

Decreased angle at lateral aspect
Less than 170

Question 6

Genu Varus bow leg

Answer 6

Increased angle at the lateral aspect of the knee
greater than 180

Question 7

Excessive genu valgum can increase load on which aspect

Answer 7

Lateral

Question 8

Excessive genu varus can increase load on which aspect

Answer 8

medial

Question 9

How can it affect pateloofemoral alingment

Answer 9

As patella sits in the midline of longitudinal axis of rotation of the lower limb

Question 10

Q angle meaning

Answer 10

oblique angle of femur when quads pulls patella superiorly and small degree laterally

Question 11

How is q angle determined

Answer 11

line running from central patella to ASIS

line intersecting the tibial tuberosity and middle patella

Question 12

Average Q angle

Answer 12

13-15

Question 13

factors that influence q angle therefore patella position

Answer 13

sex, females 3-4 increase due to wider pelvis

Excessive genu valgum

tibial torsion

Foot mechanics

Question 14

Knee Flexion how many degrees

Answer 14

140

Question 15

Extension

Answer 15

5-10

Question 16

Tibial and Femoral Osetokinematics

Answer 16

direction of knee rotation is the same as knee rotation as the tibia

Question 17

Femoral on tibial knee

Answer 17

Direction of knee rotation is opposite to the motion of the moving femru

Question 18

Flexion: femoral on tibial arthokinematics

Answer 18

femoral Condyles roll posterioly and slide anteriroly
ACL and menisci help ensure that conact is maintain

Question 19

Extension femoral-tibial

Answer 19

femoral condyles roll anteriorly and slide posteriorly
tension of PCL and menisci help facilitate

Question 20

Flexion tibial on femoral

Answer 20

tibia rolls and glides posteriorly on femoral condyles

Question 21

extension tibial on femoral

Answer 21

tibia rolls and glides anteriorly on femoral condyles

Question 22

Screw Home Mechanism its purpose

Answer 22

to result in maximus congruence of the joint surfaces, ligaments are taught and menisci tightly interposed whcihc means reduced requiremnt for muscle contraction

Question 23

Locking of the knee relies on 3 factors

Answer 23

Shape of femoral condyles, passive tension of acl slight lateral pull of quadriceps

Contraction of popliteus muscle

Question 24

Locking/unlocking (Tibial-on-Femoral)
Open Chain

Answer 24

During T-F extension as tibia moves 30 degrees of flexion into fully extended. ACL lateral pull of quads creates external rotation of the tibia

To unlock, Popliteus internally rotates the tibia to unlock knee

Question 25

Locking/Unlocking of Knee (Femoral-Tibial) Closed Chain

Answer 25

during F-T extension, knee moves from 30 degrees flexion to fully extended position the shape of the femoral condyles and tension of ACL ligament produce slight Medial rotation To unlock, poplitues externallyy rotates

Question 26

Role of Patella

Answer 26

Articulates with the intercondylar groove of the femur Work as an anatomical pulley and mechanism to reduce friction b/w quadriceps and femoral condyles

Question 27

Role of Patella regarding Moment arm

Answer 27

Patella displaces tendon of the quadriceps anteriorly which increased the moment arm of the knee extensor mechanism

Question 28

Patellofemoral Joint Forces

Answer 28

deep squat increases moment arm therefore greater force whihc reaches a maxiums to 60-90 degrees

Question 29

Patellofemoral Pain Syndrome

Answer 29

Less congruent joint May be exacerbated due to imbalance in medial and lateral forces of patella

Question 30

ACL limits

Answer 30

Knee extension Anterior translation of tibia on femur Posterior translation of femur on tibia

Question 31

ACL Injury Vectors

Answer 31

Hyperextension Rotation Valgus Force

Question 32

PCL limits

Answer 32

Knee flexion Posterior translation of tibia on femur

Question 33

PCL injury Vectors

Answer 33

Hyperflexion Posterior translation

Question 34

MCL resists

Answer 34

Valgus extension

Question 35

MCL Injury Vectors

Answer 35

Valgus Hyperextension

Question 36

LCL Resists

Answer 36

Varus Extension

Question 37

LCL Injury Vectors

Answer 37

Varus Hyperextenstion