Knee Biomechanics

Question 1

What type of joint is the tibiofemoral joint?

Answer 1

Double condyloid

Question 2

The tibiofemoral joint prevents motion in what plane?

Answer 2

Frontal

Question 3

The tibiofemoral joint has how many degrees of freedom?

Answer 3

2 degrees of freedom

Question 4

(T/F) Is the medial tibial plateau larger than the lateral?

Answer 4

YES: 50% larger (oval and long)
Articular cartilage 3x thicker than
lateral

Question 5

The Medial & lateral tibial plateau slope in which direction?

Answer 5

Slope posteroinferiorly

Question 6

What are the main functions of the menisci?

Answer 6

• Increase stability by deepening
  tibial plateau
• Decreases friction by 20%
• Increases contact area by 70%
• Enhances proprioception via
  mechanoreceptors
• Attenuates forces

Question 7

The Medial Meniscus is what shape?

Answer 7

C-Shaped

Question 8

The Lateral Meniscus is what shape?

Answer 8

O-Shaped

Question 9

Where is the medial meniscus thickest?

Answer 9

Posteriorly

Question 10

Where is the lateral meniscus thickest?

Answer 10

Uniform thickness

Question 11

What major structure is firmly attached to the medial meniscus?

Answer 11

MCL

Question 12

Menisci transmit what percent of
imposed load at knee?

Answer 12

50-60%

Question 13

Shock absorption capability
is reduced by what percent with complete menisectomy?

Answer 13

20%

Question 14

The menisci are initially well vascularized but recede to the periphery by what age?

Answer 14

11 years old

Question 15

The MCL prevents which motion?

Answer 15

Abduction (Valgus)

Question 16

(T/F) Adduction or abduction is determined by the movement of the distal extremity (tibia)

Answer 16

TRUE

Question 17

The LCL prevents which motion?

Answer 17

Adduction (varus stress)

Question 18

The MCL assists in restraining which tibial motion?

Answer 18

Anterior tibial translation

Question 19

When are ALL the MCL fibers most taut?

Answer 19

Extension

Question 20

The MCL anterior fibers are taut in which motion?

Answer 20

Mid-range knee flexion

Question 21

The MCL posterior fibers are on slack in which motion?

Answer 21

Mid-range knee flexion

Question 22

(T/F) The LCL has an attachment to the joint capsule

Answer 22

FALSE

Question 23

When are the LCL fibers most taut?

Answer 23

Extension

Question 24

The LCL helps restrict what motion other than varus?

Answer 24

IR/ER

Question 25

How many bundles are there in a typical ACL?

Answer 25

3

Question 26

What is the origin and insertion of the ACL?

Answer 26

Anterior aspect of tibial to posterior aspect of LFC

Question 27

Average ACL length and width?

Answer 27

33mm Length / 11mm width

Question 28

What motion does the ACL restrain?

Answer 28

Anterior tibial translation

Question 29

Which muscle group may help restrain anterior tibial translation?

Answer 29

Hamstrings

Question 30

Primary function of the PCL?

Answer 30

Prevents posterior translation of tibia on femur

Question 31

(T/F) The PCL is frequently injured

Answer 31

FALSE

Question 32

Which ligament prevents anterior translation of the FEMUR?

Answer 32

PCL

Question 33

Which ligament prevents posterior translation of the FEMUR?

Answer 33

ACL

Question 34

Which part of the menisci has the greatest healing potential?

Answer 34

Periphery (Red-Red Zone)

Question 35

What degree of an angle would be considered Genu Valgum?

Answer 35

<165°

Question 36

What degree of an angle would be considered Genu Varum?

Answer 36

>180°

Question 37

Genu valgum can lead to increased pressure on which compartment of the knee?

Answer 37

increased lateral compressive forces

Question 38

Genu Varum can lead to increased pressure on which compartment of the knee?

Answer 38

increase medial compressive forces

Question 39

Average Q-Angle for males?

Answer 39

10-14°

Question 40

Average Q-Angle for females?

Answer 40

15-17°

Question 41

Genu recurvatum is characterized by excessive...?

Answer 41

extension

Question 42

Decreased CKC dorsiflexion would lead to?

Answer 42

Decreased knee flexion

Question 43

Decreased CKC plantar flexion would lead to?

Answer 43

Decreased Knee extension

Question 44

What is the minimum amount of knee flexion required to ambulate?

Answer 44

60° - 70°

Question 45

Describe the screw home mechanism during open chain extension and flexion

Answer 45

Extension: Tibial ER Flexion: Tibial IR

Question 46

Describe the screw home mechanism during closed chain extension and flexion

Answer 46

Extension: Femur ER Flexion: Femur IR

Question 47

Roll/Glide mechanics during open chain extension?

Answer 47

Concave on FIXED convex Tibia rolls and glides anteriorly

Question 48

Roll/Glide mechanics during open chain flexion?

Answer 48

Concave on FIXED convex Tibia rolls and glides posteriorly

Question 49

Roll/Glide mechanics during closed chain extension?

Answer 49

Convex on FIXED concave Femur rolls anterior / glides posterior

Question 50

Roll/Glide mechanics during closed chain flexion?

Answer 50

Convex on FIXED concave Femur rolls posterior / glides anterior

Question 51

The posterior surface of the patella is covered by which type of cartilage?

Answer 51

Posterior surface is covered with thick hyaline cartilage

Question 52

The medial facet of the patellofemoral Joint is positioned?

Answer 52

Flat to slightly convex

Question 53

The lateral facet of the patellofemoral Joint is positioned?

Answer 53

longer than medial

Question 54

The "odd" facet of the patellofemoral joint is positioned?

Answer 54

medial angle

Question 55

The 1st consistent patellofemoral contact is between?

Answer 55

10° - 20° flexion

Question 56

By 90° all aspects of facets have made contact with exception of?

Answer 56

Odd facet

Question 57

The greatest PF compression force is at what degree of flexion?

Answer 57

90°

Question 58

What are the Transverse stabilizers leading to Patellofemoral Joint Stability?

Answer 58

Med/lat retinaculum VMO/VL MPFL

Question 59

What are the Longitudinal stabilizers leading to Patellofemoral Joint Stability?

Answer 59

Quad tendon Patellar tendon

Question 60

The MCL and LCL, to a lesser extent, resists?

Answer 60

External rotation

Question 61

3 parts of the unhappy triad?

Answer 61

ACL, MCL, Medial meniscus