The Knee Overview

Question 1

What are the distinct joints of the knee?

Answer 1

3 surfaces with 3 joints
- patellofemoral
- tibiofemoral
- superior tib-fib

Tibiofemoral is the largest joint in the body

Question 2

What is knee joint stability dependent on?

Answer 2

static restraints of joint capsule, ligaments and menisci

dynamic restraints from muscles and tendons (plane specfic)

Question 3

With the knee being most commonly injured body system, what are its categories?

Answer 3

Unspecified sprains and strain
- overuse injuries
Contusions
Meniscal or ligaments injuries

Question 4

What is the biomechanics of the tibio-femoral joint?

Degrees of freedom and closed pack position

Answer 4

2 degrees of freedom
- flexion and extension
- medial and lateral rotation

Closed pack = full extension

Know the concave and convex rule (!!!)

Question 5

What is the normal ROM for flexion? and end feel?

Answer 5

0-140 (with room for hyperextension)

Soft tissue approximation
- due to muscle (look @ body composition)

Question 6

What is ROM of tibial medial rotation?

Answer 6

30-40

Question 7

What is ROM of tibial lateral rotation?

Answer 7

20-30

Question 8

What is the purpose of the ACL?

Answer 8

prevent anterior translation AND medial rotation of the tibia
- AM bundles and PL bundles

Question 9

What is the purpose of the PCL?

Answer 9

prevent posterior translation AND medial rotation of the tibia

Question 10

What is the purpose of the MCL?

Answer 10

prevent valgus and lateral rotation of tibia
- secondary prevention to anterior and posterior translation of tibia

has two bands = superior and deep

Question 11

What is the purpose of the LCL?

Answer 11

prevents varus and lateral rotation of tibia
- secondary prevention to anterior and posterior translation of tibia

Question 12

What are some of the smaller ligaments of the menisci?

Answer 12

Meniscotibial (Coronary) ligament - deep MCL
Transverse ligament
Meniscofemoral
Arcuate ligament
Oblique popliteal ligament

Question 13

What is the difference between the medial and lateral meniscus regarding shape?

Answer 13

Medial is C-shaped and thicker from the back

Lateral is O-shaped and even throughout

Question 14

From extension to flexion, how does the medial meniscus move?

Answer 14

Moves to the back around 2mm

Question 15

From extension to flexion, how does the lateral meniscus move?

Answer 15

moves to the back around 10mm

Question 16

What is the functions of the meniscus?

Answer 16

helps with lubing and feeding the joint
- shock absorbers by spreading the stress over the cartilage = decrease wear and tear
- increase area of contact between condyles to help with stability

Question 17

What kind of bone is the patellofemoral joint?

Also with charactertics

Answer 17

A sesamoid bone
- w/ 5 facets and ridges
- 4 regular surfaces + odd facet

Odd facet = medial, posterior aspect of patella

Question 18

During flexion to extension, what is the articulation of the patella?

Answer 18

all the diff parts of the patella articulate with femoral condyles

Question 19

At full knee extension, how much % torque does the patella provide?

Answer 19

31% at full
- 13% @ 90-120 degrees

Question 20

What is the purposes of the patellofemoral joint?

Answer 20

increase distance from axis of motion = greater torque of quads

protection when knee is flexed

prevents compression forces on quad tendon w/ resisted knee flexion

Question 21

What is the biomechanics of the patellofemoral joint?

Answer 21

NWB = superior glide on femur with quad active

Under moving femur when foot is planted

Question 22

What is the purpose of the patellofemoral joint?

Answer 22

• Transmission of the quad forces to the tibia
• Increasing angle of pull and mechanical advantage of the quad tension
• Helps with preventing anterior shear of the femur when WB

Question 23

At 15-20 degrees, what facet is in contact?

Answer 23

At the inferior pole

Question 24

At 45 degrees, what facet is in contact?

Answer 24

At the middle pole

Question 25

At 90 degrees, what facet is in contact?

Answer 25

All the facets BUT not ODD

Question 26

At full flexion, how is the patella in connection to the facet?

Answer 26

The Odd facet is the only contact between the patella and lateral surface of the medial femoral condyle

Question 27

What is the progression of patellar loading in activities?

Answer 27

1. walking - 0.50 x BW
2. Cycling - 1.5 x BW
3. Up stairs - 3.3 x BW
4. Down stairs - 5 x BW
5. Jogging - 7 x BW
6. Squatting - 7-8 x BW
7. Deep squatting - 20 x BW
8. Jumping - 20 x BW

Question 28

What type of joint is the superior tib-fib?

Answer 28

Simple, synovial with a straight glide in the joint plane
- orientation is ant-lat / post-med

Question 29

How do we achieve closed pack for the superior tib-fib joint?

Answer 29

weight bearing DF

Question 30

What are the ligaments associated with the superior tib-fib joint?

Answer 30

anterior and posterior tib-fib
interosseous membrane

Question 31

What muscles are associated with the superior tib-fib joint?

Answer 31

Bicep femoris
peroneus longus and brevis

Question 32

What are the important hx questions regarding pain?

Answer 32

What is the mechanism of injury?
Where is it located?
How long has it been?
How bad is it?
What helps it and what makes it worse?
Were you able to bear weight right away?

Question 33

What mechanical sx questions should be asked?

Answer 33

locking or catching
popping (during and/or now)
gives out
pain up/down the stairs
hard time walking around corners

Question 34

What are the 5 ottawa knee rules?

Answer 34

1. over 55 or under 18
2. can’t walk
3. TTP on patella
4. TTP on fib head
5. can’t flex over 90 deg

98-100% sensitive when criteria are negative