Biomechanics Final

Front 1

What two articulations compose the knee

Back 1

1) tibiofemoral
2) patellofemoral

Front 2

What are the major roles of the patella

Back 2

1) increases the mechanical advantage of the extensor muscles by creating a greater moment arm
2) transmits tensile forces from quad to patella ligament

Front 3

What is the articulation that is located close to the knee joint, but is not actually a part of the knee?

Back 3

Superior tibiofibular

Front 4

What kind of joint is the knee classified as?

Back 4

a modified hinge

Front 5

What are the motions of the knee?

Back 5

-flexion
-extension
-internal rotation
-external rotation

Front 6

What is a Q angle and what two lines form it?

Back 6

The angle formed at the center of the kneecap. It is formed by a line from the anterior superior spine of the ilium to the middle of the patella and the line form the middle of the patella to the tibial tuberosity

Front 7

What are the values for normal Q angles in males and females

Back 7

males: 10-14
females: 15-17

Front 8

What is genu varum?

Back 8

An abnormally small or negative Q angle. BOWLEGGED

Front 9

What is genu valgum?

Back 9

An abnormally large Q angle. KNOCK KNEES

Front 10

How do you judge a normal ICR

Back 10

Because the line from the ICR to the knee joint forms a right angle with the surface of the tibial plateau

Front 11

The normal motion of the femur on the tibial plateaus: _________
The two abnormal motions: ________ and _________

Back 11

Glides, compression & distraction

Front 12

ICR distraction is when there is an (acute/obtuse) angle and ICR compression is when there is an (acute/obtuse) angle

Back 12

Obtuse, acute

Front 13

What is the negative impact of compression?

Back 13

tends to exert an abnormally high pressure on articular surfaces

Front 14

What are the two models of the patellofemoral joint

Back 14

1) Sliding see-saw
2) Pully model

Front 15

True or false: if moment arm of quad is greater than the moment arm of the patella, then the force of the patella is greater than the force of the quad

Back 15

True

Front 16

What wrong assumption does the pulley model make?

Back 16

That P = Q at all times

Front 17

When does P = Q?

Back 17

At full knee extension

Front 18

When is P > Q?

Back 18

At about 30 deg knee flexion

Front 19

When is Q > P?

Back 19

At about 60 deg knee flexion

Front 20

When is the moment arm of the patella the largest?

Back 20

At full flexion. Quad force is also largest here

Front 21

What are the general assumptions about patellofemoral joint contact forces when compared to P and Q forces?

Back 21

Joint force increases with both Q and P forces
Joint force increases with the degree of flexion of the knee (largest when fully flexed)

Front 22

At what degree is the FJ/FQ ratio the largest?

Back 22

60 deg of flexion

Front 23

What is osteoarthritis?

Back 23

Bone deterioration caused by the wearing away of articular cartilage

Front 24

What are some risk factors for obtaining OA?

Back 24

1. Obesity
2. Age
3. Genetics
4. Mechanical loading (repeated use)
5. Females
6. Injury

Front 25

What are two methods used to classify the existence of OA in the joint?

Back 25

1) The kellgren-lawrence grading system (0-IV)
2) Radiographs (MRIs)

Front 26

What are 3 things radiographs look for in osteoarthritic knees

Back 26

1) Status of the bone
2) Joint space narrowing (means less cartilage is present)
3) Formation of osteophytes

Front 27

In someone with varus alignment, which compartment of the knee will suffer a larger force load?

Back 27

The medial compartment--bowlegged ppl

Front 28

Adduction is to ______ moment as abduction is to _______ moment

Back 28

External, internal

Front 29

What is the major cause of the abduction moment?

Back 29

muscles surrounding the joint

Front 30

Increases in moments of the knee also increases the force of what tibial bone compartment?

Back 30

Medial

Front 31

What are 3 things that were used to prove OA

Back 31

1) modeling and simulation
2) knee instruments (transducers)
3) Increases in bone density on the medial compartment

Front 32

Is there a positive or negative relationship between BMD in the medial compartment and knee moments?

Back 32

positive relationship

Front 33

Does an increased or decreased knee variability raise the risk for OA?

Back 33

A decreased variability

Front 34

If you have OA in the medial compartment, what kind of therapeutic wedge would you want?

Back 34

a medially directed wedge

Front 35

If Q=100, P=100, and J=50...what are the P:Q and J:Q ratios for full extension

Back 35

P:Q = 1
P:J = .5