Internal Forces 2 and Surface Instability

Question 1

What % of ACL injuries are non-contact?

Answer 1

70%

Question 2

Biomechanically, how can we prevent ACL injuries?

Answer 2

• Reducing frontal + sagittal plane knee loading

- Increasing frontal + sagittal plane knee angles

Question 3

How is Q angle measured?

Answer 3

• ASIS to patella

- Patella to tibial tubercle

Question 4

What is a normal Q angle?

Answer 4

• 14 for males

- 17 for females

Question 5

What is large Q angle indicative of?

Answer 5

• Patellar subluxation

- ACL injuries

Question 6

What is the problem with bilateral jumps for knee assessment?

Answer 6

Doesn’t predict single leg kinematics

Question 7

Out of drop jump, DJ + vert, and forward DJ + vert which is best to analyse injury risk?

Answer 7

DJ + vert

Question 8

What are the key variables attained from drop jumps?

Answer 8

• Impact loading rate 10-90%
• Peak impact force
• Average impact force
• Peak propulsive force

Question 9

What is the spring loaded model for tendon stiffness?

Answer 9

MTU stiffness = pkForce / CoM displacement

Question 10

What variables do a false floor + uneven surface alter?

Answer 10

• Contact time

- EMG activity

Question 11

As we increase drop height, what happens to muscle contribution?

Answer 11

• Hip increases

- Ankle decreases

Question 12

How does a bosu modify the muscle contribution of a drop jump?

Answer 12

• Increases ankle

- Decreases hip

Question 13

How does a trampete modify drop jumps?

Answer 13

• Good vertical posture

- Focus on hip

Question 14

What are pros and cons of unstable surface drop jumps?

Answer 14

• Recalibration when surface is removed

- No mechanical or neuromuscular effects

Question 15

What are the two valid ACL risk tests?

Answer 15

• Drop jumps

- Single-legged hop