Biomechanics

Question 1

What is the load distribution through the medial and lateral joint in the knee and why the discrepancy?

Answer 1

Medial = 70%; lateral = 30%
Why?
- because the GRF goes towards the CoM which is medially located

Question 2

What is the effect of unloading braces on the medial compartment of the knee?

Answer 2

Reduced medial load by 11%

Question 3

Effect of lateral wedges on load reduction?

Answer 3

Reduced varus knee moment by by 4-14%

Improved pain and function @ 3+12 months but not 24 months

Question 4

Effect of unloader brace for reducing OA progression?

Answer 4

Reduced pain and BML volume

*earliest signs of OA actually in the patellofemoral joint

Question 5

What is the mechanism of action of a cane as a unloading device?

Answer 5

• provides BWS
• reduces GRF
• provides counter torque

Question 6

What are the benefits of cane use based on the 2 RCTs done?

Answer 6

• reduced pain/reduced analgesic use

- reduces progression of OA over time

Question 7

Whats the effect of trunk lean on knee load?

Answer 7

• larger degrees of trunk lean = reduced KAM
• implication is that don’t rush to straighten someone out of they lean; and even small degrees of lean can have a large impact on pain

Question 8

Whats the effect of toe in and toe out gait?

Answer 8

• toe out - reduces pain, reduces late stance KAM
• toe in - reduces pain and reduces early stance KAM
• alters biomechanics by changing GRF origin and GRF vector

Question 9

What are teh different theories for ACL injuries?

Answer 9

1. Ligament dominance
2. Leg dominance (higher valgus moment and asymmetry side-side)
3. Trunk dominance (greater trunk displacement during sudden release test and worse proprioception during repositioning test)
4. Quads dominance (females rely more on quads and less on hams;

Question 10

What are the components of an Injury Prevention Program for ACL?

Answer 10

1. plyos + biomechanical correction
2. high intenisty plyos
3. biomechanical correction for knee valgus/hip add/leg dominance
4. balance+core stability (holding position post landing/single leg jump landings)
5. strength training

Question 11

Whats is the relationship between a varus thrust and OA progression?

Answer 11

• varus thrust increases risk of OA progression 4x

Question 12

What does a poor single leg squat indicate?

Answer 12

• increased risk of ACL injury
• poor SLS more common in ACL injuries and PFPS
• poor SLS = worse functional outcome post injury