Hip and Knee Biomechanics

Question 1

A cane held in the contralateral hand reduces joint reactive forces through the affected hip approximately 50% by what mechanism?

Answer 1

Reduces hip abductor muscle pull;
cane’s force must substitute for the hip abductors of the affected hip and creates a moment arm that is relatively long and originates on the side opposite the hip whose abductor muscles are weak

Question 2

How does increasing offset affect hip abductor force?

Answer 2

Reduces force needed to balance pelvis by increasing abductor moment arm

Question 3

What are normal Q angles for males and females?

Answer 3

Males 13 degrees, females 18 degrees

Line drawn from ASIS to knee center, from middle of patella to tibial tubercle

Question 4

How does the tibia move in relation to the femur during initiation of knee flexion?

Answer 4

Tibia will internally rotate to “unlock” the knee

Question 5

What motion shows the greatest difference between a normal and ACL deficient knee?

Answer 5

Knee flexion starting at 30 degrees