MSC: ORT – Knee ACTUAL
Exam Question and Answer
What are the 3 bones in the knee? - - tibia
- fibula
- femur
what are the 3 joints in the knee? - - medial tibiofemoral
- lateral tibiofemoral
- patellofemoral
Where is stress put in a valgus deformity? - - lateral compartment
where is stress put in varus deformity? - - medial compartment
what is the anatomical axis? - - down the medullary canal of the femur and tibia
what is the mechanical axis? - - center of femoral head --> center of knee --> center of ankle
- axis of weight bearing in the lower limb
What is the function axis? - - where the knee rotates around
- flexion-extension axis
What are the 6 degrees of motion in the knee? - - extension/flexion
- varus/valgus
- internal/external
- medial/lateral
,- anterior/posterior
- proximal/distal
What is femoral roll back? - -allows for increased knee flexion by avoiding impingement
-lateral side rolls back farther than medial side
What do the ACL and PCL help with? - - anterior/posterior motion
what do the MCL and LCL help with? - - varus/valgus motion
- medial/lateral motion
What ligaments are usually sacrificed with a knee replacement? - - ACL (most often)
- PCL
why are the MCL and PCL not sacrificed in a knee replacement? - They play a more important
role
- MCL = very strong
- LCL = weaker
What degrees of rotation does the tibiofemoral joint have? - - flexion/extension = 0-135 (most
important)
- varus/valgus = 6-8
- internal/external = 25-30
Tibiofemoral position joint force - - standing = equal BW
- swing phase = 1/2 x BW
- stance phase = 2-4 x BW
- jogging = 6 x BW
, Tibiofemoral everyday mobility - - walking = 67 degree of flexion
- sitting = 83-110 degree of flexion (needed to do daily things)
- squatting = 130 degrees of flexion
what is the function of the patella? - - acts as slippery surface for tendon as it passes over front of
knee
- increases mechanical advantage of quad muscles
- keeps the tendon from slipping off the side of the femur
Does the patella extend the moment arm? - - Yes
- makes movement easier
What is the Q angle? - The angle between the extended anatomical axis of the femur and the line
between the center of the patella and the tibial tubercle
What are the degrees of the Q angle for men and women? - flexion
- male = 13 degrees
- female = 18 degrees
extension
- 8 degrees
What does a great degree of Q angle mean? - - greater chance for patella dislocation
Patellofemoral joint loading - - walking = .3 x BW
- up stairs = 2.5 x BW
- down stairs = 3.5 X BW
- squatting = 7 x BW
Exam Question and Answer
What are the 3 bones in the knee? - - tibia
- fibula
- femur
what are the 3 joints in the knee? - - medial tibiofemoral
- lateral tibiofemoral
- patellofemoral
Where is stress put in a valgus deformity? - - lateral compartment
where is stress put in varus deformity? - - medial compartment
what is the anatomical axis? - - down the medullary canal of the femur and tibia
what is the mechanical axis? - - center of femoral head --> center of knee --> center of ankle
- axis of weight bearing in the lower limb
What is the function axis? - - where the knee rotates around
- flexion-extension axis
What are the 6 degrees of motion in the knee? - - extension/flexion
- varus/valgus
- internal/external
- medial/lateral
,- anterior/posterior
- proximal/distal
What is femoral roll back? - -allows for increased knee flexion by avoiding impingement
-lateral side rolls back farther than medial side
What do the ACL and PCL help with? - - anterior/posterior motion
what do the MCL and LCL help with? - - varus/valgus motion
- medial/lateral motion
What ligaments are usually sacrificed with a knee replacement? - - ACL (most often)
- PCL
why are the MCL and PCL not sacrificed in a knee replacement? - They play a more important
role
- MCL = very strong
- LCL = weaker
What degrees of rotation does the tibiofemoral joint have? - - flexion/extension = 0-135 (most
important)
- varus/valgus = 6-8
- internal/external = 25-30
Tibiofemoral position joint force - - standing = equal BW
- swing phase = 1/2 x BW
- stance phase = 2-4 x BW
- jogging = 6 x BW
, Tibiofemoral everyday mobility - - walking = 67 degree of flexion
- sitting = 83-110 degree of flexion (needed to do daily things)
- squatting = 130 degrees of flexion
what is the function of the patella? - - acts as slippery surface for tendon as it passes over front of
knee
- increases mechanical advantage of quad muscles
- keeps the tendon from slipping off the side of the femur
Does the patella extend the moment arm? - - Yes
- makes movement easier
What is the Q angle? - The angle between the extended anatomical axis of the femur and the line
between the center of the patella and the tibial tubercle
What are the degrees of the Q angle for men and women? - flexion
- male = 13 degrees
- female = 18 degrees
extension
- 8 degrees
What does a great degree of Q angle mean? - - greater chance for patella dislocation
Patellofemoral joint loading - - walking = .3 x BW
- up stairs = 2.5 x BW
- down stairs = 3.5 X BW
- squatting = 7 x BW
