BIOMECHANICS - KNEE EXAM ACTUAL QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE GRADED A++
What is the normal valgus angle at the knee?
10 degrees
Excess valgus shows as what deformity at the knee?
knock knees
Excess varus appears as what deformity at the knee?
bowed legs
Which condyle projects further distally and is the larger of the two?
medial -- this projection allows the femoral condyles to sit level on top of the tibia in
weightbearing despite angulation of the shaft
what are the functions of the menisci?
increase knee joint congruency, dissipate shock
What are the shapes of the tibial condyles?
medial = concave and oval
lateral = flat and almost circular
What direction do the menisci distort during knee extension?
anteriorly
What direction do the menisci distort during knee flexion?
posteriorly
, During the screw home mechanism, which way does the femur move on tibia/tibia
on femur? What defines which occurs?
Femur rotates internally on the tibia in weightbearing, or tibia rotates externally on femur
in non-weightbearing
How does unlocking of the screw home mechanism occur?
It moves out of the fully extended joint position -- the popliteus is helpful in this action
but really it is just part of the same automatic obligatory knee joint rotations
Dysfunction with the screw home mechanism can cause what types of problems?
Damage to menisci (since they distort to maintain contact with femoral condyles during
rotation) or injure ligaments attaching menisci to tibia
MCL ligament
flat and fan shaped, attached to medial meniscus, intercapsular
-resists hyperextension, valgus stress and checks lateral rotation of tibia along with
ant/post translations of tibia on fixed femur
LCL ligament
cord-like, extracapsular
-resists varus stress, assists in limiting joint translations and rotations
ACL ligament
-passes superiorly and posteriorly to lateral femoral condyle
-comprised of AMB, IMB, PLB
-primary restraint to anterior translation of tibia (on fixed femur or post translation of
femur on fixed tibia), secondary restraint against valgus/varus joint motions when knee
is in full extension
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST
UPDATE GRADED A++
What is the normal valgus angle at the knee?
10 degrees
Excess valgus shows as what deformity at the knee?
knock knees
Excess varus appears as what deformity at the knee?
bowed legs
Which condyle projects further distally and is the larger of the two?
medial -- this projection allows the femoral condyles to sit level on top of the tibia in
weightbearing despite angulation of the shaft
what are the functions of the menisci?
increase knee joint congruency, dissipate shock
What are the shapes of the tibial condyles?
medial = concave and oval
lateral = flat and almost circular
What direction do the menisci distort during knee extension?
anteriorly
What direction do the menisci distort during knee flexion?
posteriorly
, During the screw home mechanism, which way does the femur move on tibia/tibia
on femur? What defines which occurs?
Femur rotates internally on the tibia in weightbearing, or tibia rotates externally on femur
in non-weightbearing
How does unlocking of the screw home mechanism occur?
It moves out of the fully extended joint position -- the popliteus is helpful in this action
but really it is just part of the same automatic obligatory knee joint rotations
Dysfunction with the screw home mechanism can cause what types of problems?
Damage to menisci (since they distort to maintain contact with femoral condyles during
rotation) or injure ligaments attaching menisci to tibia
MCL ligament
flat and fan shaped, attached to medial meniscus, intercapsular
-resists hyperextension, valgus stress and checks lateral rotation of tibia along with
ant/post translations of tibia on fixed femur
LCL ligament
cord-like, extracapsular
-resists varus stress, assists in limiting joint translations and rotations
ACL ligament
-passes superiorly and posteriorly to lateral femoral condyle
-comprised of AMB, IMB, PLB
-primary restraint to anterior translation of tibia (on fixed femur or post translation of
femur on fixed tibia), secondary restraint against valgus/varus joint motions when knee
is in full extension
