The Knee Flashcards
Describe the roll & glide during tibial-on-femoral extension.
anterior roll, anterior glide
During tibial-on-femoral extension, how do the menisci move?
menisci are pulled anteriorly by contracting the quadriceps muscle
Describe the roll & glide during femoral-on-tibial extension.
anterior roll, posterior glide
In order to lock the knee in full extension, approx. 10 degrees of ____________ rotation must occur. What mechanism is this referring to?
external
“screw-home” rotation of the knee
Can the “screw-home” (external_) rotation occur independently?
no - it is a conjunct rotation
meaning
it is mechanically link to flexion & extension
During tibial-on-femoral extension, what three factors contribute to the locking mechanism?
What does each of these factors contribute to?
- shape of medial femoral condyle
- tension in anterior cruciate ligament (ACL)
- lateral pull of quads
each of these contributes bias to external rotation of the tibia
In order for a knee that is fully extended to be unlocked, the joint must _____________ rotate first.
What muscle drives this action?
internally
popliteus
To initiate femoral-on-tibial flexion, the muscle can rotate the femur __________.
externally
To initiate tibial-on-femoral flexion, the muscle can rotate the tibia _______.
interally
In order to maximize independent axial rotation between the tibia and femur, the knee must be __________.
flexed
In most upright activities, an ______________ torque is acting on the knee.
*Conceptually, what does this mean?
external (flexor)
What factors are associated with joint compression force on the patellofemoral joint?
- force w/in quadriceps muscle
- knee flexion angle
What 3 movements does the medial collateral ligament (MCL) resist?
- valgus
- knee extension
- extreme axial rotation (especially knee external rotation)
What 3 movements does the lateral collateral ligament (LCL) resist?
- varus
- knee extension
- extreme axial rotation
Which ligament is more commonly injured - MCL or LCL?
MCL
What movements does the anterior cruciate ligament (ACL) resist?
- extension
- extremes of varus, valgus & axial rotation
What movements does the posterior cruciate ligament (PCL) resist?
- knee flexion
- extremes of varus, valgus, & axial rotation
Which ligament is more commonly injured - ACL or PCL?
ACL
What is the angle of inclination?
angle between the head and shaft of the femur
Coxa Vara
decreased angle of inclination (< 120 degrees)
Normal Angle of Inclination
120 - 125 degrees
Coxa Valga
increased angle of inclination (> 135 degrees)
How does a coxa vara angle of inclination affect the position of the knees?
causes the knees to go into valgus (knock-knock knees)
How does a coxa valga angle of inclination affect the position of the knees?
causes the knees to go to into varus (bowlegs)
Which patient population has a larger Q-angle - males or females?
females
Lachman’s Test
anterior pull of tibia on the femur
testing integrity of the ACL
Varus Stress Test
application of a lateral force to the medial aspect of a joint in an attempt to create a gap in the lateral joint line, thereby testing the stability of the lateral aspect of the joint
Valgus Stress Test
application of a medial force to the lateral aspect of a joint in an attempt to create a gap in the medial joint line, thereby testing the stability of the medial aspect of the joint
