Week 1 Flashcards
What type of joint is the tibiofemoral joint?
double condyloid (ovoid articular curface +condyle)
The tibiofemoral joint prevents motion in the _ plane.
frontal
How many degrees of freedom does the tibiofemoral joint allow? Describe them.
2 degrees of freedom
F/E in sagittal plane, IR/ER in transverse plane
Which of the following is indicative of the femoral articular surface?
A. large AP convexity
B. Small curvature posteriorly
C. The Lateral condyle is longer then the medial
d. The lateral condyle extends further distally for angled femur
b is true
a - small AP convexity
c - medial > lateral
d - medial extends further distally
Describe the medial and lateral tibial plateaus in terms of shape and differences.
They are concave and slope posteroinferiorly
Medial plateau is 50% larger (oval and long) and its articular cartilage is 3x thicker
Lateral: more circular
What structure(s) function to increase stability of the knee by deepening the tibial plateau?
menisci
Which of the following is not true for the menisci?
a. increases friction by 20%
b. increases contact area by 70%
c. attenuates forces
d. enhances proprioception via mechanoreceptors
a - decreases friction by that much
Debate the differences between the medial and lateral menisci.
medial: c-shaped, firm attachment to MCL, thick posteriorly
lateral: o-shaped, loose attachment to lateral capsule, uniform thickness
Both are thicker on periphery, thinner along inner margin
Menisci transmit _% of imposed load at the knee.
50-60%
How much is shock absorption capability reduced by following menisectomy?
20%
Which of the following is not true for the MCL?
a. prevents abduction (valgus stress)
b. attaches 7-10cm below joint line
c. assists in prevention of anterior tibial translation w/ ACL
d. doesn’t attach to joint capsule and medial meniscus
d - it does attach
The anterior fibers of the MCL are taut in _.
The posterior fibers of the MCL are taut in _.
midrange, full flexion
Which of the following is true for the LCL?
a. prevents abduction
b. attachment to capsule or menisci
c. assists with translational restraint
d. Less laxity than MCL
e. has pencil-like band of tissue
e is true
a - prevents adduction (varus stress)
b - no attachment there
c - assists with IR/ER restraint
d - greater laxity than MCL
LCL fibers are tight in knee _ and loosen as knee _.
extension, flexes
What are the functions of the ACL?
prevent anterior tibial translation/posterior femoral; check hyperextension; work with MCL to stabilize knee against valgus
True/False: The PCL is one of the strongest ligaments.
true
Which of the following is not true regarding the PCL?
a. prevents posterior translation of tibia on femur
b. minor restraint to varus/valgus
c. shorter and less oblique than ACL
d. injured easiest
d - rarely injured
What term is associated with an increased Tibiofemoral angle above 180 deg and increased medial compressive forces?
genu varum (knock-knee)
What term is associated with a decreased TF angle below 165deg and increased lateral compressive forces?
genu valgum
What is the Q angle?
angle formed by line drawn from ASIS to mid-patella to tibial tuberosity
What gender has a higher Q angle?
females
How much flexion is normal at the knee?
130-140deg
How much extension is normal at the knee?
5-10deg
Hyperextension can be normal (excessive >10deg = genu recurvatum)
Decreased DF = decreased knee _.
flexion
Decreased PF = decreased knee _.
extension
Match the Flexion ROM needed for the activity:
60-70, 75, 70-80, 90, 115 (one is repeated)
Gait, advanced function, sit/rise chair, in/out bath, on/off toilet, stair climbing
gait = 60-70
Advanced = 115
sit/rise chair = 90
in/out bath = 90
on/off toilet = 75
stair climbing = 70-80
ROM in knee IR/ER is influenced by amount of knee _.
flexion
Full extension = _ rotation.
90 deg flexion = _ rotation.
full extension = restricted rotation by interlocking of condyles
90 deg flexion = 0-45 ER and 0-30 IR
Concave or convex?
distal femur
proximal tibia
distal femur - convex
proximal tibia - concave
Tibial-on-femoral extension occurs in what direction?
same
Femoral-on-tibial extension occurs in what direction?
opposite
What is the screw home mechanism?
lateral rotation of tibia on femur during the last 5 deg of extension - augmented by tension on ACL and lateral pull of quads
According to the screw home mechanism, flexion requires unlocking so the femur must _ rotate on tibia (CKC) and tibia must _ rotate (OKC).
laterally, medially
What functions to unlock the knee by moving the knee in IR/ER?
popliteus
What type of cartilage is on the posterior surface of the patellofemoral joint?
thick hyaline