Exam 2 lecture: Knee Flashcards
what is the largest joint in the body?
tibiofemoral
name the 3 joints that make up the knee joint complex
tibiofemoral, patellofemoral, proximal tibiofibular joint
what type of joint is the tibiofemoral joint? (simple, compound, complex)
complex
what type of joint is the patellofemoral joint? (simple, compound, complex)
compound
what type of joint is the proximal tibiofibular joint? (simple, compound, complex)
simple
t or f: the tibiofemoral jt is bicondylar w/2 menisci
true
what joint causes the most patient complaints?
patellofemoral
t or f: the knee is the most common site of permanent injury in the lower limb.
true
where are the largest forces in the knee?
tibiofemoral joint (posterior compartment) patellofemoral joint (anterior compartment)
what separates the femoral condyles?
fossa
why does the knee have menisci?
b/c it needs a variable socket
t or f: the femoral condyles are egg-shaped: large posteriorly and small anteriorly.
false. the femoral condyles are egg shaped, but large anteriorly and smaller posteriorly
why do the femoral condyles have divergent axes?
may increase stability of joint
what is the significance of the posterior angulation of the femoral condyles?
lots of flexion, not much extension
which femoral condyle is larger? why?
medial b/c of conjoint rotation
what muscle inserts on the medial epicondyle?
medial hamstring
t or f: the medial femoral condyle is more oblique than the lateral femoral condyle (longer from A-P)
true
what is anteversion?
femoral torsion
what is the normal range for femoral torsion?
10-20˚
what is an anteverted femur (degrees)?
> 20˚
what is a common compensation for anteverted femur?
genu valgum
what is a retroverted femur (degrees)?
<10˚
what is a common compensation for retroverted femur?
genu varum
what is a squinting patella?
patella faces medially
what happens if squinting patella is uncompensated?
genu varum and toe in
what are the possible compensations for squinting patella?
genu valgum
increased external tibial torsion
foot flare
t or f: squinting patella + increased tibial torsion –> feet more parallel w/line of progression
true
are the tibial condyles concave or convex?
neither; they are flat
what are the functions of the tibial spines?
attachment points for ACL and menisci
stabilizing effect
are the tibial articular facets concave or convex?
neither, they are flat.
t or f: tibial facets are perfectly round
false. the medial side is larger than the lateral side (egg shaped)
what is the significance of the posterior angulation of the tibial condyles?
more flexion ROM
what happens if the tibial condyles are broken?
heals w/less angulation –> more hyperextension, less flexion
what attaches to gerdy’s tubercle?
ITB
what type of cartilage lines the patellar surface of the femur?
hyaline
what is the main function of the patella?
increase the angular pull of the quads
which way does the patellar apex point?
downward
which patellar facet is larger?
lateral
why does the patella have the thickest cartilage in the body?
highest compression and shear forces in the body
t or f: there is more cartilage in the tibiofemoral jt than in the patellofemoral jt.
false. there is more cartilage in the patellofemoral jt than the tibiofemoral jt.
what is the Q angle?
represents the pull of the quads; angle is taken from 2 intersecting lines:
ASIS –> center of patella
center of patella –> tibial tuberosity
what is the normal Q angle range?
5-15˚
t or f: the Q angle is highly dependent on gender
false. the Q angle is more determined by height than gender
what is the patellofemoral ratio?
distance from patella to tibia : height of patella
what patellofemoral ratio is patella baja? what does patella baja mean?
<0.8; patella too low
what patellofemoral ratio is patella alta? what does patella alta mean?
> 1.2; patella too high
what is the name for a too-large patella?
patella magna
what is the name for a too-small patella?
patella parva
what are the problems with patella alta?
more likely to dislocate, unstable
what are the problems with patella baja?
more stable, can cause abnormal wear and tear
what is the ideal patellofemoral ratio?
1 +/- .2
what happens to the Q angle during medial/internal rotation of the tibia?
decreases
what happens to the Q angle during lateral/external rotation of the tibia?
increases
what is the effect of foot flare on the Q angle
increases the Q angle
name some situations in which the patella is less stable
knee is extended VMO is weak/stretched medial retinaculum genu valgum vastus lateralis or ITB too tight patella is too small or facel angle is too flat small lateral lip or shallow groove patella alta externally rotated tibia or increased foot flart excessive foot pronation
name some situations in which the patella is more stable
knee flexed strong VMO genu varum normal patella, patellar groove, large lateral lip normal or lower patellar position normal or under pronation
t or f: compression forces on the patella increase w/extension
false. compression forces increase w/flexion
when is there the most force on the patella?
when jumping
which direction does the patella glide during flexion?
inferior and posterior
t or f: the patella increases extensor leverage more when it is less flexed.
true
t or f: the quadriceps force increases as knees flex more (i.e. during squatting)
true
VMO or VL responds faster to tension?
VMO (reverse in patellofemoral pain syndrome)
why are the anterior compartment ligaments not true ligaments?
b/c they are attached by tendon expansions
t or f: a pt with quad rupture cannot extend the knee.
false. pt with quad rupture can still extend the knee b/c of retinacular attachments
MR tear + valgus sprain + patellar dislocation = ?
lateral patellar instability
t or f: medial and lateral retinaculae have less intense forces on them during flexion/extension activities than the central tendinous band
true.
what does the ITB blend with?
lateral retinaculum
what are the parts of the ITB?
smaller patellar band
larger tibial band
what happens when ITB is tight?
rubs on lateral femoral condyle
pulls on patella
what are synovial plica?
remnant of 3 embryonic cavities, usually small and asymptomatic
what are the common complications of synovial plica?
recurrent snapping and pain
what are the functions of the menisci?
deepen socket –> stability and congruency
flexible socket –> accomodate egg shpaed femoral condyles
accomodate slide –> decreased shear stress
decrease compression on articular surfaces (force directed to periphery)
reduce wear and tear
how much compressive load does each meniscus transmit to the periphery?
lateral: 70%
medial: 50%
what shape is the medial meniscus?
C shaped
what shape is the lateral meniscus?
O shaped
which meniscus is more often injured?
medial meniscus
which meniscus is more mobile?
lateral meniscus
why is the medial meniscus less mobile?
b/c of attachment to medial collateral lig.
which way to the menisci (and synovial fluid) slide when the knee flexes?
posterior
where is stress increased during deep squats?
posterior horns
which way do the menisci (and synovial fluid) slide when the knee extends?
anterior
when is there more pressure on the menisci?
at full extension (but less focal)
t or f: menisci rotate w/tibia
false. the menisci rotate w/the femur
which way does each meniscus move during internal rotation?
medial: anterior
lateral: posterior
what is the retreating meniscus test
lateral meniscus should move posteriorly during internal rotation
which meniscus takes more pressure during internal rotation?
medial
which meniscus takes more pressure during external rotation?
lateral
what are the effects of varus stress on the menisci?
pinches medial meniscus
tractions lateral meniscus thru coronary ligs.
what are the effects of valgus stress on the menisci?
pinches lateral meniscus
tractions medial meniscus thru medial collateral lig and coronary ligs
which type of stress is more common (valgus v. varus)? why?
valgus b/c lateral leg is more accessible (e.g. via tackle, etc.)
t or f: there is potential for injury to the menisci w/any movement
true
which are the most common mechanisms of injury to the menisci?
deep flexion
hyper-extension
external rotation
valgus stress
what is the old unhappy triad?
medial meniscus, ACL, MCL
what is the new unhappy triad?
medial meniscus, ACL, LCL
why are menisci poor healers?
not well vascularized
how much of the menisci are vascularized?
outer 1/3
how do the menisci get nutrients?
from synovial fluid
what type of innervation do the mensci have and where?
pain and proprioception @ junction w/deep capsule
what are the effects of aging on the menisci?
decreased vascularization
increased wear and tear
increased fragility
name the collateral ligs
medial (tibial) CL
lateral (fibular) CL
poplitiofibular lig (post. to LCL)
which collateral lig is larger?
medial
what are the attachments for the LCL?
lateral femoral condyle, fibular head
what type of stress does the LCL mostly resist?
varus
what are the attachments for the MCL?
medial femoral epicondyle, medial tibial condyle and shaft
what type of stress does the MCL mosty resist?
valgus
t or f: medial rotation –> increased stress of collateral ligs.
false. medial rotation –> decreased stress on collateral ligs
why is the decreased stress on the collateral ligs during medial rotation significant?
allows conjoint medial rotation
what action of the foot would be affected if the collaterals limited medial rotation?
pronation (decreased)
does lateral rotation increase or decrease tension on the collateral ligs?
increase
what structures make up the posteromedial capsular complex?
posterior part of medial collateral lig.
semimembranosis tendon & tendon expansion
oblique popliteal lig.
what is the function of the posteromedial capsular complex?
resist hyperextension resist valgus stress resist anterior translation resist extremes of lateral tibial rotation protect ACL
what structures make up the posterolateral capsular complex?
LCL poplitiofibular lig arcuate lig biceps femoris tendon and tendon expansion popliteus
what motions does the posterolateral capsular complex resist?
anterior translation
hyperextension
varus stress
extremes of medial and lateral rotation
why does the LCL become lax when the knee flexes?
so it doesnt limit medial tibial rotation and foot pronation
what lig is tense during knee flexion?
PFL
t or f: PFL is more resistant to anterior translation stability than LCL
true
what is the order of ligamentous failure when the leg is extended?
LCL, PFL, popliteus & arcuate lig.
what is the most common cause of hemarthrosis?
ACL tear
