Knee Complex Flashcards
What are the 2 articulations of the knee?
tibiofem, patellofem
Tibiofem is a double condyloid joint with how many degrees of freedom? What are they?
3: flx/ext, mr/lr, abd/add
Medial & lateral condyles are separated by intercondylar notch inferiorly & jointed anteriorly by what structure?
patellar groove
(Medial/lateral) plateau of tibia longer in AP direction?
medial
Tibiofem joint: (concave/convex) distal femur + flat tibial plateau + convex tibia margins?
convex
Define genu valgum & varum.
valgum: > 185, varum: < 175
Genu valgum has compressive forces (medially/laterally) & genu varum has tensile forces (medially/laterally).
laterally, laterally
True or False: With valgum, WB line passes laterally & with varum, it passes medially.
T
Which ligament attaches to menisci anteriorly?
transverse
Which menisci has ACL attachment to ant horn, PCL attachment to post horn, and semimembranosus?
medial
Lateral menisci attachments?
anterior horn & ACL share tib insertion site, PCL through meniscofemoral ligament, popliteus muscle
(Central/peripheral) portion of meniscal gets nutrition through blood vessels while other relies on diffusion of synovial fluid.
peripheral
Bony congruence & ligament tautness are max in full ________ (close-packed position).
ext
What are the anteromedial & anterolateral portions of the extensor mechanism also known as?
medial & lateral patellar retinaculae
True or False: ACL & PCL are intracapsular & intrasynovial.
F (extrasynovial)
What is the term for loose, elastic fibrous connective tissue that moves over femoral condyles during motion that may become inflamed?
synovial plica
(Anteriorly/posteriorly) synovium breaks from fibrous capsule & is folded back on itself (anteriorly/posteriorly).
posteriorly, anteriorly
What is the thickest band in medial retinaculum & is an important stabilizer to maintain patella in femoral sulcus?
medial patellofemoral ligament
Lateral patellofemoral ligament runs from where to lateral patella?
ITB
Joint capsule medially blends with MCL, laterally blends with ITB & fascia, & posteriorly is attached to which 2 ligaments?
arcuate, posterior oblique
Varus is (abd/add) of tibia.
add
MCL runs from medial femoral epicondyle to proximal tibia superficially & where deep?
medial tibial plateau
Which ligament is the primary restraint to excess valgus, lateral tibia rotation & can help resist anterior translation of tibia on femur?
MCL
LCL attaches from lateral femoral epicondyle to fibular head & joins with which tendon?
biceps femoris
LCL is the primary restraint for varus stress & excess lateral rotation & helps to prevent _________ rotatory instability.
posterolateral
Which ligament is on the posterior medial aspect of the lateral femoral condyle & attached to the lateral & anterior aspect of the medial intercondylar tibial spine?
ACL
ACL is the primary restraint against anterior translation of tibia on femur with which bundle most taut near full extension & which more taut beyond 15 degrees knee flexion?
ext: PLB, flx: AMB
Which bundle of ACL resists hyperextension?
PLB
Most ACL injuries occur when knee is slightly flexed & in (valgus/varus) position combined with anterior tibial translation.
valgus
What 2 muscles translate tibia anterior on femur?
quadriceps & gastrocnemius
What 2 muscles translate tibia posterior on femur?
hamstrings & soleus
Which ligament runs from the anterolateral aspect of the medial femoral condyle to the posterior tibial surface between the posterior horns of the menisci?
PCL
Which PCL band is taut near full extension & which is taut at 8-90 degrees of knee flexion?
ext: PLB, flx: AMB
PCL resists posterior tibial displacement especially with knee ________.
flexed
Which 2 muscles share role of PCL while hamstring & gastrocnemius increase posterior shear?
popliteus, quadriceps
Which ligament of the posterior capsule is the tendinous expansion of semimembranosus?
oblique popliteal
Posterior oblique ligament & arcuate ligament are taut during _______ & resist varus/valgus.
extension
What is the term for when there’s damage to LCL, popliteus, arcuate, & popliteofibular ligament?
PLRI
What are the 3 bursae that formed as invaginations of capsular synovium (intrasynovial)?
suprapatellar (anterior), subpopliteal (posterior), gastrocnemius (posterior)
What are the extrasynovial bursae of the knee?
prepatellar, infrapatellar, deep infrapatellar & fat pad?
Closed chain knee flexion
femur rolls posterior & glides anterior
Closed chain knee extension
femur rolls anterior & glides posterior
Open chain knee flexion
tibia rolls & glides posteriorly
Open chain knee extension
tibia rolls & glides anteriorly
How many degrees of knee flexion does walking require? How about stairs? How about sit-to-stand?
walking: 60-70
stairs: 80
STS: 90+
Knee extension may be limited due to
fixed ankle dorsiflexion or tightness in plantarflexors.
Tightness in plantarflexors presents as genu _________ when standing.
recurvatum
In prone, knee flexion may be limited by passive insufficiency of
rectus femoris
Which ligament becomes taut in closed chain knee flexion? Extension?
flx: ACL
ext: PCL
There’s (ant/post) deformation of menisci with flexion & (ant/post) with extension.
post, ant
True or False: There’s more rotation on medial tibia/femur than lateral.
F
Medial rotation (tibia on femur) leads to deformation of (med/lat) meniscus posteriorly & (med/lat) meniscus anteriorly.
med, lat
external rotation (tibia on femur) leads to deformation of (med/lat) meniscus posteriorly & (med/lat) meniscus anteriorly.
lat, med
In 90 degrees flexion, how many degrees of medial rotation & lateral rotation is there compared to little available in close packed extension?
MR: 15, LR: 20
There’s 8 degrees total of varus/valgus in knee ________ & 13-20 degrees total in knee ________.
ext, flx
Varus/valgus often tested in _____ degrees (full extension-closed packed) & _____ degrees knee flexion (open packed).
0: closed packed
30: open packed
Due to physiological valgus, flexion occurs with_______ & extension occurs with _______.
varus
valgus
Screw Home Mechanism: open chain knee extension
lateral rotation of tibia to allow quad to extend knee
*tibia moving on femur
Screw Home Mechanism: open chain knee flexion
popliteus contracts, medially rotating the tibia on the fixed femur to allow hamstrings to flex the knee
Screw Home Mechanism: closed chain flexion
lateral rotation of femur to allow hamstrings to flex knee
Screw Home Mechanism: closed chain extension
medial rotation of femur to allow quads to extend the knee
Which of the 3 hamstrings can laterally rotate while the other knee flexors medially rotate?
biceps femoris
What are the 6 knee flexor muscles? Which ones are not 2 joint?
hamstrings (BF short head), sartorius, gracilis, popliteus, gastrocnemius, plantaris
Medial knee flexors create (valgus/varus) moments while lateral group create (valgus/varus) moments.
varus, valgus
Pes anserinus
“say grace before tea”
sartorius, gracilis, semitendinosus - medial to lateral
Pes anserinus tendons resist valgus stresses & provide dynamic __________ stability (think direction).
anterior medial
Which 2 quadriceps have large posterior compressive forces?
vastus lateralis & vastus medialis
which two muscles can influence knee extension in weight bearing?
glute max
soleus
Quadriceps resultant pull is
lateral/anterior
Roll of patella on quad function
patella lengthens the moment arm of quads –> increase torque
the torque of quads is greatest during
extension
Which ligament would be affected if the patient feels ‘giving way’ or ‘buckling’ in regards to quadriceps pull on tibia along with anterior shear?
ACL
Which 2 muscles help knee extension in weight bearing?
soleus, gluteus maximus
In full extension, line of gravity passes ________ to knee axis –> extensor moment.
anterior
Open chain: MA of resistance increases as knee extends, greater quad force is required as extension progresses –> produces __________
anterior tibial shear
Closed chain: MA of resistance is minimal in full extension and increases with squat –> produces __________
posterior tibial shear
what structures limit anterior tibial translation.
ACL, ITB, hamstrings, soleus, & gluteus maximus
what structures limit posterior tibial translation.
PCL, MFL, quadriceps, popliteus, & gastrocnemius heads
What structures limit valgus?
MCL, ACL, PCL, arcuate, POL, medial muscles, & pes anserine muscles
What structures limit varus?
LCL, ITB, ACL, PCL, arcuate, POL, & lateral muscles
what strictures limit medial rotation of tibia.
ACL, PCL, PM capsule, MFL, & biceps femoris
what structures limit lateral rotation of tibia?
PL capsule, MCL, LCL, medial muscles
Where does the patella sit on in extended knee?
femoral sulcus
patella baja
shorter and lower on femur
patella alta
longer and higher on femur –> instability
(Superior/inferior) contact point of patella occurs in extension & early flexion while (superior/inferior) occurs around 90 degrees with lateral & odd facets occurring > 90 degrees.
inferior, superior
When patella flexes, it glides _______.
inferior
when the patella extends, it glides _________.
superior
Patella shifts from lateral in ________ to medial in ________.
extension, flexion
Patellofemoral compression forces are minimized in ________.
extension
From 30-70 degrees, what dissipates patellofemoral forces? How about past 90 degrees?
30-70: thick cartilage of medial facet
past 90: quadriceps tendon on condyles
what is the difference between patellofemoral joint stresses with walking versus running?
walking: 25-50% body weight
running: 5-6x body weight
Patellofemoral joint has potential for instability at knee ________ since it’s the open/loose packed position for PFJ (but closed pack for knee joint).
extension
Physiologic valgus of femur/tibia causes patella to be pulled slightly ________ by quadriceps & patellar tendon.
laterally
what are longitudinal stabilizers of the patellofemoral joint
inferior: patellar tendon
superior: quad tendon
patellotibial ligaments of extensor retinaculum
what are the transverse stabilizers of the patellofemoral joint?
vastus medialis & vastus lateralis
medial and lateral patellofemoral ligaments from adductor tubercle to patella to ITB
excessive knee extension will increase the potential for frontal plane ________.
Which ligament resists lateral translation by large lateral lip of femoral sulcus as bony stabilizer?
medial patellofemoral
Excessive resultant lateral patellar forces:
weak VMO, tight ITB/TFL, genu valgum, femoral anteversion, external tibial torsion, pronation, stretched medial structures, anteversion, lateral
What is the normal range for q-angle which is measured in extension?
What degree indicates mal-alignment & possible excessive lateral forces?
10-15, 20
(Women/men) have larger q angle because of wider pelvis, hip anteversion, & knee valgus.
women
Increased q angle leads to genu _________.
valgum
What type of tibiofemoral injury comes from rotation on fixed tibia?
meniscal
What type of tibiofemoral injury comes from excessive forces or low level repetitive stresses?
ligament tears
What type of tibiofemoral injury comes from high load or fall?
bone/cartilage damage
What type of tibiofemoral injury comes from direct blow or repetition?
bursa or tendon
What type of tibiofemoral injury comes from sitting, stairs, or extension?
plica irritation
