Knee Flashcards
what position is the axis of the condyles of the femur and what is the relative size of teh condyles to each other
oblique relative to the vertical
larger medial condyle
what lives in the intercondylar fossa
cruciate ligaments
where does the patella live
on top of the femur
where is the pes anserine
slightly distal from level of fibula head but on the tibia
what is the tibial crest
proximal anterior ridge of the tibia (shin bone!)
what inserts in Gerry’s tubercle
IT band
how does the patella direct force of quadriceps
centralize force of quadriceps
how the patella effect teh strength of teh entire leg
increase by 30-35% via pulley mechanisms
how does the patella help with friction
reduces tendon and friction forces (tendon over patella vs tendon on femur)
thick articular cartilage between patella and femur
is patella protective
yes protects anterior surface fo knee
how does patella provide stability
limits extension of the leg
what is the formal name of knee joint
tibiofemoral joint
what type of joint is the tibiofemorla and what movements
synovial modified hinge with two DOF
IR/ER and FLEX/EX
what is the name of the mechanism what locks out the knee in WB extension
screw hole
what is the menisci and what is it made out of
fibrocartilage disc between tibia and femur
what are the parts of teh meniscus (shape and level fo mobility)
Lateral meniscus is oval shaped and very mobile
medial meniscus is c shaped and not mobile
what do teh coronary ligaments at the meniscus do
anchor the menisci to the tibia
what do does the transverse ligament at the meniscus do
holds the horns together
what do the mensicopatellar fibres do
anchor horns to patellar retinalculum
what is the function of the patella and meniscus working together
create stability during motion
what main knee ligaments attaches to meniscus
the deep MCL
muscle attachments to what sides of the meniscus
what is the function of these attachments
semimembranous to posterior medial meniscus
popliteus to lateral meniscus
–> helps the menisci “spot” the femoral condyles all teh way throughout motion
mensicofemoral ligaments to lateral meniscus
what part of meniscus has vascular and nervous tissue in it
none medially, present laterally
what side is meniscus thicker on
outer rim
in what direction does the meniscus move with knee motion and how much
moves anteriorly with knee extension
posteriorly with knee flexion
lateral meniscus moves up to 12mm
what occurs is meniscus does not move during knee movements
it can be ripped or crushed
meniscus functions (5)
deepens socket (increasing congruency) absorb and distribute force lubrication of joint prevents joint capsule from intruding on joint space partially protect against excess motion
function of collateral ligaments
provide medial and lateral stability
when are collateral ligaments tight and when are they loose
tight in full extension and loose in flexion
name collaterals and what are the size
medial (deep and superficial) –> HUGE
lateral –> TINY
what part of MCL is loose and what part is tight in flexion
anterior (superficial) is tight in flexion and posterior (deep) is loose in flexion and vice versa
is LCL extracapsular or capsular
extra capsular
name the two cruciate ligaments and what characteristic makes them unique and why are they named as they are?
anterior cruciate ligament and posterior cruciate ligament
anterior inserts anteriorly
posterior insert posteriorly
they are intracapsular but extrasynovial
what the the ACL limit?
anterior translation of teh tibia on teh femur
in CKC does tibia move on femur or femur move on tibia? in OKC?
CKC: femur on tibia
OKC: tibia on femur
what does the PCL limit
posterior translation of the tibia on the femur
what degrees of flexion is the pCL most restrictive
90-120 degrees
what structure supports against torsional stress
fabellofibular ligaments and arcuate complex
goal of the whole capsule
protect knee from twisting and torsion
what is the supra patellar pouch
pocket just above kneecap that fills with fluid post injury
bursa in the knee (4 main)
semimembranous bursa
supra patellar
subcutaneous patellar
subcutaneous infra patellar
ROM needed for regular ADLs
120 to 150 degrees
tightness where tends to limit knee flexion
Tightened in rectus femoris shorten and then hip must be extended at standing so knee cannot flex as much
knee extension is limited by
patella
tightening capsule
hamstrings
what is unique about the axis of motion of the knee throughout flexion
the axis of rotation changes because femoral condyles are larger than tibial condyles
how much rotation is available at the knee at 90 degree flexion
45 degree total (2:1 lateral to medial)
how do the femur and tibia move in relation to the knee in OKC to “lock out” the knee
20 degrees of lateral (external) tibia rotation, no femoral rotation
how do the femur and tibia move in relation to the knee in CKC to “lock out” the knee
tibia is fixed, femurs internally rotates
closed pack portion of the knee
full extension
resting position of the knee
25 degrees flexion
knee flexion ROM
130 - 150 degrees
degree of ROM of IR and ER of the tibia
IR: 15
ER: 25
what direction will the patella most likely dislocate
laterally
what tissues support the patella
retinaculum, vast medialis oblique, patellar tendon
in OKC does patella move on femur or femur on patella
patella on femur
in CKC does patella move on femur or femur on patella
femur on patella
closed packed position of patellofemoral joint
full flexion of the knee
open position of patellofemoral joint
full extension
where does the patella sit in full extension
in the intercondyler groove
position of patella in 90 degree flexion
flexed, lateral shift and lateral tilt
as knee flexed, how does patella move
move inferiorly, rotated, tilts and shifts
what is the Q angle
ASIS to patella and tibial tubercle straight up
do males are females have a larger q angle
females
functions of knee extensors
stabilize (isometric)
decelerate (eccentric)
accelerate (concentric)
name the quadriceps group
vastus medialis
vastus lateralis
vastus intermedius
rectus femoris
what is the articulates genu
pulls capsule superiorly during extension to prevent impingement
what bony movement to the hamstrings limit
anterior tibia translation
what kinetic movement do the hamstrings decelerate
rotation
name hamstrings
semimembranosus (medial) biceps femoris (lateral) semitendinosus (medial) gracilis sartorius
what inserts at the pes anserine
sartorius
gracilis
semitendinosus
what muscles does the gastroc co contract with to stabilize the knee
quadriceps
tibial rotators
medial: semitendinosus and semimembranosus gracilis sartorius popliteus lateral: biceps femoris
explain the absorption and distribution of forces at the knee in unilateral stance
compression forces double from bilateral
line of gravity passes medial to tibifemoral joint
medial compartment = 60% of forces
remaining forces are restrained by lateral restraints
peak torque position of the quadriceps
50-60 degrees knee flexion
what is extensor lag
lack of full extension at the knee due to quadriceps weakness and or pain
when is torque highest for knee flexors
full extension
normal strength ratio of hamstrings to quadriceps
2:3 hamstrings to quads
conditions that alter Normal torque of the knee
meniscal tears ligament instability ITB tightness obesity genu varus or valgum shortened femoral neck excessive pronation of feet changes in bony alignment due to fracture
what is the force couple during squatting
hamstrings act as hip extensor and quads act as knee extensors
explain length tension curve that occurs in a squat
as hip extends, knee extends as well for hamstrings and rectus femurs stay mid length
explain what occur at the muscles when someone squats down
eccentric actions control rate of knee flexion (quads) and hip flexion (hamstrings)
Mechano receptors are found in what parts of teh knee
ligaments
capsule and synovial lingin
menisci
what mechanorefelx occurs during knee effusion
reflex inhibition of the musculature –> reaction time several decreases
what is flexion contracture
a bent knee that cannot actively or passively be straightened
