Flashcards in Knee TIBIOFEMORAL joint Deck (62):
Which femoral condyle is larger and extends more distally?
What is the classification of the tibiofemoral joint and how many DOF?
double condyloid joint; 3 DOF
Femoral condyles are ______ while tibial plateau is ______.
During dynamic gait, the line of force shifts _________ to the knee joint center.
During dynamic gait, there is _________ compression and ________ tensile/distraction force.
In bilateral stance, describe the WB stress to the medial and lateral condyles?
What important component increases with genu varum?
What are 4 important properties of the medial and lateral menisci?
1. increase joint congruence
2. distribute WB forces
3. reduce friction b/w tibia and femur
4. shock absorption
Medial meniscus shape and implication?
Less surface area coverage than lateral. susceptible to injury, especially because the medial compression
Lateral meniscus shape and implication?
4/5 of a circle
covers greater proportion of smaller lateral tibial surface
What is the relationship between thickness and region for the menisci?
Translation is limited for medial meniscus due to
greater ligamentous and capsular restraints
The relative lack of mobility of the medial meniscus may contribute to
greater incidence of injury
What attaches the menisci anteriorly?
What attaches patella to menisci?
anterior capsular thickenings called the patellomeniscal ligaments
What are the peripheral attachments of menisci to tibial condyle?
Which muscle attaches through capsular connections to the medial meniscus?
What is the primary fxn of the MCL?
restrict motion of medial meniscus
What structures attach to the medial meniscus?
ACL (Anterior and posterior horns)
deep portion of the MCL
Which muscle attaches through capsular connections to the lateral meniscus? Implication?
popliteus; it restrains movement of the lateral meniscus
Removal of menisci the contact area in the tibiofemoral joint is ________. Results?
decreased contact area
increased joint stress
risk for damage of articular cartilage
Which part of the menisci have vascularity?
periphery; central portion is avascular
How does central menisci get nutrition?
depends on diffusion of synovial fluid which requires intermittent loading by WB or muscular contractions
Which part of the menisci is well innervated?
free nerve endings (nociceptors) and mechanoreceptors loacted in meniscal horns and vascular periphery
What is the close-packed position of the knee?
max bony congruence and ligament tautness
Most mobility of the joint when the knee is in what position?
periarticular passive structures tend to be lax (relative bony incongruence)
The capsule is reinforced posterolaterally by the ________ ligament and posteromedially by the ________ ligament.
posterior oblique ligament
(both restrain hyperextension)
MCL best restrains valgus motion when the knee is in which position?
extension --> MCL is taut in extension
Injury to the ACL most often occurs with which position?
WB: slight flexion and and tibia rotated either way
Does the anterior or posterior cruciate ligament resist greater loads? Why?
posterior can resist greater loads: more extensive attachment, short, wide, less oblique
In a deep squat, which component of the PCL is taut?
posteromedial bundle; it limits posterior displacement of the tibia
Which component of the PCL is taut in 90* flexion?
Which component of PCL is taut in extension?
Which ligament best restrains in flexion?
PCL: restraint to posterior displacement
Which ligament best restrains in extension?
ACL: restraint to anterior displacement
Which muscles can decrease strain on PCL when knee is flexed?
POPLITEUS and quds
Which muscles can decrease strain on ACL?
hamstrings and soleus
Does ITB resist displacement?
Resists anterior displacement with the help of LCL and popliteal tendon when knee is flexed
In flexion of femur in WB, the femoral condyles roll in which direction? What ligament "checks"?
posterior roll checked by ACL --> results in anterior translational force by ACL on femur
In extension of femur in WB, the femoral condyles roll in which direction? What ligament "check"?
anterior roll checked by PCL --> results in posterior translational force by PCL on femur
The menisci must remain under the femoral condyles to fxn in reducing friction and absorbing forces onto the small tibial plateau. How do menisci react to forces during flex/ext?
deformation allows menisci to remain under femoral condyles
With posterior deformation of menisci, which muscles contribute?
semimembranosus exerts post. pull on medial meniscus
popliteus exerts post. pull on lateral meniscus
How do menisci react to forces as knee moves into extension?
How do menisci react to forces in flexion?
The medial femoral condyle is distal to the lateral femoral condyle in an extended knee. This results in?
physiological valgus knee (in extension)
axis for flex/ext is obliquely oriented
Coupled motions about the obliquely oriented axis for flex/ext are?
What is the axis for axial rotation (IR/ER)?
medial tibial plateau --> the lateral tibial condyle rotates about the medial
Axial rotation is maximized in which position? Limited in which position?
maximized in 90* flexion
limited in full extension
What happens with forceful quad contraction when the knee close to full extension? Why?
anterior tibial translation (places stress on both anteromedial and posterolateral ACL bundles)
patella increases the length-tension relationship by increasing MA for quads
There is little to no anterior translation in which position? Why?
knee flexed >60*
because of influence of patella on quad MA and length-tension relationship
What muscles assist with knee extension in WB?
soleus and glut max
During WB, quads generate greater force as knee ___________ increases to control the increasing MA.
During NWB, quads generate greater force as knee __________ increases to overcome the increasing MA.
What structures limit anterior tibial translation?
Soleus (in WB)
Glut max (in WB)
What structures limit posterior tibial translation?
medial and lateral heads of gastric
What structures limit valgus of tibia?
MCL, ACL, PCL
posterior oblique ligament
sartorius, gracilis, semitendonosis (pes anserine)
medial head of gastroc
What structures limit varus of tibia?
LCL, ACL, PCL
posterior oblique ligament
lateral head of gastroc
What structures limit medial rotation of tibia?
posterior medial capsule
What structures limit lateral rotation of tibia?
sartorius, gracilis, semitendonosis (semitendinosus)
damage to posterolateral joint capsule, popliteus, acrcute ligament can cause excessive lateral tibial rotation and posterior instability
Dame to posterior oblique ligament, medial hamstrings, MCL and posteromedial joint capsule