knee arthrokinematics Flashcards
what assists with the discrepancy in size of the femoral condyles and the size of the tibial plateaus
presence of the menisci
what do when the knee flexes/extends
will deform to maintain joint congruency throughout ROM
in an open kinetic chain
concave tibia moving on the convex femur
BM, roll and glide –> same direction
flexion OKC first 25 degrees of motion
minimal gliding
flexion OKC from 25 to full extension
posterior glide of the tibia –> maintain contact b/w tibia and femoral condyles
extension OKC
anterior gliding of the tibia on the femur throughout ROM
closed kinetic chain
convex femur is moving on concave tibia
BM and roll –> same
glide –> opposite
CKC flexion (stand to sit)
BM and roll –> posterior
glide –> anterior
occurs throughout ROM
forces that induce posterior glide
PCL
anterior aspect of menisci
force of femoral condyle on the meniscus
tends to cause posterior movement of the menisci
screw home mechanism
automatic IR of the femur on the tibia (closed chain)
OR
automatic ER of the tibia on the femur (open chain)
during end range knee extension
what is the screw home mechanism d/t
larger medial femoral condyle and knee joint ligs
when does the 20 degrees of rotation occur –> screw home
occurs during the last 30 degrees of knee extension motion
especially the last 5 degrees (terminal knee extension)
OKC –> screw home
during end range knee extension –> lateral tibial plateau will complete its slide along the lateral femoral condyle
this occurs while the medial tibial plateau continues to glide anteriorly on the femur
–> causing the tib to ER on the femur (vertical axis is the lateral femoral condyle)
CKC –> screw home
during end range knee extension –> the lateral femoral condyle will complete its slide along the lateral tibial plateau
this occurs while the medial femoral condyles continues to glide posteriorly on the tibia (b/c it is longer/larger)
–> causes the femur to IR on the tibia (vertical axis is the lateral femoral condyle)
