MS: hip/knee Flashcards
What is the orientation of the femoral head
superior, anterior, medial
What is a normal angle of inclination
115-125
What is the normal angle of antetorsion
10-15 (anteversion= 25-30+, retroversion= less than 10)
What is the orientation of the acetabulum
laterally, inferior, anterior
What is the acetabular notch?
area without articular cartilage at inferior aspect of acetabulum
What part of the hip labrum is thickest?
superior
Iliofemoral ligament
“Y” ligament
Two bands (lateral and medial)
Taut with extension and ER
Lateral band also taut with adduction
Pubofemoral ligament
Blends with capsule, inserts along with medial iliofemoral
taut with extension, ER, abduction
Ischifemoral ligament
Attaches to GT
taut with IR, abduction, and extension
What is the zona orbicularis
circular band w/o bony attachment that helps hold femur in acetabulum
Which femoral condyle descends further?
medial
Which femoral condyle has larger surface area
lateral
MCL
medial aspect of medial femoral condyle to upper tibia
blends with capsule
runs anteriorly, inferiorly, and obliquely (same as ACL)
taut in extension
prevents ER and stability against valgus forces
LCL
lateral femoral condyle to fibular head extracapsular runs inferiorly, posteriorly, and obliquely (same as PCL) taut in extension prevents ER and stability against varus
ACL
anterior intercond fossa of tibia to femur at medial aspect of lateral femoral condyle
extracapsular, but intra-articular
limits IR of tibia during flexion and anterior rotation
Meniscofemoral ligament
Runs with PCl.
Attaches below posterior horn of lateral meniscus
Oblique popliteal ligament
inserts into expansion of semimembranosus.
Becomes floor of popliteal fossa
Arcuate popliteal ligament
Y shaped-fibular head to intercondylar area on tibia and lateral epicondyle of femur.
strengthens poserolateral capsule
Transverse ligament
connects menisci anteriorly
Medial meniscus shape
C
Lateral meniscus shape
circular/oval
Which meniscus is larger?
Medial
Medial meniscus
Large, C shaped, stable
Attaches to MCL and semimebranosus
Lateral meniscus
Smaller, oval.
Attaches to popliteus
Function of menisci
Deepens fossa of tibia Increase congruency Add stability Shock absorption Lubrication
How do the menisci move?
Along with tibia for flexion/extension, Along with femur for rotation.
How is the medial meniscus pulled during flexion/extension?
during flexion: posterior by semimebranosus
during extension: pulled anteriorly by medial meniscopatellar ligament
What causes the femoral condyles to glide anteriorly during flexion
The increased tension ACL (PCL does posterior glide during extension)
Screw home mechanism
tibial external rotation during TKE
What “unlocks” screw home mechanism
popliteus
What causes the screw home mechanism?
1) lateral femoral condyle glides posteriorly better than medial
2) More medial femoral condyle joint surface-causes more rolling on joint side
3) Medial meniscus attachment to MCL tight during extension
4) twisted cruciates cause ER
5) Lateral pull of quads
Proximal tib/fib mechanics during dorsiflexion
fibular head glides superiorly and posteriorly. Fibula rotates externally
Proximal tib/fib mechanics during plantarflexion
fibular head glides anteriorly and inferiorly. Fibula rotates medially
