Knee Flashcards
What are the two joints of the knee joint?
The tibiofemoral and the patellofemoral
What articulates in the tibeofemoral joint?
The shallow tibial plateau and the large femoral condyles
What is genu valgum?
Knees in
What is Genu varum?
Knees out
What is the role of the menisci?
wedge to improve joint congruency
shock absorption
decrease friction
Where is most of the pressure in single leg stance placed?
On the medial condyle of femur (larger)
Arthrokinematics knee flexion
Anterior roll with posterior glide
Arthrokinematics knee extension
Posterior roll with anterior glide
What is the difference in size btwn the borders and center of the menisci?
Borders are thick, center is thiner
What tibiofemoral joint alignment will you often see in OA?
Genu Varum (pain @ medial femoral condyle so put more pressure on lateral condyle), with TOES OUT to reduce load on femoral condyle
What is a knee adduction moment?
Putting more pressure on the medial side. can be measured in gait lab
What are the pointed portions of the menisci called?
Anterior and posterior horn
Which meniscus has more ligamentous attachments?
The medial meniscus
What parts of the meniscus attach to the ACL?
Anterior and posterior horn of medial meniscus
How are the medial and lateral menisci connected?
Transverse ligament
Which meniscus attaches to the PCL?
The lateral meniscus
What happens during compression at the tibiofemoral joint without a meniscus?
Loads will increase on a smaller surface area, which may cause a disruption in hyaline cartilage
What is the mechanical axis?
Where does the force go through (right through the femur and the tibia)
What is the anatomical axis?
follows the line of the femur
What is terminal rotation/screw home mechanism?
Rotation of tibia on femur or femur on tibia
WB: medial rotation of femur on tibia; NWB: lateral rotation of tibia on femur
What muscle unlocks the “screw home mechanism” of knee?
The popliteus
What is the structure of the MCL?
Broad, flat and long
When is the MCL taut? What is its primary role? Secondary role?
during extension. Limits valgus stress. Resist tibial anterior translation
What are the two components of the MCL?
Superficial-attaches from posterior ligament to medial femoral ligament (primary restraint of valgus force)
Deep- (attacks to medial meniscus, continuous w/ jt capsule)
What is the structure of the lateral collateral ligament?
Cordlike and thick
What tendon does the lateral collateral ligament join with?
The biceps femoris tendon
When is the LCL taut and relaxed?
Taut in extension, relaxed in flexion
Does the LCL attach to the lateral meniscus?
Nah
What is the attachment of the LCL?
Lateral femoral condyle to the fibular head
What is the structure of the ACL?
Oblique fibers
What is the ACL attach to
Lateral anterior portion of the tibia and the lateral femoral condyle (posterior-medial mortion)
What is the ACL responsible for?
Anterior stability (Anterior translation of the tibia) prevent hyperextension
What are the two bundles of the ACL?
anteromedial (AMB)
Posteriolateral (PLB)
What does the PLB of the ACL limit?
Anterior translation in extension
What does the AMB of the ACL limit?
anterior translation with a flexed knee
What portion of the knee gets torn with a flexed knee and rotation?
AMB
What is the structure of the PCL?
Broader, shorter, less oblique (than ACL)
What does the PCL restrain?
Posterior translation of the tibia
What are the two bundles of the PCL?
Anteriolateral
Posteriomedial
Which is easier to repair ACL or PCL?
ACL
When does the ALB best limit posterior translation?
Beginning portions of flexion
When does the PMB best limit posterior translation?
Extension
Deeper squats–> increased flexion
What does the patella articulate with?
The femur
Which facet of the patella has the most hyaline cartilage?
The medial facet, because of the high compressive loads applied to it
What is a patellectomy?
Removal of the patella
What happens with a patellectomy?
Decreased moment arm, increased compression, altered angle of pull
What does the patella do?
Increases the moment arm of the quadriceps and acts as an anatomical pulley
What is Patella alta?
Patella is higher
What is Patella baja?
Patella is lower
How is normal patellar tracking described?
A “c” curve
What happens to the patella during tracking?
Travels upward along patellofemoral groove
What happens to the patella during flexion?
Patella rotates, tilts laterally
What happens to the patella during extension
Patella rotates, tilts medially
What are the two posterior capsule ligaments?
arcuate ligament
oblique popliteal ligament
What is the primary fxn of the posterior capsule ligaments?
Restrain hyperextension
both are taut in extension
The oblique popliteal ligament reinforces which part of the joint capsule?
posteromedial
The arcuate ligament reinforces which part of the joint capsule?
posterolateral
What are the attachments of the arcuate ligament?
tendon of popliteus and posterior capsule to posterior fibular head (lateral arcuate head) and oblique popliteal ligament (medial arcuate head)
(remember, it is Y-shaped and has to heads)
What are the attachments of the oblique popliteal ligament?
central posterior joint capsule and tendinous expansion of semimembranosus to the posterior medial tibial condyle
