Knee Flashcards
What are the 3 most common types of injuries seen in the clinics for the knee?
- unspecified sprains, strains, or overuse injuries
- contusions
- meniscal or ligamentous injuries
What type of joint is the tibiofemoral joint?
Hinge joint
What are the degrees of freedom for the tibiofemoral joint?
Flex/ext
IR/ER (minute)
ABD/ADD (minute)
What structures originate on the lateral condyle?
Popliteus, lateral head of the gastrocnemius, LCL
What structure originate/insert on the medial condyle?
Adductor magnus, medial head of the gastrocnemius, MCL
What are the two tibial plateaus separated by?
Intercondylar eminence
The medial tibial plateau is ______ in the ML direction and ______ in the AP direction.
concave, concave
The lateral tibial plateau is ______ in the ML direction and ______ in the AP direction.
concave, convex
The medial plateau surface area is ___% greater than the lateral plateau, and the articular surface is ___ times thicker.
50% greater, 3 times thicker
What helps to accentuate the concavity of the tibial plateau?
The mensici
What is the resting position of the tibiofemoral joint?
25 flexion
What is the closed-packed position of the tibiofemoral joint?
full extension, ER of the tibia
What is the capsular pattern of the tibiofemoral joint?
flexion, extension
What type of joint is the patellofemoral joint?
Modified plane joint
Which surface of the patellofemoral joint is widest?
Lateral
What are the 5 facets of the patella? Which is associated with chondromalacia?
Odd, Superior, Inferior, Medial, Lateral
Odd is most frequently associated
What are the functions of the patellofemoral joint?
Provide the articulation with low friction
Protect the distal aspect of the femur from trauma and the quadriceps from attritional wear
Improve the cosmetic appearance of the knee
Improve the moment arm of the quadriceps
Decrease the amount of AP tibiofemoral shear stress placed on the joint
Where does the tibial articulating facet face?
laterally, posteriorly, inferiorly
Which joint has more motion: proximal or distal tibiofibular joint?
Proximal
What are the two directions that you can glide the tibiofibular joint?
Superior-Inferior
Anterior-Posterior
What is the concavity/convexity of the proximal tibiofibular joint?
Slight convexity of the tibial facet and slight concavity of the fibular head
What is the ACL a primary and secondary restraint for?
Primary = anterior translation and medial rotation of the tibia on the femur Secondary = restraint to valgus and varus rotation of tibia
What is the PCL a primary and secondary restraint for?
Primary = posterior translation and medial rotation of the tibia on the femur Secondary = restraint to valgus and varus rotation of tibia
What is the MCL a primary and secondary restraint for?
Primary = restraint for valgus and lateral rotation of the tibia Secondary = anterior and posterior translation of the tibia on the femur
What is the LCL a primary and secondary restraint for?
Primary = restraint for varus and lateral rotation of the tibia Secondary = anterior and posterior translation of the tibia on the femur
ACL and PCL contain ________ that if disrupted, can eliminate sensory nerve fibers to the joint.
mechanoreceptors
What can the ACL do while under internal stress?
Microscopic adjustments to the laxity, stresses and kinematics of the joint
Which of the cruciates is strongest?
PCL > ACL > MCL,LCL
Forcing the ACL more than ___ beyond its resting length may cause a rupture.
5%
How much thicker is the PCL than the ACL? How much stronger?
50% thicker, twice as strong
How much total restraint does the PCL provide to posterior translation of the tibia on the femur?
90-95%
Are MCL and LCL intra or extra-articular ligaments?
extra
Where does the MCL superficial band originate and attach?
Thick, flat band. Attaches proximally on the medial femoral condyle, blends with the posteromedial corner of the capsule
Which ligament is the first to be injured with a valgus force?
MCL Superficial Band
What is the MCL deep band a continuation of? Where does it attach?
Continuation of the joint capsule, blends into the medial meniscus
Where does the LCL originate and attach?
Arises from lateral femoral condyle, runs distally and posteriorly to insert on the head of the fibula
Is the LCL a part of the joint capsule?
No, the cord-like LCL develops independently, completely free from the joint capsule and lateral meniscus
Where are the secondary restraints located?
Posterolateral and posteromedial corners of the knee
What do the secondary restraints assist with?
Control anterior tibial translation relative to the femur
What are the secondary restraints?
Hamstrings, popliteus, patellar tendon, oblique popliteal tendon, fabella
Which region of the menisci are most susceptible to injury?
Inner regions
Which portions of the medial and lateral menisci are vascularized?
Lateral = outer 25%
Medial = outer 30%
(the remaining inner portions are considered avascular)
What shape is the medial meniscus?
Semilunar
