Knee Flashcards
What does the knee as a region consist of?
Condyles of the femur and tibia, the patella, the fibular head and the popliteal fossa
what does the knee as a joint?
A hing type synovial joint, with gliding and rolling, and some rotation
What is the largest and most superficial joint of the body?
The knee
What are the two reasons the knee joint is one of the most vulnerable joints?
The articular surfaces are incongruous and there is a mechanical disadvantage resulting from bearing weight plus momentum while serving as a fulcrum between 2 long levers
What are some features of the knee that provide compensatory support?
Strong intrinsic, intracapsular and extracapsular ligaments, splinting by tendons and menisci
what is patellofemoral syndrome?
Knee pain resulting from microtrauma/osteoarthritis and improper tracking of the patella
what are the primary movements at the knee joint?
flexion and extension (combined with gliding and rolling)
is the tibia fixed or mobile?
tibia is in a fixed position and femur rotates on top of it
where are the medial and lateral femorotibial articulations?
between the corresponding condyles of the femur and tibia
are the medial and lateral femoral condyles concave or convex?
convex with the articular surface extending superiorly on the posterior aspect
what separates the medial and lateral femoral condyles?
intercondylar fossa
which femoral condyle is larger?
the medial
what is the superior tibial surface expanded by?
the presence of the medial and lateral condyles
describe the tibial plateau?
relatively flat for articulation with femur. medial side is actually slightly concave and lateral slightly convex. with an intercondylar area containing 2 tubercles
what attaches on the medial and lateral intercondylar tubercles of the tibial plateau?
menisci and cruciate ligaments
what attaches on the medial and lateral epicondyle of the femur?
the collateral ligaments
what keeps the knee joint stable?
musculature
when is the knee most stable?
when standing erect in extension
why is the knee most stable in extension?
the articulating structures are most congruent, the collateral and cruciate ligaments are taut and there is a splinting effect by the many surrounding tendons crossing the joint
what is the largest sesamoid bone in the body?
the patella
how many total facets are on the patella?
7
what does the patella provide?
a bony surface that is able to withstand compression placed on the quadriceps tendon during kneeling, and the friction occurring during repeated flexion/extension during running. it also moves the tendon more anteriorly than the tibial tuberosity and farther from the joint’s axis, providing for greater mechanical advantage
what are the 3 functions of the patella?
- dissipates force across anterior aspect of femoral condyles
- improves the mechanical efficiency of the quadriceps muscle
- occupy (“tracks in”) the intercondylar groove
where does the suprapatellar bursa lie?
deep to the tendon of the quadriceps femoris, superior to the knee
T/F: the suprapatellar bursa is continuous with the joint space
true
what could happen if theres an infection in the suprapatellar bursa?
bc it is continuous with the joint the infection could spread to the joint
what holds the suprapatellar bursa in place superiorly?
the articular muscle of the knee
what do the prepatellar and superficial infrapatellar bursae allow?
allow the skin to move freely around the knee as it bends
what is housemaids knee?
an inflammatory process which results from trauma (anyone who kneels a lot without protecting the area with knee pads is susceptible)
what does the infrapatellar fat pad do?
separates the deep infrapatellar bursa from the joint space
what kind of joint is the knee?
synovial with an external fibrous capsule and interanal synovial membrane
why is the external fibrous capsule of the knee incomplete at some spots?
example bc poplietus tendon pierces it
what does the internal synovial membrane of the knee do?
separates the inside of joint into medial and lateral compartments by “bunching up” anteriorly, covering the cruciate ligaments
what does intra-articular mean?
being within the synovium and in contact with sunovial fluid
where does the synovium attach?
at the edge of all the articular cartilage surfaces, including the deep surface of the patella
where is the capsule most defined?
posteriorly
what is continuous with the capsule anteriorly?
the tendons of the quadriceps femoris (retinacula), iliotibial band, patella and patellar ligament
T/F: structures are either intracapsular and intraarticular or extracapsular and extraarticular
False structures can be intracapsular and extraarticular
are the cruciate ligaments intaarticular?
no they occupy a space within the external capsule but not within the synovial cavity so they are intracapsular
where are the attachments of the synvoium?
at margins of cartilage structures
are the menisci intracapsular and intrasynovial?
although it is not entirely within the synovial cavity the synovial fluid is in contact with the majority of the surface so yes intracapsular and intrasynovial
what is the suprapatellar bursa continuous with?
the synovial cavity
what is intrasynovial or intraarticular?
means within the synovial cavity
the extracapsular ligaments are what to the capsule?
intrinsic meaning they are thickened, integral parts of the capsule
what are the 5 extracapsular ligaments of the knee?
patellar ligament, tibial and fibular collateral ligaments, oblique popliteal ligament and acruate popliteal ligament
what is the patellar ligament?
the distal part of the quadriceps tendon running from the inferior border of the patella to the tibial tuberosity
what are the medial and lateral patellar retinacula?
extensions of aponeuroses from the vastus medius and lateralis muscles and deep fascia
what do the medial and lateral patellar retinacula do?
they contribute to the joint capsule and important in maintaining the alignment of the patella relative to the patellar articular surface of the femur (keeping the vertical ridge on the deep surface of the patella in the condylar groove)
what is the MPFL (medial patellofemoral ligament)?
the thickening of the transverse fibers of the medial patellar retinaculum
what is the patellar DTR?
a common clinical test for the integrity of the reflex of the arc of spinal segments L2-L4. a brisk strike with a reflex hammer of the patellar ligament should normally result in contraction of the quadriceps femoris and the knee will extend
what is the function of the extra capsular ligaments?
to strengthen fibrous joint capsule
what do the posterior extra capsular ligaments do?
resist hyperextension
what is the oblique popliteal ligament?
a recurrent expansion of the tendon of the semimembranosus tendon. spans the intracondylar fossa, arrises posterior to the medial tibial condyle and passes superolaterally toward the lateral femoral condyle blending with the joint capsule
what is the arcuate popliteal ligament?
arises from the posterior aspect of the fibular head, passes superomedially over the tendon of the popliteus muscle and spreads over the posterior surface of the knee
what is a fabella?
a small sesamoid bone sometimes found in the lateral head of the gastrocnemius that articulates with the lateral femoral condyle and can be see on an x-ray in about 5% of studies
where does the tibial collateral ligament (TCL/MCL) run?
the medial epicondyle of the femur to the medial condyle and the superior part of the medial surface of the tibia. deep fibers are firmly adherent to the medial meniscus
when is the MCL taut?
in extension
what does the MCL do?
contributes to stability when standing, limits lateral rotation of the tibia when the knee is in flexion
which is weaker LCL or MCL?
MCL so it is damaged more often
what is genu valgus and varus?
angular deformities of the knee in the coronal plane
what does the Q angle represent?
the amount of deviation of the femur off the vertical
what occurs with genu valgus?
the Q angle is exaggerated, the weight bearing line is displaced laterally relative to the center of the knee the TCL is overstretched and there is excessive stress on the lateral meniscus
what occurs with genu varus?
the Q angle is less, the weight bearing line is displaced medially relative to the center of the knee, the MCL is overstretched and there is excessive stress on the medial meniscus
what is arthrosis?
the result of genu valgus/varus, the destruction of the menisci, cartilage surfaces and subsequent arthritis
where does the fibular collateral ligament (LCL/FCL) run?
inferiorly from the lateral epicondyle of the femur to the lateral surface of the fibular head
does the LCL attach to the lateral meniscus?
NO
what does the LCL resist?
varus stress on the extended knee and flexed up to 30º. also helps limit medial rotation of the tibia when the knee is flexed
what does the LCL split?
tendon of biceps femoris
which tendon passes deep to the LCL?
the popliteus
what do the cruciate ligaments always maintain?
the contact between the femur and tibia
what are the ACL and PCL named by?
their tibial position
what do the ACL and PCL do with rotation?
wind around each other
in knee flexion, medial rotation of the leg is limited by the further winding around each other, lateral rotation is considerably more on the other hand and is limited by the TCL
which is weaker the ACL or PCL?
ACL
what does the ACL do?
limits the femoral condyles from rolling in flexion, and prevents posterior displacement of the femur on the tibia and hyperextension of the knee joint
where does the ACL run?
from the anterior intercondylar area of the tibia extending superoposterolaterally to the medial side of e the lateral femoral condyle posteriorly
where does the PCL run?
from the posterior intercondylar area of the tibia and passes superoanteromedially to the lateral aspect of the medial condyle of the femur anteriorly
what does the PCL do?
limits the anterior rolling of the femoral condyles in extension and prevents anterior displacement of the femur on the tibia. while weight bearing on the flexed knee the PCL is the main stabilizer
what does the posterior meniscofemoral ligament do?
joints the lateral meniscus to the PCL and the medial femoral condyle
what are the menisci?
crescentic plates of fibrocartilage that sit on the tibial plateau and deepen the surface and absorb shock. both are firmly adherent to the intercondylar region of the tibia and external margins attach to the joint capsule of the knee
describe the medial meniscus
adherent to the MCL, less mobile than the lateral, c-shaped
describe the lateral meniscus
o-shaped, more mobile due to contraction of popliteus muscle
what does the transverse ligament do?
joins the anterior edges of the menisci, tethering them to each other during knee movements
what are the coronary ligaments?
associated with each meniscus, they are portions of the joint capsule extending between margins of the menisci and most of the periphery of the tibial condyles
how do peripheral meniscal tears heal?
they can heal with or without surgery
how do central tears heal and why?
may need to be removed through an arthroscopic procedure because poor blood supply
what effect does the removal of the meniscus have?
no decrease in mobility but increases the chance for tibial inflammatory reactions and subsequent arthritis
what is torn in the unhappy triad?
ACL, MCL, medial meniscus
what causes and unhappy triad?
an excessive valgus stress on an extended knee or excessive lateral twisting of the flexed knee
what is the anteroposterior xray of the knee useful for?
evaluating the joint space where the radio-opaque menisci and articular cartilage are found
what is the lateral x-ray of the knee appropriate to evaluate?
patellar size/position and the femoral condyle appearance
what is the sunrise view x ray orientation best for?
visualization for patellar tracking in the intercondylar groove of the femur
