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Knee Joint

QuestionAnswer
How many bones make up the knee joint? 3 Femur, patella, tibia
How many degrees of freedom are in the knee joint? 2
What are teh articulating surfaces? Medial tibio-femoral, Lateral tibio-femoral, patella-femoral
What is the function of the knee Withstanding large forces, providing great stability, and enabling a large ROM
Mobility in the knee is given primarily by what structure? Knee bony structure
Stability is provided by what structure in the knee? Soft tissues: ligaments, muscles, and cartilage
How does the mobility and stability of the knee compare to the hip? They are opposite.
Where are the femoral condyles separated? Anteriorly - intercondylar notch
Why does the popliteus muscle add complexity to the joint capsule? Origin is inside the joint Pierces the capsule to attach on the lateral femoral condyle
Why does the semimembranosus add complexity to the joint capsule? Forms part of oblique popliteal ligament and gives off fibers to MCL, as well as its bony large attachment
Is the arcuate ligament an example of an intrinsic or extrinsic ligament? Intrinsic, over popliteal muscle
What ligaments are responsibility for the trasnverse stability of knee during extension? Collateral ligaments
Where does the medial collateral ligament run from? Medial femoral condyle to tibia, posterior to pes anserinus tendon Runs inferiorly and anteriorly
Where does the lateral collateral ligament run from? Lateral condyle to head of fibula
What are the collateral ligaments like during extension and flexion? Taut - extension Slackened - flexion
Which ligaments are contained within the intercondylar notch and fossa? Cruciate ligaments
What are the ACL attachments? Anterior intercondylar area of tibia to lateral condyle of femur Runs superiorly, posteriorly, and laterally
What are the PCL attachments Posterior intercondylar area of tibia to medial condyle of femur
What is the function of the cruciate ligaments? Stabilize knee in antero-posterior direction Allows joint to work as a hinge while keeping the articular surface in contact
What does the acronym APEX stand for? ACL attaches to anterior intercondylar area (tibia) runs posteriorly and attaches to external femoral condyle
What does the acronym PAIN stand for? PCL attaches to posterior intercondylar area (tibia) and runs anteriorly and attaches to internal femoral condyle
What is the function of ACL? Prevents anterior displace of tibia on femur
What is the function of PCL? Prevents posterior displacement of tibia on femur
How is the lack of congruency in the articular surfaces in the knee joint corrected? Menisci
What is the menisci? Semi-lunar fibrocartilages. Incomplete rings in the intercondylar tubercles of tibia. Have anterior and posterior horns
How do two menisci compare to each other? Medial - more C shapes. Horns don't come together. Lateral - more O shaped. Horns come closer together
What links the two anterior horns of the menisci? Transverse ligament of the knee
What forms the meniscopatellar ligament? Fibrous bands running from lateral edges of the patella to lateral borders of each meniscus
Which collateral ligament is attached to the medial meniscus? MCL
Why isn't the LCL directly attached to the lateral meniscus? Tendon of popliteus - sends fibrous expansion to posterior border of lateral meniscus
What muscle sends a fibrous expansion to posterior edge of the medial meniscus? Semimembranosus
What forms the meniscofemoral ligament? PCL fibers in the posterior horn of lateral meniscus
What is the attachment for both meniscus? Tibial condyle
Why is the medial meniscus more fixed than the lateral meniscus? Attaches to one more structure
What is the implication of medial meniscus being more fixed? More prone to damage
What is the terrible triad? ACL, MCL, and medial meniscus
What is the geometric center? Joint line passing horizontally through femoral condyles
What is the instant center of rotation of Reuleaux? Axis coinciding with center of cruciate ligaments in sagittal plane
What would happen if the femur rolled on tibia without sliding? After a certain measure of flexion, femoral condyle would tip over behind tibial condyle
What is the assumption we can make of the knee based on the fact that the circumference of the femur is greater than the tibia? There is no possibility of simple rolling of femur
What would happen if the femur slides without rolling on knee joint? Femur on posterior border of tibia condyle would prevent further flexion
Where does axial rotation occur in? Transverse plane when knee is flexed
What happens to the knee in extension for axial rotation? Collateral ligaments are tense and contribute to joint stability so no movement
Describe the movement of the condyles in axial rotation Lateral condyle rotates around the medial condyle
Why does the lateral condyle rotate around the medial condyle? Axis for rotation is longitudinal and located medial to intercondylar eminence of tibia
What limits the motion in axial rotation? Capsular and ligamentous structure: collateral, cruciate, oblique popliteal, retinacula, and IT band
What is the Screw-Home Mechanism? Type of automatic axial rotation linked to movements of flexion and extention
Can axial rotation take place when the knee is extended? No, only in flexion
Describe the movement of the lateral femoral condyle during lateral rotation of tibia on femur Lateral femoral condyle moves anteriorly while lateral tibial condyle moves posteriorly
Describe the movement of the medial femoral condyle during lateral rotation of tibia on femur Medial femoral condyle moves posteriorly while medial tibial condyle moves anteriorly
Describe the movement of lateral femoral condyle during medial rotation of tibia on femur Lateral femoral condyle moves posteriorly while lateral tibial condyle moves anteriorly
Describe the movement of medial femoral condyle during medial rotation of tibia on femur Medial femoral condyle moves anteriorly while medial tibia condyle moves posteriorly
Which condyle moves more during axial rotation of the knee? Lateral condyle moves 2X more than medial
What direction does the tibial condyle move during extension? Anteriorly
What direction does the tibial condyle move during flexion? Posteriorly
During rotation, meniscus follows movement of which condyle? Femoral
During flexion/extension, meniscus follows movement of which condyle? Tibial
What role does vastus medialis play in knee joint extension? Prevents displacement of patella because it moves laterally during extension
Which muscle stabilizes the patella? Quads
How is the Q-angle formed? Between longitudinal axis of femur (tendon of quads) and patellar ligament
What is the Q-angle in med and women? Men - 10. Women - 15
What is the implication of genu valgum? Patellofemoral joint abnormalities: chondromalacia patella and patellofemoral tracking problems
What stabilizes the stresses applied during walking and running of the knee, transversly? Collateral ligaments, sartorius, semitendinosus, and gracilis
What is a valgus stress? MCL torn
What prevents further flexion of knee? Quads (maintains erect posture)
What stabilizes the knee anteriorly and posteriorly? Joint capsules, arcuate ligaments, OPL, Semimembranosus, LCL, MCL, PCL, pes anserine, biceps femoris, gastrocnemius
Why is axial rotation impossible in extension? Tension of cruciate and collateral ligaments?
Describe the tension of cruciate and collateral ligaments during lateral rotation? Slack cruciate. Tight collateral.
Describe the tension of cruciate and collateral ligaments during medial rotation. Tight cruciate. Slack collateral.
What are the extensor muscles of the knee? Vastus intermedius/lateralis/medialis, Rectus femoris
What are the flexor muscles of the knee? Hamstrings, biceps femoris, semitendinosus, semimembranosus, gracilis, sartorius, gastrocnemius
What are the medial rotators of the knee? Semitendinossu, semimembranosus, popliteus, gracilis, sartorius
What are the lateral rotators of the knee? Biceps femoris, TFL, glute max
Which muscle produces highest torque for extension of the leg when the hip is in an extended position? Rectus femoris
What are the prime movers of flexion? Biceps femoris, semitendinosus, semimembranosus
What are the prime movers of extension? Rectus femoris, vastus intermedius/medialis/lateralis
What is the prime mover of lateral rotation? Biceps femoris
What are the prime movers of medial rotation? Semimembranosus, semitendinosus, popliteus
What are synergists to flexion? Gastrocnemius, plantaris, sartorius, gracilis
What are the symptoms of genu recurvatum (quads paralysis)? Can't extend leg against resistance - hyperextension
What are the symptoms of chonodromalacia patellae? Soreness and aching around patella from muscular imbalance of quads. Usually weak vastus medialis
Which side does the patella usually move to during a dislocation? Lateral
Created by: nnguyen44