Knee Joint Flashcards
What type of joint is the knee joint? Describe it.
Hinge-type bicondylar synovial joint. Joints lined with hyaline cartilage and enclosed in single joint cavity.
Name the three bones of the knee joint
Patella, femur, tibia
Name the two articulations in the knee joint. What do these consist of?
. Tibiofemoral joint and patellofemoral joint
. Tibiofemoral- condyles of femur attach to condyles of tibia
. Patellofemoral- anterior distal part of femur attaches to patella
What is the function of the tibiofemoral joint?
Weight-bearing joint
What is the function of the patellofemoral joint?
Allows tendon of quadriceps femoris muscles to insert directly over the knee, making the muscles more efficient
What does the patella do?
. Acts as fulcrum to increase power of knee extension (via quadriceps muscles)
. Stabilising structure to reduce friction on femoral condyles
What is the blood supply of the knee joint?
Genicular anastomoses are around knee, which are supplied by the genicular branches of the femoral and popliteal arteries
What is the nerve supply of the knee joint?
. Nerve supply of knee joint is the nerves of the muscles which cross the joint
. Femoral, tibial, common fibular
What are the knee menisci? Why are they important? How many are there in the knee?
. C-shaped fibrocartilage bands in knee that increase joint stability and act as shock absorbers by increasing surface are to dissipate forces and pressure
. Two in the knee: medial and lateral
Where do the menisci in the knee attach?
. Lateral meniscus has both ends attached to intercondylar area of tibia
. Medial meniscus attached to intercondylar area of tibia and tibial collateral ligament
What does damage to the tibial collateral ligament often result in?
Tear in medial meniscus
Describe the relative sizes of the knee menisci.
Medial meniscus is bigger than the lateral meniscus
What is a bursa?
A synovial fluid-filled sac found between moving structures in a joint (reduce wear and tear on these structures)
How many bursae are there in the knee? Name them.
4 bursae in the knee- suprapatella, pre-patella, infrapatella (superficial and deep), semimembranosus
Where is the suprapatella bursa found?
Above the patella between the quadriceps and femur
Where is the pre-patella bursa found?
In front of patella between patella and skin
Where is the infrapatella bursa found?
. Superficial is between patella ligament and skin
. Deep is between patella ligament and tibia
Where is the semimembranosus bursa found?
Posteriorly in knee joint behind femur and tibia
Name the 3 main ligaments/groups of ligaments in the knee joint.
Patellar ligament, collateral ligaments, cruciate ligaments
What is the patellar ligament? What does it attach to?
Continuation of quadriceps femoris tendon distal to patella, attaches to the tibial tuberosity
How many collateral ligaments are there? What is their function?
2 strap-like ligaments (medial/tibial and lateral/fibular), stabilise flexion and extension at knee and prevent excessive medial or lateral movement
What are the attachments of the medial/tibial collateral ligament?
Attaches to medial epicondyle of femur and medial condyle of tibia
What are the attachments of the lateral/fibular collateral ligament?
Attaches to lateral epicondyle of femur and depression on lateral surface of fibular head
How many cruciate ligaments are there? What do they do?
There are two cruciate ligaments (anterior and posterior), which cross eachother (hence ‘cruciate’) to connect the femur and tibia
What is the function of the anterior cruciate ligament?
Prevents anterior dislocation of tibia
What is the function of the posterior cruciate ligament?
Prevents posterior dislocation of tibia
What are the attachments of the anterior cruciate ligament?
Originates from intercondylar fossa of femur, attaches to anterior intercondylar region of tibia, where it blends with the medial meniscus
What are the attachments of the posterior cruciate ligament?
Originates from medial femoral condyle, attaches to intercondylar region of tibia
What are the main movements at the knee joint?
Flexion and extension, medial and lateral rotation
How is extension at the knee achieved?
Contraction of quadriceps femoris (Vastus medialis, vastus intermedius, vastus lateralis, rectus femoris), which inserts into tibial tuberosity
How is flexion at the knee achieved?
Contraction of hamstrings, gracilis, Sartorius, popliteus
How is lateral rotation at the knee achieved?
Contraction of biceps femoris
How is medial rotation at the knee achieved?
Contraction of semimembranosus, semitendinosus, gracilis, Sartorius, and popliteal muscles
When can medial and lateral rotation occur in the knee?
Only when the knee is flexed. If it isn’t flexed, the rotation occurs at the hip.
What is the most common injury to the knee joint? How is this injury assessed?
. Injury to collateral ligaments caused by force applied to side of knee when foot placed on ground
. Assessed by asking patient to medially and laterally rotate leg
. Pain on medial rotation indicates damage to medial ligament, pain on lateral rotation indicates damage to lateral ligament
What else is usually damaged when the medial collateral ligament is damaged?
Medial meniscus is usually torn, due to their attachement
How is the anterior cruciate ligament torn? How do you test for this?
. Hyperextension of knee or big force to back of knee with joint partly flexed
. Test using anterior drawer test, where you try to pull the tibia forward. If it moves, this ligament has been torn
What is the dashboard injury?
When knees flexed and large force applied to shins, pushing tibia backwards
How do you test for posterior cruciate ligament damage?
Posterior drawer test, hold knee in flexed position and push tibia posteriorly. If there’s movement, this ligament has been torn.
What is bursitis?
Inflammation of bursae
What is the unhappy triad? When does it usually occur
. Medial collateral ligament and medial meniscus are joined, so damage to either can affect both structures
. Large lateral force applied to knee joint when knee extended can damage anterior cruciate ligament too, which completes the triad
