Knee Joint and Leg

What kind of joint is the knee?

• synovial, modified hinge

• allows for knee flexion, extension and some rotation

What are the articulations of the knee?

• medial and lateral femorotibial articulations

• femoropatellar articulation

Where is the knee joint capsule thickest?

• medially and laterally

• resists valgus and varus stress

What stabilizes the knee joint?

• surrounding muscles and ligaments connecting the femur and tibia

List the ligaments of the knee joint

• patellar ligament

• medial (tibial) collateral ligament

• lateral (fibular) collateral ligament

• oblique popliteal ligaemnt

• arcuate popliteal ligament

• posterior meniscofemoral ligament

• anterior cruciate ligament

• posterior cruciate ligament

Patellar ligament (location)

• distal part of the quadriceps femoris tendon

• attaches from patella to tibial tuberosity

• “anterior” ligament of the knee

Lateral (fibular) collateral ligament (type, location, function)

• extracapsular ligament running from lateral epicondyle of the femur to the fibular head

• separated from lateral meniscus by the popliteus tendon

• prevents excessive varus forces

Medial (fibular) collateral ligament (type, location, function)

• capsular ligament running form the medial epicondyle of the femur to the medial condyle/superomedial surface of the tibia

• attached directly the medial meniscus

• prevents excessive valgus forces

Oblique popliteal ligament (location, function)

• expanded portion of the semimbranosus tendon, medial tibial condyle to lateral femoral condyle

• reinforces the posterior surface of the joint

Arcuate popliteal ligament

• arises from the fibular head and passes superomedial over popliteus to blend with the posterior aspect of the joint capsule

Anterior cruciate ligament (type, location, function)

• intracapsular, but extrasynovial

• attaches from the anterior portion of the intercondylar ridge to the posterior, medial/inner portion of the lateral condyle of the femur

• main stabilizer in extension, prevents anterior displacement of tibia on a fixed femur (hyperextension)

How is the ACL commonly injured?

• sudden change in direction

• deceleration that causes a valgus stress and medial rotation

Posterior cruciate ligament (type, location, function)

• intracapsular but extrasynovial

• attaches from the posterior intercondylar portion of the tibia to the anterior, lateral/inner portion of the medial condyle of the femur

• main stabilizer in flexion, prevents posterior displacement of tibia on a fixed femur (hyperflexion)

How is the PCL commonly injured?

• direct force on the tibial tuberosity on a fixed knee, driving the tibia posteriorly

Which cruciate ligament is strongest?

PCL

Menisci

• fibrocartilage structures interfacing between the femoral and tibial condyles

• deepen the surface of contact

• aid in shock absorption between the bony surfaces

Medial meniscus (shape, attachments)

• broader, c shaped

• less mobile

• adhered directly to MCL

Lateral meniscus (shape, attachments)

• smaller, rounder o shape

• freely moveable

• separated from the LCL via tendon of the popliteus m.

• attaches to PCL via posterior meniscofemoral ligament

Posterior meniscofemoral ligament

• attaches from the lateral meniscus to the PCL and medial femoral condyle

• aids in support of posterior joint capsule

List the bursae of the knee

• suprapatellar

• popliteus

• anserine

• gastrocnemius

• semimembranosus

• subcutaneous prepatellar

• subtendinous prepatellar

• subcutaneous infrapatellar

• deep infrapatellar

Swelling of the knee could be see in which bursae?

• suprepatellar

• popliteus

• anserine

• gastrocnemius

  • these all freely communicate with the joint cavity (shared synovial membrane/fluid)

What supplies blood to the knee joint?

• middle genicular a. pierces the joint capsule to supply the cruciate ligaments, synovial membrane, and peripheral aspect of the menisci

What innervates the knee joint?

• femoral

• saphenous

• tibial

• common fibular