Functional Anatomy 1 - Lecture 13: Knee

tibiofemoral joint

distal femur on proximal tibia

• largest joint cavity in the body

knee joint

• two condyloid joint surfaces (medial and lateral)

• “modified hinge” joint

• no articulation with fibula

movements of tibiofemoral joint

• flexion and extension

• internal and external rotation (minimal)

• abduction and adduction (minimal)

tri-compartmental joint

two tibiofemoral articulation

• medial femoral condyle and medial tibial condyle

• lateral femoral condyle and lateral tibial condyle

one patellofemoral joint

• posterior patella with trochlea of distal femur (middle of femoral condyles)

joint stability of knee

• rely on

  • active stability of surrounding musculature

  • passive stability from surrounding ligaments, menisci, and joint capsule

anterior knee osteology

posterior knee osteology

trochlea

intercondylar groove

• medial and lateral facets articulate with patella

• lateral facet has a steeper slope (in sagittal plane) to help stabilize patella

intercondylar fossa

• attachments for cruciate ligaments

• possible risk factor for cruciate ligament injury

  • narrower intercondylar fossa increases risk ACL injury

patella

sesamoid bone embedded in quadriceps tendon

• quadriceps tendon → (this) → patellar ligament → tibial tuberosity

posterior surface has thick articular cartilage

• thickest in the body

posterior medial patella

medial facet and odd facet

posterior lateral patella

lateral facet

patellar chondromalacia

softening and swelling of the articular cartilage of the patellar articular cartilage

• leads to anterior knee pain

condyles

(medial and lateral)

• articulate with femoral condyles

• tibial plateau

• intercondylar region (attachment for ACL/PCL)

• menisci (medial and lateral)

• tibial tuberosity

soleal line

soleus attachment

• references for muscle attachments superior and inferior

frontal plane alignment

genu varum and valgum

sagittal plane alignment

genu recurvatum, hyperextension

patellar positioning

patella alta, patella baja

genu varus

bow leg, distal segment toward midline

genu valgus (excessive)

knock-knee, distal segment

force of quadriceps line of pull

direction of patellar tracking is influenced by

Q-angle measurement

line 1: ASIS to mid-patella

line 2: mid patella to tibial tuberosity

normal: 13-18 degrees

• males < females

normal alignment

genu varum

genu valgum

5-10 degrees of hyperextension of the knee joint

normal knee alignment in sagittal plane

genu recurvatum

greater than 10 degrees of hyperextension

patella alta

patella position excessively superior

• longer patellar tendon

  • increased forces through patellofemoral joint

  • decreased medial/lateral soft tissue stability earlier in knee flexion ranges

  • increased risk of patellofemoral pain symptoms

patella baja

• patella position excessively inferior

  • shorter patellar tendon

external fibrous layer of knee joint capsule

thickest anterior, thinner posterior

internal synovial later

• reflects anterior in intercondylar space

• plicae: fold in synovial membrane can be irritated

patellar ligaments

• distal to quadriceps tendon

• apex of patella to tibial tuberosity

• strong, thick, fibrous band

• helps form anterior border of fibrous capsule of knee joint

retinacula

• medial and lateral patellar retinacula

• superficial, thinner, non-specific fiber direction

patellofemoral ligaments

thickening of retinacula

• medial and lateral patellofemoral ligaments

• deeper, transverse fiber direction

intra-capsular, extra-synovial

cruciate ligaments are described as

anterior cruciate ligament

proximal: posterior medial surface of lateral femoral condyle

distal: anterior medial intercondylar area of tibia

ACL

the weaker of two cruciate ligaments

• 10x more likely to rupture ACL than PCL

ACL resists

• posterior movement of femur on tibia

• anterior movement of tibia on femur

• internal rotation of tibia

• hyperextension of the knee joint

posterior cruciate ligament

• proximal: anterior lateral surface of medial femoral condyle

• distal: posterior lateral intercondylar area of tibia

posterior cruciate ligament resists

• anterior displacement of femur on tibia

• posterior displacement of tibia on femur

• hyperflexion of the knee joint

medial collateral ligament

• proximal: medial epicondyle of the femur

• distal (superficial): superior medial tibia

• distal (deep): knee fibrous capsule and medial meniscus

• extra-capsular, broad/flatter band

valgus force (lateral to medial)

medial collateral ligament resists

lateral collateral ligament

• proximal: lateral epicondyle of the femur

• distal: head of fibula

• extra-capsular, rounded/thinner/cord-like structure

varus force (medial to lateral force)

lateral collateral ligament resists

meniscofemoral ligaments

• posterior meniscofemoral ligament (Ligament of Wrisberg)

• anterior meniscofemoral ligament (Ligament of Humphrey)

• lateral meniscus to medial femoral condyle

• added stability to PCL

menisci

crescent-shaped fibrocartilage on proximal tibia

menisci function

• increase contact area with distal femur

• shock absorption

menisci shape

• thicker at external margin, thinner medially

  • attached at margin (coronary ligaments) and roots

  • not attached at thin inner border

transverse ligament

joints anterior edges of medial and lateral meniscus

medial meniscus

• larger than lateral

• elongated C-shape

• attachments to MCL (deep)

• very little motion on tibia

lateral meniscus

• smaller than medial

• almost a complete circle

• no attachment to LCL

• more mobile

unhappy triad

ACL, MCL, medial/lateral meniscus injured simultaneously

• often from forceful valgus force

knee bursae

• pre-patellar

• infrapatellar

• suprapatellar

• pes anserine

blood supply from popliteal artery

superior lateral genicular and superior medial genicular

• middle genicular

  • through fibrous capsule to supply cruciate ligaments, synovial membranes and outer meniscus

blood supply from anterior tibial artery

inferior lateral genicular and inferior medial genicular

meniscus blood supply

middle genicular artery, only on outer edge

popliteal fossa

diamond-shaped space posterior to knee

boundaries of popliteal fossa

semimembranosus, biceps femoris, medial and lateral heads of gastrocnemius

contents of popliteal fossa

• small saphenous v.

• popliteal a./v.

• branches of sciatic n.

  • tibial n. (medial)

    • medial sural cutaneous n.

  • common peroneal n. (lateral)

    • lateral sural cutaneous n.

• popliteal lymph nodes