Knee Anatomy

Knee Joint

• The most poorly constructed joint in the body. Femur round, tibia flat.

• Comprised of four bones.– Femur– Tibia– Fibula– Patella

Femur

• Medial and Lateral Condyles- distal ends of the femur.

• Largest bone in the body

Femur

• Landmarks to know• Add. Tubercle• Medial and Lateral

epicondyles• Medial and lateral

condyles• Intercondylar fossa• Patella fossa (not

shown)

Tibia and Fibula

Fibula

• Landmarks to know• Apex• Head• Neck• Lateral Maelleolus

Tibia

• Landmarks to know

• Intercondylar eminence

• Medial and lateral condyles

• Tibial tuberosity

Patella

• Patella tendon- attaches to the anterior of the tibia. (tibial tuberosity)

• Quadriceps tendon-attaches the quadriceps to the patella.

Joints

• Tibiofemoral– Largest joint in body

• Patellofemoral– Patella contains the thickest

cartilage found in the body• Superior Tibiofibular

– Any movement here is due to movement at the ankle

Knee Stabilizers

• PRIMARY– Medial Collateral

Ligament– Lateral Collateral

Ligament– Anterior Cruciate

Ligament– Posterior Cruciate

Ligament

• SECONDARY– Medial Meniscus

• “C” shaped

– Lateral Meniscus• “O” shaped

Cruciate Ligaments

• Major stabilizing ligaments in the knee

• Anterior Cruciate Ligament (ACL)-prevents the tibia from sliding out in front of the femur

• Injuries caused by hyperflexion, internal rotation, hyperextension

ACL

• Has Two Bundles– Anteromedial

•Tight in flexion and extension

– Posterolateral•Tight in extension

• Ligament is most lax between 30 – 60 degrees flexion

Posterior Cruciate Ligament

• Prevents posterior translation of the tibia on the femur

• Resists hyperextension of knee

• Runs from posterior tibia to anterior femur

PCL

• Fibers are tightest around 30 degrees flexion– Posterolateral fibers are the last

to become tight

• Two times stronger than ACL

Collateral Ligament

• Medial Collateral Ligament (MCL)- connect the tibia and the femur.

• A force from the lateral side could cause a tear.

• Valgus force

Medial Collateral Ligament

• Two layers– Deep layer is

actually a thickening of the joint capsule that blends into the medial meniscus

– Superficial layer is what we view as the MCL

Collateral Ligament

• Lateral Collateral Ligament (LCL)- connect the fibula to the femur.

• A force from the medial side can cause a tear of the LCL

• Varus force

Lateral Collateral Ligament

• Attaches to head of fibula

• Prevents excessive varus and IR forces

• Tightest in extension, loosest after 30 degrees flexion

Cartilage

• Articulate Cartilage-covers the moving parts of the knee.

• Chronic damage to articulate cartilage leads to arthritis.

Cartilage

• Meniscus- half moon shaped cartilage lying between the knee joint.

ARTICULAR DISCS

• Medial Meniscus

• Lateral Meniscus

Meniscal Blood Supply

• Each Meniscus has 3 zones– Red Zone

•Outer 1/3: good blood supply

– Red/White Zone•Middle 1/3: minimal blood supply

– White Zone• Inner 1/3: avascular (no blood

supply)

• Implications for injury?

Meniscal Blood Supply