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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 Condylesdistal 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 tendonattaches 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