KNEE JOINT -ANATOMY John Erasmus Klibanoff, MD, LTC USAR (ret) Orthopaedic Surgeon Orthopaedic Associates of Rochester

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

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

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

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.

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)

Meniscal Blood Supply

Distal IT Band Extension of the TFL, Vastus lateralis and Intermuscular septum – Thickened and inserts on Gerty’s Tubercle

Anatomy Summary Relevant surgical anatomy stems from the primary mesenchymal structures of the skeletal system BONY LIGAMENTOUS CARTILAGENOUS

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