Knee Structure

1. Parts of the Knee (TG p. 340-347)
   • Femur: is the large bone of the thigh
   • Tibia: is the large bone of the lower leg
   • Fibula: is the small bone of the lower leg
   • Patella: is the third bone of the knee joint
     • The Patellar Tendon connects the patella to the tibia. This tendon covers the patella and continues up the thigh as the Quadriceps Tendon.
2. Two ligaments are found on either side of the knee joint
   • Medial Collateral Ligament (MCL)
   • Lateral Collateral Ligament (LCL)
3. The Posterior Cruciate Ligament (PCL) lies behind the Anterior Cruciate Ligament(ACL).
   • Note: The difference between ligaments and tendons is that ligaments connect bone to bone while tendons connect muscle to bone.
4. Two structures called Menisci sit between the femur and the tibia.
   • The structures are sometimes referred to as the cartilages of the knee. This material is about ¼ of an inch thick in most large joints.
   • They work like a gasket to spread the force of weight bearing over a larger area
   • They help the ligaments with stability of the knee
   • Weight distribution by the meniscus is important because it protects the articular cartilage from excessive forces. Without the meniscus the concentration of force into a small area on the articular cartilage can damage the surface, leading to degeneration over time.
5. Articular Cartilage: is the material that covers the ends of the bones of any joint. This white, shiny material has a rubbery consistency.
   • The function of articular cartilage is to absorb shock and provide an extremely smooth bearing surface to facilitate motion.
   • There is articular cartilage on essentially everywhere that two bone surfaces articulate.
   • In the knee, articular cartilage covers the ends of the femur, the top of the tibia and the back of the patella.

Knee Anatomy

1. The bones of the knee are: the tibia (the shin bone), the femur (thighbone), and patella (kneecap)
2. These bones are enclosed: in the joint capsule lines with a special tissue called synovium.
   • Synovium: produces a thick liquid called synovial fluid which is necessary to lubricate, protect and nourish joints.

1. The most well known of the knee ligaments is called the anterior cruciate ligament or ACL for short. It originates near the back of the thighbone and ends at the front or anterior part of the knee.
2. The other ligament is the posterior cruciate ligament or PCL. This ligament starts in the front of the thighbone and ends at the back or posterior aspect of the knee.
3. On either side of the knee there another set of stabilizing ligaments called the collateral ligaments. There are two major sets of these ligaments on the inside (medial) and on the outside (lateral). They supply stability when the knee moves from side to side or when making sharp cutting/twisting moves.

Muscles of the anterior leg

1. Quadriceps Femoris Group (TG p. 300-304)
   • Rectus Femoris
   • Vastus Lateralis
   • Vastus Medialis
   • Vastus Intermedius
2. Tensor Fasciae Latae
3. Sartorius
4. Hip Adductors
   • Pectineus
   • Adductor Magnus
   • Adductor Longus
   • Adductor Brevis
   • Gracilis

Note: Endangerment site!

Common knee injuries

1. ACL tears: (ligament sprain, Path p. 123) Tears of the ACL deep inside the knee. Common in athletes who perform lateral movements with the legs, i.e. football, soccer, tennis, basketball.
2. Collateral ligament tears: tear of the ligament to either side of the knee.
3. Patellar Subluxation/Dislocation, Path p. 100: this is when the patella moves out of place. Either lateral or medial along the femoral epicondyle. Most subluxations happen laterally due to a weak vastus medialis.
4. Bursitis: the inflammation of the bursa
5. Tendonitis: Inflammation of the tendons, around the knee is usually caused by overuse, infection or injury.
6. Osteoarthritis: Degenerative joint disease. Deterioration off the cartilage and irritation of the joint itself.
7. Loose Body: Usually happens after trauma resulting in a loose piece of cartilage or bone in the knee.
8. Baker’s Cyst: Swelling of the synovial tissue in the back of the knee that forms into a fluid filled mess, usually in the popliteal fossa on the medial side of the leg.
9. Meniscus tear: tearing of meniscus in the bone joint, usually caused by impact or repetitive overuse or trauma. Very painful and requires medical attention.
10. Patellofemoral Syndrome: Overuse disorder that leads to damage to the patellar cartilage. Pain, stiffness and dysfunction in the knee and anterior leg.