Knee

1. Knee Tibiofemoral Joint

2. Largest and most complex • Actually 3 joints within a single synovial cavity Laterally: tibiofemoral joint: modified hinge joint– between the lateral condyle of the femur, lateral meniscus and lateral condyle of the tibia Medially: tibiofemoral joint: modified hinge joint – between the medial condyle of the femur, medial meniscus and medial condoyle of the tibia Intermediate: patellofemoral joint: planar joint – between the patella and the patellar surface of the femur

3. The knee is essentially made up of four bones, that support the knee and provide rigid structure of the joint: • femur • tibia • fibula • Patella

4. Movement at Knee • Flexion • Extension • Slight medial rotation • Lateral rotation The main muscles that move the knee joint are the quadricep and hamstring muscles. The quadriceps attaches to the patella, and the patellar tendon connect this muscle to the front of the tibia. When the quadricep muscles contract the knee extends. In contrast, when the hamstring muscles contract, they pull the knee into flexion.

6. Ligaments • anterior cruciate ligament (ACL). The critically important ACL prevents the tibia from being pushed too far anterior relative to the femur. • posterior cruciate ligament (PCL):connects the posterior intercondylar area of the tibia to the medial condyle of the femur • ligamentum patellae: the central portion of the common tendon of the Quadriceps femoris, which is continued from the patella to the tuberosity of the tibia. • medial collateral ligament (MCL a.k.a. tibial collateral ligament). The MCL protects the medial side of the knee from being bent open by a stress applied to the lateral side of the knee (a valgus / outward force). • lateral collateral ligament (LCL a.k.a. fibular collateral ligament). The LCL protects the lateral side from an inside bending force (a varus / inward force). • oblique popliteal ligament: strengthens the back of the capsule of the knee joint. It is an extension of the tendon of the semimembranosus muscle.

8. The knee joint also has a C-shaped piece of tissue which fits into the joint between the tibia and the femur, made of cartilage, which is called the meniscus or meniscal cartilage. • It helps to protect the joint and allows the bones to slide freely on each other.

10. Bursa • There are also a bursa, little fluid sacs that helps the muscles and tendons slide freely • Prepatellar: between the patella and skin • Infrapatellar: between the superior part of the tibia & patellar ligament • Suprapatellar: between the inferior part of the femur & the deep surface of the quad. femoris muscle

13. injuries • Most vulnerable joint to injury • Mobile, weight bearing • Stability depends on ligaments and muscles Mechanical knee problems can be caused by: A direct blow or sudden movements that strain the knee Osteoarthritis in the knee, resulting from wear and tear on its parts.

14. Inflammatory knee problems can be caused by: certain rheumatic diseases, such as rheumatoid arthritis and systemic lupus erythematosus (lupus). These diseases cause swelling which can damage the knees permanently. Chondromalacia (KON-dro-muh-lay-she-uh) occurs when the cartilage of the knee cap softens. This can be caused by injury, overuse, or muscle weakness, or if parts of the knee are out of alignment. Chondromalacia can develop if a blow to the knee cap tears off a piece of cartilage or a piece of cartilage containing a bone fragment.

15. The meniscus: easily injured if the knee is twisted while bearing weight. A partial or total tear may occur. If the tear is tiny, the meniscus stays connected to the front and back of the knee. If the tear is large, the meniscus may be left hanging by a thread of cartilage. The seriousness of the injury depends on the location and the size of the tear.

16. Ligament Injuries • the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL): An injury to these ligaments is sometimes called a “sprain.” The ACL is most often stretched or torn (or both) by a sudden twisting motion. The PCL is usually injured by a direct impact, such as in an automobile accident or football tackle. • The medial and lateral collateral ligaments are usually injured by a blow to the outer side of the knee. This can stretch and tear a ligament. These blows frequently occur in sports such as football or hockey.

17. tendon injuries and disorders • Tendinitis and ruptured tendons: Overusing a tendon (particularly in some sports). The tendon stretches like a worn-out rubber band and becomes inflamed. • Trying to break a fall. If thigh muscles contract, the tendon can tear. This is most likely to happen in older people with weak tendons. • One type of tendinitis of the knee is called jumper’s knee. In sports that require jumping, such as basketball, the tendon can become inflamed or can tear.

18. Osgood-Schlatter disease: caused by stress or tension on part of the growth area of the upper shin bone. It causes swelling in the knee and upper part of the shin bone. It can happen if a person’s tendon tears away from the bone, taking a piece of bone with it. Young people who run and jump while playing sports can have this type of injury. • Iliotibial band syndrome: occurs when a tendon rubs over the outer bone of the knee causing swelling. It happens if the knee is overused for a long time. This sometimes occurs in sports training.