Knee

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Knee

• Tibiofemoral Joint

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• 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

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

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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.

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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.

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• 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.

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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

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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.

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• 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.

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• 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.

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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.

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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
  jumpers knee. In sports that require jumping,
  such as basketball, the tendon can become
  inflamed or can tear.

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• 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
  persons 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.

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