knee joint

Passive Support in the Knee

• Provides strong passive support when the legs are extended

• Ligaments on the posterior side of the knee prevent tibia and fibula from moving posteriorly

  • This stability keeps the bones in alignment with the leg

• Possible injuries to the posterior side of the leg include:

  • Hyperextension injuries

  • Ligament tears

Stability of the Knee Joint

• The knee joint is described as the largest and most complex synovial joint in the body

• Functionally, it operates as a modified hinge joint

  • Primarily facilitates flexion and extension

Articulations in the Knee Joint Capsule

• Three articulations exist within the knee joint capsule:

  • Femoral Patellar Joint:

  • Interaction between the patella and the femur

  • Visual representation of the femur with the patella peeled back for clarity

  • Medial Tibiofemoral Joint:

  • Connection between femur and tibia

  • Lateral Tibiofemoral Joint:

  • Another connection between femur and tibia

  • Note: The fibula is not included in these joint articulations

Movement Dynamics

• Movement description:

  • The femoral condyles (lateral and medial) glide on the tibial surface

  • This action maintains central alignment of the femur over the tibia

  • Optimizes weight-bearing distribution

  • At full extension, the femur undergoes slight medial rotation to lock the joint in place

• Importance of locking:

  • Enables stability and support during standing or weight-bearing

  • Allows for lateral movements when unlocked

Patella Characteristics

• The patella is classified as a sesamoid bone

• Encapsulated in the quadriceps tendon, functioning to stabilize knee movements

Meniscus Functionality

• Description of the menisci:

  • Fibrocartilage pads situated in the knee joint

  • Serve to cushion the joint and absorb shock during movement

• Healing characteristics:

  • Menisci have limited blood supply, leading to slow healing processes

Ligament Structures in the Knee

• Classification of knee ligaments:

  • Extracapsular Ligaments:

  • Lateral collateral ligament (LCL)

  • Medial collateral ligament (MCL)

  • These ligaments provide lateral stability and prevent side-to-side movements

  • Intracapsular Ligaments:

  • Anterior cruciate ligament (ACL)

    • Prevents anterior sliding of the tibia

  • Posterior cruciate ligament (PCL)

    • Prevents anterior sliding of the femur

  • Cross formation of ACL and PCL inside the joint capsule reinforces stability

Common Injuries Associated with Knee Ligaments

• A specific case of injury referred to as the unhappy triad:

  • Involves rupture of the following:

  • Medial collateral ligament (MCL)

  • Medial meniscus

  • Anterior cruciate ligament (ACL)

  • This injury is particularly prevalent in sports activities

Summary of Knee Joint Functionality and Mobility

• Knee joint demonstrates modification beyond simple hinge action

  • Capable of slight lateral (side-to-side) motion in addition to flexion and extension

• Additional emphasis on the importance of awareness of potential injuries

• Discussion of regulations in contact sports, such as tackling from the side, to prevent knee injuries