Lecture Notes: Understanding the Human Knee and Hyperextension

Introduction to Knee Anatomy

• The human knee takes significant abuse daily from walking, running, and climbing stairs.
• Forces on the knee can lead to injuries if they push the joint in unintended directions, particularly hyperextension.

Knee Orientation and Anatomy

• Anterior Aspect: Front of the knee.
• Lateral Aspect: Outside of the knee.
• Posterior Aspect: Back of the knee.
• Medial Aspect: Inside of the knee.
• Superior Aspect: Includes the femur, the largest and strongest bone in the human body.
• Inferior Aspect: Includes two bones, the tibia (medial) and the fibula (lateral).
• Patella (Kneecap): A sesamoid bone developing inside a tendon.

Function of Tendons and Ligaments

• Tendons: Connect muscles to bones, aiding in movement (e.g., quadriceps tendon attaches to the patella).
• Ligaments: Connect bones to one another, defining the range of motion.
• Key Ligaments:
  • Fibular Collateral Ligament (LCL)
  • Tibial Collateral Ligament (MCL)
  • Anterior Cruciate Ligament (ACL) prevents tibia from sliding forward relative to femur.
  • Posterior Cruciate Ligament (PCL) prevents tibia from sliding backward relative to femur.

Hyperextension of the Knee

• Naturally occurs in adolescents and those with connective tissue disorders.
• Genu Recurvatum: Backward bending of the knee, not all hyperextensions are due to injuries.
• Arthritis: Can form if joint surfaces articulate improperly.

Causes and Consequences of Knee Hyperextension

• Can occur from improper landing or impact.
• Injuries: Compromises ACL, PCL, MCL, LCL, and other structures.
• Grades of Injury:
  • Grade 1: Small tears, mild inflammation, typically heals.
  • Grade 2: Partial tears, may require surgery and rehabilitation.
  • Grade 3: Full rupture, requires surgical repair or transplantation.

Meniscus and Cartilage

• Menisci help distribute forces; damage can lead to bone-on-bone contact and arthritis.
• Cartilage pads (Meniscus) move with joint during normal motion.

Long-term Effects of Knee Injuries

• Scar tissue from injuries can limit range of motion.
• Hyperextension beyond 10 degrees can damage tissues and stability.

Conclusion

• Knee injuries are serious and can have long-lasting impacts.
• Importance of taking care of knees to prevent injuries.

Final Thoughts

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