The dreaded ACL rupture epidemic: Part 3 "How do ACL injuries happen?"

How does the ACL injury happen? Can it be prevented? Lets dive in!

The dreaded ACL injury typically occurs during sports participation and is described as happening when the ACL is strained by either physical contact or  non-contact when a player cuts/pivots. Contact injuries occur when another individual hits the leg after a player changes directions quickly and pushes the knee into rotation or hyperextension. Non-contact injuries do not involve any other individuals except the injured athlete. During this scenario, the athlete’s knee is exposed to quick deceleration, hyperextension or rotation, and out of control movement causing the ligament to fail.

Click on the link to see the video of each type of ACL injury mechanism.

Noncontact injury -> http://www.youtube.com/watch?v=1JQKko6C42s

http://www.youtube.com/watch?feature=endscreen&v=LuClWeD9ouI&NR=1

Non-Contact injuries are described as hyperextension or rotational.

Hyperextension Tear: (forceful over-straightening) is most often caused by accidents associated with:

• Skiing
• Volleyball
• Basketball
• Soccer
• Football

Rotational Tear: Because the ACL becomes taut with inward rotation of the tibia, activities placing any excessive inward rotation of the tibia (usually seen from a plant and twist mechanism) are seen in sports such as:

• Football
• Tennis
• Basketball
• Soccer

Injury to the ACL may occur in other sports, but less likely due to nature of contact and training:

• Wrestling
• Gymnastics
• Martial arts
• Running

Male/Female Comparison

National Collegiate Athletic Association (NCAA) has performed research finding female athletes injure the ACL more frequently than their male counterparts. Females in soccer and basketball have the highest incidence of ACL knee injuries. Research suggests ACL injuries in females are greater due to strength imbalances, joint laxity, anatomical hip/knee angles, and training/development patterns.

Next week Part 4: “How to reduce ACL injuries”

Referenced from: http://ehealthmd.com/content/what-causes-acl-tear

The dreaded ACL rupture epidemic: Part 2 "Anatomy of an ACL rupture"

Functional Anatomy of the Knee

The knee joint consists of three bones, muscles and many ligaments. The shin bone (tibia), the thigh bone (femur) and the knee cap (patella) form the knee. The primary muscles are the quadriceps on the top of the thigh and the hamstrings on the back of the thigh. These muscles are primary controllers of how the knee moves.

 

Ligaments attach the bones together to allow the muscles to move the knee in a controlled and predictable fashion.  The knee has four main ligaments that control stability when you walk, run, and pivot. Two ligaments protect the stability of the knee from the side and are called collateral ligaments and two ligaments attach the thigh bone and shin bone from the center of the knee. The anterior cruciate ligament (ACL) is one of a pair of ligaments that cross at the center of the knee joint. This ligament crosses with the posterior cruciate ligament (PCL). This pair of ligaments work together to stabilize the knee from front to back during normal and athletic movements. They function to keep the knee joint centered and prevent wear and tear on the joint cartilage inside the knee.

The knee has shock absorbing pads between the thigh and shin bone to protect from wear and tear. These structures are called the medial and lateral meniscus. Each pad is horseshoe shaped and absorbs weight when the foot contacts the ground and allows for frictionless movement at the knee joint.

Next week the post will be discussing Part 3 of this series: ACL rupture injury mechanisms