ACL series: predisposing factors

There are many factors that can play role in an ACL injury. Looking at the big picture, we can classify these factors as;

Extrinsic meaning factors outside of our body such as shoe wear, surface played etc. Intrinsic meaning factors inside of our body such as muscle strength, flexibility etc. We can further classify intrinsic factors as biomechanical, neuromuscular, anatomical developmental and humeral. In this article, we will discuss biomechanics and neuromuscular factors.

Biomechanical Factors

  • hqdefaultFaulty posture such as anteriorly tilted pelvis can inhibit Gluteus maximus activation: Gluteus Maximus is a powerful extensor and external rotator of the lower extremity. If you are glue dominant, then during functional tasks as squats, your glue activation will prevent your knees from crossing the midline and stress your ACL. ankle
  • Decreased relative hamstring strength & recruitment can cause excessive activation of the Quads and therefore knee extension which causes an excessive pull on ACL.
  • Reduced trunk, hip, knee and ankle flexion angles during deceleration tasks and landing from a jump would cause more extension in the knee and decreased ability to absorb shock. If you are someone who stiffens his/her knees during jumping or landing from a shock, then all of the ground reaction forces will impact your ACL. F4.large
  • A weak gluteus medius will cause lateral trunk displacement which means your trunk will be more lateral in relationship to knee. Lateral displacement of the trunk is same as excessive adduction of your knee which also stresses ACL.

Neuromuscular Factors

  • Females are more likely to suffer from an ACL injury due to multiple factors when compared to males.
  • Female soccer, basketball, and volleyball players perform playing actions with Youth Teen Soccer Player on Field Ready to Kick Ball
    • Reduced hip and knee flexion angles.
    • Increased dynamic knee valgus.
    • Increased Quadriceps activation & decreased hamstring activity.
    • Decreased muscle stiffness around the knee also causes decreased stability.

Gluteal group provides muscular protection to ACL by controlling amount of hip adduction & femoral internal rotation. As the muscular fatigue increases, females are more likely to face the “at-risk” positions.

Take home points

  • Proximal Strengthening such as core, glute max and medius can decrease risk for an ACL injury.
  • Hamstring strengthening can improve shock absorption during deceleration and landing tasks and would decrease the likelihood of stiffening of the knee due to Quad over-use.

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