ACL Injury
Predisposing Factors
ACL Injury
Currently there are several factors that are believed to predispose females to ACL injuries.
This includes structural/anatomical, biomechanical and neuromuscular factors.
Structurally the female anterior cruciate ligament tends to have a decreased thickness as compared to a male’s. This has been documented by magnetic resonance imagining (MRI).
Females also have a greater ‘Q angle’ than males. The Q’ angle is an angle formed by an imaginary line extending from the anterior superior iliac spine (bump on the front of the hip bone) to the midpoint of the patella (knee cap) that is bisected by a line from the tibial tuberosity (bump below the knee cap) through the midpoint of the patella (knee cap).
Athletes that have a Q’ angle above an average of 15 degrees have leg postures that create excessive external (lateral) rotation of the tibia (shin bone). This creates a greater "valgus"(separation of the tibia from the femur) stress at the knee joint. Shin bone separates from the thigh bone.
In a dynamic situation, as in abruptly stopping and changing direction, the knee joint may be predisposed to a position of neuromuscular loss of control causing inactivity of the hip muscle stabilizers (gluteus muscles and hip lateral rotators) leaving the anterior cruciate ligament to a point of no return.
The stabilizing muscles are lengthened and therefore have a decreased ability to contract to maintain proper hip and knee alignment.
This will lead to an ACL Injury.
Next there appears to be a problem with hamstring muscle activation. Hamstring muscle activation controls the amount of anterior translation (forward motion of the tibia). There is a significant decrease in stress on the ACL with proper activation.
It is the decrease of hamstring activation in landing that may lead to ACL injuries; therefore it is important to train proper landing and jumping mechanics.
Take a look at either the
soccer speed training pages or
strength training pages to get ideas for preventing an ACL Injury
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