ACL tears or ruptures can occur in sports such as basketball, baseball, softball, soccer, lacrosse and volleyball. Sports involving an excessive amount of cutting, pivoting and jumping can all cause an injury to the ACL. While most male athletes suffer ACL tears in collision sports, according to Timothy Hewett, director of the Sports Medicine Biodynamics Center at Cincinnati Children’s Hospital, approximately 80% of female ACL injuries are non-contact! What??!!! What is the reason for this?
What are the anatomical and physiological differences between males and females?
Q-Angle
Females have a wider pelvis and corresponding Q Angle (the angle where the femur and tibia meet). The wide pelvis increases the quadriceps angle (q-angle) by 2-3 degrees. This can cause more stress on the ligament.
Q-Angle Image
Normal Values for The Q-Angle
Female: Between 16.9º and 17.3º
Male: Between 13.5º and 14.5º
Femoral Notch
The notch between the femur and tibia where the ACL and PCL cross is smaller in females.
Hormonal Factors
The menstrual cycle can affect ACL injury risk. Estrogen causes ligaments to become more lax. According to Timothy Hewett, director of the Sports Medicine Biodynamics Center at Cincinnati Children’s Hospital, the looseness of the knee increases by about a half-millimeter during peak menstrual cycle.
What other types of stress can cause injury?
Jumping and Landing
Females rely more on their quadriceps to stabilize their knee joint when they land. They land more upright which can pull the tibia forward, creating more stress on the ACL. Males tend to bend their knees and rely more on their hamstrings to stabilize the knee, which controls the joint better. This is known as co-contraction, something that most female athletes DO NOT DO!!!
Knee Collapse
Females tend to collapse their knees inward when they land, causing a twist of the tibia. They also have less control over their trunk when they land, cut, accelerate or decelerate, which puts more stress on the ACL.
So what needs to be done differently in a strength program if there are so many factors leading to possible ACL injuries? Besides the structural and physiological components of a female athlete, factors such as muscular imbalances, poor trunk stabilization, poor co-contraction and possible neuromuscular asymmetries all seem to play a role. How do we fix this?
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