By Complete Performance Coach: Rosie Shakespeare www.completeperformance.co.nz Anterior Cruciate Ligament ruptures in Women compared to men. The anterior cruciate ligament (ACL) is found behind the kneecap (patella) and connects the femur to the tibia. It s primary role is stability of the knee by preventing unwanted sideways movements (McDaniel, Rasche, Gaudet & Jackson, 2010; Kapit & Elson, 2002). Females are two to six times more likely to have an injury that affects the ACL than males in similar activities (McDaniel et al., 2010; Brukner & Khan, 2012; Hewett, 2008; O Sullivan, 2009; Newhouse, 2011; Sutton & Bullock, 2013). Most ACL injuries will occur in younger athletes, with the highest risk being aged from 14yrs to early 20 s (Sutton & Bullock, 2013; Renstrom et al., 2008; McDaniel et al., 2010; O Sullivan 2009; Brukner & Khan, 2012). 70% of ACL injuries are caused by non-contact situations with the remaining 30% from contact (Sutton & Bullock, 2013; Brukner & Khan, 2012). Landing from a jump and a sudden change in direction, also called cutting, is considered the most common mechanism of noncontact ACL injury (Sutton & Bullock, 2013; O Sullivan, 2009). This essay will discuss the possible reasons why this injury is more common in females. To best explain the contributing factors as to why ACL injury is more common in females, they need to be put into two categories: Extrinsic and Intrinsic (Ireland, 2002; Renstrom et al., 2008; Sutton & Bullock 2013). Extrinsic factors are changeable and can be controlled by the athlete and her coach (Ireland, 2002). Studies have shown that there is a relationship between the athlete s footwear and the playing surface; higher friction gives better traction but increases the risk of injury to the ACL (Renstrom et al., 2008; Ireland, 2002; Brukner & Khan, 2012). According to Brukner and Khan (2012) an uneven playing surface can also be a contributing factor, along with shoe cleats. Sutton and Bullock (2013) agree with this. Weather conditions affect sports that are played outside by changing the friction underfoot between the shoe and the playing surface. Renstrom et al. (2008) discussed a study that showed a higher risk of ACL injury to athletes during a period of low rainfall. Both Brukner and Khan (2012) and Sutton and Bullock (2013) also propose this idea that weather directly affects the playing surface, therefore the risk of ACL injury.
An athlete s level of skill, fitness, strength and conditioning and motivation to train must also be taken into account (Arendt, 1996; Ireland, 2002; Renstrom et al., 2008). Intrinsic or non-changeable factors include anatomical, neuromuscular control and hormonal (Ireland, 2002; Brukner & Khan, 2012). Anatomical: The ACL is smaller in females than males and the size and location of the ACL determines the width and shape of the femoral notch (Ireland, 2002; Sutton & Bullock, 2013; Brukner & Khan, 2012). Regardless of gender there is evidence to suggest a higher risk of ACL injury with smaller femoral notches and ACL size. As females have been shown to have smaller notches, this is a very real risk for them (Renstrom et al., 2008; Sutton & Bullock, 2013). Females tend to have wider hips than males, slightly knocked knees or knee valgus, ankle eversion and a greater quadriceps angle (Q angle). This all is suggestive of placing the ACL in a position where is it more prone to injury (O Sullivan, 2009; Sutton & Bullock, 2013; Newhouse, 2011). Neuromuscular: Women use different muscles to men when running, jumping, landing and pivoting/cutting (Hewett, 2008; Newhouse, 2011). Renstrom et al. (2008) mentions that the hard and awkward landings onto the knee when it is near extension is when ACL injuries can occur. Women favour their quadriceps muscles which tend to put the knee into extension rather than flexion. This can put the knee under great strain and increase the risk of ACL injury (Newhouse, 2011; Sutton & Bullock, 2013; McDaniel et al., 2010; Hewett, 2008; Brukner and Khan 2012). Post puberty, O Sullivan (2009), Sutton and Bullock (2013) and Renstrom et al., (2008) all noted that women have increased knee valgus and ankle eversion during kinetic movements compared to men, and that it is greater at initial contact, with a trend noted in this direction at maximum. They go on to suggest that this may mean females rely on ligaments rather than muscles to absorb forces during these movements and that this reliance on ligaments could be a risk factor for ACL injury. O Sullivan (2009) also noted that post puberty there is an increase in ligament laxity in women compared to men and that this may also be a contributing factor. Hormonal: Studies done around hormonal influences on ACL injury have been equivocal. Ruedl et al., (2009) and Adachi et al., (2007) both claim that ACL injuries were more likely to occur in the preovulatory phase than postovulatory. Both went on to suggest that hormones may play a part in ACL injury risk. Sutton and Bullock (2013), Renstom et al., (2008) and Ireland (2002) agree the evidence is insufficient to make any definite
statements around hormonal influence on ACL injury, and that the use of oral contraceptive therapy has no evidence that it would be protective. Prevention seems to be a much better answer to ACL injury than fixing what is already broken. The literature is in total agreement with the statement that an injury prevention program to address neuromuscular control will significantly lower the risk of ACL injury (Sutton & Bullock, 2013; Newhouse 2011; O Sullivan 2009; Hewett, 2008; Renstrom et al., 2008; Brukner & Khan, 2012). Sutton and Bullock (2013) talk about a prevention programme in female teenage soccer players that showed a reduction in ACL injury in the first year of 88% and 74% in the second year. This essay has talked about the higher risk that females face compared to males of ACL injury and discussed possible reasons for this. What has come from this is that there is no one factor that contributes to ACL injury, but a combination. There also seems to be a need for prevention programmes to be put in place around puberty to reduce the risk of such a debilitating injury.
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