Anterior Cruciate Ligament Injuries in Women’s Football
Anterior Cruciate Ligament (ACL) injuries in women’s football occur frequently and at an alarming rate...
Numerous studies have attempted to identify the reasons behind this. Yet these still remain a problem within the game; as does the high risk of recurrent or repeat injury.
Research has shown over the years that females appear more susceptible to ACL injury than their male counterparts and that women athletes are at a higher risk of sustaining these injuries (Dugan, 2005).
Hewett et al (2006) recorded that 70% of ACL injuries in female athletes were through non-contact mechanisms. The most common injury mechanics in these cases were described by Junge and Dvorak (2004) as being sudden deceleration with a change of direction when the foot is fixed.
It’s hardly surprising that ACL injuries of this nature occur frequently in women’s football. When you break down the mechanics of injury it becomes apparent that there is also a similarity with netball; another sport where ACL injuries are high (Stuelcken et al., 2016).
Since both sports involve twisting and turning at high speed together with jumping and landing on a fixed foot, the known risk factors exist for ACL injury.
ACL tears in women’s football continue to dominate clubs’ injury lists despite the skills and demands required for the women’s game being no different to the men’s. Stopping, starting, changing direction, jumping and landing etc. are all essential skills for a footballer to possess; whether male or female.
However, in the women’s game the incidence of ACL injury is far greater than in men’s football and this can affect players at any level; you don’t have to be at the elite end of the game to suffer a cruciate ligament tear.
As with the male athletes, injuries to the ACL usually occur in one of two different ways; either through direct contact in sport with an opponent or team-mate, or by non-contact means such as jumping and landing awkwardly.
That there is a known higher incidence of ACL injuries in female athletes than in males (Prodromos et al, 2007; Walden et al, 2011) is currently not contested.
Mufty et al (2015) however, compared lower limb injury rates between male and female footballers over ten seasons in Belgium and found that although women players sustained more ACL injuries than male footballers, the difference was not thought to be as significant in their study as that recorded in previous research.
In a study specifically designed for female athletes commissioned by the International Olympic Committee, Renstrom et al (2008) presented suggestions outlining the most-common risk factors.
Having reviewed the available evidence, it was suggested that anatomical differences, altered biomechanics and hormonal factors can all have an influence on the female athlete’s predisposition to injury; either individually or collectively.
Anatomically, the ACL runs within the knee from the medial surface of the tibia and extends upwards, backwards and laterally to insert on the lower aspect of the femur, where it’s major mechanical function is to prevent excessive forward movement of the shin in various degrees of flexion (Liu-Ambrose, 2003.)
The ACL is one of two ligamentous structures deep within the knee that connects the femur and tibia with the purpose of preventing excessive tibial movement in a backward or forwards direction; the other being the Posterior Cruciate Ligament (PCL).
Renstrom et al (2011) noted that an increased ‘Q’ angle is often thought to lead to an additional load being placed on the knee due to women having a wider pelvis than men.
The ‘Q’ angle is formed by the intersection of two imaginary lines; with the first line starting at the lateral edge of the pelvis and extending down the femur through the centre of the patella. Where this line crosses a similar imaginary line drawn upwards through the centre of the tibia bisecting defines the ‘Q’ angle.
Biomechanically speaking, the wider the hips, the greater the ‘Q’ angle. An increased ‘Q’ angle can lead to the knee giving way on landing as a result of differential stresses being placed on the joint or leading to uneven forces resulting in injury.
Players with and increased ‘Q’ angle can be identified by a proper biomechanical assessment; this can help to identify those players most likely at risk of ACL or other associated knee injuries.
The second major risk factor was also highlighted by Yu et al (2002) and acknowledges that the area of the knee where the ACL inserts on the femur is narrower in women than in men. Since there will be less space for the ACL to move, the potential for injury increases.
Renstrom (2008) also suggested that the size of the intercondylar notch and the fact that the ACL itself is smaller in women may also be considered risk factors for injury. Additionally, they queried whether the actual material of the ACL varied between men and women.
Yu et al (2002) found that in a biomechanical sense, altered movement patterns between men and women are likely to place an increased load on the female ACL, leading to a predisposition to injury.
It’s not only anatomy and biomechanics that are thought to influence ACL injuries in female football though. Hormonal changes are also thought to have an effect. In support of this, Renstrom et al (2008) presented evidence of ACL injuries being sustained during the pre-ovulatory phase of the menstrual cycle compared with the post-ovulatory phase.
So having identified some (although not all) of the most common reasons for the high incidence of ACL injuries in women’s football, the question as always is how to prevent these from occurring in the first place.
A carefully thought-out injury prevention programme considered to reduce the risk of ACL injury in women’s football was suggested by Tyler and McHugh (2001). The idea of such a programme is to gradually alter the way the body lands after jumping.
In short, the landing needs to be soft; and the knees and hips should flex slightly upon making contact with the ground. To assist with proper alignment, the knee should be over the centre of the toes as the foot hits the surface. The front part of the foot should land first before the body weight then transfers to the rest of the foot.
Sutton and Bullock (2013) agreed that neuromuscular and proprioceptive training like that suggested above which encourages female players to avoid placing their knees in vulnerable positions on landing or in twisting / turning manoeuvres have been successful in reducing the incidence of injury across various sports in addition to football.
Training the body to biomechanically adapt is not something that can be done overnight. This requires meticulous attention and the best approach is simply to ensure that jumping and landing techniques are included as an integral part of a regular training session.
It’s also thought that the effects of fatigue can contribute to injury risk by impairing the muscles of the thigh that provide dynamic knee joint stability (Ortiz et al, 2010).
Strength-endurance training to help defer the onset of fatigue together with improved body control in jumping and landing could well be the key towards minimising the risk of sustaining ACL injuries in the long-term.
Additionally, weakness of the hamstring and gluteal muscles can contribute to an unstable knee, therefore hamstring and gluteal strengthening is essential after ACL injury or surgery.
Of primary concern, though, is the high number of ACL injury recurrences after reconstruction; with several players in the women’s game reporting two and more repeat ACL injuries despite having had successful surgery following the original injury.
Where repeat or recurrent injuries are concerned, the one undisputable fact is that the biggest single risk factor for repeat injury is having had an earlier injury to the same structure (Hägglund et al, 2006).
With the ACL, therefore, the focus needs to be on considered rehabilitation based on the individual player recovering from surgery as opposed to blindly following protocols that perhaps suggest a one-method-fits-all approach.
With current available evidence showing that ACL injuries are prone to recurrence at an alarming rate, the potential for repeat or recurrent injury always needs to be considered as the various stages of rehabilitation unfold.
It is imperative that anything that doesn’t look or feel right is identified early in the rehabilitation process and addressed accordingly in case surgical revision is required. Like all injuries that end up at the operative stage, there are times when players have to be re-referred to the surgical teams if progress in rehabilitation is limited.
Over the years, perhaps more research has been conducted into ACL injuries than any other orthopaedic problem. Such research has varied between the treatment and management of ACL tears and how these are thought to have occurred in the first place.
This research is continuing. However, with ACL injuries occurring in women’s football at such a high rate, further studies are required to assess the effectiveness of injury prevention programmes.
Similarly, although the focus on research has increased our subject knowledge, the high rate of ACL injuries – and in particular recurrences of ACL injuries - still remains a cause for concern.
It’s clear that we now have a greater idea of why these injuries are likely to occur. Yet little concrete evidence has emerged as yet to contradict their findings of Renstroem et al (2011) about increased ‘Q’ angles, structural gender differences and hormonal influences being the three main predisposing factors to ACL injury in the female athlete.
As highlighted by Nilstad et al, (2014) increased knowledge on risk factors for lower extremity injuries enables more targeted prevention strategies with the aim of reducing injury rates in female soccer players.
However, despite this increased knowledge, it’s a fact that ACL injuries are still recorded as having a high rate of recurrence. The challenge to medical professionals is to ensure that players returning from ACL rehabilitation do so with the minimal risk of sustaining further injury.
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Photo credit Jeffrey F Lin