ACL Injuries In The Adolescent Female

Image of injured female athlete

Mick Hughes is a Physiotherapist at The Melbourne Sports Medicine Centre and writes a regular blog on exercise and conditioning.  Here is some of his latest work. I shared a link on LinkedIn recently to an article regarding landing technique in adolescent females during a growth spurt. This research indicated that, during a growth spurt, the female athlete will change their landing pattern in a way that is similar to the pattern of movement that results in an ACL injury The valgus collapse (where the knee displaces medially or caves in as you sink into a squat) is more obvious in this group and is linked to ACL injuries. This information is extremely valuable to us as health care providers, coaches and parents as a potential injury prevention tool.  It follows that if you know your athlete or child is going through a growth spurt, you can then modify his or her training program and playing schedule in order to minimise the risk of ACL injury.


Which brings me to the point of this article..


ACL injuries suck!


As we are all aware, an ACL injury is a long term injury. In the active population that wishes to return to sport, ACL injury often involves surgery and a very lengthy stint on the sidelines. There is plenty of research regarding ACL injury that I could talk all day about, but I'll keep it fairly brief here.  I'm just going to focus this post on the age group with the highest prevalence - you guessed it, the teenage female - and some things that you can do as a health care provider, coach and parent to identify those at risk of sustaining an ACL injury, and things you can do to help minimise the risk of injury in this age group.


Firstly, just a brief overview. Adolescent girls have ACL injury rates that are, depending on which paper you read, 2-10x greater than their male counter-parts (reference). Sports that are known to be "high-risk" for ACL injury in this female age group are; netball, touch football, soccer, volleyball and basketball.


There are many documented risks factors associated with ACL injury, some modifiable, some not. Non-modifiable ones include, a narrow intercondylar notch inside the knee, age and family history. I will focus however on the modifiable risk factors as these are the ones us as health professionals have the most control over. Themost researched modifiable risk factor is impaired neuromuscular control of the athlete. The other risk factor that I feel we potentially have good control over is an abnormal quads to hamstring ratio.


Injury prevention programs designed to improve neuromuscular control and reduce the risk of ACL injury have shown excellent results. A systematic review and meta-analysis of all ACL prevention programs, such as the PEP (Prevent Injury and Enhance Performance), have shown a 73% reduction in non-contact ACL injuries, and 44% reduction in total ACL injuries (reference). Furthermore all knee injuries have been shown to be reduced by 27% whilst undertaking these programs (reference).


In regards to quads to hamstring ratio, it has been found that females, compared to males, have a tendency to be "quad dominant" in functional tasks such as jumping and landing. Without this balance between the quads and the hamstrings, the ACL is thought be at a biomechanical risk of injury. One study has shown a direct link between deficits in hamstring strength in ACL injured knees (compared to non-injured subjects) (reference). The general rule of thumb is that, the greater dominance of quads over hamstrings the greater the risk of ACL injury - (the quads to hamstring radio above 1.5:1 was found to indicate an elevated risk).


Before I finish, I'm just going to quickly point out one other factor that has received attention in recent years, which has been linked to ACL injury - the presence of patello-femoral joint (PFJ) pain. Now PFJ pain is a completely seperate blog on its own, so I wont go too deeply into right now, but it's worth pointing out that adolescent girls also have higher rates of PFJ pain compared to males, and very interestingly, literature has suggested that PFJ pain can be a precursor to ACL injury - Largely in part due to the same poor cutting, landing and pivoting patterns of movement (ie. valgus collapse) seen in both injury profiles (reference).


So what can you do as a health care provider, coach or parent? The moral of my story today is this:


Screen and monitor your young female athletes well!! 


This is definitely not an exhaustive list of what you should be looking for, but it sure is a very good place to start if you're dealing with young females in "high-risk" non-contact sports. At the start of the season:


  • Check to see if they have a family history of ACL injury. If so, implement PEP program.


  • Check to see if they have a current or past history of PFJ pain. If so, look to address the causes with a sports doctor and physio, and implement PEP program.


  • Observe how they land, jump and pivot - do they have valgus collapse? If so, look at some dedicated one-on-one jumping and landing training. Also implement PEP.


  • Assess their Quads to Hamstring ratio. If quads strength >1.5 that of hamstrings, start hamstring strengthening program with physio, exercise physiologist or S&C coach.


  • Implement the PEP program as a matter of course for injury prevention.


  • Finally, monitor them at least once a month for a growth spurt. Anecdotally if your child has grown more than 2cm in a month, they should be on a modified training and playing program until their growth plateaus.


That will do for today and thanks for your time! As you all know, I have a strong passion for injury prevention, particularly in the athletic adolescent age group, so please feel free to share this blog far and wide to people that you think will benefit from this information. It is my firm belief that the better job we do with this age group now, the better sports performances and long term health outcomes we'll see long into the future!


Have a great week!


To arrange an appointment to see Mick please phone 9650 9372 or book online.