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ACLS – Anterior Cruciate Ligament Injuries

I recently heard the comment that an ACL rupture is a “life altering injury” and yet the rate of these injuries continues to rise in NZ and overseas along with the rates of reconstructions. Whilst there are some groups in NZ sport making gains in this area, which requires a significant amount of resource both financial and time we are a long way away from a unified approach across sports throughout our amazing country that needs to occur if we are to ensure that this increasing trend is reversed.

Why are ACL’s such a significant issue?

I was once told that the day you rupture your ACL your knee ages 30 years. That is a pretty significant issue considering the rates of ACLs in our younger population is what is on the increase. The largest increase is in the 15-19 year age group and whilst even five years ago it was uncommon to see an ACL in anyone under 14 this is no longer the case. Imagine your 10 year old with a “40 year olds knee”. On top of this is the likliehood of undergoing an ACL reconstruction of which the rehabilitation period is up to 12 months post surgery prior to returning to sport. We know that up to 50% of those who rupture their ACLs never return to sport and out of the percentage that do there is a significant proportion that never return to the performance level they were at prior to their injury. There are huge physical, social and mental health implications to this injury particularly when they occur in our teenagers whose entire social structure is often built around their sporting involvement.

A recent study in NZ investigated the incidence of Anterior Cruciate Ligament reconstruction (ACLR) surgery in New Zealand, and analysed changes over time in demographic subgroups. Note the data for this research comes from ACC is was relates to reconstructions performed from 2009 – 2016 (compared to 2000-2005). This was reconstructions not actual rupture rates).


The annual incidence of ACLR was greater in males than in females and showed a 58% increase when compared with the period 2000–2005 .The greatest increase was seen in females aged 15–19 years, with the incidence increasing by 120% in the last decade. There was also a 53% increase in reconstructions in females aged 20–24 years with netball, rugby and football accounting for the highest number of injuries. (Marked increase in the incidence of anterior cruciate ligament reconstructions in young females in New Zealand. Sutherland, Clatworth, Fulcher, Chang and Young. 2019).

This research highlights one of the other issues in this space which is the lack of consideration for conservative management of ACL injuries rather than the almost expected reconstruction post rupture. That is another whole discussion so look out for this blog in the future.

We know from research that females have 4 – 6 x higher rates of ACL ruptures than our male counterparts. We also know that until puberty these rates are equal and post puberty there is a rapid rise. There are a variety of reasons proposed for why this occurs that includes genetic and biological issues such as smaller ACLs, larger Q angles increasing the risk of reduced knee control and menstrual cycle involvement with hormonal influences on greater risk periods. Added to this is the fact that at puberty males increasing testosterone levels result in increases in strength where females tend to grow earlier over a shorter period of time without the same concurrent strength increases resulting in a reduction in motor control. This motor control deficit unfortunately puts our young female athletes at significantly higher risk of injury.

Whilst this is the case this trend of increasing rates of our young females rupturing their ACLS could be significantly reduced with some basic interventions. Recent research shows a 50% reduction in ALL (contact and non contact) ACL injuries in both males and females and almost a 70% reduction in non contact ACL injuries in females with appropriate warmups being completed prior to sport (Webster and Hewett, 2018.) This is a simple intervention that takes little time, cost and effort considering the benefits for our athletes.

What we do know about warmup programmes for ACL prevention is:

  • Must include plyometrics and sports specific skills such as cutting

  • Should be multifaceted programmes

  • Stretching doesn’t reduce injury risk

  • Balance exercises alone don’t reduce injury risk

  • Plyometrics alone don’t reduce injury risk but combined with balance exercises they do

  • Strengthening exercises and proximal control exercises provide greatest benefits – for example planks

  • A combination of balance, strength, agility and plyometric exercises are most beneficial

The below infographic is part of our WHISPA project aiming to increase awareness of the required elements in a warmup programme in order for it to be effective not just for ACL injury prevention but all significant sporting non-contact injuries. For more information on programmes that have been shown to be effective in reducing these injuries see my blog on warmups for injury prevention (can this blog be linked) or contact me on:

Meta-Analysis of Meta-Analyses of Anterior Cruciate Ligament Injury Reduction Training Programs. Webster and Hewett, 2018.

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