ACL Injury Prevention

Written By: Chloe Wilson, BSc(Hons) Physiotherapy
Reviewed by: KPE Medical Review Board

ACL injury prevention is becoming a more popular focus in many sports. 

No-one wants to be on the sidelines and ACL injuries typically have the longest recovery time of all knee injuries.

In the US, approximately 200,000 people per year suffer an ACL injury with about half of these requiring surgery. 

The recovery process is long and for sports people, it usually means being side-lined for about one year.  When it comes to ACL injuries it is definitely a case where prevention is much better than cure. 

Functionally, the ACL works for all movements of the leg, but it is especially important with starting, sudden stopping and twisting movements. 

High risk sports for ACL knee injuries include:

• Football
• Soccer
• Skiing
• Basketball
• Lacrosse
• Wrestling
• Baseball

The ACL is flexible and can stretch to a degree, but too much strain through it will cause it to tear.  This usually happens in one of two ways:

1. Direct Trauma: Anything that puts too much force through the ligament such as a sports tackle, hard fall or car accident
   
   
2. Twisting: Sudden turning and twisting the leg when the foot is stuck to the ground e.g. with studs or cleats

In some cases, other structures in and around the knee may also be damaged at the same time, such as a cartilage tear or MCL tear.

Effective training programs for ACL injury prevention should incorporate a number of things:

1. Effective Warm Up

Warming up before exercise is one of the oldest pieces of advice out there but it really does play an important role in ACL knee injury prevention. Warm ups usually last about 15 minutes and should be designed to get your body prepared for activity. 

Activities such as jogging, shuttle runs and running in different directions should be incorporated into warms ups focusing on ACL injury prevention.

Stretches are an essential part of ACL injury prevention as they help to improve the flexibility and therefore performance of the knee, both of which reduce the risk of knee injuries.

Stretches for the quads, hamstrings, calves, hip flexors, inner thigh and glutes muscles should all be done regularly. 

The most effective way to stretch is to hold the stretch for 30 seconds and repeat it 2-3 times. 

Find out all about how to effectively do stretches and check out our simple tests to see how tight your muscles are in the knee stretches section.

Neuromuscular training is becoming a very popular part of ACL injury prevention programmes, designed to improve dynamic stabilisation of the knee. Neuromuscular programmes also teach individuals how to land from jumps, pivot and change direction without putting too much force through the ACL. 

One key element of ACL injury prevention is plyometric exercises - specialised, high intensity exercises to improve power, strength and speed through various jumping and hopping activities. They work by causing the muscle to first lengthen and then quickly shorten. Plyometric exercises should only be done under close supervision as they involve high-risk movements and if done incorrectly, can result in injury.

Having good proprioception is a vital part of preventing ACL knee injuries.  Proprioception is the reflex control at the knee through small muscle and ligament adjustments that provides the stability of the knee joint.

The anterior cruciate ligament is responsible for providing the primary proprioceptive input at the knee so exercises targeting the ligament can make a massive difference.

Balance exercises such as exercises on one leg, on a wobble board and with your eyes closed helps improve balance and proprioception and thus are an important part of ACL injury prevention. 

7. Knee Braces

There is some controversy over whether wearing a knee brace helps with ACL injury prevention.

• Pros: Wearing a knee brace can help reduce the risk of over stretching the ligament but
• Cons: knee braces can create a false sense of security  

In the general population, there is usually no need to wear a knee brace when playing sports, but in high-level athletes participating in high-risk activities, an ACL knee brace may help reduce the risk of injury.

Knee braces can be particularly useful after a ACL reconstruction surgery to reduce the risk of further injury during the rehab and recovery phase, whilst working on the strength, stability and