Jack Redden, APA Physiotherapist @ Total Physiotherapy

Over the last 20 years the incidence of anterior cruciate ligament (ACL) injuries and surgeries has increased significantly due to many different factors. Female adolescent athletes are 4-6 times more likely to tear their ACL as male counterparts in the same sport however this decreases as they reach adulthood. Sports with the highest rates of ACL injuries are soccer, basketball and gymnastics.

Why do we tear our ACL?

Around 80% of ACL injuries occur without contact with another player whilst the athlete is landing from jumping, changing direction or decelerating suddenly. Video analysis has shown at the time of injury the base of support (the person’s body weight) was behind the knee with the near in near full extension and the lower extremity in “dynamic knee valgus”. In simple terms, the knee has gone inwards. This can be caused by many different factors. Some factors which have been proposed to put an athlete at greater risk of an ACL are as follows.

• A previous ACL reconstruction (15x greater risk in one study)

• Increased weight and body mass index

• Ligament laxity

• Female athletes

• Poor movement patterns - especially landing technique

• Inadequate recovery from a previous injury

So can we fix this?

In short, yes. Research shows that around 50-80% of ACL ruptures are preventable through agility and neuromuscular training, ideally for 20 minutes 3 times a week. Current evidence shows preventative programs should be a combination of core and lower limb strengthening, plyometric training and technique modification through appropriate feedback.

Strengthening should focus on the hamstrings, glutes and hip external rotators to counteract the “knee dropping in” that is the high risk position for the athlete. Exercises such as squats and lunges should be initially performed with supervision to allow proper form and maximum effect.

Plyometric training is repetitive jumping exercises that aim to strengthen the muscles around the knee building explosive power, strength and speed to lower the risk of injuring your ACL. This training should gradually increase in difficulty, starting on 2 legged take offs and landings, progressing so 1 legged jumping and landing, eventually progressing to continual jumping and landing. 

Feedback training is an important component of ACL prevention with supervision by a qualified professional who is able to properly identify “dynamic knee valgus” (knee dropping in) and adjust the athlete’s technique accordingly. Unsafe positions will be identified and corrected through cues and feedback, reminding the athlete to absorb force through appropriate muscles therefore limiting the force through the anterior cruciate ligament. Athletes progression should be monitored and only progressed once each stage is performed appropriately with the right form and control.

Over the coming weeks we will be developing our own ACL prevention program to share with our patients and associated sporting clubs with the aim to decrease the frequency of ACL reconstructions in the wider community.