One of the most significant injuries sustained by footballers is an anterior cruciate injury (ACL). These injuries occur more frequently in female footballers and can have a devastating effect on a player’s career. The injury often requires sophisticated imaging, reconstructive surgery, intensive physiotherapy and rehabilitation, and ongoing monitoring to decrease the occurrence of a re-injury. Players who tear their ACL are usually unable to play football for about one year and are more prone to developing post-traumatic osteoarthritis.
Because of the significance of this type of injury, a lot of research has gone into trying to prevent it from occurring. Neuromuscular control of the knee and altered proprioception may provide clues to identify which athletes are particularly susceptible to ACL injuries. Risk factors include altered movement patterns during sports participation, altered muscle activation patterns, and unanticipated contact from another player to the body, or the knee joint specifically.
- Hamstring/quadriceps ratio
- While the quadriceps muscle increases anterior shear force on the tibia, the hamstring muscle reinforces the ACL by preventing the excessive anterior translation of the tibia, acting as an agonist to the ACL. If the hamstring shows weakness, imbalance with respect to the quadriceps, or a motor delay in contraction time, the ACL may be at increased risk of injury, leading to failure.
- Landing strategy
- In addition, landing from a jump with minimal hip and knee flexion and/or hip adduction and internal rotation, increases the load transmitted to the knee joint and the force transmitted from the quadriceps, thereby placing undue tensile stress to the ACL.
- Balance and proprioception
- Players with limited neuromuscular control appear to be more at risk of injury. Proprioceptive training, including with perturbation, may also be a useful strategy.
There are several programmes which have been shown to be effective at reducing the risk of ACL injury by addressing these factors. One of these was developed by the Santa Monica Sports Medicine Foundation, called the Prevent Injury and Enhance Performance Program (PEP). 9 The PEP programme focuses on proper landing, cutting, and decelerating techniques. It emphasises landing softly on the ball of the foot, engaging knee and hip flexion on landing and with lateral (cutting) manoeuvres, avoiding excessive knee abduction/valgus positioning on landing and squatting, increasing hamstring, gluteal and outer hip strength, and addressing proper deceleration techniques. The programme showed a significant reduction in ACL injuries (of between 74-88%). It appeared to take 6–8 weeks for the programme to become effective.