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ACL Injury and Management

Updated: Jul 12, 2023

The knee is perhaps the most complex joint in the human body and is subjected to large forces during sporting activities. These forces are resisted by a number of structures including the five main ‘static’ restraints of the knee: two cruciate ligaments, the two collateral ligaments and the popliteus tendon. The anterior cruciate ligament (ACL) is arguably the most important and well-known structure.

Anatomy of the knee. ACL and MCL

ACL injuries are one of the most common injuries for athletes. It is estimated that there are approximately 85 ACL injuries per 100,000 people (Renstrom, 2013). Although a direct blow to the knee can injure the ACL, almost 80% of the injuries to this ligament are caused by non-contact events involving a sudden deceleration or change in direction (Renstrom et al., 2008)

Rehabilitation following an ACL injury can be a long process. Most athletes have an expected return to sport of 9 months after the injury.

Is surgery an option?

There is growing evidence to show that treating an ACL injury without surgery can be effective. Patients who have not undergone surgery noticed a slightly increased lack of stability through their knee. This can lead to re-injury in sports that involve lots of twisting and pivoting. Therefore, it is critical for patients to work with their physiotherapist to embark on a tailored treatment and rehabilitation plan.

Returning from an ACL Injury

Typically, the return to sport can be categorised into three main phases.

First Phase: strength and coordination

The first phase includes strengthening the quadriceps muscle group and making sure that not only the strength but the size on the affected side is the same as the unaffected side.

It is also important to develop an all-around strength along the muscles of the core, and other leg muscles in order to address any weaknesses that may have led to the injury in the first place. It is recommend to emphasize gluteus maximus strengthening as deficits in gluteal strength have been to shown to be a significant predictor of recurrent ACL injuries (Paterno et al., 2010).

The patient should be able to fully straighten their knee. After this is achieved, the patient can be taught how to co-contract their quadriceps and hamstrings together in order to facilitate controlled and stable movement of the knee during exercises.

Any resisted open chain kinetic exercises such as leg extension machine and freestyle swimming should be avoided before the 8 weeks mark after surgery to allow the graft to heal. However, swimming with a pool buoy between the legs is recommended for cardio exercises as well as exercising in an exercise bike.

Second phase: proprioception and agility

After the physiotherapist establishes that sufficient strength was achieved, the emphasis can then be directed to improving balance, agility and proprioceptive deficits.

This is a crucial phase of recovery and proper adherence has the potential to dramatically reduce the risks of re-injury.

In this phase running may be progressively commenced once there is good muscular strength and no knee effusion. Proprioceptive work should include hopping and jumping activities with a good landing technique. Hops and jumps can be progressed by being performed on one leg and can be progressed further by increasing height and complexity.

Agility work should only be commenced after basic running and progressed through activities such as shuttle runs, bounding runs and skipping. There should be an emphasis on good form through change of direction drills, hopping and jumping drills.

Third Phase: primarily focused on the return to sport criteria

This stage involves sports specific exercises, therefore, the exercises prescribed in this stage are specifically tailored for the athlete and the sport they play.

It is recommended that the program be performed more than once a week and for at least 6 weeks to maximize effectiveness in preventing re-injury. Each program should include plyometric and agility drills as well as some strength exercises.

Sports specific skills and drills involving significant speed or height should rarely be considered before 6 months.

Once the athlete has mastered the sports specific skill components a return to team training may be considered. However, certain aspects such as player confidence, quadriceps muscle strength, patient understanding and adherence to an ongoing injury prevention program may delay the return to sport in order to prevent re-injury.

If you would like to learn more about ACL management and rehabilitation, or have recently sustained an injury to your ACL, make a booking online with us at Breathe Physio and Pilates. Our expert physios will happily get you back on track!



Grindem, H., Snyder-Mackler, L., Moksnes, H., Engebretsen, L. and Risberg, M., 2016. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine, 50(13), pp.804-808.

Paterno, M., Schmitt, L., Ford, K., Rauh, M., Myer, G., Huang, B. and Hewett, T., 2010. Biomechanical Measures during Landing and Postural Stability Predict Second Anterior Cruciate Ligament Injury after Anterior Cruciate Ligament Reconstruction and Return to Sport. The American Journal of Sports Medicine, 38(10), pp.1968-1978.

Renström, P., 2012. Eight clinical conundrums relating to anterior cruciate ligament (ACL) injury in sport: recent evidence and a personal reflection: Table 1. British Journal of Sports Medicine, 47(6), pp.367-372.

Renstrom, P., Ljungqvist, A., Arendt, E., Beynnon, B., Fukubayashi, T., Garrett, W., Georgoulis, T., Hewett, T., Johnson, R., Krosshaug, T., Mandelbaum, B., Micheli, L., Myklebust, G., Roos, E., Roos, H., Schamasch, P., Shultz, S., Werner, S., Wojtys, E. and Engebretsen, L., 2008. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. British Journal of Sports Medicine, 42(6), pp.394-412.

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