ACL Injury Management – Pillar Health

ACL Injury – Causes, Symptoms, Treatment and Prevention

What is a torn ACL (Anterior Cruciate Ligament?)

The knee joint is a hinge joint that is made up of three parts. The thigh bone (the femur) and the shin bone (the tibia) meet to form the main knee joint and the kneecap (the patella) sits in front of the main knee joint and protects it from damage. Holding the knee joint together are four ligaments. A ligament is a fibrous connective tissue which attaches bone to bone, and usually serves to hold structures together and keep them stable. As shown in the image below, there is a ligament on each side of the knee joint and two that cross each other deep within the knee joint. The ligaments on the outside of the knee joint are known as the lateral collateral ligament and the medial collateral ligament and they work to control the sideways motion of your knee and brace it against unusual movement. The two ligaments that are positioned inside the knee joint are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The role of the PCL is to prevent the shin bone from moving posterior to the thigh bone. Conversely, the major role of the ACL is to prevent the shin bone from sliding out in front of the thigh bone. All in all, these four ligaments work together to stabilise and guide the knee during movement.


Whether you are an elite athlete, a weekend warrior or you enjoy cheering on your team from the comfort of your couch, there’s no doubt that you have heard of the common and devastating ACL rupture. ACL injuries occur commonly. Despite being largely preventable, Australia has the highest reported rates of ACL sporting injuries and reconstructions in the world! An ACL rupture may occur when excessive stress is placed on the knee joint and the ACL is stretched beyond its limits causing it to overstretch or tear. The torn ACL may be partial or complete; a complete tear of the ACL is also known as an ACL rupture.  

ACL injuries most commonly occur during sports that involve sudden stops or changes in direction, jumping or landing – such as netball, football, soccer, downhill skiing. Approximately 60-80% of ACL injuries occur in non-contact situations.


Symptoms of an ACL injury differ greatly depending on the degree of damage to the ligament. An ACL injury is classified as a grade 1, 2 or 3 sprain. 

A grade 1 sprain of the ACL: 

  • The ACL is slightly stretched but there is no tear.
  • Minimal tenderness and swelling. 
  • The knee doesn’t give way or feel unstable.

A grade 2 sprain of the ACL:

  • The fibres of the ligament are partially torn.
  • There is a little tenderness and moderate swelling. 
  • The knee joint feels unstable or may give way when doing activity.

A grade 3 sprain of the ACL (rupture):

  • The ligament is completely torn (ruptured) into two parts. 
  • There may be reports of an audible “pop” or “crack” at the time of injury.
  • Severe/intense pain and inability to continue activity. 
  • Rapid swelling around the knee joint. 
  • Loss or knee range of motion.
  • A feeling of instability or “giving way” when weight bearing on the affected knee. 
  • A feeling of initial instability which may be masked later by excessive swelling. 
  • Restricted movement, especially an inability to fully extend the knee. 

When to see a health professional

You should immediately seek medical care if you suspect that you have an ACL injury. The sooner that you get checked out the better. Physiotherapist’s at Pillar Health are highly trained in the assessment of ACL injuries and will provide you with a prompt and accurate diagnosis to determine the severity of the injury and not delay necessary treatment. 


Non-contact ACL injuries may occur when a person is running or jumping and then suddenly slows down and changes direction or pivots in a way that involves rotating or bending the knee sideways with the foot firmly planted (as pictured below)

medial rotation

Contact related ACL injuries are commonly caused by a direct blow causing hyperextension of the knee or when the knee is forced inwards towards the other leg by an external force. This is commonly seen in AFL when a player’s foot is planted and an opponent strikes his/her on the outside of the thigh. 

Although it is not clear as to why, women are at a higher risk of non-contact ACL injuries than men. This is thought to be due to the following reasons:

  • Strength
  • Anatomy
  • Hormonal variations affecting the laxity of the ligaments.
  • Greater ligament laxity in general.
  • Jumping and landing patterns
  • Genetics

Risk factors

While anyone can injure their ACL, there are a number of factors that place an individual at greater risk of injury. Having a risk factor does not mean that a person will have an ACL injury in his or her lifetime. 

Risk factors that increase the chances of ACL injury occurring include: 

Being female – The rate of ACL injury is three times higher in female athletes than in males. As previously explained, the exact reason remains unknown.

Participation in certain sports –  ACL tears occur commonly in sports that involve quick changes in direction or where bodily contact is frequently made. Some of the sports with high rates of ACL injury include: Basketball, soccer, football, downhill skiing. These sports all require frequent and sudden deceleration, change of direction, pivoting, jumping and landing on one leg. 

Previously torn ACL – The risk of re-injuring a previously repaired ACL is approximately 15% higher than the risk of tearing a normal ACL. The risk is highest in the first year after the injury and the risk of an ACL injury in the opposite knee also increases once the injury has occurred on the other leg. 

Age – ACL tears occur most commonly between the ages of 15 and 45, mostly due to a higher participation in sports in this age group.


Complications following an ACL injury vary depending on the individual and the grade of the injury. People who experience an ACL injury are at higher risk of developing knee joint osteoarthritis, deterioration of joint cartilage and reduced range of motion. When a surgical reconstruction of the ACL is performed, the major complications that can arise include patellar fracture, knee stiffness and infection. It is worth noting that most people do not have major complications after an ACL reconstruction, however complications occasionally occur during surgery or during the rehabilitation period. The most common complications include: 

  • Bleeding into the joint (effusion)
  • Joint infection
  • Blood clot in the deep veins of the leg (deep vein thrombosis)
  • Scar tissue formation. 
  • Loosening of the ACL graft.

Treatment Overview

Treatment right after an injury:

If you have a knee injury followed by pain, swelling, and/or an unsteady feeling while standing, see your Physiotherapist or Osteopath for evaluation. He or she will do a physical examination and may recommend imaging tests to look at your ligaments, tendons and bones.

Once an ACL rupture is confirmed, there are two main treatment options to consider. ACL injuries can be treated with surgery (ACL reconstruction) and post-surgical rehabilitation or with a non-surgical rehabilitation program. The decision to opt for surgical management is based upon a number of factors including your age, how active you are, and whether you have other knee injuries. It is important to consider how the recovery process of ACL surgery will impact your life. A proper ACL rehabilitation takes 12 months. 

You may decide not to have surgery if:

  • The injury to your ACL is small and will likely heal with rest and rehabilitation.
  • You do not participate in a sport that requires pivoting or stopping quickly. 
  • You understand and are willing to complete a non-surgical rehabilitation program to strengthen and stabilise the knee. 
  • You understand that if you decide to not have surgery to reconstruct your ACL, you may be at an increased risk of future knee problems including chronic pain, a decreased level of activity and injury to other parts of the knee. 

Treatment in children and teens

A child with an ACL injury can sometimes be treated without surgery to avoid damage to the child’s developing bones. A Physiotherapist may trial rehabilitation exercises with the child and may encourage the use of a brace to prevent the child from performing twisting and jumping activities. Surgery is usually recommended for active children, to keep the knee more stable and to help prevent future problems.


There are a number of programs designed to prevent ACL injury which have been proven to have great benefit. For an ACL prevention program to be successful it must be guided by a health professional and include the following:

  • High-intensity jumping exercises
  • Analysis of the athletes movement patterns and provide direct feedback about proper positioning.
  • Specific strength training to the chosen sport/activity
  • The program must be completed at least two times a week for a minimum of six consecutive weeks.


If ACL surgery is performed, some pain should be expected in the weeks that follow the surgery. This is a natural part of the healing process. Your doctor, nurses and allied health workers will collaborate to help reduce your pain, which can help you recover from surgery faster.

Medications are often prescribed for short-term pain relief after surgery. Many types of medicines are available to help manage pain, including opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local anesthetics. Your doctor may use a combination of these medications to improve pain relief, as well as minimize the need for opioids.

Talk to your doctor if your pain has not begun to improve within a few days of your surgery.


You may consider to have ACL surgery if you:

  • Participate in high-level sport or have a job that requires a strong and stable knee (eg, a job that requires frequent twisting and pivoting)
  • Are unsteady when standing on the injured knee
  • Have injured other structures in the knee as well as the ACL
  • Have tried conservative management and still have instability in the knee. 
  • Understand and are willing to complete the proper post-surgical rehabilitation program. Most ACL rehabilitation programs require daily strengthening and stretching exercises and one or more weekly visits with a Physiotherapist or Osteopath for the first three to six months after surgery. Failure to follow a rehabilitation program could increase the risk of re-injury, allow scar tissue to develop and may lead to limited movement of the knee. 

Surgical reconstruction of the ACL is performed in a hospital under general anesthesia. To reconstruct the torn ligament, a piece of healthy tendon, called an autograft is removed from another area in the leg. The most common autograft sites include the patellar tendon, the hamstring tendon and the quadriceps tendon. One last option is to reconstruct the ACL using an allograft which is a tendon from a deceased donor. The advantage of using an allograft is that there is no need for any additional incisions and there is no risk of pain or weakness at the site of usual graft harvest. There isn’t strong evidence to suggest that one type of graft is better than another, but generally the surgeon will have a preference and will guide the decision based on a range of factors. 

During surgery, the damaged ACL is removed and replaced with the chosen graft using a telescope-like device called an arthroscope. The arthroscope contains a camera and light and is inserted into the knee joint through a small incision in the skin so that the surgeon can operate with precision. The surgeon will secure the graft and will place the knee in an immobilising brace to limit movement and to allow the patient to walk easily with crutches. Most people will spend several hours in the hospital following the surgery but won’t require overnight supervision and will therefore be discharged home to begin rehabilitation.

Goals of surgery

The major goal of ACL reconstruction surgery is to allow you to return to your usual activities, sport or exercise pain and limitation free. After surgery and proper rehabilitation, the ACL works dynamically to assist in stabilising the knee joint when any twisting, jumping, or cutting motions are performed. After completing a full rehab and with clearance from your surgeon, you will be equipped with the tools to continue strengthening and training the knee to prevent re-injuring your ACL and keep you doing the exercise and sport that you love.

Exercises before surgery

Before proceeding with ACL reconstructive surgery, there should be minimal swelling in the injured knee and full range of motion should be achieved. It is important to prepare the knee as best you can for surgery to ensure a good outcome post operatively. 

Pre-operative Physiotherapy encourages strengthening of the quadriceps, hamstrings and glutes. Range of motion exercises should be included if there is no pain involved.

Once you are able to adequately bend and straighten your knee, you should incorporate stationary cycling, swimming and low impact exercise machines such as an elliptical cross-trainer to your exercise routine to develop strength and endurance. 

See below for examples of appropriate exercises that can be performed before surgery.

Isometric Quadriceps exercise

Isometric Quadriceps exercise

Straight leg raises

Straight leg raises 2

Heel props

Heel props

Prone hangs

Prone hangs 3

Wall slides

Wall slides

Knee slides

Knee slides 5

Surgery in children and teens

ACL tears were once thought to be extremely rare in children, but have received more attention in recent years. Children and teens have growth plates in each long bone in their body. Growth plates add length and width to the bone and as children grow, their growth plates harden into solid bone. On average, growth plates are completely hardened between the age of 15-20 for females and 17-24 for males. If the adolescent with an ACL injury is within a year or two of skeletal maturity, most physicians feel that the risks of surgery are small, and a standard ACL reconstruction is usually performed. However, for younger patients, alternative techniques have been developed to try to lessen the possibilities of growth plate concerns.

Post Operative Management

ACL reconstruction is a major surgery and recovery can be very challenging, both physically and emotionally. Having realistic expectations can be helpful in both making the decision to have surgery and preparing for the recovery period. Physiotherapy following surgery is a crucial part of your recovery process. Pillar Health’s Physiotherapist’s are experienced at providing outpatient rehabilitation following ACL surgery. A good post-operative Physiotherapy program will allow for quicker recovery time and significantly improve quality of life and functional outcomes. 

Post operative management will include:  

Week 1
  • Regular icing and elevation is used to reduce swelling. The goal is to regain full knee extension and 70 degrees of knee bend by the end of the first week. 
  • Knee brace and crutches are used to take additional stress off the new tendon. 
  • You will likely be encouraged to begin weight bearing on the affected leg as soon as possible. (If your surgery was more extensive, your surgeon may recommend delaying weight bearing for a longer period.)
  • Strengthening exercises for the calf muscle, hamstring and quadriceps can be performed as guided by your Physiotherapist. 
Week 3-4
  • The aim is to be walking with a normal gait with only one crutch. With good hamstring/quadriceps control, the use of crutches can be reduced earlier.
  • Stationary bike with no resistance is commenced.
Week 5
  • The use of the knee brace is progressively reduced.
  • Light intensity exercise is commenced and is progressively increased in difficulty. The progress of the exercise depends on pain, swelling and quadriceps control.
  • Proprioception and coordination exercises can start if the general strength is good. This includes balance exercises.
  • Exercises for week 3-12 post operatively include: Quarter squats, bridges, single leg calf raises, step ups, balance work.
Week 10
  • Forward, backward and lateral movements are included into the exercise regime as exercises are progressed. 
Month 3
  • After 3 months, you can move on to functional exercises such as running and jumping. As proprioceptive and coordination exercises become heavier, quicker changes in direction are possible. 
  • A focus on coordination and control throughout movements. 
  • Exercises are advanced by variation in visible input, surface stability (trampoline), speed of exercise performance, complexity of the task, resistance, one or two-legged performance, etc.
Month 4-5
  • The final goal is to maximize endurance and strength of the knee stabilizers and ensure good knee control.
  • Sport-specific exercises are implemented. 
  • Acceleration and deceleration, variations in running and turning and cutting manoeuvers included to prevent new trauma during competition.
Return to sport
  • Athletes can return to sport once the reconstructed knee has had sufficient time to heal and demonstrate strength, balance, endurance and function equal to the uninjured knee.
  • There is no specific set of criteria that guarantees that a person is ready to return to sport after an ACL reconstruction. However effective criteria should include some functional assessment that reflects the demands of the chosen sport that you are returning to. 

Make an appointment

Our Physiotherapist’s at Pillar Health want to get you back to doing what you love as quickly as possible. It is likely that your treatment will incorporate goal orientated exercise prescription, soft tissue therapy and hands-on mobilisation. You do not need a referral to see a Physiotherapist after your surgery but any information regarding your surgery is helpful and we ask that you bring that with you to your appointment. 

You can make an appointment by phoning the clinic on (03) 8899 6277 or by following this link