Anterior Cruciate Ligament Injuries
  • CBD Wellness Centre

Anterior Cruciate Ligament Injuries

Hi everyone, welcome to this week’s blog topic where we are going to cover injuries to the final ligament in the knee - the anterior cruciate ligament, or ACL. As we get into the heat of the winter sports seasons it’s important to, not only, know how to notice an ACL tear, but how to prevent it.


The ACL is one of the four main ligaments that are critical to the stability of your knee joint. It is made of tough fibrous material and functions to control excessive knee motion by limiting joint mobility.

One of the most common problems involving the knee joint is an ACL injury or tear and of the four major ligaments of the knee, an ACL injury or rupture is the most debilitating.

Damage to the ACL is usually a sports-related injury and approximately 80% of these are "non-contact" injuries. This means that the injury occurs without the contact of another player, such as a tackle in football.


Most often ACL tears occur when pivoting or landing from a jump. During these movements the thigh rolls into medial rotation, while the lower leg rolls into external rotation, overstretching the ACL in the centre of the knee, creating damage.


Many sports require a functioning ACL to perform common manoeuvres such as cutting, pivoting, and sudden turns. These high demand sports include football, rugby, netball, touch, basketball, tennis, volleyball, hockey, dance, gymnastics and much more. You may be able to function in your normal daily activities without a normal ACL, but these high-demand sports may prove difficult.



Some of the signs & symptoms of an ACL tear include:

· Feeling or hearing a pop at the time of injury

· Immediate pain, followed by instability in the knee when turning.

· Significant swelling, especially across the top of the knee.


To diagnose an ACL tear your practitioner will take you through some special tests which test the stability of the ACL itself. The main tests used are the Lachman’s test and anterior drawer test.



Lachman’s test– With the patient laying on their back the knee is flexed to approximately 20-30 degrees while the heel rests on the exam table. The femur is stabilised with the non-dominant hand to prevent the upper leg from moving, then the dominant hand pulls the tibia forward. In a normal knee you will feel a firm endpoint which is the ACL preventing excessive movement (up to 3mm). In an ACL tear there is excessive anterior translation (>4mm) and no firm end point.



Anterior drawer test – adopting a similar position to the Lachman’s test, the patient is supine but with the knee bent to 90° and the heel resting on the exam table.

The therapist places both hands on the proximal tibia and draws the upper calf forward. If the tibia moves anteriorly without a firm endpoint then the test is considered positive.



An MRI may also be used to determine an ACL tear. It will also look for signs of any associated injuries in the knee, such as bone bruising or meniscus damage, that regularly occur in combination with an ACL tear.



Many patients with an ACL tear start to feel better within a few days or weeks of an ACL injury. These individuals may feel as though their knee is normal again because the swelling has started to settle. Swelling can give the knee a false sense of stability and once it recedes the knee can become incredibly unstable.

Treating an ACL deficient knee can be done either operatively or non-operatively. ACL reconstruction surgery involves taking a graft, normally from the hamstring muscle and anchoring it to the femur and tibia to mimic the action of the ACL.

If a non-operative or conservative approach is chosen, then the person will undertake a comprehensive ACL-Deficient Knee Rehabilitation Program that involves leg strengthening, proprioception and high-level balance retraining, plus sport-specific agility and functional enhancement. Physiotherapists are the go to place for these exercises.

Your physiotherapy or chiropractic treatment will also aim to:


§ Reduce pain and inflammation.

§ Normalise the joint range of motion.

§ Strengthen the knee: especially the quadriceps, VMO and Hamstrings.

§ Strengthen the entire lower limb: Calves, Hip and Pelvis muscles.

§ Improve patella femoral (kneecap) alignment

§ Improve your proprioception, agility and balance

§ Improve technique with functional tasks such as walking, running, squatting, hopping and landing.


Many ACL injuries can be prevented if the muscles that surround the knees are strong and flexible.

Prevention focuses on proper nerve and muscle control of the knee. Exercises aim to increase muscle power, balance, and improve core strength and stability.

The following training tips can reduce the risk of an ACL injury:

· Practice proper landing technique after jumps

· When you pivot à crouch and bend at the knees and hips. This reduces stress on the ACL.

· Strengthen your hamstring and quadriceps muscles. The hamstring muscle is at the back of the thigh; the quadriceps muscle is at the front. The muscles work together to bend or straighten the leg. Strengthening both muscles can better protect the leg against knee injuries.


It’s crucial, following an ACL injury, regardless of whether surgery is chosen or not, to engage in a thorough rehabilitation program to protect the knee (and new graft) and minimize the risk of an ACL injury reoccurring.


So that’s a brief overview of how ACL injuries occur, If you have questions or comments please e-mail us at admin@cbdwellnesscentre.com.au and we will be happy to answer them for you.


If you have suffered from an ACL injury in the past or feel that your knee is unstable, feel free to call us on (08) 9486 8653 and our therapists will be happy to chat with you.






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