ACL: Symptoms, Causes, Treatment & Exercises

Key Takeaways

• An ACL injury often presents with a loud ‘pop’ in the knee, followed by pain and swelling.

• Sports like soccer, basketball, and skiing are common causes of ACL injuries.

• Non-surgical treatments include rest, physical therapy, and bracing.

• Surgical options are available for severe tears, often involving reconstructive surgery.

• At MSK Doctors, our advanced MAI-Motion AI platform provides detailed movement analysis for optimised ACL injury treatment planning by leading orthopaedic consultants. 

ACL Anatomy Overview

The anterior cruciate ligament (ACL) is one of four critical ligaments that stabilise the knee joint, connecting the femur (thighbone) to the tibia (shinbone) (image courtesy of Cleveland Clinic).

Unlike its counterparts, the ACL runs diagonally through the center of the knee, preventing the tibia from sliding forward relative to the femur and providing rotational stability during movement. 

This small but mighty structure—measuring just 31-38mm in length and 10-12mm in width—plays an important role in our mobility, especially during activities that involve sudden stops, changes in direction, or pivoting motions.

ACL Symptoms and Identification

A Popping Sound or Sensation

Many people report hearing or feeling a distinct ‘pop’ at the moment of injury. This popping sensation occurs as the ligament tears, creating an audible or tactile signal that something significant has happened within the knee joint. It's often the first indication of an ACL tear and may be accompanied by immediate pain.

Rapid Swelling

Swelling often develops within the first few hours after injury, sometimes as quickly as within 30 minutes. This occurs because blood vessels damaged during the tear release blood into the joint space. The knee may appear visibly larger compared to the uninjured knee, and the swelling can be quite pronounced.

Loss of Range of Motion

After an ACL tear, you'll likely find it difficult to fully bend or straighten your knee. This restriction in movement happens due to pain, swelling, and the mechanical disruption of normal knee function. The knee may feel stuck or unable to move through its normal arc of motion.

Instability or ‘Giving Way’

Perhaps the most characteristic symptom of an ACL injury is the feeling that your knee is unstable or ‘giving way’ beneath you like it cannot support your weight. Without the ACL's stabilising function, the knee joint may buckle or collapse during weight-bearing activities - particularly when attempting to pivot, turn, or change direction.

Tenderness Along the Joint Line

Touching the area around the knee joint, particularly along the joint line, often produces tenderness and pain. This tenderness may be more pronounced in certain areas depending on associated injuries to other structures like the meniscus or collateral ligaments.

Causes of ACL Injury

Frequent Activities Leading to Injury

ACL injuries commonly occur during sports activities that involve sudden stops, jumps, or changes in direction. These movements put immense stress on the knee joint, increasing the risk of ligament tears.

Sports and activities that commonly lead to ACL injuries include:

• Soccer

• Basketball

• Football

• Skiing

• Gymnastics

These sports often involve quick changes in direction, pivoting, and jumping, which can strain the ACL. Athletes should focus on proper techniques and conditioning to lower their risk of injury.

Risk Factors

While anyone can sustain an ACL injury, certain factors increase the likelihood:

• Gender: Females are more prone due to anatomical differences and hormonal influences.

• Age: Young athletes are at higher risk due to their active involvement in sports.

• Previous ACL injuries: History of ACL injuries can increase susceptibility.

• Improper training techniques: Lack of proper training can lead to poor form and increased injury risk

Treatment for ACL

Choosing the Right Treatment

Deciding on the appropriate treatment for an ACL injury depends on several factors:

• The severity of the injury

• The patient's activity level

• Personal preferences. 

For some, non-surgical options such as physical therapy and bracing may suffice, especially if the knee remains stable and the individual is less active.

However, for athletes or those who engage in high-demand activities, surgical intervention might be necessary to regain full knee function and prevent future injuries. 

Surgical Interventions

Surgical intervention is often recommended when the ligament is completely torn or when the knee remains unstable despite non-surgical treatments. The most common surgical procedure is ACL reconstruction, which involves replacing the torn ligament with a graft. This graft can be taken from the patient's own body (autograft) or from a donor (allograft).

The procedure is typically performed arthroscopically, meaning it involves small incisions and the use of a camera to guide the surgery. This minimally invasive approach helps reduce recovery time and scarring. 

Professional Therapies

Professional therapies, guided by physical therapists, work well for effective ACL rehabilitation. These sessions often include hands-on techniques, advanced equipment, and personalised exercise plans to address specific needs.

Therapists may use techniques such as manual therapy, electrical stimulation, and ultrasound to promote healing and reduce pain. 

Rehabilitation and Exercises

Essential At-Home Exercises

These exercises help maintain progress made during physical therapy sessions and improve overall knee health. Some effective at-home exercises include:

Heel slides: Lie on your back and slowly slide your heel towards your buttocks, bending the knee as much as possible (image courtesy of Youtube).

Quad sets: Sit with your leg extended and tighten the muscles on the top of your thigh, holding the contraction for a few seconds (image courtesy of Youtube).

Hamstring curls: Stand and bend your knee to bring your heel towards your buttocks, using support for balance if needed.

Calf raises: Stand on the edge of a step and slowly raise and lower your heels, focusing on controlled movements.

Perform these exercises regularly, but be sure to consult with a physical therapist to ensure proper form and prevent strain on the knee.

Restoring Knee Health and Function

Restoring knee health after an ACL injury involves a combination of rest, rehabilitation, and a gradual return to sports/activity. Initially, allow the knee to heal by reducing activity levels and following the RICE protocol (Rest, Ice, Compression, and Elevation) which helps manage swelling and pain.

Expert ACL Care: The MSK Doctors Difference

At MSK Doctors, we understand that ACL injuries can significantly impact your quality of life. Our patient-centred approach to ACL treatment combines multifaceted diagnostic technology with personalised care plans designed to optimise your recovery journey. 

Unlike traditional treatment pathways, our team of orthopaedic consultants specialises in both surgical and non-surgical interventions, allowing us to tailor treatment to your specific needs without unnecessary waiting times or GP referrals.

Our state-of-the-art MAI-Motion AI platform provides detailed insights into your movement patterns, enabling us to create rehabilitation programmes that address your unique musculoskeletal challenges. 

With our proven track record of successful ACL treatments and our commitment to ongoing support throughout your recovery process, you can trust MSK Doctors to help you restore knee stability, strength, and confidence with the highest standard of care.

Don't let ACL injury affect your quality of life any longer. Book your consultation today with MSK Doctors and take the first step toward recovery.

Frequently Asked Questions (FAQ)

What is the typical recovery time for an ACL injury?

Recovery time for an ACL injury varies depending on the severity of the injury and the treatment approach. Generally, non-surgical recovery can take anywhere from 3 to 6 months, while recovery after ACL reconstruction surgery may take 6 to 12 months. 

Can an ACL injury heal without surgery?

Yes, some ACL injuries can heal without surgery, especially if the tear is partial and the knee remains stable. Non-surgical treatment options include physical therapy, bracing, and activity modification. 

What exercises are recommended post-ACL surgery?

Post-ACL surgery exercises are designed to restore strength, flexibility, and stability to the knee. They include; quadriceps sets, heel slides and calf raises. 

What are the risks of delaying ACL treatment?

Delaying treatment for an ACL injury can lead to several complications, including increased pain, swelling, and instability. Over time, untreated ACL injuries may cause additional damage to the knee, such as meniscus tears or cartilage degeneration.

How can MSK Doctors help in ACL recovery?

MSK Doctors offer an intensive approach to ACL recovery, combining expert diagnosis, personalised treatment plans, and ongoing support. We are committed to carving a long-term recovery road for you.