What is Anterior Cruciate Ligament Injury?

An anterior cruciate ligament (ACL) injury is a tear or sprain of the ACL, one of the key ligaments in the knee. This type of injury commonly occurs during activities that involve sudden stops, changes in direction, jumping, and landing. Sports like soccer, basketball, football, and downhill skiing are particularly associated with ACL injuries.

When an ACL is torn, individuals often report hearing or feeling a “pop” in the knee. This is typically followed by swelling, instability, and pain, making it difficult to bear weight on the affected knee. The severity of an ACL injury can vary, and treatment options range from rest and rehabilitation exercises to surgical intervention.

Symptoms

An ACL injury can manifest through symptoms such as:

  • Audible Pop of the Knee During Injury
    Many individuals experience a notable popping sound at the time of injury, which is a primary indicator of a torn ACL.
  • Swelling
    Rapid swelling of the knee, often within 24 hours of the injury, is a common symptom.
  • Pain
    Severe pain is usually felt, especially when trying to put weight on the injured leg.
  • Instability of the Knee
    The knee may feel unstable or like it’s giving way when attempting to stand or walk.

Causes and Risk Factors

ACL injuries are often the result of certain activities and physical dynamics. The primary causes and risk factors include:

  • Sudden Strenuous Movement: Activities that involve abrupt changes in speed or direction, such as in soccer or basketball, may increase the risk.
  • Straining the Knee with Incorrect Techniques: Injuries often occur when landing from a jump with improper technique, as seen in sports like basketball and volleyball.
  • Direct Blow to the Knee: A direct blow to the knee, common in sports like football, can lead to an ACL injury.
  • Gender-Related Risks: Research indicates that female athletes are more prone to ACL injuries due to differences in muscle strength, hormonal factors, and neuromuscular control.
  • Previous ACL Injury: Individuals who have had an ACL injury previously are at a higher risk of re-injury.
  • Lack of Knee Conditioning: Inadequate muscle strength and conditioning can leave the knee more vulnerable to injuries.

Diagnosis

Diagnosing an ACL injury involves a combination of clinical evaluation and imaging tests.

  • Clinical Examination
    The knee’s range of motion will be assessed, along with its swelling and stability. Specific manoeuvres, such as the Lachman test, may be performed to check the integrity of the ACL.
  • X-ray Imaging
    X-rays are used to rule out bone fractures, which can occur alongside an ACL injury. They do not show soft tissues like ligaments or tendons.
  • Magnetic Resonance Imaging (MRI)
    MRI scans help evaluate soft tissue damage, including the state of ligaments and cartilage in the knee.
  • Ultrasound
    This might be used to inspect for injuries in the ligaments, tendons, and muscles around the knee.

Non-Surgical Treatment Options

Various non-surgical treatment options can be considered for an ACL injury, especially in cases where surgery is not immediately necessary or if the individual is not actively participating in sports that stress the knee.

  • RICE Method
    Initially, ACL specialists may recommend using the RICE method to reduce pressure on the knee and alleviate symptoms. This includes resting the knee from activities that put stress on the knee, applying ice to the knee, compressing the knee to support it, and keeping the knee elevated. These techniques can help control swelling and reduce pain.
  • Physiotherapy
    ACL specialists may suggest a tailored physiotherapy programme to restore knee function and strengthen the muscles supporting the knee.
  • Bracing
    The ACL specialist may suggest using a knee brace to provide stability to the injured knee. Crutches may also be given to avoid putting weight on the leg.
  • Medications
    Pain relief medications may be prescribed to help manage discomfort. This may include anti-inflammatory medications to reduce pain and swelling.

Surgical Treatment Options

In cases where non-surgical treatments are insufficient or if the individual wishes to return to high-level athletic activities, surgical intervention may be necessary.

ACL Reconstruction Surgery

As many ACL injuries cannot be stitched back together, surgery involves reconstructing the torn ligament. The damaged ACL is replaced with a graft, which acts as a scaffold for a new ligament to grow on. This graft can be obtained from several sources, such as the patellar tendon, hamstring tendon, or quadriceps tendon. In some cases, a graft from a cadaver (allograft) might be used.

Prevention Strategies

Preventing ACL injuries involves a combination of exercises, proper techniques, and lifestyle adjustments.

  • Strengthening the Leg and Core Muscles 
    Focusing on building the strength of the leg muscles, particularly the hamstrings, can ensure balanced muscle strength. Exercises that target the core, including the hips, pelvis, and lower abdomen, can also contribute to overall stability and injury prevention.
  • Using Proper Techniques to Avoid Knee Strain
    Emphasise the correct knee position when jumping and landing, as well as during pivoting and cutting movements.
  • Warm-ups and Stretches to Reduce Injury Risk
    Engaging in thorough warm-ups and stretching exercises before sports activities helps in maintaining flexibility and reducing injury risk.
  • Balance and Agility Training to Prevent Awkward Knee Positions
    Improving balance and agility can help prevent the knee from being placed in vulnerable positions during physical activities.

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Dr. Ambrose Yung

  • Specialist Orthopaedic Consultant

Dr Ambrose Yung Wai Yin is an experienced Specialist Orthopaedic Consultant with over 20 years of experience in the field of orthopaedics.

His area of interest extends includes complex operations such as revision knee arthroplasty, partial knee replacement and primary total knee replacement. His area of expertise also extends to minimally invasive shoulder, ankle and knee surgery as well as reconstruction of the upper and lower limbs.

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    Frequently Asked Questions (FAQ)

    How Soon Can I Walk After ACL Surgery?

    After ACL surgery, the timeline for walking depends on individual recovery. Typically, patients can start putting full weight on the operated leg without crutches 2 to 3 weeks post-surgery. Follow the specific guidance of the ACL injury specialist to ensure safe recovery.

    Does a Torn ACL Heal on Its Own?

    An ACL tear usually does not heal well independently due to poor blood supply, especially in complete tears. While partial tears might allow for some level of activity with minimal instability, it is best to consult with our ACL injury specialist for an accurate assessment and appropriate treatment plan.

    What Happens if You Ignore an ACL Tear?

    Ignoring an ACL tear can lead to chronic knee instability, increased risk of further knee damage, and potential long-term issues like osteoarthritis. Seeking prompt evaluation and treatment from our ACL injury specialist can help lead to proper healing.

    What Exercises to Avoid with a Torn ACL?

    High-impact activities and exercises that put a strain on the knee should be avoided. This includes jumping, pivoting, or heavy lifting.

    What Is the Fastest Way to Recover from an ACL Injury?

    The fastest recovery from an ACL injury involves adhering to a tailored treatment plan, which may include surgery, physiotherapy, and specific exercises. Recovery speed varies, but following a regular rehabilitation routine, guided by our ACL injury specialist, can aid the healing process.