ACL injury overview

Overview

The ACL (anterior cruciate ligament) is a strong band of tissue inside your knee that helps keep the joint stable. An ACL injury means this ligament is stretched, partially torn, or completely torn. It often happens during sports or sudden movements.

Yes, ACL injuries are quite common, especially among athletes and active people.

It can affect anyone, but it is most common in people aged 15–45 who play sports like football, basketball, skiing, or soccer. Women have a slightly higher risk due to differences in anatomy and muscle control.

Symptoms

Common symptoms

• A loud 'pop' or snapping sensation at the time of injury.
• Severe pain and inability to continue activity.
• Swelling within the first few hours.
• Feeling like the knee is unstable or 'giving way'.

Symptoms in children

• Symptoms are similar to adults, but children may have growth plate injuries as well. Any knee injury in a child should be checked by a doctor.

Symptoms in older adults

• Older adults may have less swelling, but they often have more stiffness and a longer recovery. Falls and twisting injuries can also cause ACL tears.

Causes

Main causes

• Sudden stopping or changing direction while running.
• Landing awkwardly from a jump.
• A direct blow to the knee, such as in a tackle or collision.
• Twisting the knee while the foot is planted firmly.

Risk factors

• Playing sports that require pivoting (e.g., football, basketball, skiing).
• Poor conditioning or weak thigh and core muscles.
• Wearing improper footwear.
• Previous knee injuries.
• Being female (higher risk due to biomechanics).

When to see a doctor

See a doctor urgently if:

• If you heard a pop and have immediate swelling.
• If you cannot bear weight on the injured leg.
• If your knee gives way or feels unstable.

Book a routine appointment if:

• If you have ongoing knee pain or swelling that does not improve with rest.
• If you have difficulty fully straightening or bending the knee after a few days.

Diagnosis

A doctor will take a detailed history of your injury, ask about symptoms, and perform a physical exam to check the stability of your knee.

Tests that may be done

• Physical examination (Lachman test, pivot shift test).
• MRI scan (magnetic resonance imaging) to see the extent of the tear and check for other damage.
• X-ray to look for fractures.

What to expect at your appointment

The doctor may apply gentle pressure to your leg to test the knee's movement. You might be asked to walk or stand. The exam is usually not painful but may be uncomfortable. An MRI is painless and takes about 30 minutes.

Treatment

Treatment depends on the severity of the injury, your activity level, and your goals. Options range from non-surgical management (physiotherapy) to reconstructive surgery.

Self-care at home

• Rest the knee and avoid activities that cause pain.
• Apply ice packs for 15–20 minutes every few hours to reduce swelling.
• Compress the knee with an elastic bandage.
• Elevate the leg on a pillow when sitting or lying down.
• Use crutches if needed to avoid putting weight on the leg.

Medical treatments

A doctor may recommend anti-inflammatory pain relief (such as ibuprofen) – always follow the dosing instructions on the packet. Physiotherapy is the cornerstone of non-surgical treatment, focusing on strengthening the muscles around the knee and improving balance. In some cases, a brace may be used. For complete tears in active individuals, surgery to reconstruct the ligament is often considered.

When is surgery considered?

Surgery is typically recommended for younger athletes or people who want to return to high-level sports that involve twisting and jumping. It may also be advised if the knee remains unstable after a trial of physiotherapy.

Living with this condition

Living with an ACL injury requires patience. The knee may feel unstable at first, so avoid sudden movements. Many people can return to daily activities like walking, stairs, and light work within a few weeks with proper rehab.

Lifestyle tips

• Use a knee brace if advised by your doctor.
• Avoid high-risk activities until your knee is strong and stable.
• Wear supportive footwear.
• Maintain a healthy weight to reduce stress on the knee.

Diet and exercise

Eating a balanced diet rich in protein and vitamin C (found in fruits and vegetables) can support tissue repair. Exercise such as swimming and cycling is often safe if your knee is not swollen – check with your physiotherapist first. Gradually increase activity as guided.

Mental health and emotional wellbeing

An ACL injury can be frustrating, especially if it stops you from doing sports or daily tasks. It is normal to feel upset or anxious. Talking to friends, family, or a counsellor can help. Stay connected to your hobbies and focus on small recovery goals.

Prevention

While not all ACL injuries can be prevented, you can lower your risk with proper training. Strengthening your leg muscles, especially the quadriceps and hamstrings, and learning to jump and land correctly can help. Balance exercises and using proper technique in sports are also important.

Complications

If left untreated

• Persistent knee instability, making it difficult to walk or play sports.
• Damage to other parts of the knee, such as the meniscus (cartilage) or other ligaments.
• Early onset of knee osteoarthritis.

Long-term outlook

With proper treatment and rehabilitation, most people recover well and return to their usual activities. Even if you choose non-surgical management, many people achieve good knee function. The key is to follow your healthcare provider’s guidance and be patient with your recovery.

Find support

External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.