Anterior Cruciate Ligament (ACL) Injuries

A ligament is a tissue band connecting a bone to another bone. The anterior cruciate ligament (ACL) is located inside your knee joint and connects the bones of your upper and lower leg. The ACL is one of several ligaments that keep your knee stable, help keep your leg bones in place and allow your knee to move back and forth.

An ACL injury occurs when the ligament is stretched or torn. A partial ACL tear occurs when only part of the ligament is torn. A complete ACL tear occurs when the ligament is torn into two pieces or detached from the bone.

The most common causes of ACL tears are sudden, sharp movements combined with misalignment of the knee joint and weak muscle support of the knee. An ACL injury can occur if you are struck on the side of your knee, twist your knee, land awkwardly after jumping or if you quickly stop moving and change direction while running, landing from a jump or turning.

Skiers and people who play basketball, football or soccer are more likely to have this type of injury. Women are more likely to tear their ACLs than men when they participate in sports.

Women are more likely to experience ACL tears, possibly due to hormonal, muscle strength or anatomical differences. Other factors that increase the risk include:

• Environmental factors (weather conditions that contribute to slippery surfaces)
• Footwear
• Genetics
• Hormonal factors
• Knee anatomy
• Ligament laxity
• Neuromuscular control
• Playing surface
• Previous injury
• Sports
• Strength imbalances

While ACL injuries may be unavoidable in some cases, there are steps you can take to reduce your risk. When attempting any high-intensity activity, it is essential to warm up your muscles first and practice proper form and technique. Building strength in your leg muscles can also help to protect the knee joints. Wearing braces during high-intensity activities, such as sports or running, can also provide additional stability and support.

Symptoms of an ACL injury include pain, swelling, instability and difficulty putting weight on the affected knee. In severe cases, some patients may be unable to bend their knee. It is common to hear a “popping” sound when an ACL injury occurs. You also may have:

• Knee swelling that occurs within a few hours of injury
• Knee pain, especially when you try to put weight on the injured leg
• Knee instability when you start putting weight on it

If you have a grade one or mild injury, you may notice that your knee feels unstable or seems to “give way” when you use it. Anterior cruciate ligament injuries often occur along with other knee injuries, such as to the meniscus. These injuries also may need to be treated, sometimes with surgery.

Anterior cruciate ligament injuries are usually diagnosed with a physical examination. During the exam, your doctor will palpate the knee joint to check for tenderness and swelling. They may also move the knee through its full range of motion to check for any instability or shifting of the joint. Further diagnostic tests, such as a magnetic resonance imaging (MRI) scan or X-ray, may be ordered to confirm the diagnosis and assess the extent of the damage. Depending on the findings of these tests, additional imaging, such as a computed tomography (CT) scan, can be used to measure the degree of ligament tear and structural damage.

If you have an ACL injury, you may need crutches to walk until the swelling and pain get better or a brace to support and stabilize your knee. Most patients recover from ACL injuries with regular work with a physical therapist to help improve joint motion and leg strength.

Some people can live and function normally with a torn ACL. However, most people feel like their knees are unstable and may “give out” when they do more rigorous activities. Most people will have surgery to reconstruct the ACL to return to their previous activities. Unrepaired ACL tears can lead to further knee damage, especially to the meniscus.

The experts at the Montefiore Einstein Department of Physical Medicine and Rehabilitation will design an individualized treatment plan for recovery that may include:

• Physical therapy
• Local cortisone injections for pain
• Non-narcotic pain management
• Bracing (if needed)
• Platelet-rich plasma (PRP) injections

After your injury, you should not play sports or do other strenuous activities until you and your provider decide on the best treatment. If you have surgery to reconstruct your ACL, you will need physical therapy to regain the full use of your knee. Your recovery after surgery can take about six months, but most patients resume their usual activities.

If you do not have surgery, you must work with a physical therapist to lessen swelling and pain and regain enough range of motion and strength in your leg to resume activity. This may take a few months. Depending on your injury, you may be unable to do certain activities that could re-injure your knee.

For at-home treatment and recovery from injury, follow the rest, ice, compress, elevate (RICE) protocol to help reduce pain and swelling:

• Rest your leg. Avoid putting weight on it.
• Ice your knee for 20 minutes, three to four times a day. Do not apply ice directly to your skin; wrap the ice in a clean cloth first.
• Compress the area by wrapping it with an elastic bandage or compression wrap.
• Elevate your leg by raising it above the level of your heart.

Pain and swelling can be managed with over-the-counter medications like ibuprofen or naproxen. Acetaminophen (Tylenol) helps with pain, but not with swelling. You can buy these pain medicines over the counter.