Overview
The anterior cruciate ligament (ACL) is one of the main ligaments that keeps the knee stable, especially when pivoting, cutting, or landing from a jump. An ACL tear usually happens during sports or a fall, when the knee twists or bends in an unusual direction.
Symptoms
- A pop felt or heard in the knee at the time of injury
- Swelling that develops within the first several hours
- Pain and difficulty putting full weight on the leg
- A feeling that the knee shifts, buckles, or gives way, especially when turning
- Loss of full knee motion
An ACL tear can happen together with injuries to the meniscus, cartilage, or other knee ligaments, which is one reason a careful examination matters.
Treatment
Treatment depends on your symptoms, examination and goals. Your clinician will talk through which options fit you.
Diagnosis starts with a history and physical examination. X-rays look for fractures, and an MRI can confirm the tear and show related injuries.
Non-operative treatment focuses on physical therapy to restore motion and strengthen the muscles that support the knee, sometimes with a brace and changes in activity. It can be a reasonable option for people who do not plan to return to sports that involve pivoting or cutting, and for some people whose knee feels stable in daily life.
Surgical treatment is ACL reconstruction, in which the torn ligament is replaced with a graft — tissue taken from the patient's own body or from a donor. It is usually done arthroscopically, through small incisions. Reconstruction is commonly recommended for people who want to return to pivoting sports or whose knee keeps giving way.
Recovery after reconstruction follows a structured rehabilitation program over many months. Return to sport is guided by strength, motion, and functional testing rather than by time alone.
When to seek care
See an orthopedic or sports medicine clinician soon after a knee injury with a pop, rapid swelling, or a knee that gives way.
Go to an emergency room for a knee that looks deformed, a leg that is cold, pale, or numb, or pain that cannot be controlled.
For a medical emergency, call 911.
This information is general patient education. It is not a diagnosis and does not replace advice from a clinician who has examined you. For a medical emergency, call 911.
Schedule an appointment
Book a visit with Sports Medicine online through MyChart, or call us.
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For a medical emergency, call 911.