A ligament is a band of tissue that connects bone to bone. The collateral ligaments are located on the outside of your knee joint. They help connect the bones of your upper and lower leg, inside your knee joint.
- The lateral collateral ligament (LCL) runs on the outer side of your knee.
- The medial collateral ligament (MCL) runs along the inside of your knee.
A collateral ligament injury occurs when the ligaments are stretched or torn. A partial tear occurs when only part of the ligament is torn. A complete tear occurs when the entire ligament is torn into two pieces.
More about your injury
The collateral ligaments help keep your knee stable. They help keep your leg bones in place and keep your knee from moving too far sideways.
A collateral ligament injury can occur if you get hit very hard on the inside or outside of your knee.
Skiers and people who play basketball, football, or soccer are more likely to have this type of injury.
What to expect
You may notice:
- Locking or catching of the knee with movement
- Knee swelling
- Knee pain along the inside or outside of your knee
You also may notice that your knee feels unstable or seems to "give way" when using it.
After examining your knee, your doctor may send you to have an MRI. An MRI is a device that can take pictures of the tissues around your knee. The pictures will show whether these tissues have been stretched or torn. You also may have an X-ray to see if there is any damage to the bones in your knee.
If you have a collateral ligament injury, you may need:
- Crutches to walk until the swelling and pain get better
- A brace to support and stabilize your knee
Most people don't need surgery for an MCL injury. However, you may need surgery if your LCL is injured or if your injuries are severe and involve other ligaments in your knee.
Self-care at home
Follow R.I.C.E. to help reduce pain and swelling:
- Rest your leg. Avoid putting weight on it.
- Ice your knee for 20 minutes at a time 3 to 4 times a day.
- 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.
You can use ibuprofen (Advil, Motrin), or naproxen (Aleve, Naprosyn) to reduce pain and swelling. Acetaminophen (Tylenol) helps with pain, but not swelling. You can buy these pain medicines at the store.
- Talk with your doctor before using these medicines if you have heart disease, high blood pressure, kidney disease, or have had stomach ulcers or internal bleeding in the past.
- Do not take more than the amount recommended on the bottle or by your doctor.
You should not put all of your weight on your leg if it hurts, or if your doctor tells you not to. Rest and self care may be enough allow the tear to heal. You should use crutches to protect the injured ligament.
Afterward, you will learn exercises to make the muscles, ligaments, and tendons around your knee stronger and more flexible.
- You may need to work with a physical therapist to regain knee and leg strength.
- Slowly, you can return to normal activities and perhaps return to sports again. Ask your doctor.
When to call the doctor
Call your doctor if:
- You have increased swelling or pain
- You notice knee instability
- Self-care doesn't seem to help
Medial collateral ligament injury - aftercare; MCL injury - aftercare; lateral collateral ligament injury - aftercare; LCL injury - aftercare
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Bearcroft PWP. Joint Disease. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 50.
Resnick D, Kransdorf M. Internal Derangement of Joints. In: Resnick D, Kransdorf MJ: Bone and Joint Imaging. 3rd ed. Philadelphia, Pa: Elsevier Saunders; 2005:chap 59.
Miller III RH, Azar, FM. Knee injuires. In: Canale ST, Beaty JH, Daugherty K, Jones L, et al. Canale & Beaty: Campbell's Operative Orthopaedics. 12th ed. Philadelphia, PA: Mosby Elsevier, 2013:chap 45.
Update Date 5/27/2013
Updated by: C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.