What Are Knee Ligament Injuries?

Medically Reviewed by Ross Brakeville, DPT on September 09, 2023
4 min read

Ligament injuries in the knee -- such as an anterior cruciate ligament (ACL) -- can put you on the sidelines -- fast. They hurt a lot and may limit what you can do.

But more often than not, a comeback may still be possible. Treatment is more successful than it once was.

Ligaments are tough bands of tissue that connect the bones in your body. There are four ligaments in the knee that are prone to injury:

  • Anterior cruciate ligament (ACL) is the most commonly injured knee ligament. It connects the thigh bone to the shin bone.
  • Posterior cruciate ligament (PCL) also links the thigh bone to the shin bone in the knee. 
  • Lateral collateral ligament (LCL) connects the thigh bone to the fibula, the smaller bone of the lower leg on the outer side of the knee.
  • Medial collateral ligament (MCL) links the thigh bone to the shin bone on the inside of the knee.

You may have:

  • Pain, often sudden and severe
  • A loud pop or snap during the injury
  • Swelling within the first 24 hours after the injury
  • A feeling of looseness in the joint
  • Inability to put weight on the joint without pain, or any weight at all

These injuries need medical attention. In some cases, as with ACL tears, you may need surgery so that your knee will be stable and won’t give out when you twist or pivot.

Your doctor will give you a physical exam. If your knee is very tense and swollen with blood, your doctor may use a needle to drain it. You may need X-rays to make sure you don’t have a broken bone, as well as an MRI to check on any ligament injuries.

A mild to moderate knee ligament injury may heal on its own, in time. To speed the healing, you can:

  • Rest the knee. Avoid putting much weight on your knee if it's painful to do so. You may need to use crutches for a time.
  • Ice your knee for 20 to 30 minutes every 3 to 4 hours to lessen the pain and swelling. Keep doing it for 2 to 3 days, or until the swelling is gone.
  • Compress your knee. Put an elastic bandage, straps, or sleeves on your knee to control swelling.
  • Raise your knee on a pillow when you're sitting or lying down.
  • Wear a knee brace to stabilize the knee and protect it from further injury.
  • Take anti-inflammatory painkillers. Nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, or naproxen (Naproxyn) will help with pain and swelling. Follow the directions exactly. Talk with your doctor or pharmacist if you have any questions or feel that you still need them after 7 to 10 days.
  • Practice stretching and strengthening exercises if your doctor recommends them. Never stretch so much that it hurts. Ask your doctor to recommend a physical therapist for guidance.

Only your doctor can tell you for sure. Though there can be exceptions, most collateral ligament tears (LCL and MCL) don’t need surgery.

However, when a cruciate ligament (ACL or PCL) is completely torn or stretched beyond its limits, the only option is reconstructive knee surgery. In this procedure, a surgeon will take tendons from other parts of your leg -- or from a cadaver -- to replace the torn ligament.

A ligament reconstruction for an ACL or PCL injury is complicated and involved. It's not the right choice for everyone. A person who has knee pain or severe instability may choose to have it. So might an athlete who wants to regain their level of performance.

But if the pain is not a problem, you may choose to skip the surgery and accept the risk of some lifelong instability in your leg. You may also opt for a custom-made brace. Talk about the treatment options with your doctor.

Your recovery time will depend on how bad the injury is. People also heal at different rates.

In most cases, physical therapy can help to limit problems and speed up your recovery. If you have an ACL tear, physical therapy is recommended with or without surgery to maximize recovery.

While you recover, if your medical team agrees, you could take up a new activity that won't hurt your knee. For instance, runners could try swimming.

Whatever you do, don't rush things. You shouldn’t go back to your old level of physical activity until:

  • Your doctor says it’s OK for you to take part.
  • You can fully bend and straighten the knee without pain.
  • The knee doesn’t hurt when you walk, jog, sprint, or jump.
  • It’s no longer swollen.
  • The injured knee is as strong as the uninjured knee.

If you start to use your knee before it's healed, you could cause permanent damage.

Knee ligament injuries are hard to prevent. But you can take some precautions that may make them less likely. You should:

  • Keep your thigh muscles strong with regular stretching and strengthening.
  • Warm up with light activities before taking part in tougher ones.
  • Maintain flexibility.
  • Make changes slowly. Don’t suddenly make your workouts a lot more intense.