Knee Sprain (MCL/LCL): Symptoms, Grades & Rehab

A knee sprain can happen in a split second: a hit to the side of the knee in football or soccer, an awkward landing in basketball, or a quick pivot on the pickleball court. Sometimes it takes even less, like a misstep over a doorway. Most knee sprains involve the MCL or LCL, the ligaments on the inside and outside of the knee. Here is how to recognize a knee sprain, how serious it is, and how physical therapy gets the knee stable and strong again.

What Is a Knee Sprain?

A sprain is an injury to a ligament, the tough tissue that connects one bone to another. The knee has four main ligaments:

• MCL (medial collateral ligament): on the inside of the knee. It is most often injured by a blow to the outside of the knee that pushes it inward.
• LCL (lateral collateral ligament): on the outside of the knee. It is injured when the knee is forced outward.
• ACL and PCL: the cruciate ligaments inside the knee. An ACL tear is usually a more serious injury. See ACL tear symptoms.

Some people are more prone to ligament injuries, so a movement that causes only mild discomfort in one person can sprain another person’s knee.

Knee Sprain Symptoms

• Pain on the inside (MCL) or outside (LCL) of the knee
• Swelling around the knee
• Pain when putting weight on the leg
• Tenderness along the ligament
• The knee buckling or feeling unstable, especially side to side
• Stiffness and trouble fully bending or straightening the knee

Knee Sprain Grades: Mild to Severe

• Grade 1 (mild): the ligament is stretched, with small tears. There is pain and tenderness, but the knee stays stable.
• Grade 2 (moderate): the ligament is partially torn. Expect more swelling and pain, and some looseness in the joint.
• Grade 3 (severe): the ligament is completely torn. The knee feels unstable and may give way. Grade 3 sprains sometimes happen together with other injuries, such as an ACL or meniscus tear.

How a Knee Sprain Is Diagnosed

Don’t self-diagnose a knee injury. It is easy to mistake a fracture, a meniscus tear, or a torn ligament for a simple sprain. A clinician checks your range of motion, tests the stability of each ligament, and looks at how you walk and move. An X-ray or MRI may be needed to rule out a fracture or a more serious tear.

See a provider promptly if you heard a pop, the knee swelled quickly, you can’t put weight on it, or it keeps giving way.

The First Few Days

Early on, protect the knee and calm the swelling. Ease off the activities that hurt, use ice, and elevate the leg. A brace or crutches may help for a more serious sprain. Even mild sprains take time to heal, and doing too much too soon can make things worse.

Why Complete Rest Isn’t the Answer

Keeping the knee completely still is almost as harmful as overdoing it. Healing ligaments need gradual, controlled movement and loading to regain their strength, and the muscles around the knee weaken quickly without it. Physical therapy guides that process, often without the need for pain medication, and it can help you avoid surgery.

Knee Sprain Rehab: How Physical Therapy Helps

Physical therapy for a knee sprain moves through clear steps:

1. Calm and protect: hands-on treatment to ease pain and stiffness, and education on how to walk and move without irritating the ligament.
2. Restore motion: regain full knee bending and straightening.
3. Rebuild strength: starting with exercises like quad sets, straight leg raises, and short arc quads, then progressing to squats, lunges, and step-ups. Hip strengthening is key, because the hip muscles control where the knee goes. Weak hips can cause knee pain and raise the risk of another sprain.
4. Balance and control: single-leg balance and stability work to prevent re-injury.
5. Return to sport: running, cutting, jumping, and landing drills, then testing to make sure the knee is ready.

For more on knee strengthening, see meniscus strengthening exercises for knee control and our example return to play protocol.

Get Your Knee Back to Full Strength

At Back In Motion Physical Therapy & Performance, every visit is one-on-one with a Doctor of Physical Therapy. The Gray Methodâ„¢ helps us find out why the knee got hurt, then we rebuild its strength and stability and test it before you return. Learn more about our knee pain treatment, our ACL injury and reconstruction rehab, and our sports physical therapy for knee injuries at our Fort Myers, Cape Coral, and Estero clinics.

Start with our Fixing the Cause & Not Just the Symptoms Assessment, or Inquire About an Appointment →

Call our office at (239) 223-0484 to schedule your appointment.