MCL Injury (Medial Collateral Ligament Sprain or Tear)

What the MCL does

The medial collateral ligament runs from the inner side of the thigh bone (femur) to the top of the shin bone (tibia). It has superficial and deep layers, and the deep layer attaches to the medial meniscus. Its main job is to resist "valgus" stress, the force that pushes the knee inward toward the other knee. It is the most commonly injured knee ligament.

Its outer counterpart, the lateral collateral ligament, is injured less often. Both are covered on our collateral ligament injury page.

How MCL injuries happen

• a tackle or blow to the outside of the knee (football, rugby, soccer)
• the knee buckling inward while the foot is planted and the body twists
• skiing, especially the "snowplow" position as a skier catches an edge
• landing awkwardly from a jump
• gradual overuse in breaststroke swimmers (the "breaststroker's knee"), usually a mild sprain

MCL tear symptoms

• pain on the inner side of the knee, often at the moment of injury, sometimes with a pop
• tenderness along the inner knee, above or below the joint line
• swelling over the inner knee, usually mild to moderate; whole-knee swelling suggests another injury inside the joint
• stiffness and difficulty fully bending or straightening
• a feeling of the knee being loose or giving way inward, especially with grade 3 tears
• bruising on the inner knee after a day or two

Grade 3 tears can be less painful than partial tears, because the fibers are completely torn and no longer stretched.

MCL injury grades

Grade 3 MCL tears often occur with an ACL tear or meniscus tear, sometimes called the "unhappy triad".

Diagnosis

A doctor or physical therapist will ask how the injury happened and examine both knees.

• Valgus stress test: the examiner gently pushes the knee inward at 30 degrees of bend and in full extension, comparing sides. Opening in full extension suggests other ligaments are also torn.
• Other tests check the ACL, PCL and menisci.
• X-rays rule out a fracture, or a bone flake pulled off by the ligament in teens.
• MRI shows the grade and location of the tear and any associated ACL, meniscus or bone injuries. It is used when the knee is very unstable, swelling is large, or symptoms do not improve.

MCL tear treatment

The MCL has a good blood supply, so most tears heal on their own, even complete ones.

First days

• Rest: use crutches if it is painful to walk, putting weight through the leg as tolerated.
• Ice: 15 to 20 minutes every 2 to 3 hours, wrapped in a cloth.
• Compression and elevation to reduce swelling.
• Pain relief: acetaminophen (paracetamol) or ibuprofen, following the label dose. Avoid NSAIDs if you have kidney problems, stomach ulcers or are on blood thinners.

Bracing

A hinged knee brace protects the inner knee from inward stress while allowing bending and straightening. It is usually used for grade 2 and 3 injuries for several weeks.

Rehabilitation

Physical therapy starts early:

1. regaining full range of motion (bending and straightening)
2. quadriceps and hamstring strengthening, starting with straight leg raises and mini-squats
3. stationary cycling and swimming (avoid breaststroke kick)
4. balance and proprioception training
5. running, cutting and sport-specific drills once there is no pain or instability

Surgery

Surgery is rarely needed for an isolated MCL tear. It may be recommended when:

• the MCL is torn along with the ACL or other ligaments
• the ligament has pulled off the shin bone in a way that will not heal (a "Stener-like" lesion)
• the knee remains unstable after a full course of rehab

Return to sport

You are generally ready to return when you have full range of motion, no tenderness, no instability, and strength close to the other leg, and can run, hop and cut without pain. Many athletes wear a functional brace for the rest of the season after a grade 2 or 3 tear. Returning too early increases the risk of reinjury.

Complications

• persistent inner knee instability (uncommon with isolated tears)
• stiffness, particularly if the knee is kept immobilized too long
• Pellegrini-Stieda lesion: calcium deposited in the healing ligament, causing a lump and stiffness
• missed associated injuries, such as an ACL or meniscus tear

Prevention

• strengthen the hips, quads and hamstrings
• train landing and cutting with the knee aligned over the foot (programs such as FIFA 11+)
• set ski bindings correctly
• wear a prophylactic knee brace if advised in high-risk positions, such as football linemen

Frequently asked questions

Can you walk with a torn MCL?

Usually yes. Most people can walk with a grade 1 or 2 MCL sprain, though it may be painful at first and crutches help for a few days. A grade 3 tear may feel unstable. If you cannot bear weight at all, get the knee checked for a fracture or other injury.

How long does an MCL tear take to heal?

A grade 1 sprain typically heals in 1 to 3 weeks, grade 2 in 3 to 6 weeks, and grade 3 in 6 to 12 weeks. Combined injuries take longer. Rehab quality and sticking to bracing advice strongly affect recovery time.

Does a torn MCL need surgery?

Rarely. Isolated MCL tears, even complete ones, usually heal with a hinged brace and physical therapy. Surgery is considered when the MCL is torn together with the ACL or other ligaments, or when the knee is still unstable after rehab.

How do I know if I tore my MCL or ACL?

MCL injuries cause pain and tenderness on the inner side of the knee, often after a blow to the outside. ACL tears usually happen with a pivot or sudden stop, often with a pop and rapid swelling of the whole knee within hours, and the knee feels unstable when turning. An exam or MRI confirms it.

Should I use heat or ice on an MCL sprain?

Use ice for the first 48 to 72 hours to reduce pain and swelling. After that, gentle heat before exercise can ease stiffness, with ice afterward if the knee aches. Avoid heat while swelling is still increasing.