The Medial Collateral Ligament (MCL) is a thickening of the medial or inner knee joint capsule.  The MCL is the stabilizing ligament between the medial distal femur (thigh bone) and the medial upper tibia (shin bone).  The main function of the MCL is to reinforce the medial knee joint against excessive valgus stress or inward bowing of the knee.  Another important function of the medical collateral ligament is to limit the amount of external rotation of the lower leg in relationship with the upper leg or femur.

In summary, the MCL is an important stabilizing structure that impacts most movements of the knee.  The manner in which the knee moves is significantly influenced by the MCL, thus it dictated the function of the entire lower extremity.

The medial collateral ligament is separated into two parts.  The superficial ligament fibers originate along the distal inner femur and insert along the upper inner tibia.  The deep ligament fibers attaches to the medical meniscus cartilage along with the joint edges or margins.

When stress is placed upon a ligament which is in excess of the capabilities of that ligament, the ligament is disrupted.  When a ligament, which connects bone to bone, is damaged, it is referred to as a sprain.

The grade or degree of damage to a ligament is based on the level of disruption of the ligament fibers.  MCL sprains are graded from 1 to 3 with a grade 3 being the worst.

Grade 1 MCL Sprain:

Injury:                           Stretching of the MCL fibers

Symptoms & Findings:         Point tenderness with no instability

Grade 2 MCL Sprain:

Injury:                           Partial tearing of the MCL fibers

Symptoms & Findings:         Point tenderness with mild instability

Grade 3 MCL Sprain:

Injury:                           Complete tearing of the MCL fibers

Symptoms & Findings:         Point tenderness with significant instability

The mechanism of injury is usually related to a blow to the outside of the leg and/or excessive external rotation of the lower leg in relationship to the upper leg.  With grade 3 MCL sprains, a “pop” is noted by the athlete.  When an audible “pop” is noted, the common fear is a complete tear of the anterior cruciate ligament (ACL).

Signs & Symptoms of a Sprained MCL

  • Pain along the medical or inner knee joint.
  • A sensation of “looseness” or instability when bearing weight on the involved leg.
  • A “wobble” of the inner knee is noted when the leg is lifted and swung in a side to side manner.
  • Generalized swelling of the inner knee which tends to increase with prolonged walking.
  • The quadriceps leg strength is quickly diminished secondary to pain and swelling.
  • The athlete’s confidence in the leg and the ability to be functional is typically directly related to the degree of instability.
  • When a meniscus tear accompanies a sprain of the MCL, internal knee joint catching or locking is reported.

Professional Treatment for a MCL Sprain

  • Immediate icing and immobilization of the knee.
  • Compression to the knee joint to control swelling.
  • A knee brace is utilized for all weight bearing activities for all MCL sprains and while sleeping for all grade 2 & 3 MCL sprains.
  • Painfree active and passive range of motion (ROM) while avoiding the last 20 degrees of ROM for all grade 2 & 3 MCL sprains.
  • Utilize the latest physical therapy modalities and rehab devices to reduce swelling and decrease pain.
  • Conservative quad strengthening exercises are implemented starting on Day #2 with initial ROM limited to 90 to 20 degrees.
  • Bike riding can be started on Day #2 as tolerable while avoiding the last 20 degree of extension until the swelling and pain are reduced to 50% of maximum levels.
  • Conservative measures are taken to avoid all activities that allow the knee to “drop inward” or gap medially along with all functional movements that externally rotate the foot and lower leg.

Asking the Right Questions Like a Pro

Here’s what a smart pro athlete would ask his/her sports medicine specialists to ensure a fast and safe return to sports:

  1. Are my two cruciate ligaments stable?
  2. What grade is my MCL sprain?
  3. Do you have any concern that I have any secondary damage to my knee such as a bone bruise, meniscal tear, chondromalacia, an inflamed plica or damage to my articular cartilage?
  4. What do you recommend that I do for my rehab, on my own or within a rehab clinical setting?
  5. Do I need a rehab brace now and will I need a functional brace when I return to my sport?
  6. What are my guidelines to return to running, limited activities and full-go activities?

Elite Sports Medicine Tips from Mike Ryan

  • Tighten Up – Careless treatment with a sprained MCL will result in a loose MCL.  Is that a problem?  Question: Have you ever tried to run fast or play tennis with a shoe with no laces?  Exactly…
  • Quads Rule – Strong quads or thigh muscles are directly related to your ability to return to your sport after the MCL has completely healed.
  • Build up the Sides – Progress slowly with the side-to-side movements.  Agility-type movements are important for most sports so the MCL needs to be properly prepared for that type of stress.
  • Look Down – Can you see your sneakers?  Make sure they are the proper footwear for your sport.
  • “Mirror Mirror on the Wall” – Check your legs look in the mirror.  If the involved leg looks smaller, you still have some high intensity strength work to do.