Understanding the Difference Between Medial and Lateral

By Stacey Foley, DPT, MTC

What is the Difference between Medial and Lateral?

These terms refer to which body part is midline to the body. For example, your big toe is medial to the little toe and the inside of your elbow is medial to the outside of your elbow with standing palms up. Another example is your arms are lateral to your torso, but your torso is medial to your arms. Lastly, medial is closest to midline while lateral is away from the center of the body.  Our goal is this article is for you to have a better understanding of these medical terms.

Illustration of the anatomical position. JOI Rehab

Illustration showing Medial and Lateral Position

Describing Knee Anatomy with Medial and Lateral

One of the most common body parts to injure is the knee. We will discuss the anatomy of the knee below. The structures on the inside of the knee that can be damaged are the medial collateral ligament and medial meniscus. Medial collateral ligament tears happen most often in skiing, basketball, and football. Additionally, there are three grades of tears.


Grades I-III Tears in the Knee

Grade I tear is when less than ten percent of fibers are torn, and the knee is still considered stable. Grade II tear is a partial tear of the superficial portion of the medial collateral ligament and the knee is considered loose. Patients typically have intense pain and tenderness along the inside of the knee. Grade III tear is a complete tear of the superficial and deep portions of the medial collateral ligament. A grade III tear typically accompanies other ligament tears in the knee as well. Symptoms of medial collateral ligament tears include an audible pop at time of injury, locking of the knee, pain, tenderness to palpation, and swelling or stiffness to the medial aspect of the knee.

To learn more about knee injuries, please read these articles:

What is the recovery time for an MCL Tear?, and What is the Difference Between the Symptoms of ACL and MCL Tears?

Lateral Collateral Ligament

Lateral collateral ligament tears are more common in athletes that participate in skiing, football and soccer due to:

  • Stop-and-go movements
  • Hard contact
  • Jumping
  • Repetitive twisting
  • Quick changes in direction.
Lateral Collateral Ligament highlighted. JOI Rehab

Knee Anatomy showing the Lateral Collateral Ligament

The lateral collateral ligament tears typically with a result in bruising and swelling on the outside of the knee. Lateral collateral ligament grade tears are the same as far as grading them as medial. Treatment for grade I and II tears most commonly heal with physical therapy, knee brace and decreased weight bearing with aid of crutches. Grade I tear typically heal in three to four weeks and grade II tears can take eight to twelve weeks. Grade III tears may heal in eight to twelve weeks or may need surgical interventions.

Treatment For Medial and Lateral Collateral Tears

Treatment for both of these ligament injuries starts with the RICE Technique.  It is important to keep the swelling out of the knee and the VMO of your quadricep muscle.  Depending on the grade of the tear, your physician may place you in a brace with crutches.  Physical therapy is so important at this point to control swelling and to improve the strength of the muscles surrounding the knee.

Understanding a Medial Meniscus Tear

Another structure in the knee commonly injured is the meniscus. The meniscus is two C-shaped pieces of cartilage that cushion and provide shock absorption to the knee. You have a medial and lateral meniscus which is injured with a forceful twist or rotation of the knee with full weight into the lower extremity.

Often the knee might feel “stuck” when trying to straighten the knee. Additionally, if you have pain and tenderness on the inside of your knee at the joint line, you most likely have a medial meniscus tear. If the pain and tenderness is on the outside of the knee at the joint line, it would be a lateral meniscus tear.


With any of the injuries to the medial or lateral structures of the knee, it is important to have an evaluation by an orthopedic physician.  At JOI and JOI Rehab, we are here to help you with all of your injuries and to get you back to activities that you love.

Written by: Stacey Foley, PT, DPT, MTC

Related Articles:

Finally, please watch this video from JOI and JOI Rehab on Why Knee Pain Can’t Wait!

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What is the difference between medial and lateral

Medial vs lateral

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