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What is Causing the Pain on the Side of My Knee?

Medically Reviewed by Cellaxys

By Published: May 4, 2020Updated: March 12, 2024No Comments
Causing the Pain on the Side of My Knee
Dr Pouya Mohajer


Medically Reviewed

Published on: May 4, 2020 | Updated on: March 12, 2024

Knee pain is increasingly becoming a very common ailment in today’s fast-paced and demanding living conditions. The knees support our entire body weight, and due to their complex structure and mechanics, they are prone to a number of ailments and injuries.

Pain or swelling in the knees can cause great discomfort, and can totally disrupt one’s day-to-day activities. Side knee pain can result from a variety of reasons, depending upon the individual’s age, lifestyle, and activity factors.

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Anatomy of the Knee

The knee is the meeting point of the femur (thigh bone) in the upper leg and the tibia (shinbone) in the lower leg. The fibula (calf bone), the other bone in the lower leg, is connected to the joint but is not directly affected by the hinge joint action. Another bone, the patella (kneecap), is at the center of the knee.

Two concave pads of cartilage (strong, flexible tissue) called menisci minimize the friction created at the meeting of the ends of the tibia and femur.

The knee has two menisci:

  • Medial: on the inner side of the knee, this is the largest of the two.
  • Lateral: on the outer side of the knee.

There are also several key ligaments, a type of fibrous connective tissue, that connect these bones. The four key ligaments of the knee are:

  • Anterior Cruciate Ligament (ACL): the front of the knee; this ligament connects the femur to the tibia and is the main stabilizer of the knee.
  • Medial Collateral Ligament (MCL): the inside of the knee, the MCL prevents side to side movement of the femur.
  • Lateral Collateral Ligament (LCL): the outside of the knee, the LCL prevents side-to-side movement of the femur.
  • Posterior Cruciate Ligament (PCL): the back of the knee, stops the tibia from moving backward with relation to the femur.

There are a variety of causes of side knee pain. The cause can be determined by whether the pain is medial (inside knee) or lateral (outside knee).

Causes of Lateral Knee Pain

Lateral knee pain is often caused by being active in a sport or at work. Certain causes can also be attributed to aging or poor health and obesity.

Lateral Meniscus Injury

This is an injury of the cartilage tissue at the lateral side of the joint. This is caused by awkward knee twisting especially if the knee is bent while the foot was planted. Gradual onset from wear and tear is also a cause.

Symptoms include:

Lateral Collateral Ligament (LCL) Injury

This is knee ligament damage on the outside of the knee. A rapid twisting or awkward fall that forces the lower leg inwards, as well as a hit to the inside of the knee, can cause this.

Symptoms include:

  • Outer knee pain, swelling in the outer region of the knee
  • Bruising
  • Instability
  • Locking or catching of the knee with movement

Iliotibial Band Syndrome (ITBS)

Iliotibial band syndrome (ITBS) is a very common and occasionally stubborn knee injury among distance runners and cyclists, which causes outer knee pain. Typically, this knee pain and inflammation comes on gradually and is most prominent when participating in irritating activities.

Symptoms include:

  • Knee pain while walking or running due to inflammation on the lateral part of the knee joint.
  • Lateral knee arthritis
  • Knee discomfort that is dull, achy, and persistent as well as stiffness (especially in the morning) and creaky/noisy knees

Wear and strain on the outer side of the knee joint, the loss of joint space, the production of bone spurs, and inflammation are all causes. Aging, past injuries, and/or obesity are all factors that contribute to this.

Proximal Tibiofibular Joint Dislocation

One of the rarest reasons for lateral knee discomfort is proximal tibiofibular joint dislocation. It affects the tibia and the fibula. A considerable force, such as a vehicle collision, is required to dislocate the joint, although it can even partially dislocate from a fall with the foot plantar-flexed (toes pointing down), which frequently destroys the tibiofibular ligament.

Outer knee soreness, instability, especially during deep squats, and an apparent deformity on the side of the knee are common symptoms. Damage to the peroneal nerve may also be present, causing numbness or pins and needles around the outer knee.

Nerve Problems

Outer knee discomfort can also be caused by pressure along the peroneal nerve’s route. The peroneal nerve is a branch of the sciatic nerve that goes down the outside of the lower leg and into the foot. Tingling, numbness, and pins & needles are common symptoms of nerve discomfort.

A hit to the side of the knee, which squashes the peroneal nerve just beneath the skin, is the most common cause of peroneal nerve damage. Alternatively, if the sciatic nerve splits off from the lower section of the lumbar spine, there may be pressure further up the nerve.

Discomfort on the outside of the knee, with or without back pain, can be caused by the pain traveling down the nerve.

Causes of Medial Knee Pain

The most common cause of medial knee discomfort is cartilage degradation. It can also occur as a result of a sports injury or other sort of knee damage.

Medial Meniscus Injury

The meniscus is cartilage that provides a cushion between bones in a joint. They serve as cushions between the thigh and shin bones.

A meniscus can tear or become damaged if the knee is rotated or put under pressure, most commonly during sports or athletic activities.

Symptoms include:

  • Stiffness
  • Sharp pain when twisting the knee
  • Locking knees
  • Sense of imbalance

Medial Collateral Ligament (MCL) Injury

The medial collateral ligament (MCL) stabilizes the knee joint by running along the outside of the inner knee. An MCL sprain can happen if the ligament extends too much.

The MCL can completely or partly tear. Injuries to the MCL are most likely when an impact is applied to the outside of the knee, such as in contact sports.

Symptoms include:

  • Inflammation
  • Instability while walking or standing
  • Locking knees
  • At the moment of impact, there is a popping sound


Osteoarthritis is a degenerative condition that causes the bones in the joints to grind together as cartilage breaks down.

Someone with osteoarthritis may have inner knee discomfort while applying pressure on the joint, such as when going up and down stairs or sitting in a chair. Because the discomfort is caused by the pressure, symptoms may get more severe as the day progresses.

Rheumatoid Arthritis

Rheumatoid arthritis is an auto-immune illness that can cause discomfort in the inside of the knee. Because rheumatoid arthritis produces inflammation in the joints, rheumatoid arthritis patients may have acute inner knee discomfort in the morning, with symptoms gradually diminishing over the day.

Irritation of the Medial Plica

Plica is a term used to describe tiny folds in the joint lining. The inside knee is covered by the medial plica. The medial plica can be irritated by overuse, such as continually bending the knee.

The folds thicken and become caught between the bones as a result of this. Locking knees and maybe a snapping sound are possible side effects of mild inner knee discomfort.

Treatment for Pain on Side of the Knee

The optimum therapy for lateral and medial knee pain will be determined by the underlying source of the pain. Physical therapy, exercises, and rest from aggravating activities are typically used, however, knee injections may also be used involving autologous stem cells or platelet-rich plasma (PRP).

Stem cells and PRP can help reverse the degenerative effects of certain causes of knee pain such as arthritis. It is also effective in healing ligament and muscle tears and can prevent a patient from needing surgery for more severe knee injuries.

Regenerative sport medicine and orthopedic procedures have had significant advancements in the past 10 years. These procedures have excellent outcomes on a wide array of issues with the knee.




CELLAXYS does not offer Stem Cell Therapy as a cure for any medical condition. No statements or treatments presented by Cellaxys have been evaluated or approved by the Food and Drug Administration (FDA). This site contains no medical advice. All statements and opinions are provided for educational and informational purposes only.


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Dr. Pejman Bady began his career over 20 years ago in Family/Emergency Medicine, working in fast-paced emergency departments in Nevada and Kansas. He has served the people of Las Vegas as a physician for over two decades. Throughout this time, he has been met with much acclaim and is now the head of Emergency Medical Services in Nye County, Nevada. More about the doctor on this page.

Causing the Pain on the Side of My Knee

Dr Pouya Mohajer


Pouya Mohajer, M.D. is the Director of Spine and Interventional Medicine for CELLAXYS: Age, Regenerative, and Interventional Medicine Centers. He has over 20 years of experience in pain management, perioperative medicine, and anesthesiology. Dr. Mohajer founded and is the Medical Director of Southern Nevada Pain Specialists and PRIMMED Clinics. He has dedicated his career to surgical innovation and scientific advancement. More about the doctor on this page.

Dr. Pejman Bady

Dr. Pejman Bady began his career over 20 years ago in Family/Emergency Medicine, working in fast-paced emergency departments in Nevada and Kansas. He has served the people of Las Vegas as a physician for over two decades. Throughout this time, he has been met with much acclaim and is now the head of Emergency Medical Services in Nye County, Nevada. More details about the doctor on this page.


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