Outside, or lateral, knee pain is a common condition resulting from a range of injuries or underlying medical conditions that affect the outer side of the knee joint.

Symptoms of lateral knee pain include knee tenderness, swelling, stiffness, and difficulty with movement.

This article looks at some common causes of lateral knee pain, as well as how to treat them. It also discusses diagnosis and recovery.

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IT band syndrome (ITBS) is a common cause of lateral knee pain. The IT band is a thick band of tissue that runs along the outer side of the thigh, attaching to the knee.

Overusing or injuring this band can cause pain on the outer side of the knee.

A 2022 article notes that ITBS is the most common cause of lateral knee pain in cyclists and runners.

How to treat it

Some standard treatment options for IT band syndrome include:

  • resting
  • avoiding activities that make the condition worse
  • taking part in low impact exercises
  • applying ice and heat therapy
  • performing stretching and strengthening exercises

Physical therapy may also be an option. A physical therapist can help develop an individualized treatment plan for IT band syndrome.

The LCL is a ligament on the knee’s outer side that helps stabilize the joint.

A sprain or tear in this ligament can cause pain and instability on the outer side of the knee.

The American Academy of Orthopaedic Surgeons notes that people are more likely to injure their lateral collateral ligament if they take part in direct contact sports. Examples include soccer or football.

How to treat it

The treatment for an LCL sprain or tear depends on the seriousness of the injury.

In mild cases, rest, ice, compression, and elevation (RICE) may be enough to manage symptoms and promote healing.

In more severe cases, medical treatment and physical therapy may be necessary.

The meniscus is a C-shaped piece of cartilage that helps cushion the knee joint.

When the lateral meniscus on the outer side of the knee tears, it can cause pain and swelling.

A person may damage the meniscus as a result of twisting motions to the knee. This can happen if people are playing sports that require fast changes in direction.

How to treat it

Resting the affected knee and avoiding activities that make the injury worse can help reduce pain and prevent further damage to the meniscus.

Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can help reduce pain and inflammation.

Ice and heat may also help.

The biceps femoris is one of the hamstring muscles. It runs along the outer side of the back of the thigh and attaches to the outer side of the knee.

Overusing or injuring this muscle and its tendon can cause pain on the outer side of the knee.

How to treat it

Resting the affected area and applying ice to the back of the thigh can help reduce inflammation and pain.

Stretching exercises can help improve flexibility in the hamstring muscles. Strengthening exercises can help improve the stability of the knee joint.

OA is a degenerative joint disease that can affect any joint in the body, including the knee. OA is the most common form of arthritis.

When the cartilage in the knee wears down, it can cause pain on the outer side of the knee.

How to treat it

The treatment for knee osteoarthritis typically involves a combination of therapies to manage symptoms, improve joint function, and slow disease progression.

Treatment includes:

  • physical therapy
  • strengthening exercises
  • achieving and maintaining a healthy BMI
  • pain relieving medications
  • supportive devices, such as crutches
  • surgery, as a last resort

The peroneal nerve is a nerve that runs down the outer side of the knee.

If it becomes compressed or irritated, a person will experience pain, numbness, and weakness on the outer side of the knee.

How to treat it

Doctors can treat peroneal nerve entrapment nonsurgically.

Nonsurgical treatments may include:

  • physical therapy
  • bracing
  • medications, such as NSAIDs or corticosteroids to reduce inflammation and pain

In severe cases, surgery may be necessary to relieve pressure on the peroneal nerve. The type of surgery may vary depending on the cause and severity of the entrapment.

While there are many common causes of lateral knee pain, some less common causes can also contribute to lateral knee pain.

These may include:

  • Popliteal artery entrapment syndrome: This rare condition occurs when the popliteal artery, which supplies blood to the lower leg, becomes compressed or restricted by the muscles and tendons around the knee. It can cause pain, numbness, or weakness in the leg during physical activity.
  • Osteochondritis dissecans: In this condition, a portion of the bone dies due to the lack of blood flow to the area. The bone and covering cartilage may then break loose, causing pain and swelling and limiting joint motion.
  • Iliopsoas bursitis: This condition involves inflammation or irritation of the bursa, a fluid-filled sac near the hip joint that helps cushion and reduce friction between muscles and tendons. It can cause pain in the hip or knee.

Diagnosing lateral knee pain typically involves a thorough physical examination and a review of the person’s medical history. The doctor will ask the person about their symptoms, such as when the pain started, how severe it is, and what activities make it worse.

During the physical examination, the doctor will look for swelling, tenderness, and instability in the knee. They may also check the range of motion in the knee and test for specific movements that can help diagnose certain conditions.

In some cases, the doctor may order imaging tests to help diagnose the cause of the knee pain. These may include X-rays, MRI scans, CT scans, or ultrasounds. Imaging tests can help identify ligament or meniscus tears, arthritis, or other atypical structural differences in the knee joint.

The outlook for someone with lateral knee pain depends on the underlying cause and the severity of the condition.

Doctors can often treat lateral knee pain with conservative measures, such as rest, physical therapy, and medication, and most people can soon return to their usual activities.

However, the outlook can be more variable for certain conditions that cause lateral knee pain, such as ACL tears or meniscus tears, especially if they are more severe.

In these cases, surgery may be necessary, and recovery may be more complex and time-consuming.

Lateral, or outside, knee pain is a prevalent condition that can occur due to various injuries or medical conditions affecting the outer side of the knee joint.

Treatment options range from rest and ice to physical therapy and medications. In severe cases, surgical intervention may be needed.

With appropriate care and prevention methods, individuals with lateral knee pain can recover well and improve their overall knee joint health.