Why does the knee hurt on the outside

CauseTypical signsMore
Iliotibial band syndromeBurning pain on the outside above the joint when running, especially downhill, and cyclingRunning injuries
Lateral meniscus tearJoint-line pain when twisting and squatting, clickingMeniscus tear
Lateral collateral ligament sprainAfter a blow to the inside of the knee; often with a cruciate injuryACL tear
Lateral compartment osteoarthritisMore common with knock knees; pain when walking, stiffnessKnee osteoarthritis
Popliteus or biceps femoris tendinopathyPain at the back of the outer knee when going downhill and running—
Peroneal nerve irritationNumbness on the outer shin, weak footSee a doctor urgently

Iliotibial band syndrome

The iliotibial band is a dense strip of connective tissue along the outside of the thigh. Repeated bending and straightening of the knee under load irritates the tissue beneath it. A systematic review in Sports Medicine found it to be one of the most common causes of outer knee pain in runners; a sudden increase in training volume, downhill running and weak gluteal muscles play the main role.

  • Reduce running volume for 2–6 weeks and avoid downhills; cycle with a correct bike fit.
  • Strengthen the gluteal and thigh muscles and work on running technique.
  • A corticosteroid injection is sometimes used for severe pain; surgery is very rarely needed.

How it is diagnosed

Iliotibial band syndrome is usually diagnosed by examination. MRI is needed if the pain started after an injury or there is swelling, clicking or locking — to assess the meniscus, ligaments and cartilage. Send your images for a second opinion or arrange an MRI in Munich.

Treating outer knee pain

Most causes are treated without surgery: graded loading, exercise and adjusted training. For degenerative meniscus tears, exercise in a BMJ trial gave the same result as arthroscopy. For osteoarthritis and persistent tendinopathy, PRP or hyaluronic acid may be discussed. Surgery is needed for a locked knee, instability after ligament tears or when treatment fails.

What to prepare for a free review

  • Images: MRI, ultrasound or X-ray (DICOM files or photos of the screen) and their reports.
  • When and how the pain started, where exactly it hurts, what makes it worse or better.
  • Treatment so far: injections, physiotherapy, surgery — and how it helped.
  • Other conditions and medications, especially blood thinners.

With this information, a partner-clinic physician can say whether further tests are needed and which treatment options suit you.

When to see a doctor without delay

Numb, weak foot

The foot slaps, the outer shin is numb — the nerve needs urgent examination.

Injury with instability

After a blow the knee gives way sideways, with rapid swelling.

Locking

The knee will not fully straighten.

Contraindications to injection treatment: active infection, active cancer, clotting disorders, pregnancy. Possible risks of injections are a temporary pain flare and swelling for 1–3 days and, rarely, infection; the treatment may also not work.

Scientific evidence

Studies on the causes and treatment of outer knee pain:

  1. van der Worp MP et al. Iliotibial band syndrome in runners: a systematic review. Sports Med, 2012.
  2. Kise NJ et al. Exercise therapy versus arthroscopic partial meniscectomy for degenerative meniscal tear in middle aged patients: randomised controlled trial. BMJ, 2016.

Frequently asked questions about outer knee pain

Why does the outside of my knee hurt?
In runners and cyclists usually IT band syndrome; after injury the lateral meniscus or collateral ligament; in older people lateral osteoarthritis.
Why does the side of my knee hurt when running?
A typical cause is IT band syndrome: pain starts after a certain running time and worsens downhill.
How long does IT band syndrome take to heal?
Usually 4–8 weeks with reduced load and gluteal and thigh exercises.
Can I run with outer knee pain?
Better to cut volume and avoid downhills until the pain settles; running through pain delays recovery.
Do I need an MRI?
Yes if the pain started after an injury or there is swelling, clicking or locking. For typical running overload, an examination is often enough.
Do injections help?
A corticosteroid is sometimes used for severe IT band pain; PRP may be discussed for osteoarthritis and chronic tendinopathy.
How can RegenPAS help?
RegenPAS is a patient service centre in Munich, not a clinic. We review your images and symptoms and send a request to several partner clinics at once. Clinics that can accept you send their own conditions and price; prices differ between clinics, and you choose the option that suits you. The coordinator replies within 24 hours, and a clinic physician’s preliminary opinion follows in 1–3 business days. We then arrange the appointment, visa invitation, interpreter, transfers and accommodation. Treatment decisions are made by the clinic physician. Contact a coordinator.

Related conditions and treatments

Meniscus tearKnee osteoarthritisACL tearInner knee painPain behind the kneeRunning injuries

Outer knee pain? Free review of your images

Send your MRI or ultrasound and describe where and when it hurts. The coordinator replies within 24 hours; a clinic physician gives an opinion in 1–3 business days.

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