Lateral Knee Pain (Outside)

Lateral knee pain

Most sports injuries which cause pain on the outside of the knee are gradual onset, overuse injuries rather than sudden onset sprains and strains.

The athlete is often unable to pinpoint the exact time an injury occured and may have continued to train through what they though was a minor niggle.

On this page:

  • Iliotibial band syndrome
  • Torn cartilage meniscus
  • Patellofemoral pain
  • Osteoarthritis
  • Biceps femoris tendinopathy
  • Tibiofibular joint sprain
  • Important injuries not to miss!
  • Should I see a doctor?

Common causes of lateral knee pain:

Iliotibial band syndrome

Iliotibial band friction syndrome

One of the most common causes of pain on the outside of the knee is Iliotibial band syndrome. It is also known as ITBFS or runners knee and is common in runners1, cyclists and soldiers. Symptoms consist of pain and inflammation on the outside of the knee which comes on sometime during a run. Pain usually eases with rest only to return again when training resumes.

The iliotibial band is a long fascia which runs down the outside of the thigh. The fascia is connective tissue which surrounds muscle and connects the tensor fascia latae muscle (TFL) and gluteus maximus muscle at the hip, to the tibia (shin bone). When the TFL muscle and band become tight the fascia rubs against the bone on the outside of the knee becoming inflamed. Read more on:

Lateral cartilage meniscus injury

Lateral Meniscus Tear

A lateral meniscus tear is an injury to the cartilage meniscus, which provides cushioning and support to the knee joint. A torn meniscus can be a sudden onset, acute knee injury, or it can develop gradually from wear and tear. This causes degeneration of the cartilage. Pain is felt along the joint line on the outside of the knee and may be worse when squatting. More often than not there will be swelling. The knee may also lock, or give way. Read more on:

Less common causes of outside knee pain:

Patellofemoral pain

Patellofemoral Pain Syndrome

Patellofemoral Pain Syndrome (PFPS) occurs when the patella (kneecap) is out of alignment and rubs on the femur bone underneath. Symptoms include an aching pain in the knee, with tenderness and swelling which is mostly at the front of the knee around the patella, but can also develop over the outside of the knee. Pain is often worse when walking up or down hills, or when sitting for long periods. Patellofemoral pain is more likely to cause pain under the kneecap or knee pain in general than specifically on the outside of the knee.

Read more about:


Osteoarthritis - Knee

Osteoarthritis is wear and tear of the knee joint resulting in degeneration of cartilage and eventually bone. A deep aching pain is felt, usually on the inside of the knee but can also affect the outside of the knee. Symptoms are worse after exercises and swelling and/or joint stiffness is common.

Read more on Osteoarthritis in the knee.

Biceps femoris tendinopathy/tendinitis

Biceps Femoris Tendinopathy

Biceps femoris tendonitis is inflammation of the hamstring tendon at the point where it inserts into the back of the knee. The term Biceps femoris tendinopathy is probably a more accurate description of most injuries which tend to be chronic, long term degeneration of the tendon through overuse rather than sudden onset acute inflammation.

Symptoms include tenderness and swelling at the back of the knee where the tendon attaches. The back of the knee may feel still first thing in the morning, or after sitting for a long periods of time.

Read more on Biceps femoris tendinopathy.

Superior (proximal) tibiofibular joint sprain

The tibiofibular joint is the point in the knee where the tops of the shin bones (tibia and fibula) join. Dislocation of the joint is likely to have been caused by an impact or fall onto the knee when it is in a fully bent position. Symptoms include pain and swelling on the outer surface of the shin. In addition the top of the fibula bone may appear more prominent than normal on the outside of the knee.

Read more on Tibiofibular joint sprain.


Synovitis is inflammation of the synovial membrane in the knee joint. The synovial membrane contains the synovial fluid which helps lubricate the knee. Symptoms include swelling and stiffness in the knee, which may develop following injury, or from arthritis or gout.

Read more on Synovitis.

Referred knee pain

Pain on the outside of the knee may result from injuries and problems elsewhere in the body, particularly sciatic pain from the lower back and hip. Read more on:

Important: Causes of lateral knee pain not to be missed:

Although not paticularly common causes of pain on the outside of the knee, it is essentail to consider the following as more serious complications may occur if they are missed and go untreated.

Peroneal nerve injury

Peroneal nerve injury is caused by a direct impact to the outside of the knee which damages the peroneal nerve. Symptoms which might distinguish a Peroneal nerve injury from a straightforward contusion include numbness or tingling in the front or side of the lower leg. As a result the patient will also have weakness lifting the foot up, and in severe cases, a sign known as ‘foot drop‘ will occur. A patient with foot drop will be unable to lift the foot up properly when walking and may tend to drag the toes.

Read more on Peroneal nerve injury.

Slipped capital femoral epiphysis

A Slipped capital femoral epiphysis is a hip injury more common in boys aged 11 to 16 years old. A fracture occurs of the growth plate in the thigh bone (femur) develops gradually causing pain in the hip, which may radiate to the outside of the knee.

Read more on Slipped capital femoral epiphysis.

Perthes’ disease

Perthes’ disease is a hip condition which affects children, most commonly aged between four and eight. Symptoms of tiredness and groin pain are common and the patient may also have a noticeable limp. If Perthes’ disease is suspected then seek medical advice as soon as possible because early intervention is neccessary to prevent future problems.

Read more on Perthes’ disease.

When should I see a doctor?

The majority of knee injuries, especially minor ones, can be treated at home. However, if you have any of the following symptoms you should seek professional medical assistance.

  • Severe pain in or around the knee, especially during walking.
  • Severe swelling (oedema) in the knee.
  • An audible “pop” or “crack” in the knee joint that is painful.
  • A “giving way” feeling in the knee during walking or going up/downstairs.
  • A feeling when the knee “locks” whilst bending or straightening it.
  • Altered sensation in the foot – such as a feeling of “pins and needles” (paresthesia) or a “loss of feeling” (anesthesia) in the lower leg.
  • Inability to complete your normal daily activities after the initial 72 hours.

Or, if you have followed the P.R.I.C.E. principles (see above) and are still unable to walk after 72 hours or continue to have severe pain after the first 72 hours, or if you have applied the P.R.I.C.E. principles and still have weakness or knee pain that lasts a long time (more than 2 weeks).


  1. Baker RL, Fredericson M. Iliotibial Band Syndrome in Runners: Biomechanical Implications and Exercise Interventions. Phys Med Rehabil Clin N Am 2016;27(1):53–77.
  2. Andrish JT1. Meniscal Injuries in Children and Adolescents: Diagnosis and Management. J Am Acad Orthop Surg. 1996 Oct;4(5):231-237.
  3. Kocher MS, Klingele K, Rassman SO. Meniscal disorders: normal, discoid, and cysts. Orthop Clin North Am 2003;34(3):329–40.
This article has been written with reference to the bibliography.