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Knee Pain

Pes Anserine Bursitis

Minute Read


Posted 1 year ago


Last updated: 10/05/2023


by James McCormack

Anatomy of the Pes Anserine

The pes anserine is the combined insertion point of 3 tendons on the top and inside of the shin bone, just below the knee. The term is Latin for ‘goose foot’, named because of its appearance.

The 3 tendons that form the pes anserine are the sartorius, gracilis and semitendinosus (one of the hamstrings). These muscles have different actions: to flex the hip (lift upwards), abduct the hip (lift outwards), adduct the hip (bring towards the midline), external rotation of the hip (rotate outwards), and flex the knee (bend the knee).

Due to the combination of movements, this area has multiple directions of forces acting on it. This therefore presents a greater risk of overload and irritation at the insertion of the tendons. The pes anserine bursa sits between the tendons and the bone underneath to protect their soft tissue from compression and friction against the hard bone with movement.

Muscles of the Pes Anserine

Diagram of pes anserine bursitis

What is the Function of the Pes Anserine Bursa?

  • A bursa is a thin membrane sack, similar to a deflated balloon. It has a small amount of fluid to provide lubrication, so it can slide easily to relieve friction between moving parts.
  • We have over 150 bursae around our body for this important protective function. These structures can become inflamed with enough repeated friction or compression or with a forceful, direct impact.
  • An inflamed bursa develops additional fluid inside, making it larger or appear swollen and sensitive.

Pes Anserine Bursitis Symptoms

The location pain for Pes Anserine bursitis is on the inside of the knee, usually at or just below the joint on the inside of the shin bone.

Medial (inner) joint line pain is the most common symptom reported with pes anserine bursitis (Rennie & Seifuddin 2005). Due to the inflammation, the skin in this area might be red and feel hot to the touch. It can also appear as a swollen lump in this area.

Pes Anserine Bursitis pain can develop gradually over time due to repeated overload, or it can begin suddenly if the injury is related to trauma or direct impact.

Pain is often described as an ache with occasional worse and more intense pain with specific movements that stress the bursa.

It may feel sore, hot or like a burning pain. In most cases, it will develop on one knee, but it is occasionally present in both knees.

Pes Anserine bursitis pain may get aggravated during exercise and may continue to worsen after, and it commonly takes over 24 hours to settle down.

Some static postures, such as side lying, can be an issue if there is pressure on the inside of the knee.

A pillow between your knees can make it much more comfortable if you normally sleep on your side.

Causes of Pes Anserine Bursitis

There are two main forms of Pes anserine bursitis, traumatic or overload:

Traumatic injury to the Pes Anserine bursa occurs when there is a direct impact on the bursa. Direct impact can result from a tackle in sport or simply from knocking your knee off a kitchen counter.


The more common cause of Pes Anserine Bursitis is the result of a biomechanical overload. A sudden increase in activity levels, such as walking or running, can increase the friction of local tendons over the bursa.

Other risk factors include: 

  • Obesity
  • Knee Valgus
  • Flat Feet
  • Inflammatory Arthritis

Chronic pes anserine bursitis is common in people with excessive inward movement of the knee, genu valgus, or flat feet, as this can also cause the inward movement of the knee in some cases. It is sometimes an additional symptom of knee osteoarthritis.

Pes anserine bursitis is also very common in runners, as running is a high-impact sport. Running, therefore, requires a high level of strength and muscle control to prevent inward movement of the knee.

As running is a highly repetitive sport, if this strength or control is insufficient, the runner will have a high risk of pes anserine bursitis and other injuries of the medial knee.

This is due to the repeated small overload of these structures. Most commonly, it is an overuse injury that will develop when there is an increase or change of activity, such as taking up running or increasing running volume.


Like most musculoskeletal pain, a diagnosis is made from a combination of several factors. The history of the onset of pain, history of activity and any recent changes to activity or lifestyle, and a physical examination to rule in or out different diagnoses.

Pes anserine often gradually develops over a period of time; it can be linked with an increase in a particular exercise, such as running, or a change in the exercise that might put more pressure on the structure, such as hill running or on uneven ground. It can also be something seemingly minor, like a change of footwear.

Part of the clinical examination will be to feel the area of pain. It will be sore to put pressure on the bursa and to resist the action or stretch of the three muscles that insert together and form the pes anserine. Assessing the individual’s gait may also reveal important information about the cause and the potential treatment of this issue.

Clinical tests to rule out other causes of pain inside the knee, such as the meniscus, medial collateral ligaments and saphenous nerve, help confirm the diagnosis.

While there is no specific pes anserine bursitis test, radiology can be used to confirm a clinical diagnosis. MRI is the best form of imaging to get an accurate diagnosis.

Other causes of inner knee pain

Other causes of medial knee pain include medial meniscal tear or irritation, medial collateral ligament injury, medial patella femoral joint pain or nerve pain related to the saphenous branch of the femoral nerve.

It is, therefore, important to have an assessment with a medical professional such as a physical therapist, to diagnose your pain and get you started on the most effective course of treatment.

Related Article: Best Exercises for Pes Anserine Bursitis

Physiotherapy with James McCormack

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments weekly.

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