Pes Anserine Bursitis: What Causes Inner Knee Pain and Why Does It Keep Coming Back?
Pes anserine bursitis is inflammation of a small fluid-filled sac on the inner side of the knee, just below the joint. It causes tenderness in one spot, swelling and pain that often gets worse on stairs. The knee sits in a chain between the hip and the foot. So alignment problems elsewhere can overload this area and keep the pain coming back.
Key points
- The pes anserine bursa sits where three hamstring tendons meet the inner shinbone.
- Pain is usually felt just below the inner knee, especially when climbing stairs or getting up from a chair.
- Poor leg alignment, hip position or foot mechanics can quietly overload this spot.
- A standing, weight-bearing scan shows alignment in real-life conditions. Imaging done lying down can miss this.
- EOS imaging uses about 90% less radiation than a standard X-ray, around ten times less.
You may have a nagging ache on the inner side of your knee that flares up with activity. Perhaps you have been told it is pes anserine bursitis. The name sounds complicated, but the idea is simple. A small cushioning sac, called a bursa, has become irritated and inflamed. Knowing why it happened in the first place is the key to stopping it from coming back.
What are the symptoms of pes anserine bursitis?
The main symptom is a tender pain in one spot on the inner side of the knee. It is roughly two to three finger widths below the kneecap. It often builds up slowly rather than starting with one event.
Some people also notice pain at night if they sleep with their knees together, because the inner sides press against each other.
What causes pes anserine bursitis?
Pes anserine bursitis happens when the bursa is pressed or rubbed again and again. This can come from overuse of the knee itself. But often the root cause is further up or down the leg.
Extra body weight, a sudden increase in walking or running, and poor footwear can also play a part. In many cases, several of these factors combine.
Why does alignment matter for inner knee pain?
Your body works as a connected chain from your feet to your head. When one link is out of position, the areas above and below make up for it. The inner knee often pays the price.
A hip that tilts or rotates slightly can angle the thigh bone inward. This pushes the knee into a knock-knee position. At the same time, a foot that rolls inward twists the shin outward. Both forces focus load on the inner knee, right where the pes anserine bursa sits.
This is why treating only the painful knee may bring short-term relief but not a lasting solution. If the alignment problem that caused the overload is still there, the irritation comes back.
How does a standing scan help with pes anserine bursitis?
A standing, weight-bearing scan shows your bones and joints under real load. It shows them the way they actually work when you walk, climb stairs or stand. This reveals alignment problems that imaging done lying down can hide.
When you lie down for a standard X-ray, CT scan or MRI, gravity is taken away. Your muscles relax and your joints settle into a neutral position. A slight rotation at the hip, tilt of the pelvis or inward drift of the knee may straighten out and vanish from the image. The scan looks normal, but the problem is still there every time you stand up.
EOS imaging captures your full leg alignment in a single standing image, from the hips through both knees to the ankles. This lets a clinician see the whole chain at once and find exactly where the imbalance begins. The scan uses about 90% less radiation than a standard X-ray, around ten times less, so it is a safe option for checking alignment.
Would you like to know whether a standing alignment scan could explain your inner knee pain?
Book a free video consultationWhen MRI is the better choice: EOS shows bones, joints and alignment clearly. For soft-tissue problems such as inflamed bursae, torn menisci or damaged ligaments, MRI is usually the better tool. Your clinician may recommend both, depending on your situation.
What helps manage pes anserine bursitis?
Management usually focuses on calming the irritation first. Then it deals with whatever caused the overload. ScanAlign does not provide treatment. But the alignment information from a standing scan can guide the professionals who do.
- Rest and changing your activities. Cutting down or adjusting the activities that trigger pain gives the bursa time to settle.
- Ice. Putting ice on the inner knee for short periods can help reduce swelling.
- Physiotherapy. Strengthening the muscles around the hip and knee, and stretching tight hamstrings, can improve how load passes through the joint.
- Footwear and orthotics. If overpronation is part of the problem, supportive shoes or insoles can help correct the twist at the shin.
- Alignment assessment. Seeing the full picture, from hip to ankle, helps a physiotherapist or surgeon target the real source rather than just the painful spot.
Before you start treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in the pelvis, the legs or the spine changes what will actually help.
If your knee suddenly locks, you cannot put weight on it, or you have severe swelling with redness and heat, get urgent medical help from your doctor or your nearest emergency department. These signs may point to something other than bursitis.
Frequently asked questions about pes anserine bursitis
It sits on the inner side of your shinbone, a few centimetres below the knee joint line. Three tendons from the hamstring muscles attach here. The bursa cushions the area where they meet the bone.
Climbing stairs makes your hamstrings and inner thigh muscles work hard against gravity. This increases tension on the pes anserine tendons and presses on the inflamed bursa. The result is a sharp or burning pain.
A standard X-ray does not show the bursa itself, because it is soft tissue. But a standing X-ray such as an EOS scan can reveal the alignment problems that may be overloading the area. This is valuable information for planning treatment.
No. Both can cause inner knee pain, but they affect different structures. Bursitis involves the fluid sac below the joint. A meniscus tear is cartilage damage inside the joint. An MRI can usually tell the two apart.
With proper rest and management, many people see improvement within a few weeks. But if the underlying cause, such as poor alignment, is not dealt with, the bursitis often comes back.
No. ScanAlign is a private, self-pay clinic. You can refer yourself directly without a letter from your doctor. The process starts with a free video consultation to make sure imaging is right for you.
Yes. EOS uses about 90% less radiation than a standard X-ray, around ten times less. You can find more details on safety and what to expect on our FAQs page.
The price for patients travelling from abroad is confirmed during the free video consultation. You can read more on our FAQs page.
Yes. Flat feet or overpronation cause the foot to roll inward. This twists the shin and sends force to the inner knee. Over time, this repeated stress can irritate the pes anserine bursa.
A normal X-ray is often taken lying down and captures only one area. A standing EOS scan images both legs from hip to ankle in a single upright exposure. It shows how your joints line up under your full body weight. Learn more about how EOS imaging works.
Find out what is really behind your inner knee pain
A short, free video consultation will help you see whether a standing alignment scan in London is the right next step.
Book a free video consultationWritten by Abbas Dhami (Specialist Diagnostic Radiographer)
Sources
- Helfenstein M Jr, Kuromoto J. Anserine syndrome. Revista Brasileira de Reumatologia, 2010;50(3):313-327.
- Defined by the American Academy of Orthopaedic Surgeons (AAOS), "Pes Anserine (Knee Tendon) Bursitis," OrthoInfo patient resource.
- Illés T, Somoskeöy S. The EOS imaging system and its uses in daily orthopaedic practice. International Orthopaedics, 2012;36(7):1405-1411.
This page is general information and not a diagnosis.
ScanAlign is the trading name of CoreMed Solutions Ltd and operates under The Harley Street Hospital's CQC licence.