Pes Anserine Pain — A Cause of Medial Knee Pain

Pain several centimetres below the medial knee joint line, aggravated by stairs, rising from a chair or prolonged activity, can come from the pes anserine region. Not every case of medial knee pain is caused by the pes anserinus, however: a meniscal problem, medial collateral ligament injury or knee osteoarthritis can produce similar symptoms.

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What is the pes anserinus?

The pes anserinus is the combined insertional region of three tendons on the medial side of the proximal tibia: sartorius, gracilis and semitendinosus. A bursa lies between these tendons and the deeper tissues. Symptoms may reflect tendon overload, irritation of the bursa or a combination of both, so the label “pes anserine bursitis” does not always describe the full clinical picture.

How does pes anserine pain usually present?

• pain is usually located on the medial side of the tibia, approximately 4–5 cm below the knee joint line,
• there may be focal tenderness when the area is pressed with one finger,
• stairs, rising from a chair, longer walks, running or kneeling can aggravate symptoms,
• the pain may coexist with knee osteoarthritis, so there can be more than one source of symptoms.

If the most painful point is directly at the joint line, there is true mechanical locking, or symptoms began after a twisting injury, a meniscal lesion should also be considered.

How does an orthopaedic surgeon assess a pes anserine problem?

The history and a careful examination of the knee are the foundation of diagnosis. Pain location is particularly useful because symptoms from the pes anserine region can resemble pain arising from the medial meniscus. The examination also assesses range of motion, ligament stability, limb alignment, muscle strength and other possible sources of pain.

Is ultrasound necessary?

Not always. A typical clinical presentation may be recognised without additional imaging. Ultrasound can be useful when the tendons, bursa and neighbouring tissues need to be assessed, when a fluid-containing lesion needs to be distinguished from other structures, or when a precise injection is being planned. The absence of obvious bursal fluid does not exclude symptoms from this region, and an abnormal ultrasound finding alone does not prove that it is the only source of pain.

When are X-ray or MRI more useful?

Plain radiographs are often more important than ultrasound when osteoarthritis or another bony or joint-related cause is suspected. MRI may be considered when symptoms suggest an intra-articular problem, meniscal injury or ligament damage and the clinical examination together with simpler imaging does not provide a satisfactory answer.

How is it treated?

Treatment usually starts non-operatively. The aim is not to rest the leg completely for many weeks, but to reduce and restructure loading so that the tissues can gradually regain tolerance to activity.

• activities that clearly provoke pain can be reduced temporarily,
• strength and movement-control exercises can then be progressed gradually,
• when knee osteoarthritis coexists, treatment should also address the joint itself,
• pain-relieving or anti-inflammatory medication should be used only with appropriate attention to contraindications and the patient’s other medical conditions.

Can an injection help?

For some people with persistent symptoms, an injection into the painful region or bursa may be considered. Randomized studies have reported short-term improvement after corticosteroid injection, and a trial comparing ultrasound-guided with landmark-based injection found a greater reduction in pain in the ultrasound-guided group. These are relatively small studies, however, and they do not mean that injection should be the first-line treatment for every patient.

When an injection is considered, accurate needle placement is only one part of the decision. The procedure still needs to be matched to a plausible pain source and a clear clinical indication.

What about PRP, shockwave therapy and other methods?

PRP, shockwave therapy, dextrose and other injection-based approaches have also been studied. Results from individual trials are heterogeneous, protocols differ and follow-up is often short. The available evidence therefore does not establish one of these methods as universally superior. Correctly identifying the source of pain and addressing coexisting knee pathology remain more important than choosing a treatment solely because it is technically available.

When does medial knee pain require urgent assessment?

• the knee is rapidly swelling, clearly hot and red, particularly with fever,
• after an injury, weight bearing is impossible or there is a deformity,
• the knee is truly locked and cannot be fully extended,
• there is increasing one-sided calf swelling, especially with shortness of breath or chest pain,
• pain is severe, continuously worsening or accompanied by systemic symptoms.

Key point: pain location is not yet a diagnosis

The pes anserine region is one possible extra-articular source of medial knee pain, but symptoms may coexist with osteoarthritis, a meniscal problem or another condition. Treatment should therefore follow the clinical assessment, with ultrasound, X-ray or MRI selected to answer a specific diagnostic question rather than used automatically.

References

1. Poboży T, Janowski K, Domański P, Michalak K, Poboży K, Domańska-Poboża J, Konarski W, Chuść I, Kielar M. The Hidden Burden of Entheseal Pathology in Lower-Limb Pain: A Real-World Ultrasound Study of 667 Adults. Mayo Clinic Proceedings: Innovations, Quality & Outcomes. 2026;10(4):100734. DOI: 10.1016/j.mayocpiqo.2026.100734. This study concerned a broader group of lower-limb enthesopathies and tendinopathies, not pes anserine pathology alone.
2. Hasan M, Berkovich Y, Khatib M, et al. Knee Bursae: A Comprehensive Review of Clinical Evaluation, Imaging Differentiation, and the Expanding Role of Biologic Therapies. Cartilage. 2025. DOI: 10.1177/19476035251362434.
3. Zavarei S, Khalifeh Soltani S, Raissi G, et al. Efficacy of ultrasonography-guided compared to surface landmark-based corticosteroid injection for people with chronic pes anserine tendinitis or bursitis: a randomised controlled trial. International Journal of Therapy and Rehabilitation. 2023;30(4):1–10. DOI: 10.12968/ijtr.2021.0140.
4. Babaei-Ghazani A, Eftekharsadat B, Soleymanzadeh H, ZoghAli M. Ultrasound-Guided Pes Anserine Bursitis Injection Choices: Prolotherapy or Oxygen-Ozone or Corticosteroid: A Randomized Multicenter Clinical Trial. American Journal of Physical Medicine & Rehabilitation. 2024;103(4):310–317. PMID: 37752656.

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Content prepared by: Tomasz Poboży - orthopaedic surgeon.