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Knee

Pes anserine bursitis

Pes anserine bursitis is irritation of the bursa and tendon confluence on the inner side of the knee, a few centimeters below the joint line. I look carefully at that spot because medial knee pain is not one diagnosis, and getting the tissue right changes how we load, inject, and rehab.

What it feels like

Pain sits on the inner shin just below the knee rather than deep in the joint line, and people often point with one finger to a small tender patch.

Stairs, getting out of a car, side-lying sleep with knees together, and longer walks can flare it, especially when the medial compartment is already irritable from arthritis or training load.

A recent jump in mileage, new hills, or a medial joint flare can tip a quiet area into a bursal and tendon irritation pattern that feels sharp with direct pressure.

What is going on

The pes anserinus is where the sartorius, gracilis, and semitendinosus tendons meet on the proximal medial tibia, and a bursa beneath that confluence can become inflamed under friction or overload.

Medial compartment osteoarthritis, valgus alignment stress, obesity-related load, and sudden training changes are common companions, so the bursa is often part of a broader medial knee story rather than an isolated curiosity.

MCL sprain and medial meniscus irritation can live in the same neighborhood, which is why I map tenderness relative to the joint line instead of treating every inner-knee ache as one problem.

How we evaluate

I palpate below the medial joint line over the pes insertion, compare that to joint-line and MCL tenderness, and watch how stairs and resisted medial hamstring or adduction loads behave.

X-rays help when osteoarthritis is part of the picture. Ultrasound can confirm bursal fluid or guide an injection when the exam and story fit.

If locking, true giving way, or a clear traumatic valgus story is present, I widen the workup toward meniscus and ligament pathways rather than assuming bursitis alone.

What we may offer

Load coaching and progressive strength through physical therapy come first for most people, with attention to hip and medial knee control so the insertion is not constantly re-irritated.

When inflammation is clearly bursal and limiting progress, an image-guided corticosteroid injection to the pes region can calm a flare so rehab can stick. Bracing is used selectively when medial compartment load or instability cues suggest it will help.

If medial knee osteoarthritis or a meniscus problem is driving the picture, we treat that source as well. PRP is discussed when joint biology, not just the bursa, is part of the plan. Surgery is uncommon for isolated pes bursitis.

Is pes anserine bursitis the same as a meniscus tear?

No. Pes pain sits below the joint line over the tendon-bursa confluence. Meniscus pain more often tracks the joint line and can include catching or locking. Both can coexist with medial arthritis, so exam location matters.

Will an injection fix it permanently?

An injection can reduce bursal inflammation and open a better rehab window. Lasting improvement usually still depends on load management and strength around the medial knee and hip.

Why does sleeping on my side hurt the inner knee?

Knees pressed together can put direct pressure on the pes region. A pillow between the knees often reduces nighttime irritation while we calm the tissue.

Do I need an MRI?

Often not if the exam is classic. MRI is useful when trauma, locking, ligament concern, or an unclear medial pattern would change the plan.

References

Short list of sources behind the clinical framing on this page.

  1. Helfenstein Jr M, Kuromoto J. Anserine syndrome. Rev Bras Reumatol. 2010;50(3):313-327. Clinical overview of pes anserine / anserine pain syndrome and how it presents on the medial knee.
  2. Uysal F, Akbal A, Gökmen F, Adam G, Resorlu M. Prevalence of pes anserine bursitis in symptomatic osteoarthritis patients: an ultrasonographic prospective study. Clin Rheumatol. 2015;34(3):529-533. Shows how often pes bursal findings accompany symptomatic knee osteoarthritis.
  3. American Academy of Orthopaedic Surgeons. Management of Osteoarthritis of the Knee (Non-Arthroplasty). Evidence-Based Clinical Practice Guideline. 2021. Guideline frame for nonoperative knee OA care that often coexists with medial soft-tissue pain patterns.

Dr. Adam Nessim, interventional spine physician, Westport Longevity, Pain & Performance.

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