Presenting Symptoms of Pes Anserine Bursitis
Pes anserine bursitis presents with spontaneous medial knee pain and tenderness localized to the proximal medial tibia, approximately 2-3 inches below the medial joint line, at the insertion site of the conjoined tendons (sartorius, gracilis, and semitendinosus). 1, 2
Primary Clinical Features
Pain Characteristics
- Spontaneous medial knee pain that is the hallmark presenting complaint 3
- Pain localized to the inferomedial aspect of the knee joint, specifically over the proximal medial tibia just below the knee 2, 3
- Pain often mimics a medial meniscal tear due to its location along the medial joint line, which is a critical diagnostic pitfall 1
- Pain typically worsens with activity and resisted knee flexion 4
Physical Examination Findings
- Point tenderness over the pes anserine insertion site on the medial anterior aspect of the tibia, approximately 2-3 inches below the medial joint line 2, 3
- Palpable swelling of the bursa may be present in some cases 2
- Reduced range of motion and decreased knee strength may accompany the pain 4
- Pain with resisted knee flexion is characteristic 4
Patient Demographics and Risk Factors
Typical Patient Profile
- Predominantly affects women (23 of 24 patients in one series were female) 2
- Most commonly occurs in patients over 50 years of age (only 4 of 24 patients were under 50) 2
- Obesity is a major risk factor (18 of 24 patients were obese in one study) 2, 3
Associated Conditions
- Degenerative knee osteoarthritis is present in approximately 83% of cases (20 of 24 patients) 2
- Varus knee deformities are commonly associated (10 of 24 patients had varus deformities) 2
- Diabetes mellitus is a known predisposing factor 3
- May occur following total knee replacement surgery, though this is rare 5
Critical Diagnostic Pitfall
The most important clinical trap is that pes anserine bursitis pain mimics medial meniscal tear pain due to its location along the medial joint line. 1 This can lead to unnecessary arthroscopy if the diagnosis is not accurately established. The key distinguishing feature is that tenderness is located below the joint line at the tibial insertion site, rather than directly on the joint line itself. 2, 3
Prevalence in Symptomatic Knees
- Pes anserine bursitis is detected on MRI in approximately 2.5% of symptomatic knees presenting with suspected internal derangement 1
- Despite being relatively uncommon, it is a frequently diagnosed condition in clinical practice, suggesting possible overdiagnosis based on equivocal clinical features 3