Review Question - QID 106151

This obese, middle-aged female presenting with localized pain over the anteromedial portion of the proximal tibia is most likely suffering from pes anserine bursitis.

Pes anserine bursitis is most commonly seen in overweight, middle-aged females, diabetics, patients with concomitant knee arthritis, and young, active individuals. The pes anserine bursa lies superficial to the superficial MCL and deep to the pes anserinus. Overuse causes excessive friction between the bursa and the overlying pes anserinus, leading to inflammation. Management should include rest, NSAIDs, stretching, and physical therapy. A corticosteroid injection may be indicated for refractory cases.

Calmbach et al. review how to differentiate pes anserine bursitis from other possible causes of medial knee pain. Pes anserine bursitis may be confused with either an MCL sprain or arthritis. The diagnosis can be confirmed by localized tenderness on the anteromedial proximal tibia just posterior and distal to the medial joint line.

Uysal et al. conduct a study investigating the prevalence of pes anserine bursitis in patients with primary knee osteoarthritis. Using ultrasound, the authors found a prevalence of bursitis of 20% in this population. The rate of pes anserine bursitis was higher in females and with advancing age.

Illustration A is a coronal MRI showing increased signal intensity and fluid accumulation around the pes anserine bursa, findings suggestive of bursitis. Illustration B is an axial MRI of a patient with pes anserine bursitis; the three blue arrow-heads denote the 3 components of the pes anserinus, (from anterior to posterior) the sartorius, gracilis, and semitendinosus. Illustration C highlights the anatomy of the pes anserine bursa; note that the bursa lies superficial to the superficial MCL but deep to the pes anserinus.

Incorrect Answers:
Answer 1: Stress fractures of the proximal tibia can yield pain located in a very similar location to that seen in pes anserine bursitis; however, the negative radiographs (in the setting of pain for 3 months) makes stress fracture a less likely diagnosis.
Answer 2: The lack of inciting trauma or injury combined with the absence of knee locking, catching, or clinking on physical examination makes a medial meniscus tear less likely.
Answer 3: The lack of knee instability and pain valgus stress of the knee makes the diagnosis of MCL sprain less likely.
Answer 5: The tenderness and pain of patellar tendonitis is more centered over the patellar tendon, just distal to the inferior pole of the the patella (lateral to the pain associated with pes anserine bursitis).