What is the role of MRI in the workup of pes anserine bursitis?

Updated: May 08, 2018
  • Author: P Mark Glencross, MD, MPH, FACOEM, FAAPMR; Chief Editor: Milton J Klein, DO, MBA  more...
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Magnetic resonance imaging (MRI) is the preferred imaging technique for confirming the diagnosis of pes anserine bursitis and differentiating it from concurrent pathology of the medial compartment. [29, 30] On MRI, the pes anserine bursa is observed between the pes anserinus (ie, the insertion of the conjoined gracilis, semitendinosus, and sartorius tendons into the anteromedial proximal tibia) and the upper tibial metaphysis.

The appearance of pes anserine bursitis on MRI is characterized by increased signal intensity and fluid formation around the area of the pes anserinus bursa. A collection of fluid with low signal intensity is observed on T1-weighted images, and a homogenous increase in signal intensity is observed on T2-weighted images. Fluid-filled anserine bursae have been reported with a prevalence of 5% in asymptomatic knees; consequently, the diagnosis of pes anserine bursitis cannot be based solely on MRI findings. [29]

Limited axial and sagittal T2-weighted or T2 gradient-echo sequences usually are adequate for diagnosis. More extensive imaging with additional planes may be required to exclude other clinically relevant possibilities. Axial images are particularly helpful for differentiating fluid in the pes anserine bursa from other medial fluid collections, such as Baker and meniscal cysts, bone cysts, and fluid in the semimembranosus bursa. [31] MRI also is helpful for ruling out a proximal tibial stress fracture. [29]

At least 1 case of chronic pes anserine bursitis manifested as a solid, inflammatory synovial mass. One report describes tibial erosion under bursitis. Pigmented villonodular synovitis with hemosiderin deposits can occur focally in the bursae.

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