Gruberi bursa

The Gruberi bursa, or the bursa mucosa of Gruberi, is a bursa situation in the dorsal region of the ankle which extends from the sinus tarsi and along the frondiform ligament to surround extensor digitorum longus tendons.

Terminology

Defined as the bursa that lines the inferior extensor retinaculum (frondiform ligament) as it passes over the extensor digitorum longus tendons at the anterior ankle joint. It will only usually only be evident on imaging if distended and can be mistaken for tenosynovitis, thus also referred to as 'pseudotenosynovitis' of the extensor digitorum longus tendons .

Differential diagnosis

• tenosynovitis of the extensor digitorum longus tendons

Practical points

• on ultrasound, it is most commonly unilocular, anechoic, and compressible
• a distended bursa of Gruberi will extend from the sinus tarsi and wrap around the tendons, differentiating it from fluid due to tenosynovitis which will extend along the tendon
• on MRI there will be usually signal or morphological changes of extensor digitorum longus associated with tenosynovitis
• on MRI and ultrasound, the fat surrounding the extensor digitorum longus will be edematous and /or inflamed in tenosynovitis