Age / Sex : 77 / F

Chief complaint: pain in the right ankle

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to Jae Hyuck Yi, MD ([email protected])
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Courtesy :  Jung Jee Young, MD, Chung-Ang University Hospital

Longitudinal tear of peroneus brevis tendon

Discussion

Findings: Axial Proton density-weighted MR images show a split of the peroneus brevis tendon and anterior migration of the peroneus longus tendon. Also, tenosynovitis of the peroneus brevis and peroneus longus tendons is seen. Coronal fat saturated Proton density-weighted MR image shows a split of the peroneus brevis tendon with formation of medial and lateral limbs around peroneus longus tendon.

Differential Diagnosis:

Normal bifurcated peroneus brevis tendon

Diagnosis: Longitudinal tear of peroneus brevis tendon

Discussion: Peroneus Brevis Tendon Rupture

Pathogenesis: The peroneus brevis tendon is susceptible to degenerative tears due to its vulnerable position in between the bony retromalleolar groove and the peroneus longus tendon. As the foot undergoes dorsiflexion, the peroneus brevis tendon is repeatedly compressed between the peroneus longus tendon and the lateral malleolus, predisposing to a tear. Once a tear is initiated, the peroneus longus tendon migrates forward into the peroneus brevis tendon tear, thereby preventing healing. With superior peroneal retinaculum insufficiency or tear, the peroneus brevis tendon undergoes increased friction against the sharp lateral ridge of the fibula as it subluxates in and out of the retromalleolar groove. This increased friction also predisposes to tendon tear