Superior peroneal retinaculum injuries

Superior peroneal retinaculum injuries refer to a spectrum of acute and chronic injuries to the superior peroneal retinaculum in the ankle. They are one of the causes of lateral ankle pain and instability. 

Pathology 

Classification

One method of grading is the Oden's classification ^1,7 which classifying injuries into four types:

• type I 
  • elevation or stripping off of the periosteal attachment of the superior peroneal retinaculum to the lateral malleolus at the level of the fibular groove 
  • stripped-off periosteum and superior peroneal retinaculum form a pouchlike configuration lateral to the distal fibula into which the peroneal tendons can dislocate
• type II: tear of the superior peroneal retinaculum at its attachment to the distal fibula
• type III: distal fibular avulsion fracture at the attachment of the retinaculum to the lateral malleolus
• type IV: tear of the retinaculum at its posterior attachment

Radiographic features

Plain radiograph

If a distal fibular avulsion fracture is present, a bony fleck is seen lateral to the lateral malleolus ⁸. The lateral malleolar fleck sign is pathognomonic for peroneal retinacular avulsion.

MRI

Axial images of the ankle are probably the best for assessment and allows direct visualization of any disruption ⁶. In a complete disruption the peroneal tendons may sublux.

Treatment and prognosis

Treatment of acute and chronic injuries varies. Plaster immobilization is initially attempted, particularly with acute dislocations while surgery is reserved for patients with painful, chronic, unstable dislocations and varies depending on the extent and classification.