Peroneal Tendon Instability Etiology / Epidemiology / Natural History
often accompanied by avulsion of the posterior osteochondral ridge of the distal fibula seen on plain xray
mechanism of injury (acute dorsiflexion and violent reflex peroneal musculature contraction) precipitates an avulsion of the superior peroneal retinaculum, allowing dislocation ot the peroneal tendons anteriorly.
Common in soccer and skiing.
Peroneal Tendon Instability Anatomy
Superior peroneal retinaculum: primary retaining structure for the perneal tendons. Origin: posterior margin of the distal 1-2cm of the fibula. Travels posteriorly to the lateral calcaneus with extensions into the paratenon of the Achilles tendon. Most commonly avulses from the fibula often with a small fleck of bone. (Maffuli N, AJSM 2006;34:986).
Deficient posterior distal fibular groove may contibute to peroneal instability. Approximately 25% of people have a flattened or convex peroneal groove.
Hindfoot varus alignment is a predisposition to peroneal tendon injury.
Os peroneum is a sesamoid bone present in 10% to 20% of people located along the peroneus longus near the peroneal groove of the cuboid. (Sobel M, Foot Ankle Int 1994;15:112)
A/P, Lateral and Mortise views of the ankle are generally normal. May demonstrate a "fleck" sign: small avulsion fracture of the lateral malleolus which is pathognomonic for acute dislocation of the peroneal tendons and indicates Grade III injury to the superior peroneal retinaculum.
MRI: demonstrates peroneus brevis +/- peroneus longes dislocated anterolateral to the lateral malleolus with disruption of the peroneal retinaculum.
Dynamic ultrasound: may be indicated to evaluated for pseudosubluxation of the peroneal tendons.
Surgical exploration with reduction of tendons and repair of superior peroneal retinaculum +/- deepening of the retromalleolar groove(axially ream the fibula to remove cancellous bone and then impact the posterior cortex in the groove with a bone tamp; or trapdoor osteotomy of posterior fiblula). Must also correct any varus hindfoot malalignment. If >50% of peroneal tendon cross-section is torn or attenuated consider peroneal tendon tenodesis (suture longus and brevis together). (Krause JO, Foot Ankle Int 1998;19:271). (see AAOS The Athlete's Ankle Volume 1 for technique videos)
Pseudosubluxaiton: no subluxation for the retrofibular groove with dorsiflexion-eversion maneuver but with painful snapping symptoms related to the peroneus longus snapping through or over the peroneus brevis. Treatment = repair of tendon tears with peroneal groove deepening. (Raikin SM)
Poor outcome with non-op treatment. Consider bracing or taping for in season athletes with definitive surgical treatment after season ends.
Outcomes of peroneal tendon tear operative treatment: 90% return to employment at the same level. 58% scar tenderness; 54% lateral ankle swelling; 46% successfully return to sports.(Steel MW, Foot Ankle Int 2007;28:49)
Peroneal Tendon Instability Review References
Philbin TM, JAAOS 2009;17:306
Murr S: Dislocation of the peroneal tendon with marginal fracture of the lateral malleolus. J Bone Joint Surg 1965;43B:563-565.
Eckert WR, Davis EA Jr: Acute rupture of the peroneal retinaculum. J Bone Joint Surg 1976;58A:670-672.