Peroneal Tendon Dislocation S86.399A 726.79

synonyms: peroneal tendon instability

Peroneal Tendon Instability ICD-10

• S86.391A Other injury muscle(s) and tendon(s) peroneal muscle group at lower leg level, right leg, initial
• S86.392A Other injury muscle(s) and tendon(s) peroneal muscle group at lower leg level, left leg, initial
• S86.399A Other injury muscle(s) and tendon(s) peroneal muscle group at lower leg level, unspecified leg, initial
• See all Other Peroneal muscle ICD-10 codes. 

Peroneal Tendon Instability ICD-9

• Peroneal tendinitis ICD-9 = 726.79

Peroneal Tendon Instability Etiology / Epidemiology / Natural History

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)
• Anatomic varients in peroneal tendon sheath: low-lying peroneal brevis muscle belly; anomalous peroneal quartus tendon.

Peroneal Tendon Instability Clinical Evaluation

• Lateral ankle pain, swelling and ecchymosis.
• Tenderness posterioly along the peroneal tendons.
• Pain and weakness with active ankle dorsiflexion and external rotation.
• Lateral tenderness, no medial tenderness.
• May complain of popping in the posterolateral ankle with push off.
• Ankle Circumduction Test:

Peroneal Tendon Instability Xray / Diagnositc Tests

• 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.

Peroneal Tendon Instability Classification / Treatment

• 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. 

Peroneal Tendon Instability Associated Injuries / Differential Diagnosis

• PER ankle fracture (Weber type C)
• SER ankle fracture (Weber type B)
• Proximal fibula fx (Maisonneuve).
• Ankle dislocation.
• Peroneal Tendon instability
• 5th Metatarsal fracture
• Calcaneal fracture
• Ankle Instability

Peroneal Tendon Instability Complications

• Recurrent instability
• Continued pain
• Stiffness
• CRPS

Peroneal Tendon Instability Follow-up Care

• 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