Dislocation

Definition

 

Anterior displacement of peroneal tendons out of peroneal groove

 

Epidemiology

 

Most common in young adults

 

Acute injury often missed 

 

Aetiology

 

Congenital

 

3 % neonates

- resolves spontaneously

 

Traumatic  

 

Occurs following sporting activities

- snow skiing

- football

- gymnastics

 

Forced DF and inversion

 

Anatomy

 

Fibro-osseous tunnel

- retro-malleolar groove

- lined by fibrocartilage

 

Anterior

- fibula 

 

Medial

- PTFL

- CFL

- PITFL

 

Peroneus longus

- posterolateral to PB

 

Superior Peroneal Retinaculum

- 2 bands

- fibula to lateral T Achilles

- fibula to posterolateral calcaneum

 

Inferior peroneal retinaculum

- lateral wall calcaneum below sinus tarsi

- no role in stability

 

Pathogenesis

 

1.  Traumatic

 

Violent contraction of Peroneal muscles 

 

Forced dorsiflexion and inversion

- injury to superior peroneal retinaculum

 

May be predisposition

- laxity of retinaculum

- shallow groove

 

Patient may also have tears

 

2.  Subluxation within sheath

 

Raikin JBJS Am 2009

- described intrasheath subluxation

- superior retinaculum intact

- patients still having painful snapping

- demonstrated by US

- half had peroneal tendons switching positions

- these patients had a convex groove

- these where treated with groove deepening and retinaculum reefing

- other half had a tear in PB through which PL could sublux

 

History

 

Acute

- sudden pain behind lateral malleolus

- snap may be heard

- unable to continue with activities

 

Chronic

- painful snapping of lateral ankle with activity

 

Examination

 

Tenderness & swelling behind LM

- pain or dislocation reproduced by active eversion & DF

 

Peroneal Tendon Dislocation 1Peroneal Dislocation 2

 

X-ray

 

Usually normal

 

May be avulsed fragment of cortical bone lateral to LM

- fleck sign

 

CT

 

Defines anatomy & relationships of tendons

- may detect anatomical variants

 

US

 

Very good at demonstrating subluxation

 

MRI

 

Detects tendinous & ligamentous injuries

 

Management

 

Opinion divided regarding acute injuries

- non-operative management v surgical repair

 

Most treat chronic injuries surgically

 

Non-operative

 

Acute injuries

- cast in plantarflexion for 6/52

 

Operative 

 

Indications

- acute injury in athletes

- chronic injuries

 

Acute Repair

 

Options

 

1.  Superior retinaculum stripped

- reattach to fibula via trans-osseous sutures / anchors

 

2.  Retinaculum torn

- primary repair

 

3.  Bony avulsion

- fragment reattached with sutures, wires or screws

 

Chronic

 

1.  Groove Deepening

- if necessary

- elevate cortical flap / decancellation / cortical recession

 

2.  Address tears in tendons

 

3.  Address superior peroneal retinaculum

 

A.  Direct repair / Advancement of superior peroneal retinaculum if able

 

B.  Reconstruction of SPR if attenuated

- periosteal flap from fibula

- slip of T Achilles left attached distally

- free plantaris / palmaris graft

 

C.  Rerouting under CFL

- substitution of CFL for peroneal retinaculum

- tendons transposed into inframalleolar tunnel

- division & repair CFL or fibular bone block with CFL

 

4.  +/- lateral ligament repair if needed

 

Surgical Technique

 

Findings

- chronic subluxation / anterior dislocation

- normal groove

- retinaculum stretched and not attached to normal insertion anterior fibula

- repair and tightened with suture anchors

 

Anterior Peroneal DislocationAnterior Peroneal DislocationAnterior stripping of SPR

 

Normal GrooveNormal GrooveSuture Anchors

 

Sutures PassedSutures Passed 2Repair 1