Posterior impingement

 

Os tos tos

 

Epidemiology

 

Repetitive plantar flexion

- compression of structures between posterior tibia and calcaneus

- soccer players, ballet dancers, cricket, volleyball, basketball

 

Cause

 

Os trigonum - non fused talus ossicle

Steida's process - elongated lateral process of the talus

FHL tenosynovitis

Synovitis / capsule impingement

 

Symptoms

 

Deep posterior ankle pain caused by plantar flexion of the ankle joint

 

Examination

 

Plantar flexion test

- posterior ankle pain with forced plantarflexion

- pain anterior to tendo achilles

 

Pain with resisted FHL

 

Differential diagnosis

 

Tarsal tunnel syndrome

- neurological symptoms

 

http://www.boneschool.com/lower-limb/foot-and-ankle/miscellaneous/tarsal-tunnel-syndrome

 

Os trigonum / Stieda's process

 

Impinge against plafond with forced plantarflexion

Can cause FHL tenosynovitis

 

Os Trigonum Stieda's process

Non fused talus ossicle

Secondary center of ossification of talus lateral to groove for FHL

Elongated lateral process of the talus

Rafare et al Surg Radiol Anat 2024

- systematic review of 17,000 ankles

- incidence of os trigonum 10%

Kalbouneh et al International J Morphology 2021

- 1500 ankle CT

- Stieda's process / elongated lateral tubercle: 26%

- os trigonum: 21%

 

 

posterolateral tubercle

Variations of posterolateral tubercle of the talus from Kalbouneh et al International J Morphology 2021: License CC BY-NC 4.0

 

Kalbouneh et al International J Morphology 2021

- 1500 ankle CT

- Type 1: absent lateral tubercle 7%

- Type 2: normal lateral tubercle 46%

- Type 3: Stieda's process / elongated lateral tubercle 26%

- Type 4: os trigonum 21%

 

Xray

 

Os tos t

Os trigonum

 

Os t

Stieda process - elongated lateral process of talus

 

CT

 

os tos t

Os trigonum

 

os t

Fractured Stieda process

 

os tos t

Os trigonum with osteochondral fracture posterior tibia

 

MRI

 

Findings

- synovitis over posterolateral process talus

- fluid in sheath about FHL

- edema around os trigonum

- edema posterior tibia bone

- thickened posterior capsule

 

os tos t

Os trigonum                                                                      FHL tenosynovitis with posterior ankle joint soft tissue

 

os t

Stieda's process with ankle joint effusion

 

os tos t

 

Management

 

Non Operative

 

Options

 

Physiotherapy

 

US guided cortisone and local anesthetic

 

Heel lifts

 

Operative

 

Goals of surgery

 

Remove os trigonum / debride Stieda's process

Release FHL

 

Options

 

Open FHL release and os trigonum excision

Endoscopic FHL release and os trigonum excision

 

Georgiannos et al AJSM 2017

- RCT of open versus endoscopic excision os trigonum in 50 athletes

- no difference in outcome

- faster return to sport with endoscopic:

- lower complication rate with endoscopic: 4 v 23%

 

Zwiers et al AJSM 2022

- systematic review of treatment posterior ankle impingement

- no difference in outcomes

- open: 91% good or excellent results, 11 weeks return to sport

- endoscopic: 86% good or excellent results, 9 weeks return to sport

- increased minor complications with open

 

Open FHL release and os trigonum excision

 

Vumedi open excision os trigonum

 

Posteromedial approach

- incision between medial malleolus and T achilles

- divide superficial retinaculum

- neurovascular bundle immediately anterior

 

Identify FHL by moving great toe

- open FHL fibro-osseous tunnel releasing FHL compartment

- retract FHL anteriorly

 

Open posterior capsule over os trigonum and excise

 

Os Trigonum Skin MarkingOs Trigonum Superfical Dissection

Posteromedial approach and identification of FHL fibro-osseous tunnel

 

Os Trigonum FHL Accessory MuscleOs Trigonum Capsule

FHL identified and released, retracted anteriorly, capsule incised and os trigonum exposed

 

Os Trigonum ExcisedOs Trigonum Posterior Talus Cartilage

 

Arthroscopic FHL release and os trigonum excision

 

scopescope

 

Technique

 

Vumedi arthroscopic os trigonum resection 1

 

Vumedi arthroscopic os trigonum resection 2

 

FHL Arthroscopic Release 1FHL Arthroscopic Release 2

FHL exposure in posterior ankle arthroscopy