Os Trigonum FHL Impingement

Posterior Ankle Impingement

 

Epidemiology

 

Repetitive plantar flexion

- soccer players, ballet dancers

 

Cause

 

Os trigonum

FHL stenosing tenosynovitis

Soft tissue mass

 

Os Trigonum

 

Secondary centre of ossification of talus

- lateral to groove for FHL

- 2-7% of normal feet

- impinges against plafond with forced PF

- can cause FHL tenosynovitis

 

Os TrigonumOs TrigonumOs Trigonum

 

Examination

 

Pain with forced plantarflexion

Pain with resisted FHL

 

MRI

 

Classically

- synovitis over posterolateral process talus

- fluid in sheath about FHL

 

May also see

- posterior tibia bone oedema

- thickened posterior capsule

- os trigonum

 

Management

 

Non Operative

 

US guided HCLA

- good results reported

 

Operative

 

Options

 

1.  Lateral approach

 

Indication

- resection of os trigonum only

 

2.  Medial approach

 

Indication

- also release of FHL

 

Technique

- incision between medial malleolus and T achilles

- T post, FDL and neurovascular bundle anterior

- release FHL compartment, look for accessory muscle or nodule

- open capsule over os trigonum

- excise

- need to ensure don't damage posterior talus articular cartilage

 

Os Trigonum Skin MarkingOs Trigonum Skin IncisionOs Trigonum Superfical Dissection

 

Os Trigonum FHLOs Trigonum FHL Accessory MuscleOs Trigonum Capsule

 

Os Trigonum ExposedOs Trigonum ExcisedOs Trigonum Posterior Talus Cartilage

 

FHL Tenosynovitis

 

Clinical

 

Pain behind medial malleolus

Pain with stressing FHL

 

Xray

 

No os trigonum

 

Arthroscopic release

 

FHL Arthroscopic Release 1FHL Arthroscopic Release 2