Ankle Arthrodesis

Results 

 

90% fusion rates

 

Lose70% sagittal plane ROM

 

Disadvantages of Arthrodesis 

 

Non union rates up to 12%

Decreased gait speed

Poor mobility over uneven surfaces

Need for shoe modification

Arthritic degeneration in STJ of up to 100%

 

Types

 

Tibiotalar arthrodesis

 

1.  Intra-articular

 

A. Open

- gold standard

- especially significant deformity / mal-alignment

- screws from tibia into talus

 

B. Arthroscopic

- 8 Vs 14 weeks for fusion time

- minimal deformity only

 

2.  Extra-articular / Frame

- children

- sepsis

- osteopenia

 

Tibiotalocalcaneal (TTC)  Intramedullary Nail

- commonly needed in RA

 

Blair Fusion

- refer to talar fracture complications

 

Position

 

1.  5° Valgus

- excess varus causes cavovarus

 

2.  Neutral Dorsiflexion

- if fused in plantar flexion develop genu recurvatum to put foot on floor

 

3.  5-10° ER

 

4.  Tibia anterior on talus

- preserves heel

- decreases lever arm = less energy required for toe-off

 

5.  Subtalar Joint 5°Valgus

- for TTC hindfoot fusion nails 

 

Surgical Techniques 

 

1. Intraarticular Technique 

Dual incision reciprocal flat-cut technique

 

Ankle Fusion APAnkle Fusion Lateral

 

Incision

- over distal fibular, curved forward over ST joint

- inter nervous plane between sural and superficial peroneal nerves

- full thickness down to bone

 

Superficial dissection

- subperiosteally expose distal fibula

- protect peroneal tendons posteriorly

 

Fibula osteotomy / excise distal fibula

- oblique cut ending 1.5 cm proximal to joint

 

Fibula Osteotomy Ankle FusionFibula Osteotomy and Reflected Posteriorly

 

Deep dissection

- expose talar neck anteriorly

- expose tibia posteriorly

- protect anterior tendons and NV bundles with retractors

- protect posterior peroneal tendons with retractors

- open the tibio-talar joint with lamina spreaders

 

Distal tibial cut

- oscillating saw

- perpendicular to tibial axis

- just above subchondral bone / 2-3 mm

- care not to take off medial malleolus

- if cut is too thick, will enter medial malleolus

 

Make a separate antero-medial incision

- medial to T anterior, protect saphenous nerve and vein

- use osteotome to complete tibial cut and protect medial malleolus

- denude medial malleolus of articular cartilage

- also clear medial talus

- note that the deltoid ligament carries the primary blood supply to the talus, and should be preserved

 

Talar dome cut

- place foot in desired position

- 5o valgus and neutral DF

- make a parallel cut to distal tibia

- again only 2-3 mm

- ensure two cuts appose

 

Stimulate bleeding bony surfaces

- drill holes in distal tibia and talar dome / sharp osteotome

- especially if sclerotic bone

 

Position foot

- ER 5 – 10o depending on other foot position

- with respect to patella

- hold with wires for 6.5 mm cannulated screws

 

Fixation

 

Option 1

- medial tibia down to talus

- one into dome & one into neck / parallel

 

Option 2

- lateral talus up to medial tibia

- region sinus tarsus / lateral process

- parallel

 

Supplement

- medial malleolar screw

- fibular to talus screw

 

Check II 

 

Options for fibular 

- discard 

- reattach to tibia and talus as onlay graft 

- morcellize with reamer and insert 

 

Postop 

NWB 6/52 in cast

PWB in moon boot further 6/52

Double time if diabetic

 

2.  External Fixation

 

2 circular rings distal tibia

- 4 half pins

 

2 wires metatarsals

- connect to half ring

 

2 x wires calcaneum

- foot plate

- connect to half ring

 

Rods between and compress

 

3.  Tibiotalocalcaneal (TTC) Fusion 

 

Pantalar Fusion APPantalar Fusion Lateral

 

Technique

- prepare ankle arthrodesis site as per compression arthrodesis

- approach and prepare subtalar joint between peroneus brevis and tertius

- elevate EDB

- stabilize both joints with K wires placed to not interfere with nail insertion 

 

Insertion site

- line from 2nd toe through centre of heel pad

- line in coronal plane / junction anterior & middle 1/3 of heel pad

- should pass through anterior part of posterior facet of calcaneum

- posterior to lateral plantar artery and nerve

- screw fixation in calcaneum and talus (lateral to medial ; possible posterior to anterior calcaneal screw)  

- compression (distally locking and tapping on inserter or company specific jig) 

- 2 x proximal screws medial to lateral 

 

Complications

 

Intraoperative 

-NV Damage 

-Metalwork Breakage 

 

Postoperative 

- Immediate - Infection ; compartment syndrome 

- Medium Term - Delayed or nonunion ; painful malunion 

- Long Term - Stiffness and Gait Changes ; Arthrosis in adjacent joints 

 

Nonunion

 

Arthrodesis nonunionArthrodesis nonunion lateral