Results
90% fusion rates
Lose 70% 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
- 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
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
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
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