History
First generation (late 70s early 80s)
Results
- 80-85% Good / excellent in short term
- severe osteolysis, aseptic loosening 90%
Problems
- cemented
- highly constrained
- considerable bone resection
- subsequent revision technically challenging
Second Generation (mid 80s onwards)
Design
- semiconstrained
- uncemented
- mobile and fixed bearing options
- bone preserving
Indications
1. Older patient with low demand
2. Other joints arthritic
- degenerative SJT / midtarsal joint
- contra-lateral AKJ AO
- previous triple arthrodesis
Absolute Contraindication
Infection (Acute or Chronic)
Neuroarthropathies i.e Charcot
PVD
Poor soft tissue envelope
Severe malalignment or instability that cant be corrected intraoperatively
Major AVN affecting >1/3 of talus
Relative Contra-indication
Dx - Posttraumatic worse outcomes than RA which has worse outcomes OA
Age - Younger (worse outcomes in < 50 years)
Minor Malalignment (>10 degrees of varus or valgus as compromises ligament stability)
Instability
Stiffness (preoperative ROM = Postoperative ROM)
Minor AVN talus
Second Generation Implants
STAR
Design
- cobalt chrome tibia and talus
- titanium porous coating
- talus single keel
- tibial component two rounded keels
- mobile bearing poly
Anderson et al JBJS Am 2004
- 51 STAR
- 12 revisions
- 5 year survival 70%
Depuy Agility
Design
- fusion of the distal tibio-fibular syndesmosis to support tibial component
- titanium tibial component with cobalt chrome talar resurfacing
- uncemented
- modular poly inserts into tibial component
Knecht et al JBJS Am 2004
- 69 followed clinically with 90% reporting decreased pain and satisfactory outcome
- 11% revision rate
- 76% demonstrated peri-implant radiolucency
- 20% progressive subtalar OA and 15% progressive TNJ OA
Techique
Anterior approach
- protect SPN
- between T ant and NV bundle
- remove anterior osteophytes
Tibial cut
- distal alignment jig
- resect few mm above eroded bone
- neutral cut
- must not cut medial or lateral malleolus
Talar dome
- resurfaced
- 3-4 mm removed
Results
Haddad et al JBJS Am 2011
- systemic review
- similar satisfaction rates and and ankle scores in arthroplasty and arthrodesis groups
- 5 and 10 year survival of arthroplasty 77%
- 7% revision rate in arthroplasty (loosening and subsidence)
- 9% revision rate in arthrodesis (non union)
- Meta-analysis of 37 studies comparing arthrodesis and arthroplasty
- Arthroplasty PROMs > arthrodesis in the short term (<2y)
- Arthroplasty PROMs = arthrodesis in the medium term (2-5y)
- Arthrodesis PROMs > arthroplasty in the long term (>5y)
Complications
Loosening
Revision
