Updated: 5/11/2019

Total Ankle Arthroplasty

Topic
Review Topic
0
0
Questions
2
0
0
Evidence
5
0
0
Videos
7
https://upload.orthobullets.com/topic/12133/images/star.jpg
https://upload.orthobullets.com/topic/12133/images/taaex.jpg
https://upload.orthobullets.com/topic/12133/images/apankoa.jpg
https://upload.orthobullets.com/topic/12133/images/latankoa.jpg
https://upload.orthobullets.com/topic/12133/images/avntalus.jpg
https://upload.orthobullets.com/topic/12133/images/taaintraop.jpg
Introduction
  • Total ankle arthroplasty (TAA) is an alternative to ankle arthrodesis for the treatment of end-stage ankle OA  
    • TAA attempts to preserve functional ROM, which would otherwise be sacrificed with ankle arthrodesis
  • History
    • first generation TAA
      • majority of designs were highly constrained, or semi-constrained two component prostheses
      • used cement fixation on both the talar and tibial sides
      • high incidence of loosening, wide osteolysis, subsidence, and mechanical failure of prosthesis components
    • second generation TAA
      • majority are two-component fixed-bearing systems with a polyethylene bearing surface incorporated into the talar or tibial component
      • more conservative bone cuts
      • elimination of bone cement in favour of press-fit designs with porous coating for bony ingrowth
    • third generation TAA
      • characterized by the addition of a third component, an independent polyethylene mobile-bearing meniscus
      • place a greater importance on the use of ligaments to retain stability, the need for anatomic balancing following component insertion, and minimal bone resection.
  • Implants approved by the FDA
    • Scandinavian Total Ankle Replacement (STAR; Small Bone Innovations, Morrisville, PA)
    • INBONE (Wright Medical Technology, Arlington, TN)
    • Agility (DePuy, Warsaw, IN)
    • Salto Talaris (Tornier, Montbonnot, France)
  • Outcomes
    • pain and function
      • significant improvement in pain and function
      • pre-operative ROM best predictor for post-operative ROM with minimal additional benefit in ROM gained from TAA
      • little high quality evidence comparing TAA vs. ankle arthrodesis
    • survivorship
      • TAA survivorship at 10 years ranges from 70% to 90%
      • no evidence that three component designs are better than two component designs
Indications
  • Indications
    • diagnosis
      • unilateral or bilateral end-stage ankle OA
    • favorable patient factors  
      • older (middle- to old-aged), low demand, reasonably mobile patient with no significant
        co-morbidities
      • normal or low body mass index  
      • well-aligned and stable hindfoot
      • good soft tissues conditions
  • Contraindications
    • active infection
    • peripheral vascular disease
    • inadequate soft-tissue envelope
    • Charcot arthropathy
    • insufficient bone stock
    • severe osteoporosis
    • osteonecrosis of the talus
Preoperative Imaging
  • Radiographs
    • recommended views
      • weight-bearing AP and lateral views of the ankle
    • findings
      • extent of arthritis
  • MRI 
    • findings 
      • presence of osteonecrosis, amount of involvement, bone loss,and size of subchondral cysts
Surgical Technique
  • Approach 
    • vast majority of systems utilize an anterior approach to the ankle, via the interval between tibialis anterior and extensor hallucis longus 
  • Goals
    • to restore mechanical alignment to the ankle
      • achieved by alignment guides that allow for precise cuts of the tibia, talus, and in some systems the fibula
      • recent iterations of TAA systems have incorporated ligamentous balancing as a crucial part of the operative procedure
      • imperative to achieve a stable, neutrally aligned, plantigrade, weight-bearing position of the ankle and hindfoot
        • ligament reconstruction, tendon transfers, osteotomies, heel cord lengthening and arthrodesis may be necessary
  • Technical Considerations
    • soft tissue considerations
      • use a long incision to decrease the tension on the skin
      • perform thick skin flaps to maintain vascularity
      • minimize use of retractors has been emphasized in the literature
      • avoid the tibialis anterior sheath
        • prevents tendon bowstringing and its resultant wound complications
    • implant placement
      • common technical errors include
        • placing the prosthesis too lateral
        • using too small a prosthesis, which subsides
        • failing to solve preoperative varus or valgus malalignment and attempting to replace an ankle that is too anteriorly subluxated
Complications
  • Delayed wound healing 
    • most common
    • reported in 4% to 17% of cases in the literature
  • Superficial wound infection
  • Deep wound infection
    • ranges from 0.5% to 3.5% of cases
    • studies have shown a low success rate of component reimplantation  
  • Sensory deficits
    • secondary to anterior incision and its proximity to the superficial and deep peroneal nerves
    • reported rates are as high as 21%
  • Intraoperative Fracture  
    • medial >  lateral malleolus
    • occur in the narrow bone bridge between the ankle joint and the outer cortex of the tibia or fibula 
    • causes
      • overextending the plafond cut too medially or laterally
      • making a cut too proximal in the tibia
      • using an over-sized tibial component
      • distraction of the ankle with an external fixator
    • prevention
      • prophylactic K-wire pinning (or screw fixation) prior to osteotomy cut  
  • Component loosening
    • talar component fails more commonly than the tibial component
  • Subsidence  
    • may need to convert to ankle fusion
      • decide if there is infection
      • decide whether to fuse across subtalar joint (TTC fusion)
      • decide what bone graft to use
        • particulate cancellous graft (<2cm talar bone loss)
        • bulk allograft (>2cm bone loss)
          • femoral head allograft 
            • graft of choice if TTC fusion is chosen
          • Cambell allograft graft (wedges of tricortical iliac crest)
          • fresh-frozen distal tibial allograft
      • decide what type of fixation
        • nail
        • plate
        • nail and plate
  • Osteolysis
    • polyethylene wear results in osteolysis, with large, expansive cystic lesions in the tibia or talus
 
 

Please rate topic.

Average 4.4 of 11 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (2)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
ARTICLES (6)
VIDEOS (7)
Topic COMMENTS (3)
Private Note