Total Ankle Arthroplasty Flashcards
What is the indication for total ankle arthroplasty
Severe painful post-traumatic osteoarthritis
What are some causes of secondary OA
- trauma
- fractures
- repetitive ligamentous injuries
What are some causes of primary OA
- misalignment
- wear and tear
- aging
- family history
What percentage of secondary OA is responsible for TAR
78-80%
What percentage of primary OA is responsible for TAR
10%
What is=s the gold standard for ankle arthritis
Ankle arthrodesis
What are some advantages of ankle arthrodesis
- pain relief
- improved mobility
What are some disadvantages of ankle arthrodesis
- time to healing (12-20 weeks)
- immobilization
- muscle atrophy
- mal union/pseudoarthrosis
- limitations wit inclines, uneven ground, driving and athletic activities
- decreased cadence and stride
- adjacent joint arthritis (STJ)
What are some indications are TAR
- ligamentous integrity
- hindfoot alignment
- bone stock
- vascular status
- physical demands
- midfoot/hindfoot arthrosis
What are some absolute contraindications for TAR
- Charcot neuroartropathy
- active/recent infection
- AVN of more than 50% of talus
- hyper mobility
- uncorrectable ankle mal alignment - eg 50% valgus
- poor soft issue envelope
- sensory/motor dysfunction
- High physical demands
- absent fibula
What would you look for on physical exam before ankle TAR
- hindfoot stability
- WB ankle alignment and ROM
- Assessment of STJ motion
What is the importance of CT scan prior to TAR
Evaluate cystic changes/bone stock
If you would like to assess and localize the degenerative changes in adjacent joints for a TAR, what imaging would you use
SPECT-CT
What did the 1st generation of TAR implants not respect??
- anatomy
- kinematics
- alignment
- stability
Why did the 1st generation of TAR implants did not work
- excessive bone resections
- poor cement fixation in fatty bone marrow
- changed the pronatory-supinatory motion of the ankle
TAR implants were first constrained. What type of joint did the ankle mimic when the implants were constrained
Hinge joint
What type of TAR implants were constrained
- TPR
- ICLH
- Conaxial
- Mayo
What was the problem with constrained TAR implants
As a hinge joint, it transferred stresses to the bone-cement interface
What type of joint was mimicked with the unconstrained TAR implants
Ball-in-socket joint
What was the problem with the unconstrained joint TAR implants
Unstable, malleolar impingement
What were the types of unconstrained TAR implants
- mayo
- buckholz
- smith
- newton
- irvine
What did the next generation of ankle replacements take into consideration
- preserve bone stock
- respect rotational axis
- respect ankle alignment
- semiconstrained
- biological fixation
What are the current FDA-approved TARs
- Tornier Salto-Talaris
- Stryker S.T.A.R.
- Wright Medical INBONE II
- Zimmer Trabecular Metal
- Depuy Agility - only for Depuy revisions
Which TAR implant is customized
Wright medical inbone II
Purpose/benefits of Wright Medical Inbone II
- fixed bearing
- primary/revisional ankles
What does the Wright Medical Prophecy uses
- 3D printed alignment blocks
- Pre-operative CT
What are the benefits of the Wright Medical Infinity
- fixed bearing
- primary ankles
Which TAR implant is the only FDA approved mobile-bearing device
Stryker S.T.A.R.
Describe the Stryker STAR
- 3 component design
- Only FDA approved mobile-bearing device
- Free-gliding polyethylene meniscus
- Rotation/gliding between tibia and meniscus
Which is the only TAR implant that uses the lateral approach incision
Zimmer Trabecular Metal
What are some features of the Zimmer Trabecular Metal TAR implant
- lateral approach
- minimal bone resection
- titianium cancellous/porous
- difficulty with balancing in frontal plane
- arch is supportive
Which TAR implant is only used in revisional cases
Depuy Agility
Which TAR implant relies/relied on distal tib-fib arthrodesis/ syndemosis fusing
Depuy Agility
Which are you primary TAR implants
- Infinity
- Salto
- STAR
- Zimmer
Which TAR implant would you use for revision, obese patients are patients with high deformity
Inbone
Which TAR implant would you use for adjacent hindfoot DJD
STAR
Where do you make the incision for TAR implants
Between TA and EHL,
Avoid TA sheath - it will bow string
Which structures are you retracting laterally in you TAR implant incision
Superficial peroneal nerve, NV structures
What are some ancillary procedures you’ll have to consider for TAR implant placement
- equinus release
- calcaneal osteotomy
- ligamentous reconstruction
- supramalleolar osteotomy
- medial column alignment
What is the post op course for TAR implant
- layered closure
- drain vs. incisional VAC
- NWB/ no ROM x 2 weeks
- 2-6 weeks NWB
- Aggressive PT
What are the most important ligaments for TARq
- Deep deltoid
- syndesmosis
Why is the syndesmosis important in a TAR
- valgus rotation of talus
- prevent lateral and anterior talar excursion
Why is the syndesmosis important in the TAR
- posterior migration of fibula
- rotation instability with external rotational forces
What are revisional TAR/adjunct procedures
- gutter clean out
- arthroscopy
- rebalancing
- management of loosening and cyst formation
- polyethylene exchange
- fusion adjacent joint
What are failed TAR options
- Arizona brace
- infection - antibiotic PMMA spacer
- conversion to inbone
- arthrodesis with/without allograft/autograft
- BKA
