The clinical question
Fifteen years after a well-executed ankle fusion for post-traumatic arthritis, this patient has developed progressive pain in the subtalar and talonavicular joints. She is otherwise active, a non-smoker, with good bone stock on CT and no evidence of talar AVN. The question: do we revise her to a pan-talar or tibiotalocalcaneal fusion, or do we convert her to a total ankle arthroplasty?
Imaging
Weightbearing radiographs showed a solid ankle fusion in neutral coronal alignment with significant adjacent-joint narrowing at the subtalar and talonavicular joints. CT confirmed the fusion was fully consolidated and — critically — that the talar body was intact with no AVN and adequate remaining bone stock for a contemporary TAR implant.
The decision
Conversion to TAR over revision fusion. The arguments for conversion in this patient: preserved talar bone stock, no AVN, no significant hindfoot malalignment, non-smoker, reasonable functional demands, and a strong preference from the patient for motion over additional fusion surgery. The arguments against — the technical demands of the operation and the historically higher complication rate of conversion versus primary TAR — were real but manageable in an experienced hands.
Operative approach
Anterior ankle approach incorporating the previous fusion scar. Tibial and fibular hardware removed. Fusion takedown performed with a thin osteotome along the original fusion line under fluoroscopic guidance. Once motion was restored at the tibiotalar interface, a contemporary fixed-bearing TAR implant was placed with standard instrumentation, accepting for the altered anatomy with careful component sizing. Polyethylene trial, stability check, and final implant seating completed the case.
No adjunct procedures were required at the same sitting — the subtalar and talonavicular joints were symptomatic but did not require fusion at the index operation.
Outcomes
Short-leg splint for two weeks, boot with graduated weightbearing through week six, walking shoe by week eight. At three months she was ambulating without an assistive device and her adjacent-joint pain had resolved. At one year she had maintained alignment, painless range of motion, and had returned to walking for exercise.
References
The conversion-from-fusion TAR literature is small but maturing. The studies from the Mayo, Duke, and International TAR groups are the primary references, along with the comparative series on conversion-versus-primary outcomes.