Outcomes Following Conversion of Ankle Fusion to Transfibular Total Ankle Arthroplasty in Complex Patients

Category: Ankle Arthritis; Ankle Introduction/Purpose: Ankle fusion takedown with conversion to total ankle arthroplasty (TAA) shows promising results with regards to patient satisfaction and functional outcomes. The objective of this study is to present the results of tibiotalar fusion takedown via a lateral approach with conversion to TAA in complex patients with prior lateral approaches or compromised anterior tissues. Methods: A retrospective review was completed using the senior author’s total ankle replacement database. 16 patients underwent an ankle fusion takedown (TD) with conversion to transfibular TAA. 9/16 patients had prior tiobiotalar fusions; 7/16 patients had either a pantalar or tibiotalar calcaneal fusion. A matched cohort of patients who underwent primary transfibular TAA (TF TAA) was compared. Patient demographics, complication profiles, subjective pain questionnaires, and radiographic parameters were collected. Patient reported outcome measures (PROMs) were analyzed with Short Form-12 (SF-12), Visual Analog Scale (VAS), and the Ankle Osteoarthritis Scale (AOS). Radiographic parameters included plantarflexion and dorsiflexion range of motion (PF,DF) measured by tibiopedal excursion on standing flexion-extension radiographs. Radiographic indicators of implant subsidence (alpha, beta, and gamma angles) were measured. Results: Average age was 56.81 ± 13.11 years with 3.23 ± 1.46 years of follow-up. ASA was 2 or 3 in 15/16 TD and 16/16 TF TAA. Operative time was longer in TD due to additional procedures (6:04 ± 0.4 vs 4:55 ± 1.0, p=0.004). 6/16 per group underwent reoperation(s), most commonly fibular hardware removal (p=1). Radiographic parameters of TD revealed a 2°change in the beta angle (p=0.02) and increased plantarflexion 7.89 (5.65) to 13.51 (9.09) degrees (p=0.02). Compared to TD, TF TAA had greater PF 17.61 ± 6.52 vs 7.89 ± 5.65 (p = 0.002) and DF 18.95 ± 6.70 vs 12.48 ± 5.61 (p=0.011). Postoperative PROMs showed no significant difference between groups. There was no significant difference in cyst formation or lucency between groups. Conclusion: Tibiotalar fusion conversion to a lateral total ankle replacement in complex patients with prior lateral approaches or compromised anterior tissues appear to be a safe and effective surgery. When compared to primary lateral ankle replacements, ankle fusion takedown with conversion to total ankle arthroplasty yields similar patient reported outcomes, radiographic results, and complication rates at 3.2 years follow-up. Although technically challenging, transfibular total ankle replacement following ankle fusion takedown is a reasonable treatment option for symptomatic ankle, pantalar, or tibiotalar calcaneal fusion.