Fusion Rates in Tibiotalocalcaneal Arthrodesis with Tantalum Coated Metal Cup Augmentation

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: Tantalum coated metal spacers (TCMS) have recently been utilized to fill and provide structure to large bony defects in the hindfoot. TCMS have a porous structure and elastic modulus similar to cancellous bone, increasing resistance to collapse, as well as osteoconductive properties that allow for bony ingrowth. At this time, there is still a paucity of literature assessing the use and outcomes of TCMS in foot and ankle surgery, more specifically as bridging structures for large bony defects when performing tibiotalocalcaneal (TTC) arthrodesis. This study serves to assess clinical outcomes and fusion rates of patients who underwent TTC arthrodesis utilizing intramedullary nailing with tantalum coated metal cup augmentation for large bony defects. Methods: We retrospectively reviewed the charts of 20 patients who underwent TTC fusion with TCMS augmentation at our local tertiary care center between 2015-2021. The CT scans at the six-month post-operative window were reviewed by one orthopaedic surgeon to determine the presence of bony fusion, which was defined as having at least 50% fusion mass. From the initial cohort, we collected the following modified foot function index scores for 13 patients: PROMIS Physical Health (0-20), PROMIS Mental health (0-20), Foot Function Index (0-170), Activity Limitation Scale (0-30), Pain Scale (0-50) and Disability Scale (0-90). Results: The mean age of our cohort was 53.9 (± 12.9) with a mean CCI of 1.54 (± 1.127) and mean follow up of 451.5 days (± 353.3). Mean modified foot function index scores included: PROMIS Physical Health 12.15 (± 3.34), PROMIS Mental health 12.23 (± 4.82), Foot Function Index 91.08 (± 47.59), Activity Limitation Scale 15.00 (± 10.42), Pain Scale 25.00 (± 14.77) and Disability Scale 51.00 (± 25.06). The post-operative complication rate was 30.8% in which 3 patients required a revision surgery via nail dynamization and one patient required a below knee amputation due to an infected nonunion of the TTC arthrodesis. The overall fusion rate at the 6-month postoperative visit was 69.2%. Conclusion: Unlike prior studies, we were able to obtain 6-month post-operative CT scans to delineate successful fusions with a larger number of patients (n=13). Given the paucity of literature looking at TCMS augmented fusions in foot and ankle surgery, our data will contribute to our understanding and efficaciousness of this relatively new use of TCMS in foot and ankle surgery. Further studies are needed to evaluate the efficacy of TCMS augmented fusions as a viable surgical approach as well an alternative to standard nail dynamizations with structural grafts.