A Prospective Evaluation of a 3D-Printed 4th-Generation Total Ankle Prosthesis with 1-Year Follow- Up

Abstract

Introduction/Purpose: Fixation of fourth-generation ankle replacements is evolving. Given the concern for tibial tray loosening or radiolucencies, three-dimensional (3-D) printing has been suggested as a solution. Additive manufacturing allows for the creation of an optimal implant surface for improved initial stability and bony on growth. To date, there are no reported data concerning survivorship and clinical improvement following a 3-D printed ankle replacement. Documentation of implant survivability and comparison studies of the latest generation implants are limited. The purpose of this study is report on prospectively-collected patient reported outcome measures (PROMs) in a multi-institutional study of a 3-D printed fourth-generation total ankle. Methods: Patients presenting for a total ankle replacement at 12 institutions were prospectively enrolled and implanted in both academic and private settings. Patients had demographics and PROMs recorded pre-operatively and at 6 month and 12-month intervals. The following PROMs were collected: Ankle Osteoarthritis Score (AOS), PROMIS Global Physical Health, Foot and Ankle Outcome Score (FAOS), and satisfaction scores. The preoperative and latest follow-up scores for patients with two years of follow-up were analyzed. Results: 91 of 177 subjects enrolled have reached one-year in follow-up currently. From the 177 enrolled (52.5% male) with an average age of 64.0±10.3 years old with an average BMI of 30.8±6.2. The pre-operative diagnosis for arthritis type was degenerative arthritis (27.7%), rheumatoid arthritis (1.7), post-traumatic arthritis (70.1%), and other (0.50%). There were 3 (1.69%) clinical failures:1 early infection: at 2 months, 1 tibial subsidence at 7 months, and 1 deep infection associated with trauma at 8 months post-operatively. The patients improved in all PROMs domains at one year including: Mean Total AOS (19.0. ± 17.5) p<.0001); PROMIS Global Physical Health (49.6 ± 17.1 p<.0001); Total FAOS Symptom Scores at 1 year (75.0 ± 19.5, p<.0001). The Total FAOS QOL at 1 year is 65.3 ± 25.2. Conclusion: At one-year post-implantation follow-up, the fourth generation 3D printed total ankle replacement had a low revision rate and proved to be safe and effective compared to historical ankle replacement outcomes. Patients were overwhelmingly satisfied and had statistically significant clinical improvements in each domain of their PROMs.