3D Printed Total Talus Replacement after Free Vascularized Medial Femoral Condyle Osteocutaneous Flap for Avascular Necrosis of the Talus Leads to Poor Clinical Outcomes

Abstract

Category: Hindfoot Introduction/Purpose: Talar avascular necrosis (AVN) is a difficult pathology to diagnose and manage. Traditional treatment options include both joint sparing procedures (vascularized bone graft, core decompression, intraosseous stem cell injection) and joint sacrificing procedures (arthrodesis or arthroplasty). Three dimensional (3D) printed total talus replacement (TTR) has recently gained more popularity as an intervention to salvage joint motion in patients with talus pathology. Although vascularized bone grafting can treat localized talar AVN, failure of this procedure to improve talar vascularity and prevent further subchondral collapse may require revision surgery. This is the first study to compare outcomes of patients with talar AVN who underwent primary 3D printed TTR and patients who underwent a secondary TTR subsequent to failure of a free vascularized medial femoral condyle (MFC) flap. Methods: This case series analyzed the outcomes of two patients who underwent a secondary 3D printed TTR subsequent to failure of the index revascularization procedure using an MFC flap in 2016. These patients were compared to a cohort of patients who underwent a primary 3D printed TTR to treat talar AVN between 2016 and 2019. Preoperative and postoperative assessment included ankle range of motion, foot and ankle outcome score (FAOS), visual analogue scale (VAS) pain scores, and radiographic imaging. A minimum 12-month follow-up period was reported for patients. Results: Within the group that underwent a secondary TTR after a failed revascularization, both patients had a mean followup of 23.5 months. The 25 patients in the comparison group who all underwent a primary 3D printed TTR had an mean follow-up period of 22.1 (range:12-43) months. All patients in the study experienced improved VAS pain scores and ankle dorsiflexion post- operatively. In the secondary 3D printed TTR group, both patients demonstrated reduced plantarflexion of 20 degrees and ankle motion of 15 degrees relative to the comparison group which showed a minimal increase in both. When analyzing FAOS functional outcome score subscales, patient two demonstrated improvement in pain from 44 to 46, symptoms from 29 to 46, and activities of daily living from 47 to 76. Patient one experienced a decrease in sports and recreation from 15 to 5 and quality of life from 38 to 31. Conclusion: This case series demonstrated poor functional outcomes of two patients who underwent 3D printed TTR after talar revascularization with MFC grafts when compared to the cohort of patients who solely underwent a primary 3D printed TTR for talar AVN. Further investigation is warranted to determine which patients may benefit from a revascularization procedure or a primary 3D printed TTR.