Purpose: Tibiotalocalcaneal (TTC) fusion using a femoral head allograft is commonly performed for complex ankle pathologies, but radiographic nonunion is not uncommon. This paper describes the clinical course of patients with radiographic nonunion after TTC fusion and explores the clinical relevance of a possible “stable nonunion” pattern. Materials and Methods: Thirty-eight patients who underwent TTC fusion using femoral head allograft between 2014 and 2023 were reviewed retrospectively. Among them, 10 cases (26.3%) with radiographic nonunion were included. Nonunion was defined as the absence of osseous union at the tibiotalar or subtalar joint on plain radiographs at 6 months postoperatively. Serial follow-up radiographs were also reviewed. The clinical outcomes were assessed using the Visual Analog Scale (VAS), Foot and Ankle Ability Measure (FAAM), and RAND Short Form-36 (SF-36). This study was designed as an exploratory retrospective case series of the nonunion group. Results: Ten cases were identified as radiographic nonunion. Despite the persistent nonunion, the mean VAS decreased from 6.2 to 1.2 (p<0.001). Several SF-36 domains and the FAAM Activities of Daily Living score also improved. No hardware failures or reoperations were observed during follow-up. Conclusion Some patients with radiographic nonunion after TTC fusion using a femoral head allograft showed pain reduction and functional improvement without hardware failure or reoperation. These findings suggest that radiographic nonunion may not always indicate immediate clinical failure. Nevertheless, the results should be interpreted cautiously because of the small sample size, lack of a comparison group, and the absence of a CT-based union assessment.