Background: A variety of operative approaches and fixation techniques have been described for tibiotalocalcaneal (TTC) arthrodesis. The intramedullary (IM) nail and lateral, fixed-angle plating are commonly used because of ease of use and favorable biomechanical properties. A lateral, transfibular (LTF) approach allows for direct access to the tibiotalar and subtalar joints, but the posterior, Achilles tendon–splitting (PATS) approach offers a robust soft tissue envelope. The purpose of this study was to compare the results of TTC arthrodesis with either a PATS approach with IM nailing or LTF approach with fixed-angle plating. Methods: A retrospective review was performed on all patients who underwent simultaneous TTC arthrodesis with minimum 1 year clinical and radiographic follow up. Patients were excluded if they underwent TTC arthrodesis through an approach other than PATS or LTF, and received fixation without an IM nail or fixed-angle plate. Primary outcomes examined were union rate, revisions, and complications. Thirty-eight patients underwent TTC arthrodesis with a PATS approach and IM nailing, and 28 with a LTF approach and lateral plating. Results: The overall union rate was 71%; 76% (29 of 38 patients) for the PATS/IM nail group, and 64% (18 of 28) for LTF/plating group (P = .41). Symptomatic nonunion requiring revision arthrodesis occurred in 16% (6 of 38) of the PATS/IM nail group versus 7% (2 of 28) in the LTF/lateral plating group (P = .45). There were no significant differences in individual tibiotalar or subtalar union rates, superficial wound problems, infection, symptomatic hardware, stress fractures, or nerve irritations. Conclusion: Union, revision, and complication rates were similar for TTC arthrodesis performed with a PATS approach and IM nail compared with an LTF approach and fixed-angle plate in a complex patient population. Both techniques were adequate, especially when prior incisions, preexisting hardware, or deformity preclude options. Level of Evidence: Level III, retrospective comparative study.