Background <p>Retrograde intramedullary nailing with tibiotalocalcaneal arthrodesis (TTCA) is a well-established procedure for management of hindfoot arthritis. This study aimed to evaluate the functional and radiological outcomes of TTCA with or without open debridement of the subtalar joint to determine whether formal subtalar joint is preparation necessary.</p> Methods <p>A retrospective analysis of 48 patients who underwent TTCA with retrograde intramedullary nailing was conducted. Patients were divided into two groups: Group 1 (<i>n</i> = 20) underwent open debridement of both the tibiotalar and subtalar joints, while Group 2 (<i>n</i> = 28) underwent open debridement of the tibiotalar joint only, with closed intramedullary nail reaming of the subtalar joint. Outcomes were evaluated at mid-term and long term follow-up. Radiological findings, fusion rates, complications, and functional scores were compared between the groups.</p> Results <p>Subtalar fusion rates were significantly higher in Group 1 compared to Group 2 (80% vs. 32%, <i>p</i> = 0.001). Mid-term complication rates were significantly lower in Group 2 (<i>p</i> = 0.007), though Group 1 had a higher rate of nerve complications (<i>p</i> = 0.004). Tibiotalar fusion rates did not differ significantly between the groups (<i>p</i> = 0.936). Functional improvement, based on the American Orthopaedic Foot and Ankle Society (AOFAS) and visual analog scale (VAS) scores, showed no significant differences between the groups at any follow-up time points (<i>p</i> &gt; 0.05). Subtalar nonunion was associated with significantly poorer long-term functional outcome scores.</p> Conclusions <p>Open debridement of the subtalar joint during TTCA is essential for achieving optimal subtalar fusion. However, in cases where soft tissue conditions limit safe access to the subtalar joint, satisfactory functional outcomes and pain relief can still be achieved through tibiotalar fusion and subtalar joint immobilization, even without complete fusion. This approach may be particularly advantageous in post-traumatic or infectious cases with compromised soft tissue envelopes.</p> Level of evidence <p>Level 3, Retrospective cohort study.</p> Trial registration <p>Retrospectively registered.</p>