Background <p>Chronic periprosthetic knee infection is a highly debilitating complication. In case of failed R-TKA, with significant bone loss and extensor mechanism failure, re-revision procedures could not even be feasible. The most appropriate therapeutic strategy in these cases remains unclear. This study aims to evaluate the clinical and subjective outcomes, as well as the reinfection rate, in nine patients with extensor mechanism failure following chronic PJI treated with knee arthrodesis using a cemented intramedullary nail with a bridging technique.</p> Methods <p>The series included nine patients who underwent knee arthrodesis with a cemented intramedullary nail at our Institute between 2020 and 2024. All patients were treated by a single operator using a standardized two-stage revision procedure. Clinical scores (OKS and VAS), subjective scores (SF-36), postoperative limb length discrepancy, and the reinfection rate were evaluated for each patient.</p> Results <p>All patients achieved good clinical and subjective scores, indicating good functional recovery and pain reduction. No patient had clinically relevant limb length discrepancy. One patient (11.1%) experienced a recurrence of infection. Literature shows that re-revision surgery with extensor mechanism reconstruction has high complication and reinfection rates, while transfemoral amputation results in lower clinical and functional scores. Knee arthrodesis ensures good functionality and a low reinfection rate.</p> Conclusions <p>Knee arthrodesis with a cemented intramedullary nail is a valid therapeutic alternative for patients with extensor mechanism failure following chronic periprosthetic infection. Patients in our study achieved good functional recovery and pain reduction. Further comparative studies with larger series are needed to confirm these results.</p>