Background: There is lack of consensus regarding best operative fixation strategy for periprosthetic femoral fractures (PFFs) around a stable stem. Based on our experience in the treatment of nonunions after PFFs and other challenging cases and on Literature, we propose an algorithm that can guide in choosing the ideal surgical technique even for first-time PFFs with a stable stem.Methods: We retrospectively reviewed data on patients who failed to heal after a surgically treated Vancouver type B1 or C PFF. All patients were treated with locking plate, double structural allograft and autologous bone marrow concentrate (BMC) over a platelet-rich plasma (PRP)-based membrane at fracture site. All patients were also pharmacologically treated with Teriparatide in the postoperative period. We studied patients with radiograms, histological evaluation of the nonunion area, and phosphocalcic metabolism. Patients were assessed subjectively, clinically and radiographically until healing and then annually.Results: All nonunions healed over a six months period, and functional recovery appeared to be good. Retrospective evaluation of the proposed algorithm showed that none of the patients met biological or mechanical criteria such as to make valid the treatment with locking plate alone.Conclusion: Mechanical factors are not the only issues that should be taken into account when choosing the surgical approach to PFFs over a stable stem. Systemic and local biological conditions are factors that should drive to a rigid fixation with absolute stability (using a plate and structural allograft) plus local biological support (structural allograft and autologous BMC in a PRP-based scaffold) and systemic anabolic treatment (Teriparatide) in the first instance. A therapeutic algorithm is proposed, given the prosthetic stem to be stable, taking into account mechanical and biological criteria.