This study aimed to investigate the effectiveness of the sliding double flexible intramedullary nail technique (SDFIN) in managing lower extremity long bone fractures and deformities in patients with osteogenesis imperfecta (OI) based on radiographic measurements. This study was conducted involving type III or IV Silence OI patients who underwent treatment with SDFIN for fractures, deformity correction, or previous device failure. The surgical technique involved the insertion of two straight flexible intramedullary nails in each bone segment, with one inserted from the caudal epiphysis and the other from the proximal region. Clinical and radiological outcomes were evaluated with a mean follow-up of 62.8 ± 20.3 months. Among the 33 lower extremity long bone segments treated with SDFIN, revision was required in 12 segments, resulting in an overall complication rate of 51.5%. Complications included nail migrations observed in 10 cases, decreased joint range of motion in seven, refractures and malrotations in five, nail fracture, and nail extrusion in one case were observed. The femur group had a complication rate of 50%, while the tibia group had a rate of 53.3%. The SDFIN technique demonstrated satisfactory outcomes in managing leg fractures and deformities in OI patients. The technique showed comparable results to newly designed Faisser-Duval rods at a lower cost. Further research and refinement of the technique are necessary to reduce complications and improve patient outcomes.