A study protocol of multicenter randomized controlled trial comparing three cannulated screws and dynamic condylar screw with medial anatomical buttress plate in treating old femoral neck fracture

Currently, there is no standardized consensus regarding hip preservation strategies for managing old femoral neck fractures. Our previously developed technique, utilizing a dynamic condylar screw (DCS), medial anatomical buttress plate (MABP), and iliac bone grafting (IBG), has been shown to reconstruct the proximal triangular structure, thereby providing adequate mechanical stability. The present study aims to establish a prospective cohort to evaluate the clinical outcomes of this combined technique in treating old femoral neck fractures. The old femoral neck fracture trial comparing DCS + MABP + IBG with three cannulated screws (TCS) + IBG is an ongoing multicenter, randomized controlled clinical trial of 400 patients. Patients diagnosed with old femoral neck fractures are randomized either to DCS + MABP + IBG methods or to TCS + IBG surgery, with a single-blind design. The trial's primary outcome will be “fracture healing rate” assessed radiographically with 12 months of follow-up after surgery. Secondary outcomes include: (1) osteonecrosis of the femoral head, assessed with imageological examination; (2) hip function evaluated postoperatively and at final follow-up with the Harris Hip Score; (3) Visual Analog Scale (VAS) to assess pain intensity in the hip and lower extremities; (4) complication monitoring, including surgical site infections, fracture redisplacement, implant loosening, and implant failure. This multicenter prospective randomized controlled trial aims to validate the efficacy and safety of medial augmentation technique (DCS + MABP) combined with autologous iliac bone grafting (IBG) for nonunion of femoral neck fractures. Successful implementation will establish a novel internal fixation strategy, enhancing clinical outcomes and reducing complication rates in the surgical management of old femoral neck fractures. This study was first approved by the Ethics Committee of the lead institution, Chinese PLA General Hospital (S2024-342-01), and was conducted simultaneously across multiple centers. All collaborating sites had to obtain approval from local ethics institutional review boards before initiating the respective controlled cohort studies. This study was prospectively registered on ClinicalTrials.gov (Medial Enhancement Technique for the Public Treatment of Old Femoral Neck Fractures, NCT06713031, registered on December 03, 2024, https://clinicaltrials.gov/study/NCT06713031 ).