A rat model of the induced membrane technique using autologous iliac cancellous bone graft

The induced membrane technique (IMT) is widely used for the treatment of segmental bone defects; however, small-animal models that faithfully reproduce clinical conditions remain limited. In particular, no rat IMT model using autologous iliac cancellous bone grafts (AICB) has been previously established. This study aimed to develop and characterize such a clinically relevant rat IMT model. A 5-mm segmental femoral defect was created in rats and stabilized with an external fixator. A polymethyl methacrylate spacer was inserted and replaced with bone graft two weeks later. Outcomes were compared among groups receiving no graft, artificial bone, AICB with IMT, and AICB without spacer placement. Bone regeneration was evaluated using computed tomography, histology, and real-time RT-PCR. AICB with IMT group achieved the highest bone union rate (66.7%) and demonstrated progressive increases in CT values and new bone formation. In the group, histological analyses demonstrated bone formation mediated by the induced membrane, accompanied by increased expression of osteogenic and angiogenic factors on real-time RT-PCR. This study establishes a reproducible rat IMT model using AICB, closely replicating the clinical IMT and providing an experimental platform for invnestigating IMT biology and therapeutic strategies for segmental bone defects.