Forearm Nonunion and Segmental Bone Defects: A Focused Review of Masquelet Reconstruction and Free Vascularized Bone Grafting.

Segmental bone loss and chronic nonunion of the forearm present major reconstructive challenges due to the forearm's unique functional anatomy and the frequent coexistence of biological compromise, infection, and soft-tissue deficiency. The purpose of this review is to analyze the pathophysiology of forearm nonunion and to compare the Masquelet induced membrane technique (IMT) and free vascularized bone grafting (VBG) as contemporary reconstructive strategies, focusing on indications, biological rationale, outcomes, and complications. A narrative review of the English-language literature was conducted using PubMed, Embase, and the Cochrane Library, with searches performed through December to February 2026. Search terms included combinations of: forearm nonunion, segmental bone defect, Masquelet technique, induced membrane, vascularized bone graft, free fibular graft, upper extremity reconstruction, and forearm fracture. Clinical and experimental studies addressing forearm nonunion or segmental defects treated with IMT or VBG were included; non-English publications and studies not reporting union or functional outcomes were excluded. Emphasis was placed on biological principles, surgical techniques, union rates, functional outcomes, complication profiles, and factors influencing technique selection. Based on predominantly retrospective, single-center series with heterogeneous defect characteristics, both IMT and VBG appear to demonstrate favorable union rates when applied in appropriately selected patients; however, direct forearm-specific comparative evidence remains limited and largely low-level. IMT provides a staged, biologically favorable environment for graft incorporation and is particularly effective in infected or moderate-sized defects, while avoiding microsurgical complexity. VBGs, especially free vascularized fibular grafts, offer intrinsic vascularity and structural stability, making them advantageous for large defects, compromised local biology, or salvage after failed reconstruction, though with increased technical demands and donor-site morbidity. IMT and VBG are complementary rather than competing strategies in forearm reconstruction. Given the scarcity of high-quality comparative data, outcome optimization relies on individualized decision-making informed by defect size, biological environment, soft-tissue status, patient factors, and surgical expertise, pending more robust prospective evidence.