Bone complications after hand and face transplantation: Mechanisms and management.

Vascularized composite allotransplantation (VCA) has expanded the frontiers of reconstructive surgery by enabling restoration of form and function in patients with devastating facial and extremity defects. While advances in surgical techniques and immunosuppression have improved short- and mid-term outcomes, bone-related complications remain a critical yet underexplored challenge. This review provides a comprehensive overview of the mechanisms and clinical manifestations of bone problems in VCA, including delayed union, nonunion, avascular necrosis, and osteoporosis. Particular emphasis is placed on the detrimental effects of long-term immunosuppressive therapy on bone metabolism and repair. Current and emerging strategies to address these issues-such as glucocorticoid-sparing regimens, pharmacological therapies like bisphosphonates and teriparatide, and regenerative medicine approaches-are also discussed. By synthesizing clinical experience, translational studies, and experimental models, this review underscores that bone complications represent a major determinant of graft integration, functional recovery, and long-term success in VCA. Greater recognition of these challenges and development of targeted management strategies are essential to optimize outcomes for recipients of bone-containing allotransplants.