What's New in Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is a diverse group of genetic disorders mainly caused by pathogenic variants in COL1A1 and COL1A2 that interfere with type I collagen production, resulting in bone fragility and multisystem issues. Since 2019, the understanding and treatment of OI have improved considerably. Advances in molecular genetics have broadened the OI classification to 22 types, with new variants affecting pathways beyond collagen synthesis, including osteoblast differentiation and bone mineralization. Bisphosphonates continue to be the primary pharmacologic treatment, effectively reducing fracture risk, and increasing bone mineral density, although recent studies highlight delayed osteotomy healing and some differences among specific agents. Newer therapies-including denosumab, antisclerostin antibodies such as setrusumab, and mesenchymal stem cell transplantation-show promise but need further validation through randomized trials. Overall, nonoperative care, including good nutrition, vitamin D supplementation, personalized physical therapy, and orthotic support, remains essential for improving function and preventing fractures. Intramedullary stabilization with telescoping rods has become the standard for both fracture fixation and deformity correction, providing better long-term outcomes and lower reoperation rates compared to static rods. Advances in surgical planning highlight the importance of precise rod alignment, avoiding cortical stress shielding, and protecting the periosteum to promote healing. Spinal deformities, including scoliosis and basilar invagination, are increasingly managed through multidisciplinary monitoring, bisphosphonate therapy, and refined surgical strategies that prioritize stability over maximum correction. Optimal outcomes in OI require coordinated multidisciplinary care involving orthopaedic surgeons, medical colleagues, physical therapists, and other specialists. Ongoing research continues to refine medical and surgical methods to improve function, quality of life, and long-term skeletal health for children with OI. (1)Multidisciplinary care is vital in caring for children with OI.(2)Medical optimization through nutrition, medications like bisphosphonates, vitamin D supplementation, and physical therapy is important for both preoperative and postoperative children with OI.(3)Intramedullary stabilization with telescoping or nontelescoping nails to protect the entire length of the bone is the mainstay of surgical treatment.