Adolescent locked femoral nail for recurrent femoral fractures in children with osteogenesis Imperfecta: a case report and literature review.

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder characterized by increased bone fragility and recurrent fractures. The femur is the most frequently fractured site in pediatric OI patients. Traditional internal fixations such as plates and elastic intramedullary nails carry high complication rates. Although extendable intramedullary nails represent the gold standard for children with OI, they show insufficient stability in adolescent patients with large medullary cavities and severe osteoporosis. Adolescent Locked Femoral Nail (ALFN) is a fixation system designed for adolescents, but its specific efficacy in recurrent femoral fractures in adolescent OI patients has been rarely reported. A 13-year-old male patient with a confirmed COL1A1 pathogenic variant (Sillence type III OI) experienced four left femoral fractures within 5 years. The first two fractures were treated with plate fixation at a local primary hospital and both resulted in postoperative refracture; the third fracture was managed with plate fixation in our hospital, which also ended in refracture.For the fourth fracture, closed reduction and titanium alloy ALFN fixation were performed, combined with intravenous zoledronic acid infusion. At the 3-year follow-up, the fracture healed uneventfully without refracture; the lower limb alignment was normal, with a 0.5 cm limb-length discrepancy and satisfactory knee function. ALFN provides central, stable intramedullary fixation, preserves bone blood supply, and matches the anatomical features of the adolescent femur. Combined with anti-osteoporotic medication, ALFN may serve as a valuable option for selected adolescent OI patients with recurrent fractures, wide medullary canals, or failure of previous fixation methods to reduce refracture risk. For adolescents with unexplained recurrent fractures, early genetic testing and individualized surgical planning are critical to improve clinical outcomes.