Rationale:Kirschner wires (K-wires) are the most commonly used implants in orthopedic surgery. Although complications are not uncommon, they are mostly benign in nature and easily managed. While migration of K-wires is a rare complication, fatal outcomes have been reported. A review of the literature showed that only 7 cases of wire migration in the hip and pelvic region have been reported. Only 2 occurred in the pediatric population. Although K-wires are routinely used in osteogenesis imperfecta (OI) patients, there has been no report of complications in this vulnerable patient population.Patient concerns:A 10-year-old girl with OI, presenting with gastrointestinal symptoms 1 year after operative fixation of a subtrochanteric femoral fracture. Pelvic x-ray showed a missing K-wire.Diagnosis:The patient was diagnosed with migration of a K-wire from the left femoral neck to the right retroperitoneal space.Interventions:The patient underwent surgery. During the operation, the migrated K-wire was extracted from just below the 12th rib on the right side.Outcomes:The patient had an uneventful rehabilitation, recovered completely, and was asymptomatic at 2-year follow-up.Lessons:There has been no prior report of migrated K-wires in the OI population. This is also the first report of a K-wire migrating from the femoral neck to the contralateral retroperitoneal region. Proper intraoperative bending of K-wires, timely removal of temporary K-wires, and considering K-wire migration in patients with retained hardware complaining of respiratory or gastrointestinal symptoms will prevent potentially life-threatening complications.