Case Report: Life-saving external hemipelvectomy after missed external iliac artery occlusion in severe pelvic trauma

External hemipelvectomy is a radical procedure traditionally reserved for advanced malignancy, with its use in trauma being exceedingly rare. We report a 15-year-old female with severe pelvic trauma complicated by a missed external iliac artery occlusion following internal iliac artery embolization, resulting in irreversible limb ischemia and progressive soft-tissue necrosis. Despite fasciotomy, above-knee amputation, and repeated debridement, the infection advanced proximally with recurrent sepsis, ultimately necessitating a life-saving external hemipelvectomy. Reconstruction was achieved using a deep inferior epigastric artery perforator flap, followed by staged wound management and rehabilitation, leading to complete wound healing. At 28 months of follow-up, the patient was able to ambulate independently with a customized hemipelvic prosthesis. This case highlights a critical diagnostic pitfall in pelvic trauma and demonstrates that timely recognition, multidisciplinary management, and advanced reconstructive strategies can achieve meaningful functional recovery even after radical limb-sacrificing procedures.