Newborn with an open posterior hip dislocation and sciatic nerve injury after intrauterine radiofrequency ablation of a sacrococcygeal teratoma.

Advanced prenatal ultrasonography techniques have allowed for better understanding of the natural history, treatment, and prognosis of sacrococcygeal teratomas. Several intrauterine surgical techniques to debulk the tumor when fetal and maternal life are in jeopardy have been described. Orthopaedic impairment, such as lower extremity weakness and swelling, also has been described in association with sacrococcygeal teratomas. The authors report on a newborn in whom a large soft tissue defect overlying the posterior hip region with direct exposure of the disarticulated hip joint existed at the time of birth, which resulted from intrauterine radiofrequency ablation of a sacrococcygeal teratoma. This unexpected complication has resulted in a loss of sciatic nerve function, malformation of the acetabulum and femoral head, and loss of the left ischium, coccyx, inferior sacrum, gluteal, adductor and piriformis muscles, and posterior hip capsule. At 16 months of age, the patient has a flaccid left lower extremity with a hypoplastic hip joint.