A juvenile opossum was found after an episode of trauma caused by a vehicular collision. In the emergency care, vital parameters and changes related to the trauma were measured, and it was not possible to verify any changes, other than a crepitation in the left femur. Radiographic examinations revealed a complex fracture in the femur, requiring surgical intervention. The animal was submitted to an anesthetic procedure using dexmedetomidine, ketamine, and isoflurane. Femur osteosynthesis was performed using the external fixation technique in tie-in configuration, associated with absorbable poliglecaprone 25 sutures modified cerclage. The post-surgical analgesia was performed with dipyrone, tramadol chloride, and meloxicam. After 40 days of care, including removal of fixation, healing, and rehabilitation, the animal was reintroduced to its natural habitat.