Hemifacial microsomia (HFM) is a craniofacial anomaly characterized by the unilateral underdevelopment of the structures that originate from the first and second branchial arches. The asymmetry involves the mandible, ear, maxilla, zigomatic arch and temporal bone. The V and VII cranial nerves and facial muscles may be affected too. Numerous treatment approaches have been proposed in the literature. Usually in growing patients distraction osteogenesis is recommended, and in grown up patients orthognathic surgery is suggested. The objective of this study is to establish an algorithm for the surgical treatment of HFM according to the age of the patient and the severity of the microsomia (Pruzansky classification). The different surgical techniques, and their long-term stability will be compared and analyzed. This is a retrospective descriptive study of eight non-syndromic patients with HFM. A clinical and x-ray follow up of eight patients will be presented. All of them have been surgically treated with different techniques according with the algorithm. The algorithm consists in conventional orthognathic surgery for M1 and M2a patients. The M2b and the M3 patients will need an early mandibular ramus reconstruction with distraction osteogenesis or osseous graft depending on the bone availability. In grown up patients who have not had any mandibular reconstruction, one option is a mandibular ramus reconstruction with anterior iliac crest graft with the orthognathic surgery in the same surgery. The second choice is the mandibular ramus reconstruction with osteogenic distraction and the Le Fort I osteotomy in a second surgery. All of the patients have a long-term skeletal stability and a successful aesthetic outcome. This algorithm allows an accurate treatment for the functional and aesthetic disorders in the HFM patients according to the age and severity of the defect.

Key words : hemifacial microsomia; treatment protocol; orthognathic surgery; distraction osteogenesis