Modification of mandibular advancement osteotomy in a patient with Hanhart syndrome

The oromandibular limb hypogenesis syndrome is a group of anomalies affecting the mandible, tongue, and maxilla with or without reductive limb anomalies. It was first described by Hanhart in 1950. In severe syndromic cases of mandibular hypoplasia, a number of techniques have been described for mandibular advancement including sagittal split osteotomies, segmental osteotomies, or distraction osteogenesis just to name a few. A 25-year-old male patient presented to our clinic with symptoms including difficulty in speech and eating, disability in opening the mouth, together with hand and foot abnormalities; we want to describe a modification in the technique of mandibular advancement and the patient's late postoperative results. The design of the step osteotomy is modified by softening the angles of the steps and elongating the horizontal segment of the step to approximately 25 mm to allow for a more efficient advancement of the mandible. The postoperative period was uneventful, with no signs of inferior alveolar nerve disturbance. The patient showed an increase of the mouth opening distance immediately after surgery. We believe that this tongue-in-groove-like modified mandibular step osteotomy technique is a good alternative in patients where advancement greater than 15 mm is required, preserving the nerve and achieving solid bony intact surfaces.