Lower Face Asymmetry: Can We Distract the Mandibular Lower Border?

Abstract

Hemifacial microsomia (HFM) is a chromosomal abnormality with an incidence of 1:5,600. Bone grafting, alloplastic grafting, orthognathic surgery, orthomorphic surgery and distraction osteogenesis (DO) are the various options available for the management of HFM. DO has been used for the correction of the mandibular corpus length and ramal deficiency, but there is no previous report stating its use in increasing the height of the mandible.1 Basal osteotomy of the mandible has been reported for reduction of the height of the mandible and advancement of the mandibular corpus.2 We present a method incorporating the basal osteotomy with the principles of DO to correct hemimandibular hypoplasia associated with HFM type I. Case ReportA 20-year-old male patient presented with a chief complaint of asymptomatic asymmetry of the face first noticed in the childhood that worsened over the period of time. He has no history of trauma or major hospitalizations. He presented with gross asymmetric face with decreased lower facial height on the left side. The chin was deviated to the right side (►Fig. 1).On temporomandibular joint (TMJ) evaluation, jaw movements were normal bilaterally. On orthopantomograph (OPG), the mandible on the left side was smaller in size with maintained anatomy. Condyles were symmetrical, and teeth were symmetrical which was reconfirmed using study models.Audiometry revealed decreased hearing capability on the left side. No cardiac abnormalities, no abdominal, or visceral abnormalities were noted. An IQ score of 86 was obtained on Stanford-Binet Intelligence scale suggesting low average. The condition was diagnosed as asymmetry secondary to mandibular hemihypoplasia associated with HFM type I. Surgery PlanningGrummon cephalometric analysis and analysis on the OPG showed a deficiency of 9 mm in the anterior region and 5 mm in the posterior region. Patient was planned for surgical management sequenced in two stages with addressing the hard tissue corrections in the first stage and soft tissue corrections in the second stage. Basal osteotomy followed by distraction was planned to increase the height of the mandible using an alveolar distractor (D1) intraorally and a mandibular internal distractor (D2) extraorally. Procedure Stage IUnder general anesthesia with nasal intubation, 2% lignocaine with 1:200,000 adrenaline was infiltrated and submandibular incision was placed. Inferior border of the mandible was Keywords ► asymmetry ► distraction osteogenesis ► hemifacial microsomia AbstractOrthognathic surgery and alloplastic grafting are the main stay in management in hemifacial microsomia. Distraction osteogenesis is used to increase the ramus and corpus length in the management, but here we have described a technique to increase the height of the body of the mandible using the principles of basal osteotomy and distraction osteogenesis.