Sequential treatment for a patient with hemifacial microsomia: 10 year-long term follow up
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Hemifacial microsomia (HFM) is the most common craniofacial anomaly after cleft lip and cleft palate; this deformity primarily involves the facial skeleton and ear, with either underdevelopment or absence of both components. In patients with HFM, the management of the asymmetries requires a series of treatment phases that focus on their interception and correction, such as distraction osteogenesis or functional appliance treatment during growth and presurgical orthodontic treatment followed by mandibular and maxillary surgery. Satisfactory results were obtained in a 9-year-old girl with HFM who was treated with distraction osteogenesis. At the age of 19, genioplasty and mandible body augmentation with a porous polyethylene implant (PPE, Medpor®, Porex) was sequentially performed for the functional and esthetic reconstruction of the face. We report a case of HFM with a review of the literature.
KeywordsHemifacial microsomia Distraction osteogenesis Facial augmentation
Hemifacial microsomia (HFM) is a deformity derived from the first and second branchial arches and primarily involves the facial skeleton and ear, resulting in the underdevelopment or absence of both components. HFM is the most common craniofacial anomaly in humans after cleft lip and cleft palate. A classification of HFM has been described by Pruzansky  and developed to qualify and quantify the severity of the deformity of the facial skeleton and associated soft tissues [2, 3, 4, 5, 6].
It is difficult to reconstruct hard and soft tissues of the deformed face in HFM, and the treatment of this condition requires multiple steps over a period of several years . Costochondral grafts have been widely used for the reconstruction of deficient mandibular ascending ramus in children with Pruzansky–Kaban types IIB and type III HFM between the mid-1970s and mid-1990s . Children with types I and IIA HFM were not treated until the end of pubertal growth . In some instances, they were treated with functional orthodontic therapy to induce harmonious maxillomandibular growth . Distraction osteogenesis (DO) was first performed in 1992 by McCarthy, in a patient with HFM . We present the case of a 9-year-old girl who was diagnosed with HFM, and was treated with sequential distraction osteogenesis, genioplasty, and mandible body augmentation. She was later treated with a porous polyethylene implant (PPE, Medpor®, Porex) at 19 years of age for the functional and esthetic reconstruction of her face.
The treatment goal of HFM is to attain a good facial profile without the loss of function. The severity of the temporomandibular joint (TMJ) complex deformity is the main factor influencing its reconstruction, which involves TMJ reconstruction, costochondral grafts, maxillary osteotomy, mandibular osteotomy, application of bone grafts, and distraction osteogenesis of the mandible [5,8,13, 14, 15, 16, 17]. Surgery, before skeletal maturity, is necessary for preventing secondary growth deformities and for cosmetic correction . In general, the treatment protocol in these patients is a two-stage process, comprising DO during pubertal growth followed by a secondary orthognathic surgery at the end of pubertal growth.
DO is a technique by which a new bone is formed between the surfaces of 2 bone segments as a result of the tension that is created by the gradual movement of the two segments in the opposite direction, thereby lengthening the original bone structure . This technique was first described in 1905 by Codivilla who performed osteotomies and elongated femur bones by gradual distraction . It was later popularized by Ilizarov in 1951 by the elongation of the upper and lower limbs; since then, this technique has undergone several developments.
In 1973, Snyder reported mandibular lengthening by gradual distraction in animal models . Mandibular lengthening by gradual distraction in a human mandible was first performed in 1992 by McCarthy, with the aid of an extraoral device in a patient with HFM . Since then, it has been applied to bones of individuals with craniofacial deformities, and several studies have reported the use of this treatment, resulting in the development of an effective device.
Kim et al.  reported the effectiveness of a new DO protocol for over-distraction following compressive stimulation against the conventional DO protocol. Another study by Kim et al.  examined the expression of TGF-ß1, osteonectin, and BMP-4 in mandibular distraction osteogenesis with compression stimulation; the expression levels of TGF-ß1, osteonectin, and BMP-4 on DO with a compression force during early consolidation were increased, illustrating the effect of compression force during DO. Therefore, we applied a new DO protocol for over-distraction with compressive forces on this patient.
The DO method with compression force used in the present study is different from other conventional DO techniques because of the extended amount of distraction obtained, and the interventional as well as intermittent compression force applied during the early period of consolidation [11,12]. In the present study, after DO, vertical discrepancy had improved and the deviation of mandible was corrected to the normal midline position. The patient was treated by DO with compression force, due to which the consolidation period was shortened to 6 weeks. In general, facial skeleton growth is almost complete after the pubertal growth period. In the present study, orthognathic surgery was planned as a second stage treatment option. The patient presented with HFM type 2a, and owing to the absence of temporomandibular joint problems and the presence of mild facial asymmetry, an advanced, sliding genioplasty and left mandibular body, inferior border augmentation was planned, with the simultaneous use of a PPE implant. Mandibular body augmentation using a PPE implant is a simplified method, instead of an autograft, and provides satisfactory esthetic results by reinforcing the buccal width as well as the length of the inferior border of mandible. After the second operation, the patient’s facial profile was visibly improved. Further, periodic, close observation has been advised for this patient to assess the fate of the PPE implant. If facial asymmetry recurs, a free tissue composite flap transfer or iliac bone graft will be applied to the affected side of the face.
In conclusion, satisfactory results were obtained in the patient diagnosed with HFM during the first visit. Distraction osteogenesis of the mandibular angle at an early age, followed by genioplasty and mandibular body augmentation with a PPE implant after puberty, could be sequentially performed for the final functional and esthetic reconstruction of the face.
Written informed consent was obtained from the patient for the publication of this report and any accompanying images.
This study was supported by Korea National Research Fund (No.NRF-2012R1A1A2003550).
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