Is early osteodistraction a solution for the ascending ramus compartment in hemifacial microsomia? A literature study Maurice Y. Mommaerts, 1 Krisztia´n Nagy 2 1 Division of Maxillo-Facial Surgery, General Hospital St. Jan, Bruges, Belgium; 2 Applied and Clinical Anatomical Laboratory, Department of Anatomy, Histology and Embryology, Faculty of Medicine, Semmelweis University, Budapest, Hungary SUMMARY. Aim: In hemifacial microsomia, osteodistraction before skeletal maturation claims to induce both bone- and soft-tissue generation in such a way that conventional bone grafting and soft-tissue grafts are not necessary. Early osteodistraction in facial microsomia would have a positive effect on the ‘functional matrix’, and allow symmetrical vertical and sagittal expansion of the midface and mandible. The aim of this literature survey was to find evidence for this hypothesis by analysing long-term follow-up reports on distraction histiogenesis in the ascending ramus. Material: Only eight published studies were found, of which only two had more than ten patients, two were case reports, and three were from the same institution. Result: Invariably, the results pointed towards over-correction, repeated osteodistraction procedures, soft-tissue stretching (but no lateral augmentation), and to soft-tissue complications. The studies did not allow a conclusion to be made as whether increased vertical gain in the ascending ramus was unstable because of decreased growth on the affected side, inborn or iatrogenic, or due to resorption of the bone generated by distraction. To date, there is no evidence that osteodistraction produces better results and has lower morbidity than conventional growth centre transplantation and separate soft-tissue augmentation. Conclusion: Recommendations for prospective studies are: sharp differentiation between the four Pruzansky–Kaban mandibular types, multi-centre study of a surgical protocol to increase the sample number using a standard three-dimensional evaluation protocol, and differentiation between decreased growth and collapse of the newly generated bone. r 2002 European Association for Cranio-Maxillofacial Surgery. Published by Elsevier Science Ltd. All rights reserved. INTRODUCTION Hemifacial or facial microsomia is the second most common facial birth disorder after cleft lip and palate (Murray et al., 1985), with an incidence of 1/3500– 6000 live births (Grabb, 1965; Poswillo, 1974b). The condition is bilateral in 10% of cases (Converse et al., 1977). Reconstruction of the malformed hard and soft tissues of the microsomic face is a difficult task which is usually staged over many years. The choice of an appropriate treatment concept has therefore always been of concern to craniomaxillofacial cen- tres. The tissue deficiency in the ascending ramus (postero-lateral face), composed of the ascending mandibular ramus, the muscles of mastication and the integument, remains especially challenging. From the mid-1970s till the mid-1990s, costochon- dral grafting (Poswillo, 1974a; Samman, 1996; Padwa et al., 1998) was a widely adopted technique to reconstruct a deficient ascending ramus in Pruzans- ky–Kaban types IIB and III pre-pubertally (Table 1; Pruzansky, 1969; Mulliken and Kaban, 1987; Kaban et al., 1988). Less-affected children (mandibular types I and IIA) were not treated until adolescence (Obwegeser, 1970, 1974), or received ‘functional’ orthodontic appliances and early mandibular osteo- tomies to keep up with vertical midfacial development (Kaban, 1990). After skeletal correction, the soft-tissue deficiency in the posterior face was initially corrected with fat or derma-fat transplantations (Davis, 1968) and later with free microvascular flaps (LaRossa et al., 1980; Kaban, 1990, Siebert et al., 1996). Since 1995, distraction osteogenesis has been applied increasingly in young patients to induce bone- and soft-tissue generation. Both extra-oral (McCarthy et al., 1992, 1997; Molina and Ortiz Monasterio, 1995; Kaban et al., 1998) and intra-oral (McCarthy et al., 1995, 2001; Diner et al., 1996 and 1999) techniques have been used. It was proclaimed that distraction osteogenesis would affect the entire facial milieu with an increase in soft-tissue envelope due to expansion and muscle hypertrophy (McCarthy, 1994; Molina and Ortiz Monasterio, 1995; Rachmiel et al., 1995; McCarthy et al., 1998). Molina and Ortiz Monasterio (1995) stated that ‘The skeletal distraction proceeds parallel to an expansion of all the soft tissues of the face and upper neck (skin, muscles, vessels and nerves), achieving aesthetic results much superior to those obtained by skeletal surgery, by soft-tissue surgery done independently, or by a combination of both’. The photographs in their article are indeed convincing. However, recent follow-up studies of early distraction before skeletal maturation (before the permanent dentition is This paper was read in part at the autumn meeting of the Dutch Association for Cleft Palate and Craniofacial Anomalies, Alkmaar, 2001. This study was supported by a Hugo Obwegeser Travel Scholarship of the EACMFS. 201 Journal of Cranio-Maxillofacial Surgery (2002) 30, 201–207 r 2002 European Association for Cranio-Maxillofacial Surgery. Published by Elsevier Science Ltd. All rights reserved. doi:10.1054/jcms.2002.0314, available online at http://www.idealibrary.com on