Unilateral Craniofacial Microsomia Research Articles

The Importance of Vector Selection in Preoperative Planning of Unilateral Mandibular Distraction

Unilateral craniofacial microsomia is characterized by soft-tissue and bony deficiencies. Mandibular distraction osteogenesis can be used to augment the hypoplastic skeleton and improve facial symmetry. The aim of this study was to determine how the vector of unilateral mandibular distraction affects treatment outcomes. A retrospective chart and radiographic review was conducted of all patients treated with external mandibular distraction osteogenesis between October of 1990 and February of 2004 (n = 185). A subset of 42 patients underwent primary unilateral, uniplanar, external distraction, and 13 patients were found to have satisfied inclusion criteria and had adequate predistraction and postdistraction lateral and posteroanterior cephalograms. Cephalometric tracings were made and multiple points and planes were assessed before and after distraction. A strong correlation was noted between the vector of distraction and the movement of the mandible. A horizontal vector of distraction resulted in minimal increase in ramal length but a marked shift in the mandibular midline (r = 0.68, p < 0.05). In contrast, a vertical vector of distraction resulted in marked mandibular ramus lengthening but minimal mandibular midline shift (r = 0.73, p < 0.05). Mathematical formulas were derived to correlate the distraction vector and mandibular movements to improve preoperative planning. Successful distraction is dependent on accurate preoperative planning and prediction of outcomes. This study demonstrates a predictable relationship between the vector of unilateral distraction and the mandibular response.

Comparison of Skeletal and Soft-Tissue Changes following Unilateral Mandibular Distraction Osteogenesis

The purpose of this study was to investigate the relationship between soft-tissue and underlying skeletal structures before and after unilateral mandibular distraction osteogenesis. The sample consisted of 11 patients (three girls and eight boys) with an average age of 4.6 years at the time of treatment. All patients had unilateral craniofacial microsomia (four right-sided and seven left-sided unilateral craniofacial microsomia) and all underwent unilateral mandibular distraction osteogenesis. Measurements were performed on frontal medical photographs and posteroanterior cephalograms at predistraction (time 1) and postdistraction (time 2) periods. Left and right ramus heights, skeletal midline deviation, and transverse occlusal plane were measured on the posteroanterior cephalograms and compared with the linear distances between the lip commissures and the orbital plane, the circumference of both sides of the faces, and the angulation of the oral commissure plane as recorded on the medical photographs, respectively. To reduce magnification error, ratios of affected to less affected sides of the mandibles and soft-tissue facial structures were selected and studied. A similar relationship was observed between soft-tissue and skeletal components. However, there was no 1:1 relationship between the changes in ramus height and improvement in parallelism of lip commissures to the orbital plane. A significant improvement in soft- and hard-tissue anatomy has been observed following unilateral distraction osteogenesis of the mandible. The relationship between the soft-tissue and skeletal correction was different for all patients because of the large range in severity of the craniofacial malformation. Greater skeletal deficiency requires more correction to achieve symmetry of both hard and soft tissue.

Marriage of Hard and Soft Tissues of the Face Revisited

Patients with craniofacial anomalies can have hard and soft tissue deficiencies. In some cases, distraction osteogenesis can restore the bony deficiencies, but the soft tissue contour defect remains problematic. For these patients, the union of distraction osteogenesis and microvascular free flaps (MVFF) can restore bone and soft tissue form and function. A retrospective review of all patients treated with mandibular distraction osteogenesis between 1989 and 2005 was performed. A similar review of all patients treated with MVFFs was performed. These 2 cohorts were cross-referenced to identify all patients treated with both procedures. The indications, choices, safety, and efficacy of MVFF reconstruction of facial soft tissues following mandibular reconstruction are reviewed. Over a 16-year period, 141 patients underwent mandibular distraction osteogenesis; 8 patients treated with mandibular distraction osteogenesis subsequently underwent 12 MVFFs. Patient diagnoses included unilateral craniofacial microsomia (n = 2), bilateral craniofacial microsomia (n = 3), Goldenhar syndrome (n = 1), Nager syndrome (n = 1), and Treacher-Collins syndrome (n = 1). Free flap choices included 10 parascapular fasciocutaneous, 1 parascapular osteofasciocutaneous, and 1 fibular osteocutaneous flap. Four patients underwent staged bilateral free flaps. A single case of partial flap loss was the only complication. In all cases, facial contour was improved following MVFF transfer. In certain circumstances, facial rehabilitation may require the marriage of craniofacial and microsurgical techniques to restore both form and function. In these cases, mandibular distraction osteogenesis and MVFFs can be safely and effectively combined.

Long-Term Stability and Growth following Unilateral Mandibular Distraction in Growing Children with Craniofacial Microsomia

The purpose of this study was to evaluate long-term mandibular skeletal stability and growth following unilateral mandibular distraction in growing children. This retrospective longitudinal study of 12 consecutive patients with unilateral craniofacial microsomia who underwent mandibular distraction had a range of 5 years of postdistraction follow-up; five patients were followed for 10 years. Records included clinical photographs, dental study models, lateral and posteroanterior cephalograms, and panoramic radiographs obtained before distraction, at the time of device removal, and 1, 5, and 10 years after distraction. The mean patient age at the time of distraction was 48 months. The device was activated an average of 21.7 mm at the rate of 1 mm per day. The mean latency period was 6.1 days, and the mean consolidation period was 60.6 days. Fifty-two parameters were examined at each of the five time intervals. On average, the ramal length (condylion to gonion) increased 13.04 mm in the distracted rami. At 1 year after distraction, this dimension decreased by 3.46 mm. At 5 and 10 years after distraction, the average condylion-gonion dimension increased by 3.83 and 4 mm, respectively, with an average growth rate of 0.87 mm per year; during the same period, the unaffected ramus grew 1.15 mm per year. The distraction technique does not eliminate the inherent growth potential of the affected mandibular side. Facial asymmetry is significantly improved after distraction, and despite mild relapse observed during the first year, surgical correction is stable in the later years of follow-up.

Morphometric analyses of the mandible in prepubertal craniofacial microsomia patients treated with an inverted-L osteotomy.

To analyze changes in mandibular form associated with an inverted-L osteotomy and autogenous bone graft, preoperative, early postoperative (EPO), and late postoperative (LPO) lateral cephalographs of 14 children (mean age approximately 9 years) with unilateral craniofacial microsomia (CFM) were scanned and nine mandibular landmarks digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Cephalometry, Euclidean distance matrix analysis (EDMA), and thin-plate spline (TPS) analyses were carried out on mean mandibular configurations. Cephalometric results showed increases in oblique mandibular length (approximately 9% on average, P < 0.05) and increased ramus height (P < 0.05). Similarly, using EDMA there were also significant differences (P < 0.05) between the mean preoperative, EPO, and LPO configurations. The most demonstrable EPO change in the mandibular configuration using EDMA was increased oblique length (approximately 11%). This improvement depended on ramus oblique lengths increasing by approximately 26%, ramus height increasing by approximately 25%, and mandibular body length increasing by approximately 5%. For TPS analysis, affine and nonaffine changes contributed to the total spline. In all three comparisons the affine transformation showed an antero-inferior rotation of the mandibular configuration. For nonaffine changes the EPO configuration indicated a supero-inferior stretch of the mandibular configuration. The nonaffine LPO changes maintained the supero-inferior stretch of the mandibular configuration. It is concluded that improvements in the lateral facial profile of CFM patients can be achieved using an inverted-L osteotomy, with little relapse approximately 2 years postoperatively.

Treatment of obstructive sleep apnea syndrome by mandibular elongation using osseous distraction followed by a Le Fort I advancement osteotomy: Case report

The work of Snyder et al 1 Snyder CC Levine GA Swanson HM et al. Mandibular lengthening by gradual distraction: Preliminary report. Plast Reconstr Surg. 1973; 51: 506 Crossref PubMed Scopus (461) Google Scholar in 1973 on canine mandibles made it possible to apply the principle of bone elongation that was already widely used by Ilizarov in clinical orthopedics for elongation of the long bones. 2 Ilizarov GA Basic principles of transosseous compression and distraction osteosynthesis. Ortop Travmatol Protez. 1971; 32: 7 PubMed Google Scholar Application of this technique in maxillofacial surgery dates back to 1992, when McCarthy and co-workers 3 McCarthy JG Schreiber J Karp N et al. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg. 1992; 89: 1 Crossref PubMed Scopus (1566) Google Scholar , 4 McCarthy JG The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg. 1994; 21: 625 PubMed Google Scholar reported the first cases of mandibular elongation using an external device in 4 patients with congenital mandibular defects (facial microsomia, Nager syndrome). Since then, large series have been reported, 5 Molina F Ortiz Monasterio F Mandibular elongation and remodeling by distraction: A farewell to major osteotomies. Plast Reconstr Surg. 1995; 96: 825 Crossref PubMed Scopus (447) Google Scholar and new indications have been described using this principle, in particular in preprosthetic surgery and reconstruction of mandibular continuity defects after surgical resection or trauma (bone transport). The devices available were initially applied externally, 3 McCarthy JG Schreiber J Karp N et al. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg. 1992; 89: 1 Crossref PubMed Scopus (1566) Google Scholar , 4 McCarthy JG The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg. 1994; 21: 625 PubMed Google Scholar but they have now been miniaturized and can be applied intraorally. 6 McCarthy JG Staffenberg DA Wood RJ et al. Introduction of an intraoral bone-lengthening device. Plast Reconstr Surg. 1995; 96: 978 Crossref PubMed Scopus (72) Google Scholar , 7 Chin M Toth BA Distraction osteogenesis in maxillofacial surgery using internal devices: Review of five cases. J Oral Maxillofac Surg. 1996; 54: 45 Abstract Full Text PDF PubMed Scopus (465) Google Scholar , 8 Diner PA Kollar EM Martinez H et al. Intraoral distraction for mandibular lengthening: A technical innovation. J Craniomaxillofac Surg. 1996; 24: 92 Abstract Full Text PDF PubMed Scopus (111) Google Scholar

Mandibular Growth after Distraction in Patients under 48 Months of Age

Distraction osteogenesis is an effective technique for reconstruction of the congenitally deficient mandible. However, the age at which it is best performed remains under discussion. Distraction performed at an early age, while possibly allowing the face to develop with a more normal functional matrix, may entail a higher rate of complications. Additionally, it is possible that subsequent asymmetric growth of the mandible may necessitate serial distraction. To address this issue, the clinical records and cephalometric radiographs of all patients less than 48 months of age undergoing mandibular distraction at New York University Medical Center between August of 1989 and August of 1997 were examined. There was a total of 14 patients ranging in age from 19 months to 43 months. Nine patients had a diagnosis of unilateral craniofacial microsomia, three had Treacher Collins syndrome, one had Nager syndrome, and one had bilateral developmental micrognathia. The average amount of distraction was 27 mm (range, 23 to 39 mm) in unilateral cases and 24 mm in bilateral cases (range, 15 to 31 mm). The period of clinical follow-up averaged 32.6 months (range, 12 to 92 months). All patients showed significant improvement in craniofacial appearance, and in four patients, long-term tracheostomy tubes were removed. There were two major complications. In one patient with craniofacial microsomia, there was a relapse in the early postretention phase related to the presence of a dentigerous cyst. This required removal of the cyst and repeat distraction. In the patient with Nager syndrome, a coronoid ankylosis developed requiring surgical release. There were no other major complications. The scars required revision in only two of the patients. Cephalometric analysis of the patients in the study revealed a differential in the rate of growth between the affected and the unaffected side in all cases of craniofacial microsomia. The affected side always grew at a slower rate than the contralateral side after the distraction process was complete. This led to a progressive asymmetry of the rami, clinically expressed by some degree of facial asymmetry and an occlusal cant. For this reason, secondary distraction was required in one patient and is planned in a second. Initial overcorrection of the patient would seem to minimize the likelihood that secondary distraction will be necessary. Distraction osteogenesis for reconstruction of the mandible in this subset of young patients was a safe and effective technique for improving the craniofacial skeletal form and appearance, with minimal associated morbidity. Longer follow-up is necessary to assess the full impact of growth in these cases. (Plast. Reconstr. Surg. 103: 1361, 1999.)

Mandibular growth after distraction in patients under 48 months of age.

Distraction osteogenesis is an effective technique for reconstruction of the congenitally deficient mandible. However, the age at which it is best performed remains under discussion. Distraction performed at an early age, while possibly allowing the face to develop with a more normal functional matrix, may entail a higher rate of complications. Additionally, it is possible that subsequent asymmetric growth of the mandible may necessitate serial distraction. To address this issue, the clinical records and cephalometric radiographs of all patients less than 48 months of age undergoing mandibular distraction at New York University Medical Center between August of 1989 and August of 1997 were examined. There was a total of 14 patients ranging in age from 19 months to 43 months. Nine patients had a diagnosis of unilateral craniofacial microsomia, three had Treacher Collins syndrome, one had Nager syndrome, and one had bilateral developmental micrognathia. The average amount of distraction was 27 mm (range, 23 to 39 mm) in unilateral cases and 24 mm in bilateral cases (range, 15 to 31 mm). The period of clinical follow-up averaged 32.6 months (range, 12 to 92 months). All patients showed significant improvement in craniofacial appearance, and in four patients, long-term tracheostomy tubes were removed. There were two major complications. In one patient with craniofacial microsomia, there was a relapse in the early postretention phase related to the presence of a dentigerous cyst. This required removal of the cyst and repeat distraction. In the patient with Nager syndrome, a coronoid ankylosis developed requiring surgical release. There were no other major complications. The scars required revision in only two of the patients. Cephalometric analysis of the patients in the study revealed a differential in the rate of growth between the affected and the unaffected side in all cases of craniofacial microsomia. The affected side always grew at a slower rate than the contralateral side after the distraction process was complete. This led to a progressive asymmetry of the rami, clinically expressed by some degree of facial asymmetry and an occlusal cant. For this reason, secondary distraction was required in one patient and is planned in a second. Initial overcorrection of the patient would seem to minimize the likelihood that secondary distraction will be necessary. Distraction osteogenesis for reconstruction of the mandible in this subset of young patients was a safe and effective technique for improving the craniofacial skeletal form and appearance, with minimal associated morbidity. Longer follow-up is necessary to assess the full impact of growth in these cases.

The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia.

The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia.

The Role of Distraction Osteogenesis in the Reconstruction of the Mandible in Unilateral Craniofacial Microsomia

Laboratory and clinical studies have shown that mandibular distraction is an effective and powerful reconstructive surgical technique. It is safely performed without the need for blood transfusion or bone graft. Because of concomitant expansion of the functional matrix (the associated skin, subcutaneous fat, and muscles of mastication), there is a multidimensional expansion of the lower jaw with minimal, if any, evidence of relapse. Moreover, the surgical reconstruction can be commenced by 2 years of age, and the vector of distraction can be controlled by preoperative design. Finally, the increase in resulting mandibular bone stock will provide more reconstructive options in the future for traditional orthognathic surgical techniques. The technique has been criticized, either for the cutaneous incision for the approach to the mandible or for the scar resulting from the path of the distracting screws. However, with careful placement of the device, the resulting scar can be placed in the lines of minimal tension with a resulting satisfactory scar. It has been assumed that the osteotomy results in interruption of the inferior alveolar nerve. However, questioning of the older patients has failed to detect any change in sensation of the lower lip. The status of the inferior alveolar nerve in the hypoplastic mandible has also never been studied. Insertion of the screws required an area of bone stock that is edentulous, and this finding can make application of the device difficult in some patients. The length of treatment has been criticized--approximately 3 months. However, this is offset by the ease of treatment, the degree of safety, and the reduction in hospital time without the need for blood transfusion or bone graft. The results to date indicate that the technique can be applied to the correction of the milder mandibular deficiencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Unilateral craniofacial microsomia: Part I. Mandibular analysis

Various attempts to describe the skeletal characteristics of unilateral craniofacial microsomia have been made with the use of cephalometric and panoramic roentgenograms. Previous studies have been only descriptive in nature. To date, a detailed (quantitative) cephalometric analysis of the mandibular deformity has not been reported. The purpose of this study was to describe the skeletal jaw deformity by means of cephalometric landmarks in the lateral view. The patient population consisted of sixteen boys and eight girls who ranged in age from 6 to 16 years. They were compared to the University of Michigan normal control population for the following measures: gonial angle, mandibular plane angle, overall oblique length of the mandible, ramal height, and body length. The affected side showed a larger gonial angle and mandibular plane angle. The oblique length of the mandible (Cd-Gn) was decreased on both sides, as were ramal height and body length. Paradoxically, body length appeared shorter on the unaffected side than on the affected side. This paradoxical observation could be attributed to a shift of the mandible in relation to the midsagittal plane of the cranial base, the film cassette, and the path of the x-ray beam. Observation of the mandible in the basilar cephalogram explained the geometry of the projection error found in the lateral view. Similar projection errors exist for patients with other types of craniofacial asymmetry. It is suggested that two radiographic views, orthogonal to each other, should be used to define the x, y, and z planes for studies of craniofacial abnormality.