Distraction osteogenesis for lengthening of the hard palate: Part II. Histological study of the hard and soft palate after distraction

To correct velopharyngeal incompetence, a new treatment concept was proposed in Distraction Osteogenesis for Lengthening of the Hard Palate: Part I (using lengthening of the hard and soft palate by distraction osteogenesis). Cephalometry and computed tomography showed successful elongation of the posterior hard palate with gradual calcification. Here the sequential use of fluorochrome markers (oxytetracycline, xylenol orange, DCAF [2,4-bis-N-N'-dicarboxymethyl aminomethyl fluorescein], and alizarin complexone) during the distraction and retention period is reported together with the histologic investigations using light and laser scan microscopy without prior demineralization. The experimental gap showed de novo osteogenesis in all dogs. The new bone was always in continuity with the original anterior and posterior palatal bone margins. It either bridged the experimental gap fully or left a small central zone of fibrous tissue, in which eventual ossification occurred. Several distinct zones could be distinguished: A small central zone was found with parallel strains of collagen fibers, oriented longitudinally in the direction of the distraction. Next to this zone a layer of undifferentiated mesenchymal precursor cells was seen in direct contact to newly formed bone. The next zone was coarse woven bone, showing a transition to mature lamellar bone through remodeling. No evidence of endochondral bone formation was found, i.e., all dogs showed exclusively intramembranous bone formation. The soft tissues showed no signs of alteration: in particular, there was no necrosis or scar formation. The soft tissues were not thinned but appeared to have followed the longitudinal displacement. In conclusion, gradual distraction osteogenesis of the hard palate could be a possible method for lengthening the palate to treat velopharyngeal incompetence.     

Cloning, characterization, and chromosomal localization of human superillin (SVIL)

The specific aim of this study was to determine the response of alveolar bone after it was augmented vertically using distraction osteogenesis and subsequently loaded with implant restorations. Four dogs each had four implants placed horizontally into an edentulous mandibular quadrant and, after integration, a distraction osteogenesis device was fabricated in the laboratory. An osteotomy was made to allow the crest of the alveolar ridge to be distracted vertically. After 10 mm of vertical distraction, the device was stabilized with light cured resin. Following bone fill confirmation of the distraction gap at 10 weeks, two implants were placed into the ridges, one in distracted bone and one in nondistracted bone. After 4 months for implant integration, freestanding prostheses were fabricated. Crestal bone levels were evaluated throughout the period of function. Animals were sacrificed after 1 year of loading, for histologic evaluation of the bone. The vertical ridge augmentation averaged 8.85 +/- 1.05 mm after 10 weeks of healing following distraction, without change over 1 year of implant loading. Histologic examination showed that bone had formed between the distracted segments, creating an augmented ridge. The average thickness of the labial cortex in the distraction gap was significantly thinner than the lingual cortex in distracted bone and the lingual and labial nondistracted cortical bone. The presence of the dental implant did not significantly affect cortical bone thickness. Serial sections showed that implants remained integrated and functional without soft tissue inflammation. Dental implants placed into alveolar ridges augmented with the technique of distraction osteogenesis maintained bone and were functional for the length of this study.     

Content and predictors of the ethnic identity of Russian-speaking immigrant adolescents in Finland

Even though osteodistraction has been well established in the extremities, the parameters used in craniofacial distraction have been essentially borrowed from orthopaedic experience. Latency is widely practised but its relevance has not been fully investigated. The purpose of this study was to establish the role of latency in mandibular distraction osteogenesis. Twenty-two growing Wethers sheep were allocated to four experimental groups. Six animals were allocated to each of Groups A, B and C and underwent bilateral mandibular corticotomies and attachment of an external lengthening device. Latent periods of 0, 4 and 7 days respectively were observed prior to beginning distraction. The distraction protocol consisted of a rate of 0.5 mm twice daily for 20 days, followed by a consolidation phase of 20 days after which the sheep were killed. Histology, bone densitometry and 3-point mechanical testing were performed on the harvested mandibles. Group D formed the control group (n = 4). Histologically, the distracted bone exhibited bone formation primarily via intramembranous ossification with scattered islands of cartilage. The regenerated bone had mechanical properties significantly weaker than the undistracted control group (P < 0.05), but between the experimental groups no statistically significant differences were demonstrable either in mechanical strength or DEXA density. These data indicate that a change in latency does not alter the properties of the regenerated bone in mandibular distraction osteogenesis and indeed no latent interval may be necessary at all in craniofacial distraction. This has implications for the duration of device fixation in distraction procedures.     

Unilateral palatal adhesion for paralysis after high vagal injury

Tumor involvement or sacrifice of the vagus nerve at the level of the jugular foramen is a cause of significant morbidity in skull base surgery. Management of the resulting dysphagia and dysphonia has been significantly improved by the development of vocal cord medialization. However, rehabilitation of palatal paralysis with the resulting velopharyngeal incompetence has not been widely addressed. In an effort to alleviate the symptoms of hypernasality and nasal reflux, unilateral adhesion of the palate to the posterior wall of the nasopharynx is proposed. This report summarizes the operative approach and results in eight patients. Results have been favourable with no significant postoperative complications observed to date.     

Intratumor and retroperitoneal massive hemorrhage caused by retroperitoneal liposarcoma]

It is now widely accepted that snoring causes significant social dysfunction. In the absence of obstructive sleep apnoea syndrome, palatal surgery offers a very good chance of eliminating or reducing snoring. The traditional operation of uvulopalatopharyngoplasty remains the 'gold standard', but may be complicated by velopharyngeal incompetence, severe post-operative pain and even nasopharyngeal stenosis. A newer technique to reduce snoring caused by palatal flutter by using a neodymnium:yttrium aluminum garnet laser to stiffen the soft palate has been introduced recently by another unit. We show that this procedure can be carried out using a CO2 laser, and present the initial results of the first 29 patients operated on at The Royal National Throat, Nose and Ear Hospital.     

Rat mandibular distraction osteogenesis: Part I. Histologic and radiographic analysis

The application of distraction osteogenesis to craniofacial surgery has altered the approach and treatment of congenital and acquired craniofacial defects. Although the histologic and ultrastructural changes associated with distraction osteogenesis have been described extensively, relatively little is known about the molecular regulation of this process. The elucidation of the molecular mechanisms of distraction osteogenesis has important clinical implications because it may facilitate the use of recombinant proteins or gene therapy to accelerate bone regeneration. Molecular analysis of distraction osteogenesis has been hindered by the use of large animal models in which only limited genetic information is available. In this study, a rat model of mandibular distraction osteogenesis is described. This report includes a pilot study (n = 50) to develop an appropriate distraction device and to determine the optimal placement of the osteotomy. The study subsequently included 80 animals, 35 of which were distracted at a rate of 0.25 mm per day for 6 days (1.5 mm total) and 35 that were distracted at a rate of 0.25 mm twice per day (3.0 mm total). These animals were killed at various time points (after latency and during the distraction and consolidation periods) and displayed histologic and radiographic findings of membranous bone distraction osteogenesis that were consistent with those in large ,animal and clinical models. In addition, five animals each were acutely lengthened 1.5 mm and 3.0 mm and demonstrated a fibrous nonunion. Furthermore, the utility of this model is demonstrated in the analysis of the molecular mechanisms of distraction osteogenesis by applying the polymerase chain reaction to total cellular RNA isolated from normal and distracted rat mandibles. In conclusion, it is believed that the rat model of distraction osteogenesis has significant advantages over traditional models, including decreased costs and facilitation of molecular analysis.     

Rat mandibular distraction osteogenesis: II. Molecular analysis of transforming growth factor beta-1 and osteocalcin gene expression

Distraction osteogenesis is a powerful technique capable of generating viable osseous tissue by the gradual separation of osteotomized bone edges. Although the histologic and ultrastructural changes associated with this process have been extensively delineated, the molecular events governing these changes remain essentially unknown. We have devised a rat model of mandibular distraction osteogenesis that facilitates molecular analysis of this process. Such information has significant clinical implications because it may enable targeted therapeutic manipulations designed to accelerate osseous regeneration. In this study, we have evaluated the expression of transforming growth factor beta-1, a major regulator of osteogenesis during endochondral bone formation and development, and osteocalcin, an abundant noncollagenous extracellular matrix protein implicated in the regulation of mineralization and bone turnover. The right hemimandible of 36 adult male rats was osteotomized, and a customized distraction device was applied. Animals were allowed to recover and, after a 3-day latency period, were distracted at a rate of 0.25 mm twice daily for 6 days followed by a 2- or 4-week consolidation period. Distraction regenerate was harvested after the latency period, days 2, 4, or 6 of distraction, and after 2 or 4 weeks of consolidation and processed for Northern analysis (n = 4 at each time point) and immunohistochemical localization of TGF-beta1 (n = 2 at each time point). Six sham-operated animals (i.e., skin incision without osteotomy) were also killed (immediately postoperatively), and the mandibles were harvested and prepared in a similar fashion. Equal loading and transfer of RNA for Northern analysis was ensured by stripping and probing membranes with a probe against GAPDH (a housekeeping gene). Our results demonstrate that the spatial and temporal patterns of TGF-beta1 mRNA expression and protein production coincide with osteoblast migration, differentiation, and extracellular matrix synthesis. In addition, we demonstrate that TGF-beta1 production may be an important regulator of vasculogenesis during mandibular distraction osteogenesis. Finally, we have shown that osteocalcin gene expression coincides temporally with mineralization during rat mandibular distraction osteogenesis.     

"Primary" orthostatic tremor. 10 clinical electrophysiologic observations

Distraction osteogenesis has been shown to be an effective method of lengthening and augmenting endochondral bone. It has also been applied effectively in the reconstruction of the membranous bones of the craniofacial skeleton. With the accumulation of clinical experience in mandibular distraction, the differences between endochondral and membranous bone distraction have become apparent, especially in the limitations of uniplanar distraction for the three-dimensional reconstruction of the deficient mandible. Distraction of the mandible in a single plane cannot satisfy fully the functional and structural requirements of the patient with malocclusion as well as deficiency of the skeletal and soft tissue. This study reports the development and clinical use of a multiplanar mandibular distraction device with the ability to achieve linear distraction (Z-plane or sagittal), angular distraction (Y-plane or vertical), and transverse distraction (X-plane or coronal). The device contains two independent gear arrangements attached to two arms that extend from the central unit. Therefore, the trajectory of the regenerated bone may be changed during the distraction process. The device also allows manipulation of the various planes of movement independent of each other. Furthermore, the rotational points for the multiplanar distraction devices are located at a single point; therefore only a single osteotomy and two pin sites are required. The multiplanar distraction device allows the surgeon to customize and contour the dimensions of the distraction process by controlling the trajectory of the translation of the regenerated bone.     

Recombinant growth hormone accelerates bone regenerate consolidation in distraction osteogenesis

The purpose of the present study was to prove whether homologous GH has a stimulating effect on bone healing. Therefore, left tibiae of 30 micropigs were osteomized and distracted over an external fixator at the rate of 2 mm/day on each of 10 consecutive days. Animals were killed after a healing period of another 10 days. The treatment group received 100 microg of recombinant porcine growth hormone (rpGH) per kilogram of body weight per day. Serial torsional nondestructive biomechanical tests were performed in vivo using a newly developed measurement device. After killing, destructive torsional strength testing of the sites of distraction was performed. To determine the endocrine response to the administration of rpGH, serum levels of insulin-like growth factor-I (IGF-I) were determined. Nondestructive in vivo testing showed that torsional stiffness of the regenerate was significantly higher in the treatment group than in the control group. Final regenerate torsional failure load was 131% higher and ultimate torsional stiffness was 231% higher in the treatment group than in the control group. The mean serum level of IGF-I increased to 440% of preoperative basal level in the treatment group and remained unchanged in the control group. Our data indicate that systemic administration of recombinant homologous growth hormone greatly accelerates ossification of bone regenerate in distraction osteogenesis.     

Development of the residual cleft in the hard palate after velar repair in a 2-stage palatal repair regimen

Delayed closure of the hard palate is believed to improve maxillary growth and facial appearance in cleft lip and palate patients. However, the cleft opening in the hard palate after velar closure might impair speech development. The aim of this investigation was to study the development of the residual cleft in the hard palate after 2-stage palatal repair (TSPR) in children born with complete cleft lip and palate (bilateral [BCLP]; n = 7 or unilateral [UCLP]; n = 22) or isolated cleft palate (CP; n = 9). Moreover, we aimed to investigate whether any morphologic factors before surgery might predict development of the residual cleft. Dental casts obtained prior to velar repair (mean age 7 months) and postoperatively at 1 1/2, 3, 4, 5 and 7 years were analyzed with a Reflex Microscope regarding the width, length and area of the cleft in the hard palate. The palatal cleft varied in size both pre- and postoperatively in all 3 types of cleft patients. The width of the cleft in the UCLP subgroup showed a marked reduction immediately after velar repair, but then, on average, remained stable until final surgical closure of the hard palate. In the BCLP subgroup the initially rather narrow width of the clefts remained unchanged postoperatively. Clefts in the CP subgroup, especially in those with a complete cleft, remained large after veloplasty. In 4 of the UCLP and 2 of the BCLP patients, the cleft width increased gradually. In some other subjects, both in the UCLP and BCLP subgroups, the residual cleft closed functionally with time, but this development could not be foreseen.     

Deformation of the palate in preterm infants

AIM: To investigate the effect of gestation, postmenstrual age, and orotracheal intubation on palate morphology. METHODS: A prospective study was made of 76 newborn infants of 25 to 41 weeks' gestation. Palate dimensions were measured on plaster models produced from serial palatal impressions. Palate size relative to that of the mouth was assessed using a ratio of palate depth to palate width (Palatal Index). RESULTS: Palate depth and width were related to postmenstrual age and gestation. Palatal Index ranged from 0.15 to 0.57, indicating a wide variation in palate shape, but gestation and postmenstrual age had no effect. Prolonged intubation had a small effect, equivalent to an increase in palatal depth of less than 2 mm at 32 weeks' postmenstrual age. The effect was transient. CONCLUSION: Prolonged orotracheal intubation (> 10 days) leads to a small and temporary increase in palatal depth. However, this is unlikely to account for palatal grooving, which is probably caused by an overgrowth of the lateral palatine ridges.     

Effect of methotrexate on distraction osteogenesis

To assess the potential of using distraction osteogenesis to reconstruct bone deficient limbs after limb salvage for musculoskeletal sarcomas, the authors examined the effect of methotrexate on distraction osteogenesis in a rabbit tibial lengthening model. Eighteen rabbits underwent tibial corticotomy and application of a ring external fixator. Rabbits were assigned randomly to one of two groups in which either methotrexate (n = 12) or placebo (n = 6) was administered during a 21-day distraction period. Serum methotrexate levels and complete blood cell counts were monitored during distraction, and radiographs of the tibia were obtained weekly. Half of the animals from each group were sacrificed at the end of distraction, and the remaining animals were sacrificed after 6 weeks of neutral fixation when bone normally bridges the gap. Using methotrexate at serum concentrations similar to those used clinically for the treatment of human osteosarcomas, the authors were unable to show significant radiographic, histologic, or chemical differences in the effect of this antineoplastic drug on distraction osteogenesis in the rabbit model.     

Palatal thickening and facial form in Paranthropus: examination of alternative developmental models

Paranthropus is distinctive among hominoids in its possession of a greatly thickened hard palate. Although traditionally considered a structural adaptation to counter high-magnitude masticatory stress, alternative developmental models are equally viable. Three models of palatal thickening were evaluated in this study. A mechanical model interprets palatal thickening as a compensatory response to increased instability of the midpalatal suture effected by an anterior placement of the masseteric muscle mass. This model predicts that palatal thickness is correlated with the length of the palate posterior to the masseteric tubercle. Two non-mechanical models consider the thickness of the hard palate to be structurally related to and therefore correlated with either 1) the degree to which the premaxilla overlaps the hard palate in the subnasal region or 2) the height of the posterior facial skeleton. The correlation of craniofacial variables was assessed intraspecifically in ontogenetic series of great ape and human crania. Tests of correlation were performed for each comparison using both residuals calculated from reduced major axis regression of the variable of interest against a measure of cranial size and shape ratios. A significant correlation of palatal thickness with posterior facial height in Pan suggests that the unusually thick hard palate of Paranthropus is directly related to the increased posterior facial height characteristic of this taxon. Further evaluation suggests that extreme palatal thickening in these specimens occurred by virtue of their possession of a nasal septum morphology in which the vomer extends onto the superior and nasal surface of the premaxilla. Such a morphology would have constrained the palatal nasal lamina to maintain the approximate level of the premaxillary nasal lamina throughout the growth process thereby promoting palatal thickening.     

Use of distraction osteogenesis for maxillary advancement: preliminary results

In this pilot study, the principle of distraction osteogenesis to advance the anterior maxilla of the dog was used. After an anterior maxillary osteotomy, the anterior segment was advanced 10 mm in 10 days. Soft and hard tissue formation resulted in complete healing across the distraction gap without a soft tissue defect.     

Pharyngoplasty in patients with cleft lip and palate after maxillary advancement

The development of velopharyngeal incompetence and increased hypernasality after maxillary advancement has been described previously by several authors. If speech and velopharyngeal function deteriorate after maxillary advancement, pharyngoplasty is frequently the treatment procedure of choice because of the natural cause of the deficit. Of 91 cleft lip and palate patients who have undergone maxillary advancement at the Australian Cranio-Facial Unit, 23 patients received a pharyngoplasty after surgery. Thirteen of these patients who had pre- and postoperative speech evaluations were included in this study. Of the 13 patients, six patients received a superiorly based pharyngeal flap, two patients underwent an orticocheal pharyngoplasty, and five patients received either a revision or augmentation of the previous flap based on results of preoperative examinations. Serial nasendoscopic evaluations were available for 11 of these 13 patients, and they demonstrated that velopharyngeal function improved after pharyngoplasty in six patients and was unchanged in five patients. Of the 13 patients, 10 improved and three patients were unchanged on an intelligibility rating. Nine of the 13 patients demonstrated decreased hypernasality and four patients were unchanged. Hyponasality decreased in two patients increased in one patient, and was unchanged in one patient. Because the results obtained are considered acceptable, the authors conclude that pharyngoplasty can be used effectively to treat velopharyngeal dysfunction subsequent to Le Fort I maxillary advancement.     

Evaluation of the mechanical environment during distraction osteogenesis

Physical forces have been hypothesized to direct the process of bone regeneration during distraction osteogenesis. However, despite significant clinical experience, relatively little is known about how the mechanics of distraction influence bone formation. This study investigated net fixator forces and strains in the distraction callus during bilateral lengthening of tibiae in New Zealand White rabbits. Distractions yielded a classic viscoelastic response with a sharp increase in fixator force, followed immediately by significant relaxation. Tension acting on mesenchymal gap tissue caused by distraction was estimated to reach more than 30 N by the time full lengthening was achieved. Average maximum cyclic strains within the distraction zone during ambulation were estimated to be 14% to 15% and supported by the results of fluoroscopic imaging. Paradigms for fracture healing have hypothesized that such strains are incompatible with new bone formation. The documented clinical success of distraction osteogenesis at stimulating large volumes of new bone suggests that other mechanisms that warrant additional investigation may be at work during distraction.     

Excess mortality and its relation to hypertension and proteinuria in diabetic patients. The world health organization multinational study of vascular disease in diabetes

The speech problem in patients born with cleft lip and palate is mainly due to the insufficiency of the velopharyngeal (VP) valving mechanism, manifested as in visually seen nasal emission, and auditorily perceived hypernasality and articulation disorders. Evaluations of resonance and VP function can be conducted by: (1) perceptual rating scale based on speech pathologist's subjective judgement and (2) objective instrumental assessment, by the use of specific instrument. Nasopharyngoscopy has been commonly used clinically to diagnose VP function. The purpose of this study is: using nasopharyngoscopy to investigate the differences in VP mechanism between those with VP competence and VP incompetence in the dimension of velar displacement, lateral pharyngeal wall (LPW) displacement, degree of VP closure and pattern of VP closure. Ninty-eight subjects were studied from June 1990 to August 1991. They were divided into 4 groups: (1) group 1: normals with normal speech; (2) group 2: cleft of lip only, with normal speech; (3) group 3: cleft palate without nasal emission, but normal articulation; (4) group 4: cleft palate with nasal emission, with or without articulation error. Age range was from 6-47 years old with equal sex distribution. Ten Chinese sentences were used for standard test sentences, and were grouped according to Mandarin phonological distinctive features into 5 categories: (1) nasals; (2) vowels; (3) plosives; (4) fricatives/affricates; (5) connected number counting. The result indicates that the insufficient velar displacement to contact posterior pharyngeal wall is a determining factor causing velopharyngeal insufficiency in group 4; however, the lateral pharyngeal wall movement is not significantly different among 4 groups. Coronal pattern of velopharyngeal closure is the most common pattern among 4 groups of speakers.     

Preparation for upper gastrointestinal endoscopy: opportunity or inconvenience?

A 59-year-old man, who manifested lower back pain, was admitted with sepsis and disseminated intravascular coagulation (DIC). A computed tomographic scan showed a slight thickening of the abdominal aortic wall. A blood examination revealed pancytopenia. Myelodysplastic syndrome was diagnosed after bone marrow aspiration and a chromosome analysis. Sepsis due to a Staphylococcus aureus infection and DIC subsided after medical treatment; however, an aortobifemoral bypass was performed upon the detection of a localized rupture of a mycotic abdominal aortic aneurysm 1 month later. The patient is still alive 2 years after operation despite the presence of a hematological disorder.     

UDP-GlcNAc:Galbeta1-->3GalNAc (GlcNAc to GalNAc) beta1-->6N-acetylglucosaminyltransferase holds a key role on the control of CD15s expression in human pre-B lymphoid cell lines

Distraction osteogenesis has become an important technique to treat craniofacial skeletal dysplasia. In this study, the technique of maxillary distraction with a rigid external distraction device is presented. Cephalometric results in the first 14 consecutive patients are analyzed. The study sample consisted of 14 patients with various cleft types and maxillary hypoplasia treated with the rigid external distraction technique. Analysis of the predistraction and postdistraction cephalometric radiographs revealed significant skeletal maxillary advancement. All patients had correction of the maxillary hypoplasia with positive skeletal convexity and dental overjet after maxillary distraction. The morbidity for the procedure was minimal. Surgical and orthodontic procedures are thoroughly described.