Trans-sinusoidal maxillary distraction in three cleft patients

The trans-sinusoidal maxillary distractor (TS-MD) was used to achieve maxillary advancement in three patients with repaired cleft lip and palate. After preoperative computer-aided planning of the distraction vectors, each TS-MD was bent on a stereolithographic model of the maxilla of the patient. The devices were intraoperatively positioned using a methyl-methacrylate template. After standard Le Fort I osteotomy the devices were intraorally activated. After distraction the devices remained in situ for 3 months as rigid internal fixation of the maxilla. All patients were successfully distracted according to protocol. Maxillary advancement was 12, 8 and 11 mm. In two patients, additional maxillary widening of 6 and 8 mm was achieved by choosing divergent distraction vectors. After distraction a clockwise rotation of the maxilla was observed in two patients. There was no relapse during the 3 months of consolidation and 12-month follow-up. The TS-MD allows not only distraction but also rigid internal fixation after distraction. It was easy to apply but difficult to remove. Owing to preoperative 3D planning of the distraction vectors, the results were predictable, but clockwise rotation of the maxilla during distraction should be considered in planning. The distractor did not interfere with function or social activities during distraction and retention periods. After removal it left no extraoral scars.     

Maxillary distraction using a trans-sinusal distractor: technical note

In this pilot study, the principle of distraction osteogenesis was used to advance the midface of a boxer dog. A modified high Le Fort I-type osteotomy was performed. Following a latency period of 5 days the maxilla was distracted 14 mm in 14 consecutive days at a rate of 1 mm per day. Ten weeks after the completion of the distraction, multiple biopsies were taken across the distraction gap. Histological observation showed bone deposition in the osteotomy sites. Soft and hard tissue formation resulted in complete healing across the distraction gap. The maxillary sinus was used to accommodate the distraction device. Superimposition of the standardized lateral cephalograms taken at the end of distraction and 14 months after the removal of the distractors showed no sign of relapse in the achieved sagittal advancement of the maxilla. This small, intraoral trans-sinusal placed distractor has a completely new conceptual design, and may be helpful in distraction of maxilla in children and adults with midfacial hypoplasia.     

Rapid maxillary distraction protocol utilizing the halo distraction system and rigid internal fixation.

OBJECTIVE: To shorten head frame wear time associated with external halo distraction (HD), we have adapted a protocol for maxillary distraction with the halo system that integrates plate fixation. PARTICIPANTS: All patients had a history of cleft lip and/or palate and maxillary retrusion > or = 8 mm. Five patients treated with this protocol and followed for at least 1 year were included in this study. INTERVENTIONS: The protocol included a 3-day latency period, variable maxillary distraction, and removal of the halo device with simultaneous rigid internal fixation. Two patients had a variable period of maxillomandibular fixation (MMF), which maintained the maxillary advancement and idealized intercuspal position while permitting further callus maturation. Cephalographs were obtained preoperatively, immediately following distractor removal, and 1 year after rigid internal fixation. RESULTS: The mean age at time of surgery was 18.7 years. The maxillary deficiency ranged from 8 to 15 mm (mean = 10.6 mm). All five patients demonstrated excellent occlusion. Cephalometric analysis 1-year post rigid internal fixation revealed minimal (<1 mm) skeletal relapse. CONCLUSIONS: Rapid maxillary distraction followed by MMF to maintain maxillary advancement may reduce halo device wear to 1 to 2 weeks. MMF optimizes occlusion by forcing the maxillary teeth into maximal intercuspal position. Rigid fixation is not only associated with less long-term relapse compared to nonrigid forms of fixation, but also minimizes the incidence of nonunion. This treatment protocol provides the advancement possible with distraction osteogenesis and the accuracy of orthognathic surgery, thereby minimizing external head frame wear.     

Bilateral mandibular distraction in adult dogs with an epiperiosteal distractor

We tested the function and efficiency of a new intraoral, bone-borne distraction device for mandibular lengthening, and the effect of bilateral transsection of the inferior alveolar arteries on osteogenesis in adult dogs. Nine adult Beagles had bilateral complete mandibular osteotomies and epiperiosteal placement of the distractor. After 7 days, the mandibles were distracted at 1 x 1mm/day, 1 x 0.5 mm/day or 2 x 0.25 mm/day for 15 or 30 days, respectively. Hemimandibles were harvested after 1, 14, or 42 days consolidation and evaluated clinically, radiographically and histologically. The mean distraction achieved was 11 mm (range 4-16 mm). New bone formation and clinical stability increased with increasing consolidation time and was independent of the distraction protocol used. Osteogenesis at the distal and proximal mandibular fragments did not differ. In 10/18 distraction sites, wound dehiscences compromised osteogenesis. The new epiperiosteal distractor permitted successful distraction osteogenesis despite complete bilateral osteotomy with section of the medullary vessels in adult dogs.     

LeFort I soft tissue distraction: a hybrid technique

Distraction osteogenesis of the craniofacial skeleton has greatly enhanced traditional osteotomies and bone grafting techniques. The obvious drawbacks to an external distraction device are visibility and awkwardness. A hybrid technique of maxillary distraction for soft tissue expansion and formation of regenerate, combined with rigid internal fixation, is proposed. This technique permits maxillary advancement that may be unattainable by traditional methods and obviates the extended use of external hardware during latency and consolidation of the regenerate. It also allows for optimization of the dental occlusion. The study group was composed of five patients with severe skeletal class III malocclusion who had combined maxillary distraction followed by rigid internal fixation. The average age at the time of LeFort osteotomy was 17 years, with a range of 13 to 19 years. The latency period ranged from 1 to 5 days, and distraction was done at the rate of 1 mm/d in all patients. After the proposed advancement was attained, all patients had reoperation, consisting of distractor removal, optimized interdental relationships with intermaxillary fixation, and placement of rigid internal fixation. The average anterior-posterior maxillary advancement was 11.6 mm, with a range of 10 to 13 mm. Lateral cephalograms and clinical examination showed no relapse at an average follow-up of 25 months, with a range of 5 to 40 months.     

Monobloc distraction in an infant, using the rigid external distractor: problems and solutions--a case report.

INTRODUCTION: Patients with craniofacial dysostosis frequently develop functional problems including raised intracranial pressure, ocular dysfunction, obstructive sleep apnoeas and failure to thrive. These functional problems can be treated by a number of different techniques. The monobloc frontofacial advancement has the ability to correct all of these functional problems in one procedure, but can be associated with high morbidity particularly in the young infant. AIM: A case report of a 4-month-old infant with Pfeiffers syndrome and severe functional problems treated by monobloc osteotomy and distraction using the rigid external distractor is reported. The management, problems and complications encountered with this patient are discussed together with the role of monobloc distraction in the infant. Adaptation of the rigid external distraction (RED) technique using two titanium mesh sheets to prevent penetration of the skull by the cranial pins is described. CONCLUSIONS: Monobloc frontofacial advancement in the very young can be successfully achieved using the RED frame, thus treating exophthalmus, raised intracranial pressure and upper airway problems in one operation. However, it may be associated with significant complications and should only be used for those extreme cases where the severity of the functional problems prevent treatment being delayed.     

Radiographic evaluation of bone formation in the pterygoid region after maxillary distraction with a rigid external distraction (RED) device

In recent years, distraction osteogenesis has been used to correct skeletal disharmonies in the craniofacial region including the mandible and maxilla. Rigid external distraction has been used successfully to correct severe maxillary skeletal discrepancies. However, the characteristics of the newly formed bone have not been studied. A modified tomogram technique was used to analyze the radiological characteristics of the bone generated after maxillary advancement with rigid external distraction. The newly developed protocol may assist the clinician to evaluate the distracted area and to determine the length of stabilization required after active treatment with rigid external distraction.     

Callus distraction of the midface in the severely atrophied maxilla--a case report.

OBJECTIVE: This report introduces the possibilities of callus distraction in the extremely atrophied, edentulous midface in a cleft lip and palate patient. INTERVENTION: After a subtotal Le Fort II osteotomy, tension wires were fixed to the zygomatic buttresses and frontal sinus walls by way of titanium miniplates and mesh and connected to a rigid external distractor. Then distraction of the whole midface (1 mm/d) was performed. RESULTS: Even in severe atrophy a distraction of the maxilla of 20 mm was possible. Stability has been shown for more than 5 months. CONCLUSIONS: Rigid external midfacial distraction may be used in difficult cases for the correction of sagittal discrepancies where conventional orthognathic surgery is likely to be insufficient. Further investigations will concentrate on the long-term outcome.     

A case of improved obstructive sleep apnea by distraction osteogenesis for midface hypoplasia of an infantile Crouzon's syndrome

We performed Le Fort III midfacial advancement with gradual distraction using internal devices on a 2-year 5-month-old boy with Crouzon's syndrome with associated severe obstructive sleep apnea. The device was not activated until 7 days after surgery, after which the distraction was initiated, 1 mm per day, and the midface was advanced 4 mm intraoperatively and distracted 12 mm postoperatively. A total advancement of 16 mm was obtained. The obstructive sleep apnea improved remarkably after the distraction. In infants and younger children with associated severe obstructive sleep apnea, advancement by distraction osteogenesis of the midface in Le Fort III maxillary osteotomy will be initially indicated to obviate tracheostomy improving the upper airway obstruction.     

Effect of recombinant human bone morphogenetic protein-2 on mandibular distraction osteogenesis

The purpose of this investigation was to study the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) on bone formation of mandibular distraction osteogenesis. Six skeletally mature sheep underwent 10 mm of bilateral mandibular distraction osteogenesis via a custom-made distractor. Three micrograms of rhBMP-2 with a collagen carrier was implanted in the osteotomy site of one side of the mandible during the osteotomy phase. The contralateral side was used as the control group, and no material was implanted into the distracted area. At 10 days after the end of distraction, all animals were killed, and the distracted calluses were harvested for radiologic and histologic analysis. New bone was generated in the distracted zone in all groups. Histologic and radiologic examination showed that the new bone formation was greater in the rhBMP-2 group than in the control group. Quantitative computed tomography evaluation, however, did not demonstrate a significantly different mean bone density of the regenerates between the 2 groups. The results indicate that application of a rhBMP-2/collagen implant during the osteotomy phase of distraction osteogenesis increased bone formation but did not have a significant effect on bone density of the regenerates.     

Comparison of different distraction rates in the mandible: an experimental investigation.

This study evaluated bone distracted in rabbit mandibles at different intervals and with different daily rates of distraction histologically with the goal of attaining a universally accepted distraction protocol. Osteogenesis was investigated in mandibles distracted at different rates in 24 New Zealand rabbits using a custom-made submerged distractor. Distraction was started on the third postoperative day for a total of 10 mm. The animals were divided into four groups each containing six rabbits. Group 1 was distracted 0.5 mm twice a day; Group 2 was distracted 1.0 mm once a day; Group 3 was distracted 1.0 mm twice a day and Group 4 was distracted 2.0 mm once a day. All the animals were sacrificed 6 weeks after completion of distraction. Half of the distracted mandibles were decalcified for H&E staining and polarized light microscopy studies. Sections of the undecalcified half of the samples were stained with Goldner's stain. The results indicate that a distraction rate of 1.0 mm per day produced the best osteogenesis among the tested rates. There was no great difference in osteogenesis between 1.0 mm once a day and 0.5 mm twice a day. However, 0.5-mm distraction may result in immature bone healing. Distraction of 1.0 mm twice a day resulted in incomplete osteogenesis, while distraction of 2.0 mm once a day resulted in fibrous union. It is clear from these results that a shorter period of device fixation should be achieved by methods other than rapid distraction.     

Use of an internal bidirectional distractor to elongate goats' mandibles

We investigated the feasibility of using an internal bidirectional mandibular distractor to elongate the mandibular bodies and rami of 4 mature male goats. An osteotomy was made at the right mandibular angle and the distractor placed within the osteotomy and allowed to heal in place for 5 days. The mandibles were simultaneously distracted vertically and horizontally at a rate of 0.5mm/day for 30 days. After a 12-week consolidation period, all the goats were killed for gross, radiographic, and histological evaluation. Smooth new bone had been restored in the distracted area after 12 weeks' consolidation, and the gross, radiographic, and histological evaluations showed that the new bone was similar to the native bone. These results suggest that the internal bidirectional distractor could permit bidirectional distraction osteogenesis in a goat model.     

硬腭两维牵张器的研制及体外实验研究

目的：探讨腭骨外固定两维牵张器在腭裂修复中关闭骨裂隙和后退腭骨的可行性。方法：设计并制作两维硬腭骨牵张器，在离体犬颅骨模型上制造人工腭裂模型，根据机械移动原理和牵张成骨原理，在硬腭后部设计2块可相对移动的转移盘，在一定范围内使骨块向内和向后移动，进行两维牵张成骨，并进行了手术模拟。结果：研制的两维缝牵张器可将转移盘前后方向移动16mm，近中方向左右各移动4mm，牵张器固定牢靠，转运盘稳定，牵张控制准确，在离体模型上可实现关闭裂隙、后退硬腭的设计要求。结论：设计的外固定两维牵张器可以向后、内牵张腭骨，从而达到关闭裂隙和硬腭后退的目的。     

Cost, operation and hospitalization times in distraction osteogenesis versus sagittal split osteotomy.

INTRODUCTION: Distraction osteogenesis in 'common' surgical orthodontics is mentioned as an alternative for conventional sagittal split osteotomy. After a 'learning curve' in the surgical skills of distraction, the two techniques can be compared concerning time and cost aspects. PATIENTS: Forty-seven patients (male n=28, female n=19, age 11.7-17.9 yr (mean 14.2) with an Angle's class II division 1malocclusion of skeletal mandibular origin were operated on using distraction osteogenesis and were compared with a second group of 21 patients (male n=4, female n=17, age 16-36yr (mean 22.8) who underwent bilateral sagittal split osteotomies in the same period in order to correct the same type of dysgnathia. METHOD: The first group of 47 patients was treated with intraorally placed bone-born distraction devices to correct mandibular deficiency following a standard protocol, with removal of the third molar tooth germs if present. The second group of 21 patients underwent standard sagittal split osteotomies to correct the mandibular deficiency. The costs of hospitalization, distraction devices and operation time were compared. RESULTS: In this study, distraction osteogenesis took on average more operative time (mean 37%), but 1 day less hospitalization than the bilateral sagittal split osteotomies. The surgical cost of distraction osteogenesis was 36% higher than the conventional sagittal split osteotomy. CONCLUSION: In this study, correcting Angle's class II deficiencies by means of distraction osteogenesis was shown not to be a time-saving procedure when compared with sagittal split osteotomy. Surgical costs were significantly higher using distraction, mainly due to the price of the distractors. Changes in hospital policies concerning hospital admission of adults and children and European legislation concerning re-usability of surgical instruments may balance the cost of both procedures.     

Use of a new curvilinear distractor to repair mandibular defects in dogs

We have investigated the feasibility of using a new curvilinear distractor to repair mandibular defects in 6 mature male dogs. A mandibular defect was created by an oblique osteotomy between the distal planes of the bilateral second premolars, and a transport disc 10mm wide was made. After a 7-day latency period, distraction was activated at 0.5mm/12h and consolidation lasted for 6 or 12 weeks. Three dogs were killed after 6 and 12 weeks' consolidation for gross, radiographic, and histological observations to be made. Curvilinear distraction osteogenesis was successful in 5/6 animals. At both time points smooth curved bone had been restored in the distracted areas, and radiographic and histological examination showed that the generated bone was similar to normal bone after 12 weeks' consolidation. These results suggest that the curvilinear distractor could complete curvilinear distraction osteogenesis in dogs' mandibles.     

Modified Le Fort III osteotomy: A simple solution to severe midfacial hypoplasia

Purpose

There are multiple conditions that may affect the development of the middle third of the face and with varying degrees of severity. The surgical treatment alternatives for major midfacial sagittal deficiencies consist in Le Fort I, II, or III with conventional osteotomies or with distraction osteogenesis (DO). Both techniques have advantages and disadvantages that should be evaluated specifically in each case. The aim of this report is to present a group of patients with severe hypoplasia of the middle third of the face, with different origins, and their treatment with a Modified Le Fort III osteotomy and distraction osteogenesis, using a minimally invasive surgical approach.

不同速率牵张山羊下颌后下齿槽血管变化与血管生成的实验研究

目的:研究不同速率牵张延长山羊下颌骨后下齿槽动静脉的变化和新骨组织内血管生成情况。方法:8只成年山羊随机分为3组,A组(3只)以110 mm/d牵张,B组(3只)以210 mm/d牵张,C组(2只)为对照。A、B两组均牵张延长下颌10 mm,于牵张结束固定后第2周时处死动物,取牵张区下齿槽动静脉及新骨组织行组织学和定量组织学研究,观察下齿槽血管的管壁厚度和管径大小变化,以及新骨中微血管数量变化。结果:两种速率牵张后均未见下齿槽血管壁有病理性改变,但210 mm/d组的血管管径变小,管壁变薄,与对照组相比有显著差异(P<0105)。110 mm/d牵张后微血管密度较210 mm/d牵张后微血管密度高,且新生骨小梁更为成熟,其差异具有统计学意义(P< 0105)。结论:下颌骨牵张后下齿槽血管无明显变化,但快速牵张可能对牵张间隙内血管生成有不良影响。     

Simultaneous maxillary distraction osteogenesis using a twin-track distraction device combined with alveolar bone grafting in cleft patients: preliminary report of a technique

The simultaneous use of cleft reduction and maxillary advancement by distraction osteogenesis has not been applied routinely because of the difficulty in three-dimensional control and stabilization of the transported segments. This report describes a new approach of simultaneous bilateral alveolar cleft reduction and maxillary advancement by distraction osteogenesis combined with autogenous bone grafting. A custom-made Twin-Track device was used to allow bilateral alveolar cleft closure combined with simultaneous maxillary advancement, using distraction osteogenesis and a rigid external distraction system in a bilateral cleft lip and palate patient. After a maxillary Le Fort I osteotomy, autogenous iliac bone graft was placed in the cleft spaces before suturing. A latency period of six days was observed before activation. The rate of activation was one mm/d for the maxillary advancement and 0.5 mm/d for the segmental transport. Accordingly, the concave facial appearance was improved with acceptable occlusion, and complete bilateral cleft closure was attained. No adjustments were necessary to the vector of the transported segments during the activation and no complications were observed. The proposed Twin-Track device, based on the concept of track-guided bone transport, permitted three-dimensional control over the distraction processes allowing simultaneous cleft closure, maxillary distraction, and autogenous bone grafting. The combined simultaneous approach is extremely advantageous in correcting severe deformities, reducing the number of surgical interventions and, consequently, the total treatment time.     

Trans-sinusal maxillary distraction for correction of midfacial hypoplasia: long-term clinical results

Maxillary distraction osteogenesis is indicated in severe angle class III malocclusions, and severe maxillary hypoplasia among some cleft patients and other craniofacial deformities. Twenty patients, aged 8-48 years (mean 17.8+/-10.5 SD) with maxillary and midfacial hypoplasia were treated. The follow-up period was 13-65 months (mean 35+/-16.3 SD). A trans-sinusal maxillary distractor was placed intraorally at each side of the maxilla. The distraction vector was predicted using specialist software, and was transferred to the patients using stereolithographic models and individual templates. A (high) Le Fort I type osteotomy was performed. The amount of activation varied from 8 to 17.5 mm (mean 13.1+/-2.9 SD). Soft and hard tissue formation resulted in complete healing across the distraction gaps. The distractors are almost completely submerged, and can be left in place as long as necessary to avoid relapse. Wit's appraisal was used to measure the stability of the long-term distraction results. Results up to 5 years after distraction showed considerable maxillary advancement with long-term stability. Ongoing growth of the facial skeleton must be considered when distraction osteogenesis is chosen in growing patients.     

犬下颌骨单侧不全截骨牵张时牵张侧位移状况有限元分析

目的 运用犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨在牵张过程中牵张侧各部分位移状况。方法 有限元模型模拟犬下颌单侧不全截骨牵张,观察当滑动骨块未被牵开和被牵开时牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移状况。结果 下颌滑动骨块未被牵开时牵张侧第五臼齿、髁状突前斜面前缘中点所受最大主应力为压应力,髁状突后斜面后缘中点为拉应力,各标志点在空间X、Y、Z三轴位移不明显;当下颌骨滑动骨块被牵开1 mm时,上述各点位移明显增加。结论 从牵张侧观察,牵张侧下颌骨在矢状平面上和冠状平面上都有以髁突顶点(横嵴中点)为中心的逆时针旋转趋势。