Reconstruction of mandibular condyle by transport distraction osteogenesis: Experimental study in rhesus monkey.

PURPOSE: This study investigated histomorphologic changes in the newly formed condyle reconstructed by transport distraction osteogenesis through a nonhuman primate model. MATERIALS AND METHODS: Six adult rhesus monkeys were used in this study. Bilateral condyles and articular discs were extirpated, and the technique of transport distraction osteogenesis was carried out to reconstruct the condyles. X-ray and 3-dimensional (3D) computed tomography (CT) scanning films were taken at various intervals. Two monkeys were killed respectively at 4, 12, and 24 weeks after completion of distraction; the transport segments and the distracted calluses were harvested and processed for histologic examination. The original condyles removed at surgery served as normal control. RESULTS: Open bite was seen in all animals postoperatively and diminished at the end of distraction. Bone regeneration was perfect in the distraction gap between the transport disc and the pre-existing mandible. The bony transport disc gradually remodeled to a neocondyle that was similar to the original condyle in the appearances and structures. The head of neocondyle was covered with a fibrous cap, which might play the role of an articular disc. CONCLUSION: A neocondyle with functional shape can be created by transport distraction osteogenesis. This suggests that this technique is an alternative method for reconstruction of the mandibular condyle.     

运用输送盘牵张成骨术重建猴下颌髁突的实验研究

目的研究在猴颞下颌关节（TMJ）缺损动物模型上运用输送盘牵张成骨术重建髁突的可行性及其整复效果。方法选取6只成年恒河猴,手术截除其双侧关节髁突与关节盘,在下颌升支部行“L”形骨切开术,形成骨输送盘,并安置自行研制的牵张器。按每次0.4 mm,每次间隔12 h的牵张速率向上牵引输送盘至关节窝。牵张结束后第4、12、24周各处死2只动物。通过影像学分析和组织学检查评价输送盘改建与牵张间隙内新骨生成情况。以术中切除的髁突作为正常对照组。结果术后所有动物都有不同程度的咬合错乱,牵张结束后咬合基本恢复正常。骨输送盘形态基本接近正常髁突,其下方可见大量软骨细胞;牵张间隙内新骨生成良好。结论输送盘牵张成骨术可以重建一个形态和功能都基本接近正常的髁突,这种技术可以作为一种整复TMJ缺损的新方法。     

内置自加载牵张器重建兔下颌支的实验研究

目的 :探索牵张成骨重建下颌支缺损的新方法。方法 :以成年新西兰兔为实验动物 ,手术切除下颌骨一侧部分升支及髁状突 ,造成 1.5cm的节段性骨缺损 ,骨断端”L”形截骨形成传送盘 ,安置可完全埋置于组织内的镍钛记忆合金牵张器 ,术后 2个月时处死实验动物 ,取下颌骨观察骨缺损修复情况。结果 :镍钛记忆合金牵张器能自动完成牵张成骨 ,初步重建了缺损的下颌支 ,组织学检查可见牵张区有良好的新骨再生。结论 :内置镍钛记忆合金牵张器可自动持续弹性加载牵张成骨 ,可望成为一种具有良好应用前景的简便实用技术。     

颞下颌关节强直的牵引成骨治疗

目的探讨牵引成骨技术在颞下颌关节强直治疗中的应用。方法应用内置式牵引器治疗8例单侧颞下颌关节强直患者,患侧升支区制备一个1.5～2.0cm颊舌向等宽的骨间隙,并去除喙突,恢复开口度,升支后缘方块截骨,截骨块保留翼内肌附着,与下颌骨间安装牵引器,术后采用升支牵引成骨术,每日牵引1mm,分2次完成,重建颞下颌关节结构及恢复颞下颌关节功能,并坚持开口训练18个月以上。结果经牵引成骨后,患者牵引间隙成骨良好,新形成的关节形态得到改建,升支高度延长1.2～2.1cm,开口度达到正常。结论牵引成骨是治疗颞下颌关节强直的有效方法。     

Transport distraction osteogenesis using nitinol spring: an exploration in canine mandible

Some experiments in rabbits have presented the potential feasibility of using shape memory alloy spring for continuous distraction osteogenesis. To confirm the effectiveness of such method, we established canine models for the exploratory experiments of transport distraction osteogenesis using nitinol springs. Simple devices, including an internal 60-mm long sinusoid-shaped nitinol springs were used in the study. All dogs needed only one operation. In the operation, osteotomy was performed to create a 40-mm unilateral segmental mandibular body defect and a tooth-bearing transport bone disc. After reconstructive fixation of the remnant mandible, the spring was constricted and anchored across the distraction gap to activate transport distraction immediately. At the second experimental stage, an ePTFE sheet was further fixed to protect the defect and distraction gap before closing the incision. Control dogs underwent the same operation except for anchoring of the spring to examine the spontaneous bone regeneration. Automatic bone transportation, as a gradual slowdown process, was observed under the effect of the spring. The transport disc could get to the opposite side of the defect, or stopped halfway when ePTFE sheet intervened. Mandibular reconstruction was achieved in all these dogs and better in dogs with sheet protection. No integrated bone mass was found in the defect of control dogs. The study further proves that continuous distraction osteogenesis using nitinol springs is a practical technique, although the devices need more improvement for better control of the process of distraction and the quality of regenerated bone.     

Experimental mandibular regeneration by distraction osteogenesis with submerged devices: preliminary results of a canine model

The authors describe a new technique for reconstruction of mandibular body defects. The feasibility of distraction osteogenesis with submerged (internal) devices for reconstruction of segmental mandibular defects is investigated in an experiment with five adult dogs. A segmental mandibulectomy was performed on the horizontal ramus. The bony defect was regenerated using distraction osteogenesis (bone transport) at a rate of 1 mm daily. The animals were killed after the consolidation period. Complete bone regeneration of the surgically created gap was successful in three of five dogs. Two animals failed to create new bone. In these two cases, the screws did not offer proper stability to the bony fragments, and this caused a lack of ossification. This experimental study demonstrates the possibility to use internal distraction devices to reconstruct segmental mandibular defects in a canine model. Internal devices show enormous advantages in comparison with the external ones. This method with no donor-site morbidity may become a very useful option in human mandibular reconstruction.     

膜引导辅助弹力牵引成骨重建节段缺失下颌骨的实验研究

目的利用膜引导骨再生技术促进记忆合金牵引器弹力自动牵引成骨进程。方法手术截除杂种犬一侧下颌骨2．5-4．0cm骨段，按bi-focal牵引成骨原理安置记忆合金牵引固定装置，并将聚四氟乙烯膜覆盖于骨膜剥离的下颌骨颊侧面；术后3个月取下颌骨观察并测量骨密度和强度。结果节段缺失下颌骨得到重建，传送盘前后各形成1．5-2．5cm再生骨段；新骨高度及厚度接近正常下颌骨，骨密度和强度接近或超过正常骨半量值。结论膜引导技术可以避免骨不连，加快弹力牵引再生骨的骨化成熟过程。     

下颌骨弹力牵引成骨再生骨密度及强度测量

目的：初步了解下颌骨持续弹力牵引成骨再生骨密度及强度的变化过程,为弹力牵引成骨这一新技术提供基本数据参考。方法：制作bi-focal技术牵引成骨重建一侧下颌骨3．5～4cm节段缺失的杂种犬动物模型,采用6cm长内置正弦波形记忆合金弹力牵引器自动完成牵引成骨,分别利用双能X线骨密度仪和生物力学检测仪测量术后不同时期牵引再生骨段的骨密度及强度。结果：各实验犬牵引再生骨段长度均达到3．0cm以上,术后3个月再生骨中央生长区强度和密度达同侧正常骨段的15％左右,术后4个月时可接近正常骨的40％,术后5个月时可达正常骨密度的60％左右。结论：以较快速度弹力牵引获得的再生骨,后期的骨化成熟过程也较为满意。     

Transport distraction osteogenesis as a method of reconstruction of the temporomandibular joint following gap arthroplasty for post-traumatic ankylosis in children: a clinical and radiological prospective assessment of outcome

This clinical and radiographic study investigated the use of transport distraction osteogenesis in unilateral temporomandibular joint (TMJ) ankylosis patients. Six patients aged between 4 and 8 years were selected for the study; the mean preoperative maximal inter-incisal opening (MIO) was 3.5 mm without lateral and protrusive mandibular movements. The ankylotic mass along with the posterior border of the ascending ramus was exposed via ‘lazy-S’ incision. A gap arthroplasty was performed, followed by a ‘reverse L’ osteotomy on the posterior border of the ramus. In-house manufactured extraoral distraction devices were used for this prospective study. Follow-up clinical and radiographic evaluation was carried out for 13–27 months after completion of the activation period. After a mean follow-up of 19 months, the mean MIO was 29.1 mm and the lateral and protrusive movements changed from none to slight. Cone beam computed tomography images of all patients showed remodelled neocondyle created by transport distraction osteogenesis with no statistically significant differences observed for average cancellous bone density, trabecular number, and trabecular spacing between the neocondyle of the operated side (test) and the condyle of the non-operated side (control). Neocondyle formation by transport distraction osteogenesis using the in-house distraction device is a promising treatment option for TMJ reconstruction in ankylosis patients.     

输送盘牵张成骨重建下颌髁突的骨密度和力学性能变化

目的 探讨运用输送盘牵张成骨术重建髁突的骨密度和力学性能变化.方法 成年山羊16只.截除右侧髁突后运用输送盘牵张成骨术重建髁突,左侧作为正常对照组.牵张结束后24周处死所有动物.采用双能X线吸收法和压缩力学性能测试技术.定量分析并对比两侧髁突的骨密度和压缩力学性能变化.结果 手术侧髁突骨密度较正常侧显著升高;其轴向弹性模量和最大应力较正常侧显著升高,横向弹性模量和最大应力两侧无显著性差异,轴向和横向最大应变两侧均无显著性差异.髁突骨松质的力学性能具有明显的各向异性.结论 运用输送盘牵张成骨术重建的髁突的骨密度和生物力学性能明显升高;这种适应性改建与颞下颌关节的功能刺激直接相关.     

Experimental study of reconstruction of the temporomandibular joint using a bone transport technique.

PURPOSE: This study investigated the applicability of transport distraction osteogenesis with an internal appliance for reconstruction of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Fifteen millimeters of the ascending ramus, including the condyle and intra-articular disc, was extirpated in 42 white rabbits (3.0 kg weight). After an L-osteotomy was performed from the anterior border of the coronoid process to the posterior border of the mandible, an internal distraction appliance was applied. The transport segment was advanced 0.9 mm/day for 14 days after a 14-day healing period. During a 24-week period after the completion of the lengthening, the rabbits were killed at various intervals. RESULTS: Eight weeks after the completion of the lengthening, the distraction gap between the transport segment and the preexisting mandible was indistinguishable in the radiographs. New bone and a large amount of cartilage were observed microscopically in the distraction gap. New bone was also observed at the leading edge of the transport segment. This bone seemed to form from the surrounding periosteum. At 8 weeks after the completion of lengthening, the mature cortical bone was reconstructed. A collagenous-like structure formed a cap over the leading edge of the transport segment. This cap may substitute for an articular disc. The new bone remodeled and resembled the condyle. CONCLUSION: The bone transport technique is promising for the reconstruction of TMJ.     

Distraction osteogenesis: the effects of orthodontic tooth movement on distracted mandibular bone

The application of distraction osteogenesis in craniomaxillofacial surgery has created new treatment methods for patients with craniofacial skeletal dysplasias. Most of the applications in the craniofacial skeleton have been for the correction of severe congenital or acquired conditions. As more understanding is gained with these new approaches, refinements in techniques will enhance treatment planning and outcome. This will expand the application of distraction osteogenesis to more common, less severe types of skeletal dysplasias. One of the important areas in mandibular distraction osteogenesis is the management of the dental gap created when distraction is applied within the tooth-bearing segment of the mandibular body. In this study, the authors investigated the effects of orthodontic tooth movement into new bone created through the process of distraction osteogenesis. Orthodontic tooth movement through newly formed mandibular bone in the canine model was performed and, through histologic studies, was found to create compact bone along the path of the moving tooth. This compact bone replaced the more unstructured woven bone that was originally created by the process of mandibular distraction osteogenesis. These findings indicate that orthodontic tooth movement can be performed in distracted bone and can have significant influence on the stability and long-term structural preservation of the bone created by distraction osteogenesis within the tooth-bearing segment of the mandible.     

Alveolar distraction osteogenesis of bone graft reconstructed mandible

This case report describes a patient who had severe mandibular bony deficiency as a result of excision of aggressive central giant cell granuloma. The defect was reconstructed with iliac bone graft. Four years later vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of mandibular ridge. Distraction osteogenesis can be a good alternative for the reconstruction of mandibular deficiencies.     

Distractor with supporting computer program for the reconstruction of arc defects in mandible by distraction osteogenesis

Distraction osteogenesis as a technique seems to be a promising method in craniofacial bone lengthening and reconstruction through the process of bone and soft-tissue regeneration under stimulation of gradual tensile stress. Distractor plays a very important role especially in the reconstruction of large, irregular bone defects. We designed a new-type distractor and supporting computer program for the reconstruction of arc defects in the mandible by distraction osteogenesis. This distractor was applied for the reconstruction of the monkeys' artificial mandibular median defects. Owing to computer program, perfect distracting plan was made to finish this task. X-ray files showed that the mandibular defects in all animals were repaired successfully, and the anterior mandibular contours were similar to the normal ones. The success of distraction osteogenesis for repair of mandibular median defects in monkeys suggests that this distractor and supporting computer program met the needs of the reconstruction of arc defects in the mandible by distraction osteogenesis.     

Stable vertical distraction osteogenesis of highly atrophic mandibles after ablative tumour surgery of the oral cavity – a salvage pathway for mandibular reconstruction prior to oral rehabilitation with dental implants

Mandibular reconstruction is still a challenge for surgeons. Distraction osteogenesis (DO) might contribute in certain instances to solve this problem. A principal advantage of DO is the expansion of the surrounding soft tissues that accompanies the bony regeneration. In addition there is no donor site morbidity when compared with reconstruction by autologous bone grafting. However its application may be limited by the thinness of the mandible and the attendant fracture risk.This article describes a technique that combines stable internal fixation with vertical distraction of the alveolar ridge in six patients with critical mandibular thickness after ablative surgery for cancer of the oral cavity. Prior to implant insertion for further prosthodontic restoration stable vertical mandibular distraction produced an additional 11–20 mm. Improvement of the surrounding soft tissues, especially intraorally was achieved and dental implants were inserted after bony consolidation.This method can be a useful salvage technique for the augmentation of the atrophic mandible in patients who are not able or willing to undergo the risks and disadvantages of established methods such as free autologous bone transfer or microsurgical techniques.     

Vertical distraction osteogenesis of the mandible applied to an iliac crest graft: report of a case

OBJECTIVES: This clinical case represents a particular application of vertical distraction osteogenesis of the mandible. The surgical technique was applied to an iliac crest bone graft previously positioned on an anterior mandibular defect with the aim to restore the vertical height after a partial resorption in a trauma patient. CASE REPORT: Distraction osteogenesis was applied because it was necessary to restore the mandibular height in a young male patient who presented with a post-trauma anterior mandibular bony deficiency. Because of the irregularity of the mandibular surface and the depth of the defect, the patient first underwent an iliac crest bone grafting that, after 3 months, showed partial resorption. Vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of the mandibular ridge. Then the patient was successfully rehabilitated by means of an implant-supported prosthesis. CONCLUSION: Vertical distraction osteogenesis appears to be a versatile surgical procedure, which can be applied as a secondary treatment in patients presenting with mandibular trauma sequelae.     

有限元法探讨犬下颌单侧不全截骨牵张时非牵张侧位移趋势

目的 分析犬下颌单侧不全截骨牵张成骨有限元模型,计算下颌骨非牵张侧各部分在牵张过程中位移状况.方法 模拟犬下颌单侧不全截骨牵张成骨,当滑动骨块受力未被牵开和被牵开时观察非牵张侧关节、下颌角、喙突及牙齿等6个标志点的位移情况.结果 当滑动骨块未被牵开时,非牵张侧下颌骨各标志点所受Von Mises应力为0,在空间X、Y、...     

Alveolar reconstruction by distraction osteogenesis under unfavorable conditions

We present a patient who underwent alveolar reconstruction using vertical mandibular lengthening by distraction osteogenesis under unfavorable conditions. Part of the alveolar bone in the center of the mandible was resected, together with a squamous cell carcinoma located on the oral floor. We used vertical mandibular lengthening from the region of the remaining mandible inferior to the bony defect to reconstruct the alveolus, combined with a free musculocutaneous flap as a cover. However, the transferred flap underwent complete necrosis and was replaced with another flap on the seventh postoperative day. Radiotherapy at a total dose of 50 Gy was administered from day 75 to day 109 after completion of the distraction, because of suspected residual tumor. Despite the severe conditions, most of the distraction gap became filled with new bone. This case indicates that distraction osteogenesis can be used even in irradiated or poorly vascularized areas, as in our patient.     

内置自动弹力牵引成骨装置的设计应用

目的　完善记忆合金弹力牵引器的辅助固定导引装置设计,初步探索其应用的可行性。方法　利用正弦波形记忆合金弹力牵引器、医用重建钛板、小型钛板配合构成内置式自动弹力牵引装置,构建牵引成骨重建下颌骨颏部约6 cm节段缺失的杂种犬动物模型,观察新型装置的应用效果。结果　实验设计装置可基本按照预想方式自动完成骨牵引,手术后2个月内即可形成节段再生骨,可延长截短的双侧下颌骨。结论　内置自动弹力牵引装置显示了实际应用的可行性和优越性,但在牵引力控制等方面还需要深入研究。     

Use of a plate-guided distraction device for transport distraction osteogenesis of the mandible.

BACKGROUND: Transport distraction osteogenesis has been used to reconstruct continuity defects by regenerating bone and soft tissues. A challenge has been to maintain the correct vector during the distraction process. A new type of distraction device was recently developed that uses a standard reconstruction plate to "guide" the transported segment of the bone. This plate-guided distractor device (PGD) intimately follows the shape of the plate, thus allowing for 3-dimensional vector control during the distraction process. PATIENTS AND METHODS: Four patients underwent transport distraction osteogenesis for reconstruction of segmental mandibular defects ranging in size from 4 to 7 cm. The age of the patients ranged from 27 to 62 years. Two patients had been treated with radiotherapy as part of treatment for oral malignancy. A standard locking reconstruction plate was placed to bridge the continuity gap. An osteotomy was performed to create a bone transport segment. The PGD was secured to both the reconstruction plate and the transport bone. After a latency period of 7 days, the device was activated at a rate of 1 mm/d. The distraction process continued until the transport segment reached the opposing bone or sufficient bone and soft tissue were reconstructed for oral rehabilitation. RESULTS: All patients achieved hard and soft tissue formation. Two patients had premature consolidation of the distraction regenerate but had sufficient tissue for rehabilitation. CONCLUSION: A PGD can be used to regenerate missing hard and soft tissues. An advantage of this technique is that it uses a reconstruction plate that is routinely placed to bridge mandibular continuity defects. This device allows for ultimate vector control by intimately following a carefully adapted plate.