1. Mandibular Distraction For Management of Temporomandibular Joint (TMJ) Ankylosis
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2. Introduction
DO is a new and effective technique that offers an alternative to autogenous bone grafting and prosthetic total joint replacement in the treatment of TMJ.

3. Indications
Patients with mandibular micrognathia accompanied by OSAHS secondary to TMJ ankylosis is the best indications of DO.

4. Treatment procedure
Panoramic and cephalometric radiographs were taken at frist.
Surgery for TMJ arthroplasty or reconstruction.
Orthodontic treatment begin after arthroplasty.
Surgical for correction of micrognathia using mandibular DO.

5. The initial surgery
Surgical procedures were performed under general anaesthesia with nasotracheal intubation and total total muscle relaxation. Access to TMJ was achieved through a pre-auricular incision combined with a temporal extension. Dissection of the superficial layers was performed with freeing of the temporal vessels and then the capsule was opened to expose the ankylotic joint (Fig. 1A). Excision of the fibrous tissue and ankylotic bony mass was carried out with burs and osteotomes (Fig. 1B). Burring of the glenoid fossa and the condylar stump created a gap of about 10 mm between the roof of the fossa and the top of the condylar stump (Fig. 1C). Mouth opening was tested during the procedure. An interincisal opening distance of at least 25 mm was considered as proof of completed resection. Liberal coronoidectomy was completed when the interincisal opening distance was less than 25 mm. When the height of the ramus was not enough, reverted ramus or rib transplantation was performed to reconstruct the condylar process.在12周的巩固期之后，患者接受第二阶段的手术，包括通过一个颌下的切口取出牵引器和颞下颌关节成形术。耳前切口可以暴露融合的关节球，在关节窝与髁突应该在的位置的间隙处截骨，脱臼的关节盘重新定位并缝合固定于颧根和颞浅筋膜上。双侧都进行了关节成形术，并获得了最大40mm的开口。
髁突应该在的位置的间隙处截骨，脱臼的关节盘重新定位并缝合固定于颧根和颞浅筋膜上。双侧都进行了关节成形术，并

6. An individualized occlusal pad was made from self-curing acrylic resin intraoperatively according to the maximal mouth-opening.
术后第一天开始开口训练，咬合板在接下来的一个月内帮助患者被动开口，一个月之后接受正畸治疗，建议患者自己进行主动地开口训练。

7. The second surgery 首先做一完整的口腔前庭部位切口和双侧颌下切口（长约3cm).暴露下颌骨骨膜下。
图4：术中照片：a.（右侧）&b.（左侧）下颌乙状切迹前做一垂直截骨术。为了保护下牙槽神经，分在颌骨的颊侧和舌侧
分别使用锯截骨。然后在根尖与和下颌管之间与颌平面平行做一全厚的水平截骨。所有的截骨线都是根据颅颌面三维重建CT设计的。在垂直和水平线之间的截骨都是使用一种合适的楔骨刀来保护下牙槽神经。一个单向。口内的牵引器以轴线与颌平面呈向下的10°角被固定在它的每一个站点上并且被激活，以确保移动。在经过5天左右的潜伏期后，以每天4次，每次0.2mm进行牵引。并且一直持续到获得满意的效果之后再过去牵引2~3mm.

8. single-stack or double-stack genioplasty was performed while insetting the distractor or removing the distractor at 12 weeks after distraction.

9. Preoperative

10. Postoperative

11. Long term result
The long term effect of mandibular distractionosteogenesis on patients with temporomandibular joint (TMJ) ankylosis and mandibular micrognathia is safe and stable.
Each patient has been evaluated with X-ray film cephalometry and polysomnography(PSG) pre and postoperation. The patients follow-up once or twice every year after consolidation period. Mean follow-up time was 37.6 months(24 months to 116 months).One hundred two sides of mandible in 53 patients were lengthened. The mean distraction distance was 23.2mm (ranged from 14 to 35mm).Postoperation, the average posterior airway space(PAS) was enlarged from 4.9mm to 10.4mm and the average angle of sella-nasion-point B (SNB) was increased from 64.2°to 74.5°.The apnea hypopnea index (AHI) was decrease significantly. The profile was improved distinctly and OSAHS was cured effectively in each patient. No severe complication occurred during treatment. All patients were satisfied with treatment result. After long term follow-up period of 37.6 months, the position of mandible was stable, no relapse of micrognathia and OSAHS was observed.

12. Advantages Ability to produce larger skeletal movements
Elimination of the need for bone grafts (secondary surgical site)
Better long-term stability
Less trauma to TMJ
Distraction of soft tissue along with lengthening the bone

13. Disadvantages Two procedures. Increased cost.
Longer Rx time, patient compliance & frequent appointments.

14. Applications Infection Scar Facial nerve paralysis
The damage of temporomandibular joint

15. Conclusion
As a relatively new surgical approach,DO is a feasible and safe method in the management of TMJ ankylosis with mandibular micrognathia and will play an important role in advanced head and neck reconstruction. The 3D craniomaxillofacial model is helpful for DO accuracy and success.

16. References
1.Ping Feiyun,Liu Wei, Chen Jun, Xu Xin, Shi Zhu ,Fengguo.Simultaneous Correction of Bilateral Temporomandibular Joint Ankylosis With Mandibular Micrognathia Using Internal DistractionOsteogenesis and 3-Dimensional Craniomaxillofacial Models.
2.Sven Erik Nørholt, John Jensen,Søren Schou, Thomas Klit Pedersen, Complications after mandibular distractionosteogenesis: a retrospective study of 131 patients.
3.P. Anantanarayanan, V. Narayanan, R. Manikandhan, D. Kumar
Primary mandibular distraction for management of nocturnal desaturations secondary to temporomandibular joint (TMJ) ankylosis Int J Pediatr Otorhinolaryngol, 72 (2008), pp. 385–389.
4.R.F. Elgazzar, A.I. Abdelhady, K.A. Saad, M.A. Elshaal, M.M. Hussain, S.E. Abdelal et al.Treatment modalities of TMJ ankylosis: experience in Delta Nile, Egypt .Int J Oral Maxillofac Surg, 39 (2010), pp. 333–342.
5.B. Krishnan .Autogenous auricular cartilage graft in temporomandibular joint ankylosis – an evaluation.Oral Maxillofac Surg, 12 (2008), pp. 189–193.

17. References
6.H.C. Schwartz, R.J. Relle.Distraction osteogenesis for temporomandibular joint reconstruction.J Oral Maxillofac Surg, 66 (2008), pp. 718–723.
7.Hongtao Shang1, Yang Xue1, Yanpu Liu, Jinlong Zhao, LishenHe.Modified internal mandibular distraction osteogenesis in the treatment of micrognathia secondary to temporomandibular joint ankylosis: 4-Year follow-up of a case.
8.Tae-Geon Kwon,Hyo-Sang Park,Jong-Bae Kim, Hong-In Shin, Staged Surgical Treatment for Temporomandibular Joint Ankylosis: Intraoral Distraction After Temporalis Muscle Flap Reconstruction.
9.E. Xiao, Y. Zhang, J. An, J. Li, Y. Yan: Long-term evaluation of the stability of reconstructed condyles by transport distraction osteogenesis. Int. J. Oral Maxillofac.Surg
10.Aysegul Mine Tuzuner-Oncul*, Reha S. Kisnisci,Response of ramus following vertical lengthening with distraction osteogenesis.

18. thank you!