- Email: [email protected]
Mandible reconstruction with transport-disc distraction osteogenesis in children of deciduous dentition
Int. J. Oral Maxillofac. Surg. 2012; 41: 1223–1228 http://dx.doi.org/10.1016/j.ijom.2012.04.021, available online at http://www.sciencedirect.com
Case Report Reconstructive Surgery
Mandible reconstruction with transport-disc distraction osteogenesis in children of deciduous dentition
Y. Liu, J. Chen, F. Yan, F. Ping Department of Oral and Maxillofacial Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, PR China
Y. Liu, J. Chen, F. Yan, F. Ping: Mandible reconstruction with transport-disc distraction osteogenesis in children of deciduous dentition. Int. J. Oral Maxillofac. Surg. 2012; 41: 1223–1228. # 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Reconstructing segmental mandibular defects in children of deciduous dentition is a challenge. The authors treated a 23-month-old girl with a segmental mandibular defect secondary to tumour resection. Considering the unpredictable negative impacts of the autogenous bone grafting method on the musculoskeletal system of the donor sites, which was growing rapidly at this age, the authors applied transport disc distraction osteogenesis (TDDO) to reconstruct the mandible discontinuity. To the best of the authors’ knowledge, this is the first time TDDO has been used for mandible reconstruction in such a young patient with deciduous dentition. Aesthetics and function were restored satisfactorily at the end of treatment. The facial appearance and occlusion were stable through the 35 month follow-up, possibly due to the growth of the regenerated bone parallel with the rest of the maxillofacial skeleton. The satisfactory reconstruction also contributed to the patient’s physical and psychological development. The success of mandible reconstruction with TDDO in this study casts new light on the management of segmental mandibular defect in children with deciduous dentition.
It is imperative to reconstruct the profile and functions of paediatric segmental mandible defects effectively1,2 to avoid hurting the patients’ psychiatric and physical development. Mandible reconstruction is more complicated in very young pre-school patients than in adults. Autogenous vascularized bone grafting is often the first choice for adult mandible reconstruction due to its predictable effect.1,3,4 For pre-school patients whose musculoskeletal system is undergoing rapid growth, this technique may cause unpredictable 0901-5027/01001223 + 06 $36.00/0
damage to donor sites during bone harvesting. Vessel anastomosis in very young patients also requires more skill than in adults; increasing the risk of failure.5,6 Transport disc distraction osteogenesis (TDDO), which does not require bone harvesting, is another option for mandible reconstruction. Despite the effectiveness of TDDO in adults and teenagers,7–10 there are few clinical reports of TDDO in patients with deciduous dentition. The authors present the case of a 23-month-old girl with mandible ameloblastoma who
Accepted for publication 26 April 2012 Available online 29 May 2012
was reconstructed using TDDO following tumour ablation. Clinical case
A 23-month-old girl presented with a painless bony expansion in her left mandible (Fig. 1a). Panoramic radiography confirmed a large radiolucent lesion in the left mandible distal to the first deciduous molar and extending to the lower twothirds of the ramus (Fig. 1b). The tooth germs of the second deciduous molar and
# 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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Fig. 1. (a) Preoperative photograph of the patient, showing her asymmetric face. (b) Panoramic radiograph, demonstrating a radiolucent lesion in the left mandible from the posterior part of the body to the low two-thirds of the ramus.
the first permanent molar were included in the lesion. Initially diagnosed as an odontogenic cyst, the lesion was just enucleated and the bone cavity was packed with iodoform ribbon gauze, which was regularly changed before healing. The lesion was diagnosed pathologically as ameloblastoma. Segmental mandibulectomy was therefore necessary to obtain sufficient surgical margins and a discontinuity defect was expected. Immediate reconstruction was planned to alleviate aesthetic and functional damage and potential negative effects on the patient’s physical and psychological development. After having been informed of the extent of bone resection, as well as the advantages and disadvantages of autogenous bone grafting and TDDO, the parents finally agreed with the authors to apply TDDO to the patient’s mandible reconstruction. The extent of resection and aspects of TDDO such as transport-disc size and distraction length were decided preoperatively through simulated surgery on a solid model of the mandible which was manufactured based on CT scanning. A plastic
guiding plate was also pre-manufactured to assist in positioning the distraction device in the later operation (Fig. 2). Under general anaesthesia, the left mandible was exposed through the sub- and retro-mandibular approach (Fig. 3). Periosteum beyond the safe surgical margin was preserved to maintain osteogenecity. Mandibulectomy was performed 0.5 cm away from the anterior and posterior walls of the bone cavity with a Gigli saw. The opening of the oral mucosa was closed well with sutures. The osteotomy line for the transport disc was decided by accurately loading the internal distraction device (Cibei Med, Cixi, China) on the mandible stump with the assistance of the prefabricated plastic guiding plate. A bone block of 16 mm 10 mm was subsequently osteotomized as the transport disc (Fig. 4a and b). It was crucial to avoid lacerating the soft tissues on the medial side of the transport disc. The distraction device was replaced on the transport disc and the mandibular stumps, with the distraction activation arm submandibularly placed. After a 7 day latency period, distraction was started at a rate of twice
0.4 mm/day and continued for 58 days (Fig. 5a). Satisfactory calcification in the distraction gap had already been indicated by radiography after 4 months of consolidation (Fig. 5b). The distraction device was removed at the end of 6 months to ensure high-degree calcification of the distraction area (Fig. 5c). When the distraction device was removed it was found that the distraction area was fully ossified and the transport disc was completely fused with the posterior mandibular stump (Fig. 6). No complication was found in the whole treatment period. The girl has been followed up periodically for 35 months, with no signs of tumour recurrence. The midline of the mandible shifted left by 2.0 mm at the end of treatment and did not change thereafter. With fair occlusion and a normal optimal interincisal opening in the last 35 months (Fig. 7a and b), she has eaten a regular diet and her speech is pronounced clearly. Her facial appearance was satisfactory to both her parents and the authors (Fig. 8). As demonstrated in the latest CT scan, the height and width of the reconstructed mandible were acceptable and the shape was roughly symmetrical (Fig. 9). Her physical condition (judged by weight and height) is within the normal range and her behaviour is no different from that of other Chinese girls her age. Discussion
Vascularized autogenous bone grafting is the mainstay of reconstruction for adult segmental mandible defects because of its predictable effect.4,11–14 Additional problems emerge when applying it to children with deciduous dentition, such as the 23month-old girl in this case. For these patients, the soft and hard tissues are very delicate and difficult to harvest. Complications of bone harvesting include osteomyelitis, nerve damage, and necrosis of soft tissues,5,6,15 and if they occurred would be more severe in pre-school children than in adults. Since the body is rapidly growing, it is unclear to what degree bone harvesting would have negative impacts on the musculoskeletal development of the donor sites in very young patients. The small vessel calibre and delicate vessel wall also make vessel anastomosis more difficult in children, thus increasing the risk of bone grafting failure. TDDO is another option for reconstructing mandible defects and has proved effective in adults and teenagerss.7,8,16,17 Although most of these clinical scenarios were a single defect of mandibular body or
Distraction osteogenesis in mandible reconstruction in children
Fig. 2. (a) Preoperative CT scan for manufacture of three-dimensional model. (b) Simulated operation on the model to decide aspects of distraction including osteotomy line, traction orientation and distance. A plastic guide plate was fabricated preoperatively.
1225
Fig. 4. A distraction disc was osteotomized with the help of (a) a placement plastic guide plate and (b) a distraction device on the mandible stump.
Fig. 3. Intra-operative view, demonstrating the bulging left mandible due to tumour expansion.
ramus, some cases involved both body and ramus. In these cases, two steps of TDDO were applied to restore the shape of the angle.7,17 In comparison to autogenous bone grafting, a major advantage of TDDO is that bone harvesting and potential donor site damage are avoidable.18,19 Gonza´lez-Garcı´a et al. described its usefulness in treating patients who were unsuitable for more aggressive surgery or undergoing prolonged surgical time because of poor general health or for patients in whom primary treatment using a vascularized free-osseous flap had failed. TDDO has also been reported to provide sufficient bone to allow dental implant placement, an important functional outcome.20 These advantages are of great significance to the patients with
1226
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Fig. 7. Satisfactory occlusion (a) and mouth opening (b) were demonstrated 35 months after treatment. Fig. 5. Postoperative panoramic radiographs. (a) At the intermediary stage of distraction. (b) At completion of distraction with appliance in situ. (c) After removal of appliance and completion of treatment.
Fig. 6. Full ossification of the distraction area was confirmed intraoperatively when the distraction device was removed.
Fig. 8. Satisfactory appearance at the end of a 35 month follow-up.
Distraction osteogenesis in mandible reconstruction in children
1227
the growth of the jaws. Nevertheless, this case boosts the authors’ confidence in the long-term effect of this technique. Undoubtedly a longer follow-up period and more clinical cases are needed to reach the final conclusion. In summary, the satisfactory results achieved in this 23-month-old girl, together with the avoidance of autogenous bone harvesting, indicate the feasibility of reconstructing a segmental mandibular defect with TDDO in patients with deciduous dentition, even at its early stage. This case encourages further attempts in similar clinical scenarios. It may, if strengthened by more cases, cast new light on the challenging mandible reconstruction in patients with deciduous dentition. Competing interests
None declared. Funding
Fig. 9. Three dimensional CT demonstrated that both the shape and bone volume of the reconstructed mandible were acceptable at the last follow-up.
deciduous dentition, such as the girl in this case. There was little information about the effectiveness of TDDO in young patients whose maxillofacial skeletons are undergoing rapid growth and whose permanent teeth are far from eruption. The significance of this case is that it demonstrated the effectiveness. The girl’s satisfactory occlusion and facial profile were stable through the 35 month follow-up. This indicates that new bone generated by TDDO, similar to the rest of the maxillofacial bones, continued to grow after treatment. Most cases of mandibular defect reconstructed with TDDO have been caused by benign tumour resection or trauma. It is still controversial to apply TDDO to patients suffering from malignant tumour who have undergone radiotherapy.21–24 Radiotherapy may interrupt a complex cascade of bone formation which is stimulated by distraction and involves several cytokines, such as bone morphogenetic proteins and insulin-like growth factors. Radiation may cause hypovascularity, hypoxia, and hypocellularity, an adverse environment for bony formation during distraction.21,23 Therefore, for patients who have undergone radiotherapy, vascularized autogenous bone
grafting may be a safer and more reliable option for mandible reconstruction. Mandible reconstruction with TDDO in pre-school patients is different from that in adults. Firstly, the mandible stump from which a transport disc is created contains tooth germs and some tooth germs may be lost in creating a transport disc. It is critical that the osteotomy line should not cut through any tooth germ otherwise there will be poor or no bone formation within the distraction area. In this regard, preoperative radiographs, CT-based rapid prototyping solid models and carefully simulated model surgery are helpful. Secondly, the potent osteogenicity of the residual mandible stump, in combination with highly vascularized soft tissue, is highly beneficial to bone formation in the distraction area. It also enhances the chance of fusion between the transport disc and the stump of ramus, as was shown in this case. In contrast, nonunion is not rare in adult patients with TDDO.16,25 For these adult patients, a small autogenous bone graft is necessary to bridge the gap at the time of distraction device removal.16,25 Thirdly, the maxillofacial skeleton on which TDDO is performed is rapidly growing. This leads to the concern that the reconstruction effect is not stable with
This study was supported by National Natural Science Foundation of China (No. 30901686), Technological Project Fund of Zhejiang Province of China (No. 2007C33012) and Qianjiang Intelligent Project Fund of Zhejiang Province (No. 2010R10070). Ethical approval
Not required. References 1. Guo L, Ferraro NF, Padwa BL, Kaban LB, Upton J. Vascularized fibular graft for pediatric mandibular reconstruction. Plast Reconstr Surg 2008;121:2095–105. 2. Warren SM, Borud LJ, Brecht LE, Longaker MT, Siebert JW. Microvascular reconstruction of the pediatric mandible. Plast Reconstr Surg 2007;119:649–61. 3. Goh BT, Lee S, Tideman H, Stoelinga PJ. Mandibular reconstruction in adults: a review. Int J Oral Maxillofac Surg 2008;37: 597–605. 4. Li JS, Chen WL, Huang ZQ, Zhang DM. Pediatric mandibular reconstruction after benign tumor ablation using a vascularized fibular flap. J Craniofac Surg 2009;20:431–4. 5. Chopra S, Enepekides DJ. The role of distraction osteogenesis in mandibular reconstruction. Curr Opin Otolaryngol Head Neck Surg 2007;15:197–201. 6. Hartman EH, Spauwen PH, Jansen JA. Donorsite complications in vascularized bone flap surgery. J Invest Surg 2002;15:185–97. 7. Chen J, Liu Y, Ping F, Zhao S, Xu X, Yan F. Two-step transport-disk distraction osteogenesis in reconstruction of mandibular
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11.
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defect involving body and ramus. Int J Oral Maxillofac Surg 2010;39:573–9. Elsalanty ME, Taher TN, Zakhary IE, AlShahaat OA, Refai M, El-Mekkawi HA. Reconstruction of large mandibular bone and soft-tissue defect using bone transport distraction osteogenesis. J Craniofac Surg 2007;18:1397–402. Gonza´lez-Garcı´a R, Naval-Gı´as L, Rubio-Bueno P, Rodrı´guez-Campo FJ, Usandizaga JL. Double-step transport osteogenesis in the reconstruction of mandibular segmental defects: a new surgical technique. Plast Reconstr Surg 2006;118: 1608–12. Kashiwa K, Kobayashi S, Nohara T, Yasuoka T, Hosoya Y, Fujiwara H, et al. Efficacy of distraction osteogenesis for mandibular reconstruction in previously irradiated areas: clinical experiences. J Craniofac Surg 2008; 19:1571–6. Gaggl A, Bu¨rger H, Mu¨ller E, Chiari FM. A combined anterolateral thigh flap and vascularized iliac crest flap in the reconstruction of extended composite defects of the anterior mandible. Int J Oral Maxillofac Surg 2007; 36:849–53. Gonza´lez-Garcı´a R, Naval-Gı´as L, Rodrı´guez-Campo FJ, Mun˜oz-Guerra MF, SastrePe´rez J, Dı´az-Gonza´lez FJ. Vascularized free fibular flap for the reconstruction of mandibular defects. Clinical experience in 42 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:191–202. Lo´pez-Arcas JM, Arias J, Castillo JL, Burguen˜o M, Navarro I, Mora´n MJ, et al. The fibula osteomyocutaneous flap for mandible
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reconstruction: a 15-year experience. J Oral Maxillofac Surg 2010;68:2377–84. Virgin FW, Iseli TA, Iseli CE, Sunde J, Carroll WR, Magnuson JS, et al. Functional outcomes of fibula and osteocutaneous forearm free flap reconstruction for segmental mandibular defects. Laryngoscope 2010;120:663–7. Fodor L, Dinu C, Fodor M, Ciuce C. Severe compartment syndrome following fibula harvesting for mandible reconstruction. Int J Oral Maxillofac Surg 2011;40:443–5. Gonza´lez-Garcia R, Rubio-Bueno P, NavalGı´as L, Rodrı´guez-Campo FJ, Escorial-Herna´ndez V, Martos PL, et al. Internal distraction osteogenesis in mandibular reconstruction: clinical experience in 10 cases. Plast Reconstr Surg 2008;121:563–75. Muraki Y, Tominaga K, Yoshioka I, Fujita M, Khanal A, Matsushita S, et al. Mandibular reconstruction with bone transport in a patient with osteogenesis imperfecta. Int J Oral Maxillofac Surg 2008;37:870–3. Bak M, Jacobson AS, Buchbinder D, Urken ML. Contemporary reconstruction of the mandible. Oral Oncol 2010;46:71–6. Hurvitz KA, Kobayashi M, Evans GR. Current options in head and neck reconstruction. Plast Reconstr Surg 2006;118:122e–33e. Gonza´lez-Garcı´a R, Naval-Gı´as L. Transport osteogenesis in the maxillofacial skeleton: the outcomes of a versatile reconstruction method following tumor ablation. Arch Otolaryngol Head Neck Surg 2010;136: 243–50. Gonza´lez-Garcı´a R, Rodrı´guez-Campo FJ, Naval-Gı´as L, Sastre-Pe´rez J, Dı´az-Gonza´lez FJ. The effect of radiation in distraction
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osteogenesis for reconstruction of mandibular segmental defects. Br J Oral Maxillofac Surg 2007;45:314–6. Matsui Y, Shirota T, Iwai T, Ozawa T, Watanuki K, Hirota M, et al. Mandibular reconstruction using 2-step bone transport in an irradiated cancer patient with type 2 diabetes mellitus. Int J Oral Maxillofac Surg 2009;38:1223–5. Sacco AG, Chepeha DB. Current status of transport-disc-distraction osteogenesis for mandibular reconstruction. Lancet Oncol 2007;8:323–30. Seitz O, Harth M, Ghanaati S, Lehnert T, Vogl TJ, Sader R, et al. Secondary mandibular reconstruction after oral squamous cell carcinoma resection: clinical reevaluation of transport disk distraction osteogenesis. J Craniofac Surg 2010;21:59–63. Kuriakose MA, Shnayder Y, DeLacure MD. Reconstruction of segmental mandibular defects by distraction osteogenesis for mandibular reconstruction. Head Neck 2003;25: 816–24.
Address: Jun Chen Department of Oral and Maxillofacial Surgery Second Affiliated Hospital Zhejiang University School of Medicine 88 Jiefang Rd. Hangzhou 310009 PR China Tel.: +86 571 87783513 fax: +86 571 87767078 E-mail: [email protected]
Case Report Reconstructive Surgery
Mandible reconstruction with transport-disc distraction osteogenesis in children of deciduous dentition
Y. Liu, J. Chen, F. Yan, F. Ping Department of Oral and Maxillofacial Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, PR China
Y. Liu, J. Chen, F. Yan, F. Ping: Mandible reconstruction with transport-disc distraction osteogenesis in children of deciduous dentition. Int. J. Oral Maxillofac. Surg. 2012; 41: 1223–1228. # 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Reconstructing segmental mandibular defects in children of deciduous dentition is a challenge. The authors treated a 23-month-old girl with a segmental mandibular defect secondary to tumour resection. Considering the unpredictable negative impacts of the autogenous bone grafting method on the musculoskeletal system of the donor sites, which was growing rapidly at this age, the authors applied transport disc distraction osteogenesis (TDDO) to reconstruct the mandible discontinuity. To the best of the authors’ knowledge, this is the first time TDDO has been used for mandible reconstruction in such a young patient with deciduous dentition. Aesthetics and function were restored satisfactorily at the end of treatment. The facial appearance and occlusion were stable through the 35 month follow-up, possibly due to the growth of the regenerated bone parallel with the rest of the maxillofacial skeleton. The satisfactory reconstruction also contributed to the patient’s physical and psychological development. The success of mandible reconstruction with TDDO in this study casts new light on the management of segmental mandibular defect in children with deciduous dentition.
It is imperative to reconstruct the profile and functions of paediatric segmental mandible defects effectively1,2 to avoid hurting the patients’ psychiatric and physical development. Mandible reconstruction is more complicated in very young pre-school patients than in adults. Autogenous vascularized bone grafting is often the first choice for adult mandible reconstruction due to its predictable effect.1,3,4 For pre-school patients whose musculoskeletal system is undergoing rapid growth, this technique may cause unpredictable 0901-5027/01001223 + 06 $36.00/0
damage to donor sites during bone harvesting. Vessel anastomosis in very young patients also requires more skill than in adults; increasing the risk of failure.5,6 Transport disc distraction osteogenesis (TDDO), which does not require bone harvesting, is another option for mandible reconstruction. Despite the effectiveness of TDDO in adults and teenagers,7–10 there are few clinical reports of TDDO in patients with deciduous dentition. The authors present the case of a 23-month-old girl with mandible ameloblastoma who
Accepted for publication 26 April 2012 Available online 29 May 2012
was reconstructed using TDDO following tumour ablation. Clinical case
A 23-month-old girl presented with a painless bony expansion in her left mandible (Fig. 1a). Panoramic radiography confirmed a large radiolucent lesion in the left mandible distal to the first deciduous molar and extending to the lower twothirds of the ramus (Fig. 1b). The tooth germs of the second deciduous molar and
# 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
1224
Liu et al.
Fig. 1. (a) Preoperative photograph of the patient, showing her asymmetric face. (b) Panoramic radiograph, demonstrating a radiolucent lesion in the left mandible from the posterior part of the body to the low two-thirds of the ramus.
the first permanent molar were included in the lesion. Initially diagnosed as an odontogenic cyst, the lesion was just enucleated and the bone cavity was packed with iodoform ribbon gauze, which was regularly changed before healing. The lesion was diagnosed pathologically as ameloblastoma. Segmental mandibulectomy was therefore necessary to obtain sufficient surgical margins and a discontinuity defect was expected. Immediate reconstruction was planned to alleviate aesthetic and functional damage and potential negative effects on the patient’s physical and psychological development. After having been informed of the extent of bone resection, as well as the advantages and disadvantages of autogenous bone grafting and TDDO, the parents finally agreed with the authors to apply TDDO to the patient’s mandible reconstruction. The extent of resection and aspects of TDDO such as transport-disc size and distraction length were decided preoperatively through simulated surgery on a solid model of the mandible which was manufactured based on CT scanning. A plastic
guiding plate was also pre-manufactured to assist in positioning the distraction device in the later operation (Fig. 2). Under general anaesthesia, the left mandible was exposed through the sub- and retro-mandibular approach (Fig. 3). Periosteum beyond the safe surgical margin was preserved to maintain osteogenecity. Mandibulectomy was performed 0.5 cm away from the anterior and posterior walls of the bone cavity with a Gigli saw. The opening of the oral mucosa was closed well with sutures. The osteotomy line for the transport disc was decided by accurately loading the internal distraction device (Cibei Med, Cixi, China) on the mandible stump with the assistance of the prefabricated plastic guiding plate. A bone block of 16 mm 10 mm was subsequently osteotomized as the transport disc (Fig. 4a and b). It was crucial to avoid lacerating the soft tissues on the medial side of the transport disc. The distraction device was replaced on the transport disc and the mandibular stumps, with the distraction activation arm submandibularly placed. After a 7 day latency period, distraction was started at a rate of twice
0.4 mm/day and continued for 58 days (Fig. 5a). Satisfactory calcification in the distraction gap had already been indicated by radiography after 4 months of consolidation (Fig. 5b). The distraction device was removed at the end of 6 months to ensure high-degree calcification of the distraction area (Fig. 5c). When the distraction device was removed it was found that the distraction area was fully ossified and the transport disc was completely fused with the posterior mandibular stump (Fig. 6). No complication was found in the whole treatment period. The girl has been followed up periodically for 35 months, with no signs of tumour recurrence. The midline of the mandible shifted left by 2.0 mm at the end of treatment and did not change thereafter. With fair occlusion and a normal optimal interincisal opening in the last 35 months (Fig. 7a and b), she has eaten a regular diet and her speech is pronounced clearly. Her facial appearance was satisfactory to both her parents and the authors (Fig. 8). As demonstrated in the latest CT scan, the height and width of the reconstructed mandible were acceptable and the shape was roughly symmetrical (Fig. 9). Her physical condition (judged by weight and height) is within the normal range and her behaviour is no different from that of other Chinese girls her age. Discussion
Vascularized autogenous bone grafting is the mainstay of reconstruction for adult segmental mandible defects because of its predictable effect.4,11–14 Additional problems emerge when applying it to children with deciduous dentition, such as the 23month-old girl in this case. For these patients, the soft and hard tissues are very delicate and difficult to harvest. Complications of bone harvesting include osteomyelitis, nerve damage, and necrosis of soft tissues,5,6,15 and if they occurred would be more severe in pre-school children than in adults. Since the body is rapidly growing, it is unclear to what degree bone harvesting would have negative impacts on the musculoskeletal development of the donor sites in very young patients. The small vessel calibre and delicate vessel wall also make vessel anastomosis more difficult in children, thus increasing the risk of bone grafting failure. TDDO is another option for reconstructing mandible defects and has proved effective in adults and teenagerss.7,8,16,17 Although most of these clinical scenarios were a single defect of mandibular body or
Distraction osteogenesis in mandible reconstruction in children
Fig. 2. (a) Preoperative CT scan for manufacture of three-dimensional model. (b) Simulated operation on the model to decide aspects of distraction including osteotomy line, traction orientation and distance. A plastic guide plate was fabricated preoperatively.
1225
Fig. 4. A distraction disc was osteotomized with the help of (a) a placement plastic guide plate and (b) a distraction device on the mandible stump.
Fig. 3. Intra-operative view, demonstrating the bulging left mandible due to tumour expansion.
ramus, some cases involved both body and ramus. In these cases, two steps of TDDO were applied to restore the shape of the angle.7,17 In comparison to autogenous bone grafting, a major advantage of TDDO is that bone harvesting and potential donor site damage are avoidable.18,19 Gonza´lez-Garcı´a et al. described its usefulness in treating patients who were unsuitable for more aggressive surgery or undergoing prolonged surgical time because of poor general health or for patients in whom primary treatment using a vascularized free-osseous flap had failed. TDDO has also been reported to provide sufficient bone to allow dental implant placement, an important functional outcome.20 These advantages are of great significance to the patients with
1226
Liu et al.
Fig. 7. Satisfactory occlusion (a) and mouth opening (b) were demonstrated 35 months after treatment. Fig. 5. Postoperative panoramic radiographs. (a) At the intermediary stage of distraction. (b) At completion of distraction with appliance in situ. (c) After removal of appliance and completion of treatment.
Fig. 6. Full ossification of the distraction area was confirmed intraoperatively when the distraction device was removed.
Fig. 8. Satisfactory appearance at the end of a 35 month follow-up.
Distraction osteogenesis in mandible reconstruction in children
1227
the growth of the jaws. Nevertheless, this case boosts the authors’ confidence in the long-term effect of this technique. Undoubtedly a longer follow-up period and more clinical cases are needed to reach the final conclusion. In summary, the satisfactory results achieved in this 23-month-old girl, together with the avoidance of autogenous bone harvesting, indicate the feasibility of reconstructing a segmental mandibular defect with TDDO in patients with deciduous dentition, even at its early stage. This case encourages further attempts in similar clinical scenarios. It may, if strengthened by more cases, cast new light on the challenging mandible reconstruction in patients with deciduous dentition. Competing interests
None declared. Funding
Fig. 9. Three dimensional CT demonstrated that both the shape and bone volume of the reconstructed mandible were acceptable at the last follow-up.
deciduous dentition, such as the girl in this case. There was little information about the effectiveness of TDDO in young patients whose maxillofacial skeletons are undergoing rapid growth and whose permanent teeth are far from eruption. The significance of this case is that it demonstrated the effectiveness. The girl’s satisfactory occlusion and facial profile were stable through the 35 month follow-up. This indicates that new bone generated by TDDO, similar to the rest of the maxillofacial bones, continued to grow after treatment. Most cases of mandibular defect reconstructed with TDDO have been caused by benign tumour resection or trauma. It is still controversial to apply TDDO to patients suffering from malignant tumour who have undergone radiotherapy.21–24 Radiotherapy may interrupt a complex cascade of bone formation which is stimulated by distraction and involves several cytokines, such as bone morphogenetic proteins and insulin-like growth factors. Radiation may cause hypovascularity, hypoxia, and hypocellularity, an adverse environment for bony formation during distraction.21,23 Therefore, for patients who have undergone radiotherapy, vascularized autogenous bone
grafting may be a safer and more reliable option for mandible reconstruction. Mandible reconstruction with TDDO in pre-school patients is different from that in adults. Firstly, the mandible stump from which a transport disc is created contains tooth germs and some tooth germs may be lost in creating a transport disc. It is critical that the osteotomy line should not cut through any tooth germ otherwise there will be poor or no bone formation within the distraction area. In this regard, preoperative radiographs, CT-based rapid prototyping solid models and carefully simulated model surgery are helpful. Secondly, the potent osteogenicity of the residual mandible stump, in combination with highly vascularized soft tissue, is highly beneficial to bone formation in the distraction area. It also enhances the chance of fusion between the transport disc and the stump of ramus, as was shown in this case. In contrast, nonunion is not rare in adult patients with TDDO.16,25 For these adult patients, a small autogenous bone graft is necessary to bridge the gap at the time of distraction device removal.16,25 Thirdly, the maxillofacial skeleton on which TDDO is performed is rapidly growing. This leads to the concern that the reconstruction effect is not stable with
This study was supported by National Natural Science Foundation of China (No. 30901686), Technological Project Fund of Zhejiang Province of China (No. 2007C33012) and Qianjiang Intelligent Project Fund of Zhejiang Province (No. 2010R10070). Ethical approval
Not required. References 1. Guo L, Ferraro NF, Padwa BL, Kaban LB, Upton J. Vascularized fibular graft for pediatric mandibular reconstruction. Plast Reconstr Surg 2008;121:2095–105. 2. Warren SM, Borud LJ, Brecht LE, Longaker MT, Siebert JW. Microvascular reconstruction of the pediatric mandible. Plast Reconstr Surg 2007;119:649–61. 3. Goh BT, Lee S, Tideman H, Stoelinga PJ. Mandibular reconstruction in adults: a review. Int J Oral Maxillofac Surg 2008;37: 597–605. 4. Li JS, Chen WL, Huang ZQ, Zhang DM. Pediatric mandibular reconstruction after benign tumor ablation using a vascularized fibular flap. J Craniofac Surg 2009;20:431–4. 5. Chopra S, Enepekides DJ. The role of distraction osteogenesis in mandibular reconstruction. Curr Opin Otolaryngol Head Neck Surg 2007;15:197–201. 6. Hartman EH, Spauwen PH, Jansen JA. Donorsite complications in vascularized bone flap surgery. J Invest Surg 2002;15:185–97. 7. Chen J, Liu Y, Ping F, Zhao S, Xu X, Yan F. Two-step transport-disk distraction osteogenesis in reconstruction of mandibular
1228
8.
9.
10.
11.
12.
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Address: Jun Chen Department of Oral and Maxillofacial Surgery Second Affiliated Hospital Zhejiang University School of Medicine 88 Jiefang Rd. Hangzhou 310009 PR China Tel.: +86 571 87783513 fax: +86 571 87767078 E-mail: [email protected]