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Technical considerations in distraction osteogenesis
Int. J. Oral Maxillofac. Surg. 2004; 33: 89–94 doi:10.1054/ijom.2003.0462, available online at http://www.sciencedirect.com
Technical Note Distraction Osteogenesis
Technical considerations in distraction osteogenesis
M. A. A. Suhr, Th. Kreusch Department of Oral and Maxillofacial Surgery, Klinikum Nord, Tangstedter Landstrasse 400, 22417 Hamburg, Germany
M. A. A. Suhr, Th. Kreusch: Technical considerations in distraction osteogenesis. Int. J. Oral Maxillofac. Surg. 2004; 33: 89–94. 2003 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Five cases are presented to exemplify technical difficulties and complications which may be encountered when performing distraction osteogenesis in the facial skeleton. The procedure should be performed under close supervision by the surgical and orthodontic colleagues. Errors in the choice of vector may be managed by earlier removal of the distractor and subsequent traction on the previously osteotomized segments using orthodontic appliances and principles. Multiple distractors may be inserted in the same jaw and bimaxillary procedures are possible, increasing the likelihood of encountering technical difficulties. Detailed planning and close follow-up, with early recognition and active management of the complications, may be useful in ensuring a successful outcome of this versatlie procedure.
Introduction Distraction osteogenesis (DO) is a method of correcting deformities and augmenting deficiencies not only of bone but also of soft-tissue. The indications have expanded greatly. The basic technique of insertion of the device, 5–7 days rest and subsequent activation at the rate of 1 mm per day, followed by a 8–12 week consolidation phase15,16,36, has remained essentially unchanged over the years. Difficulties arise in the selection of the distractor, the vector, the osteotomy site, and patient compliance. Patients should be followed up closely by the operator and an orthodontic colleague. Accurate planning is not able to foresee all eventualities. Interim prostheses may perforate the mucosa, occlusal disturbances may arise, segments may change direction, and equipment may fail. We present a synopsis of our own experience and suggest possible ways of preventing and managing these problems. Use of the ‘floating bone concept’ 0901-5027/04/010089+06 $30.00/0
is a useful tool for correcting unexpected problems. Complications These may occur in up to 35% of cases and are related to a learning curve, with most complications documented by colleagues who have inserted less than 10 distractors (57% of those questioned)23. These figures were obtained using anonymous questionnaires and reflects the clinical situation. Only 4% of clinicians have performed DO in more than 100 cases. This group reports a complication rate of 22.8%. A recent review of the literature33 shows similar results. Complications can be classified into immediate, early and late and include the following: Immediate 1. Damage to the primary (1,9%)23 or secondary dentition including pulp necrosis and loosening
Key words: alveolar atrophy; bimaxillary; distraction osteogenesis; floating bone; mandible; maxilla; multiple osteotomies; vector. Accepted for publication 3 June 2003
2. Damage to the orthodontic appliance 3. Inability to find the screw-holes after performing the osteotomy12 4. Undercuts 5. Distractor plate or screw fracture 4.5%23 Early 6. Infection 5.2%23 7. Distractor loosening 3%23 8. Paraesthesia 3.6%14,23 9. Problems of compliance 4.7%23 Late 10. Occlusal disharmony5,23,30 11. Tooth elongation by elastic traction 12. Incorrect vector 7.2–8.8%23 13. Relapse 4%33 and up to 50%23 14. Premature bony consolidation 1.9%23 15. Facial nerve damage 0.4%23 16. Condylar resorption32 17. Alterations in the articulation8 18. Atypical facial pain <0.1%23 19. Injury through the distractor29
2003 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
90 20. 21. 22. 23. 24.
Suhr and Kreusch Fibrous union 0.5%23 Quadriparesis <0.1%23 Maxillary sinus perforation <0.1%23 Parotid fistula <0.1%23 Alterations in speech6
We do not know how much bone and soft-tissue is retained after distraction. We also do not know how this is aided by the insertion of implants. The rate of distraction is based upon laboratory animal work and differences between facial and long bones in terms of distraction have not been adequately studied, if such exist. The effect of the rate on sensory function of the inferior alveolar nerve has been documented elsewhere14. Multivector1,39 and combined distraction of the mandible and maxilla2,35 increase the risk of problems arising during and after the procedure.
Case reports Case 1. Insufficient screw length and plate fracture
A 21-year-old patient presented with a left-sided hemifacial microsomia. Examination of the 3D-milling models suggested distraction at the angle of the mandible21,27,35 of 12 mm, combined with a lateral sliding genioplasty. A TRACK 1.5 mm distractor (Tissue regeneration by alveolar callus distraction Ko¨ln, Martin Medical, Tuttlingen, Germany) was chosen9,27. At insertion it became apparent that the screw would protrude insufficiently into the vestibulum. No further suitable distractors were available for use and soft-tissue had to be reduced sufficiently to be able to reach the screw on a regular basis. We distracted the segment to 12 mm in 12 days. Application of the screwdriver was associated with severe pain. The patient was lost to follow-up for 6 months and at recall we found a fracture on the superior plate. Removal was technically demanding as there was callus formation over the entire length of the distractor plates and screws. Figures 1 and 2 show the orthopantanograms before and after the procedure. The gonial angle had been distracted insufficiently. Recommendations include the choice of a significantly greater distance of distraction, a different distractor size, better consideration of the soft-tissue relationships in the region of the external oblique ridge and the direction of distraction to achieve a better gonial angle.
Fig. 1. Orthopantanogram of case 1 before distraction. Case 2. Unsuccessful distraction osteogenesis
A 51-year-old patient presented with a left-sided cleft-lip and palate. She had never had an alveolar bone graft performed. The hard- and soft palate had been closed simultaneously at 2 years of age. She had been edentulous for 10 years. We found a severely retruded and atrophic maxilla, as well as a persistent oro-nasal fistula. The SNA was 64. We performed an alveolar bone graft and closed the oro-nasal fistula. Two months later we applied a RED II (Rigid External Distraction II System, Martin Medical, Tuttlingen, Germany) and performed a Le Fort I osteotomy7,19. The alveolar bone-graft site was not absolutely rigid. Two Leipzig rods connected the miniplates with the external distractor. Distraction was performed daily to a total of 19 mm with resulting velo-pharyngeal incompetence6,7. Figure 3 shows the patient in retention at 19 mm of forward distraction. After the retention period of 8 weeks, distractor removal was combined with the inser-
tion of miniplates to minimize or prevent relapse8. At surgery, an anteroposterior defect of 20 mm was noted, suggesting that distraction osteogenesis per se had not taken place. As the final treatment plan includes the insertion of implants, further bone-grafting should have been decided upon at the time of distractor removal in order to ensure sufficient bone volume at the site of the intended implant placement. Furthermore, the intended location of the implants should have been determined at the beginning of treatment in addition the considerations of the lateral cephalometric analysis. Case 3. Mucosal perforation by interim prosthesis, accidental damage to adjacent teeth
A 21-year-old patient presented with loss of the tooth 11 following dento-alveolar trauma. The loss of vertical height precluded implant insertion. A TRACK 1.0 mm device (Martin Medical, Tuttlingen, Germany) was inserted. Particular attention was paid to
Fig. 2. Orthopantanogram case 1 after distraction.
Technical considerations in distraction osteogenesis
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resulted in one of the plates fracturing off the distractor. The screws protruded through the lips and this caused the patient significant discomfort. A complex occlusal relationship developed6,35. At the completion of distraction (14 mm on the right, 13 mm on the left) the screws were removed using a wire-cutter. There was a residual anterior open bite. The retention was reduced from 8 to 3 weeks, the distractor removed at this time. Elastic traction was applied via the orthodontic appliance to the osteotomized segment and gradually distracted into the desired occlusal relationship (lateral radiograph Fig. 6 and orthopantanogram Fig. 7). Initially the segment was quite mobile, with differences of 3 mm with and without elastics. As the weeks progressed however, and the patient had had the anterior open bite closed, the segment unified and there has been no relapse at 3 months of follow-up. Case 5. Asymmetric bony requirements Fig. 3. Lateral photograph of case 2 after distraction.
the avoidance of undercuts in performing the osteotomies. An interim prosthesis was fitted at the completion of surgery. Postoperatively we noted a palatal mucosal perforation which was managed by relieving the prosthesis and removing a small amount of bone using a Luhr bone-nibbler. The tooth 12 was shown to be non-vital, but did not show any signs of discoloration. This tooth has not been treated endodontically. The distraction was completed (11 mm) and a Frialit II (Friadent, Mannheim, Germany) implant inserted at the time of distractor removal. It was noted at this procedure that the bucco-lingual dimension was inadequate. We performed an intra-oral bone-graft in the same sitting. The postoperative course has been uneventful.
between teeth 33 and 34 as well as between 43 and 44. There was hardly any interdental bone in these sites and the tooth 34 was loosened during the procedure. We applied a composite resin to the orthodontic appliance to fix the tooth. Due to the prominent rugae, excessive plate-bending was required for accurate and passive adaptation. This
Case 4. Metal fatigue and worsening of the anterior open-bite
An 18-year-old patient presented with severe mandibular hypoplasia, having already had distraction osteogenesis performed at the angles of the mandible some years previously5,32. A lateral radiograph (Fig. 4) and orthopantanogram (Fig. 5) show the patient at the time of presentation. We found an anterior open bite and insufficient archwidth to accommodate the dentition. We performed distraction osteogenesis
A 43-year-old patient presented with a necrotic bone transplant protruding through a loose implant and an associated mucosal perforation. The intention was to treat an edentulous space left after the loss of teeth 12–14. We removed the implant together with the necrotic bone and were able to achieve healing by secondary intention. An interim prosthesis was fitted. We performed distraction osteogenesis using a TRACK 1.5 mm distractor (Martin Medical, Tuttlingen, Germany). Distally, sufficient bone was present, however, mesially the defect reached almost to the piriform rim. A distance of 9 mm was distracted at the site where sufficient bone was available for attachment of the distractor plates and the patient is presently in retention. The proximal region remains deficient in bone quantity and soft-tissue and we plan to perform a bone-graft at the time of distractor removal and implant insertion. Discussion
Fig. 4. Lateral cephalometry of case 4 before treatment.
A review of 828 reported cases in the literature from 1966–1999 and attempted to assess the method of distraction osteogenesis as well as the complication rate33. M et al.23 attempted to analyse realistic experiences using anonymous questionnaires. Areas of controversy centre around possible differences between mono- and bicortical
92
Suhr and Kreusch as 8 years although there may be problems with patient compliance. We therefore usually offer this treatment option to patients older than 10 years of age and in particular to patients who live close by. Forces acting on the distractor
Fig. 5. Orthopantanogram of case 4 before treatment.
osteotomy, rate and rhythm of distraction, and length of retention. We have attempted to objectively assess the problems we have had with the technique and present five illustrative cases. We have had for example to resort to additional bone-grafting for all our alveolar bone distraction osteogeneses although in the majority of cases these have needed to be quite small. Complication rate
The number of complications may be related to operator experience, as determining the indication, deciding on the type of distractor, the vector and rate of
distraction as well as determining the success of the distraction at the time of the removal or at the time of, for example, the implant-insertion are empirical variables. Four per cent of centres actively involved in performing DO can report having performed this technique in >100 cases23. The rest perform the technique on a sporadic basis and may therefore be expected to have a greater complication rate per case treated. We have had for example to resort to additional bone-grafting in all our alveolar bone distractions and count this as a complication. Efforts at trying to circumvent this problem in osteotomy line design and choice of distractor have not proven to be successful as yet. Distraction and patient age
Fig. 6. Lateral skull radiograph of case 4 after treatment.
Midline expansion is performed only after the age of 12 years33. Otherwise there appears to be no age-limit for the performance of the procedure4. Intra-oral devices for example in the treatment of mandibular hypoplasia have been inserted in patients as young
Movement of dentate bone or bone that is intended for dental rehabilitation is exposed to a multitude of forces which determine the final quantity and position9,20,22,27. Attached gingiva and periosteum is required, and the location of the incision should be chosen such that the final restoration may successfully be placed. Directional stability should be ensured in order to counteract soft-tissue forces26 which still seems to be a problem, even after the manufacturer has augmented the distractor with a vertical extension. This is assumed to be due to metal fatigue and an inability to overcome the forces. Expanding indications
If implants have been placed in the incorrect position, distraction may present a treatment option for their correction. DO may also be an option for retained teeth. Combinations of DO with other (cosmetic) surgery techniques such as onlay grafting may occasionally be required17,18,24. The screws must remain accessible throughout and the limits set by the distractor not be reached. The choice of distractor should be adequate to meet the treatment needs, and not be too large or too small. Continuous relief of interim prostheses where used should be performed in order to avoid mucosal perforation. Limits of distraction
Geniohyoid musculature can be lengthened to a maximum of 20% resting length. The inferior alveolar nerve may be able to be distracted14. Other than these two limitations, tissue expansion has shown the immense potential of skin and subcutaneous tissue for increasing surface area. The segment must remain attached to vital tissue. We are not aware of any other limits to date, and have not received reports of ischaemic (bone) necrosis after distraction osteogenesis. Duration of retention Fig. 7. Orthopantanogram of case 4 after treatment.
We routinely perform retention for 6 weeks, unless correction of an
Technical considerations in distraction osteogenesis incorrectly chosen vector is required. Retention may be longer in patients of the age-ranges 10–12 and 13–16 years33. Retention in the maxilla after rigid external distraction is only 2–4 weeks23 in some centres. Longer retention is recommended although this does not decrease the incidence of relapse. ‘Floating bone’
Errors in determining the vector may be corrected by the ‘floating bone concept’ as suggested by H13. Unsatisfactory positioning of the fragment should motivate the clinician to shorten the retention phase of the distractor to 3–4 weeks and continue distraction using elastic traction and the opposing dentition. The segment should be amenable to elastic traction by providing attachments for the elastics. We have applied this principle using intermaxillary elastic traction devices on fixed orthodontic appliances but have found it difficult to control the movement of the segments, resulting in sub-optimal treatment outcomes. We look forward to further developments in this field. Follow-up and relapse rate
Of mandibular DO only 26% patients were followed up for more than a year, with a 4% relapse-rate. No relapse was noted in alveolar bone DO group over a follow-up period of 13 months23. Nevertheless over-correction of alveolar segment distraction is recommended for the same reasons as apply in alveolar bone-grafting. M et al.23 reported a relapse-rate of up to 60% in the maxilla, which concurs with our clinical impression. Overcorrection is strongly recommended. General remarks
Reports are increasingly able to report bigger series10,11,20,22,28,34,37,38, pointing to an increasing acceptance of the procedure in routine clinical practice. DO is used sporadically in the majority of cases. The spectrum of indications and innovations is expanding17,18,19. An entire issue of the aesthetics journal ‘Annales Chirurgie Plastique et Esthetique’ (2001; 46(4) French) was devoted to the technique, yet consisted only of case reports. Representative articles are those of M et al.23 and S et al.33. In conclusion, the avoidance of undercuts, the movement of the segment into
the final planned position (and overcorrection) using the distractor at the time of insertion, avoidance of collateral damage and support of the patient throughout the procedure are prerequisites for the performance of this procedure. Clear advantages over conventional osteotomies and bone-grafting are still to be described. It is an unusually complex process which is reserved for the unusual patient to fulfil a complex requirement. DO is a continuous and fluid process which requires careful planning and close observation in order to detect errors early. There is a lack of evidence in support of the current method and the above should be seen as a consensus approach. It may be taken into the armamentarium of the treating surgeon as one way of obtaining bone quantity25,26 and movement of tooth- or implant-carrying bone34,39.
10.
11.
12.
13.
14.
15.
References 1. A C, O OR, L HW. Shortening of mandibular linear distance with multivector distraction. J Craniofac Surg 2001: 12: 505–514. 2. C BC, S DP, P JW, B BS. Bimaxillary osteodistraction for the treatment of facial asymmetry in adults. Br J Plast Surg 2001: 54: 491–498. 3. C JY, H KG, B SH, L JH, K TW, K MJ, C YI. Original sagittal split osteotomy revisited for mandibular distraction. J Maxillofac Surg 2001: 29: 165–173. 4. D AD, T R, H PR, R RF. Mandibular distraction osteogenesis in very young patients to correct airway obstruction. Plast Reconstr Surg 2001: 108: 302–311. 5. G M, B WH, G CA, B PH, S ML. Positional changes and stability of bone segments during simultaneous bilateral mandibular lengthening and widening by distraction. Br J Oral Maxillofac Surg 2001: 39: 169–178. 6. G TW, P JW, F A, S BE. Changes in speech following maxillary distraction osteogenesis. Cleft Palate Craniofac J 2001: 38: 199–205. 7. H K, B Y, O K, E S. Maxillary distraction osteogenesis for cleft lip and palate children using an external, adjustable, rigid distraction device: A report of 2 cases. J Oral Maxillofac Surg 2001: 59: 1492–1496. 8. H TH, H A. A novel modular retention system for midfacial distraction osteogenesis. BJOMFS 2000: 38: 623–626. 9. H J, L F, Z¨ JE. Erste Ergebnisse bei der Distraktionsosteogenese des atrophischen Alveo-
16.
17.
18.
19.
20.
21.
22.
23.
24.
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larkammes. Mund Kiefer Gesichtschir 1999: 3: 48. H T, P T, K¨ R, H H. Distraktionsosteogenese im Mittelgesichtsbereich. Quintessenz 2000: 51: 247–256. H T, K R, H A. Midfacial distraction osteogenesis without major osteotomies: a report on the first clinical application. Plast Reconstr Surg 2001: 108: 1667–1672. H T, H A. Endoscopically assisted intraoral mandibular distraction osteogenesis. Int J Oral Maxillofac Surg 2001: 30: 339–341. H B, M CH, W KD. The floating bone concept in intraoral mandibular distraction. J Craniomaxillofac Surg 1998: 26: S76. H J, T Z, W D, B MJ. Changes in the inferior alveolar nerve after mandibular lengthening with different rates of distraction. J Oral Maxillofac Surg 2001: 59: 1041–1045. I GA. The principles of the Ilizarov method. Bull Hosp Joint Dis Orthop Inst 1988: 48: 1. I GA. The tension-stress effect on the genesis and growth of tissues. Part II: The influence of the rate and frequency of distraction. Clin Orthop 1989: 239: 263. K DT, M CM, T V. Mandibular distraction combined with tongue-base traction for treatment of obstructive sleep apnea syndrome. Plast Reconstr Surg 2001: 108: 1673–1676. K CN, M-S GA, M W, W F, E R. Preprosthetic vertical distraction osteogenesis of the mandible using an L-shaped osteotomy and titanium membranes for guided bone regeneration. J Oral Maxillofac Surg 2001: 59: 1302–8. K M, C CP, R M, B M, R S. External distraction of the maxilla in patients with craniofacial dysplasia. J Craniofac Surg 2001: 12: 458–463. L PJ. Reflections on: distraction osteogenesis. Distraction osteogenesis. Br J Oral Maxillofac Surg 2001: 39: 181. M C, C P, R N. Mandibular distraction osteogenesis in unilateral craniofacial microsomia: preliminary report. J Med Assoc Thai 2001: 84: 811– 820. MC JG, S EJ, M BJ, L MT. Distraction osteogenesis of the craniofacial skeleton. Plast Reconstr Surg 2001: 108: 1501–1508. M MM, M PN, R BC, T AP, E JJ, V K CA. Craniofacial distraction osteogenesis: a review of 3278 cases. Plast Reconstr Surg 2001: 108: 1103–14. M MY, A JS, G H. Mandibular angle augmentation with the use of distraction and homologous lyophilized cartilage in a case of
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25.
26.
27.
28.
29.
30.
Suhr and Kreusch morphing to Michael Jackson surgery. Ann Chir Plast Esthet 2001: 46: 336–340. P AR, D F, B E, G G, C D. Vertical alveolar distraction osteogenesis of the posterior edentulous mandible: a case report. Ann Chir Plast Esthet 2001: 46: 330–335. R GM, H K, V A. Vertical distraction of the severely resorbed mandible. The Groningen Distraction Device. Int J Oral Maxillofac Surg 2000: 29: 416–420. R A, M R, P M, L D. Intraoral distraction osteogenesis of the mandible in hemifacial microsomia. J Oral Maxillofac Surg 2001: 59: 728–733. R JP. Reflections on: distraction osteogenesis. Distraction osteogenesis— the future? Br J Oral Maxillofac Surg 2001: 39: 180–181. R J, J IT, T JS, A B. Traumatic cranial injury sustained from a fall on the rigid external distraction device. J Craniofac Surg 2001: 12: 237– 241. R-B P, V E, C A, N L, S J, M R,
31.
32.
33.
34.
35.
D-G FJ. Intraoral mandibular distraction osteogenesis: special attention to treatment planning. J Craniomaxillofac Surg 2001: 29: 254–262. S JD, S D, T B. Distraction osteogenesis of the mandible for airway obstruction in children. Laryngoscope 2001: 111: 1137– 1146. V S PJ, B KH, B AG, T DB. Condylar resorption following distraction osteogenesis: a case report. J Oral Maxillofac Surg 2001: 59: 1104–1107. S G, S H, D R, S H, M C. Craniofacial distraction osteogenesis: a review of the literature: Part 1: clinical studies. Int J Oral Maxillofac Surg 2001: 30: 89–103. V RL. Arch form and emerging treatment options. Int J Adult Orthodon Orthognath Surg 2001: 16: 5. V HL, P J, L N. Combined simultaneous distraction osteogenesis of the maxilla and mandible using a single distraction device in hemifacial microsomia. J Craniofac Surg 2001: 12: 253– 258.
36. W K, G H. [Der enorale Zugang bei Ilizarov Kallus-Distraktionenim Unterkiefer]. Dtsch Z Mund Kiefer Gesichts Chir 1995: 19: 303. 37. W K. [Distraction in mouth, jaw and facial surgery]. Mund Kiefer Gesichtschir 2000: 4: S226–236. 38. W D, R M, L P. Distraktionsosteogenese. Mund Kiefer Gesichtschir 2001: 5: 221–226. 39. Z W, B T, Z K, C A, W G. Multidimensional osteodistraction for correction of implant malposition in edentulous segments. Clin Oral Implant Res 2001: 12: 531–538.
Address: Mr Manfred A. A. Suhr Department of Oral and Maxillofacial Surgery Klinikum Nord Tangstedter Landstrasse 400 22417 Hamburg, Germany Tel.: 0049-40-5271-3760 Fax: 0049-40-5271-3767 E-mail: [email protected]
Technical Note Distraction Osteogenesis
Technical considerations in distraction osteogenesis
M. A. A. Suhr, Th. Kreusch Department of Oral and Maxillofacial Surgery, Klinikum Nord, Tangstedter Landstrasse 400, 22417 Hamburg, Germany
M. A. A. Suhr, Th. Kreusch: Technical considerations in distraction osteogenesis. Int. J. Oral Maxillofac. Surg. 2004; 33: 89–94. 2003 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. Five cases are presented to exemplify technical difficulties and complications which may be encountered when performing distraction osteogenesis in the facial skeleton. The procedure should be performed under close supervision by the surgical and orthodontic colleagues. Errors in the choice of vector may be managed by earlier removal of the distractor and subsequent traction on the previously osteotomized segments using orthodontic appliances and principles. Multiple distractors may be inserted in the same jaw and bimaxillary procedures are possible, increasing the likelihood of encountering technical difficulties. Detailed planning and close follow-up, with early recognition and active management of the complications, may be useful in ensuring a successful outcome of this versatlie procedure.
Introduction Distraction osteogenesis (DO) is a method of correcting deformities and augmenting deficiencies not only of bone but also of soft-tissue. The indications have expanded greatly. The basic technique of insertion of the device, 5–7 days rest and subsequent activation at the rate of 1 mm per day, followed by a 8–12 week consolidation phase15,16,36, has remained essentially unchanged over the years. Difficulties arise in the selection of the distractor, the vector, the osteotomy site, and patient compliance. Patients should be followed up closely by the operator and an orthodontic colleague. Accurate planning is not able to foresee all eventualities. Interim prostheses may perforate the mucosa, occlusal disturbances may arise, segments may change direction, and equipment may fail. We present a synopsis of our own experience and suggest possible ways of preventing and managing these problems. Use of the ‘floating bone concept’ 0901-5027/04/010089+06 $30.00/0
is a useful tool for correcting unexpected problems. Complications These may occur in up to 35% of cases and are related to a learning curve, with most complications documented by colleagues who have inserted less than 10 distractors (57% of those questioned)23. These figures were obtained using anonymous questionnaires and reflects the clinical situation. Only 4% of clinicians have performed DO in more than 100 cases. This group reports a complication rate of 22.8%. A recent review of the literature33 shows similar results. Complications can be classified into immediate, early and late and include the following: Immediate 1. Damage to the primary (1,9%)23 or secondary dentition including pulp necrosis and loosening
Key words: alveolar atrophy; bimaxillary; distraction osteogenesis; floating bone; mandible; maxilla; multiple osteotomies; vector. Accepted for publication 3 June 2003
2. Damage to the orthodontic appliance 3. Inability to find the screw-holes after performing the osteotomy12 4. Undercuts 5. Distractor plate or screw fracture 4.5%23 Early 6. Infection 5.2%23 7. Distractor loosening 3%23 8. Paraesthesia 3.6%14,23 9. Problems of compliance 4.7%23 Late 10. Occlusal disharmony5,23,30 11. Tooth elongation by elastic traction 12. Incorrect vector 7.2–8.8%23 13. Relapse 4%33 and up to 50%23 14. Premature bony consolidation 1.9%23 15. Facial nerve damage 0.4%23 16. Condylar resorption32 17. Alterations in the articulation8 18. Atypical facial pain <0.1%23 19. Injury through the distractor29
2003 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
90 20. 21. 22. 23. 24.
Suhr and Kreusch Fibrous union 0.5%23 Quadriparesis <0.1%23 Maxillary sinus perforation <0.1%23 Parotid fistula <0.1%23 Alterations in speech6
We do not know how much bone and soft-tissue is retained after distraction. We also do not know how this is aided by the insertion of implants. The rate of distraction is based upon laboratory animal work and differences between facial and long bones in terms of distraction have not been adequately studied, if such exist. The effect of the rate on sensory function of the inferior alveolar nerve has been documented elsewhere14. Multivector1,39 and combined distraction of the mandible and maxilla2,35 increase the risk of problems arising during and after the procedure.
Case reports Case 1. Insufficient screw length and plate fracture
A 21-year-old patient presented with a left-sided hemifacial microsomia. Examination of the 3D-milling models suggested distraction at the angle of the mandible21,27,35 of 12 mm, combined with a lateral sliding genioplasty. A TRACK 1.5 mm distractor (Tissue regeneration by alveolar callus distraction Ko¨ln, Martin Medical, Tuttlingen, Germany) was chosen9,27. At insertion it became apparent that the screw would protrude insufficiently into the vestibulum. No further suitable distractors were available for use and soft-tissue had to be reduced sufficiently to be able to reach the screw on a regular basis. We distracted the segment to 12 mm in 12 days. Application of the screwdriver was associated with severe pain. The patient was lost to follow-up for 6 months and at recall we found a fracture on the superior plate. Removal was technically demanding as there was callus formation over the entire length of the distractor plates and screws. Figures 1 and 2 show the orthopantanograms before and after the procedure. The gonial angle had been distracted insufficiently. Recommendations include the choice of a significantly greater distance of distraction, a different distractor size, better consideration of the soft-tissue relationships in the region of the external oblique ridge and the direction of distraction to achieve a better gonial angle.
Fig. 1. Orthopantanogram of case 1 before distraction. Case 2. Unsuccessful distraction osteogenesis
A 51-year-old patient presented with a left-sided cleft-lip and palate. She had never had an alveolar bone graft performed. The hard- and soft palate had been closed simultaneously at 2 years of age. She had been edentulous for 10 years. We found a severely retruded and atrophic maxilla, as well as a persistent oro-nasal fistula. The SNA was 64. We performed an alveolar bone graft and closed the oro-nasal fistula. Two months later we applied a RED II (Rigid External Distraction II System, Martin Medical, Tuttlingen, Germany) and performed a Le Fort I osteotomy7,19. The alveolar bone-graft site was not absolutely rigid. Two Leipzig rods connected the miniplates with the external distractor. Distraction was performed daily to a total of 19 mm with resulting velo-pharyngeal incompetence6,7. Figure 3 shows the patient in retention at 19 mm of forward distraction. After the retention period of 8 weeks, distractor removal was combined with the inser-
tion of miniplates to minimize or prevent relapse8. At surgery, an anteroposterior defect of 20 mm was noted, suggesting that distraction osteogenesis per se had not taken place. As the final treatment plan includes the insertion of implants, further bone-grafting should have been decided upon at the time of distractor removal in order to ensure sufficient bone volume at the site of the intended implant placement. Furthermore, the intended location of the implants should have been determined at the beginning of treatment in addition the considerations of the lateral cephalometric analysis. Case 3. Mucosal perforation by interim prosthesis, accidental damage to adjacent teeth
A 21-year-old patient presented with loss of the tooth 11 following dento-alveolar trauma. The loss of vertical height precluded implant insertion. A TRACK 1.0 mm device (Martin Medical, Tuttlingen, Germany) was inserted. Particular attention was paid to
Fig. 2. Orthopantanogram case 1 after distraction.
Technical considerations in distraction osteogenesis
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resulted in one of the plates fracturing off the distractor. The screws protruded through the lips and this caused the patient significant discomfort. A complex occlusal relationship developed6,35. At the completion of distraction (14 mm on the right, 13 mm on the left) the screws were removed using a wire-cutter. There was a residual anterior open bite. The retention was reduced from 8 to 3 weeks, the distractor removed at this time. Elastic traction was applied via the orthodontic appliance to the osteotomized segment and gradually distracted into the desired occlusal relationship (lateral radiograph Fig. 6 and orthopantanogram Fig. 7). Initially the segment was quite mobile, with differences of 3 mm with and without elastics. As the weeks progressed however, and the patient had had the anterior open bite closed, the segment unified and there has been no relapse at 3 months of follow-up. Case 5. Asymmetric bony requirements Fig. 3. Lateral photograph of case 2 after distraction.
the avoidance of undercuts in performing the osteotomies. An interim prosthesis was fitted at the completion of surgery. Postoperatively we noted a palatal mucosal perforation which was managed by relieving the prosthesis and removing a small amount of bone using a Luhr bone-nibbler. The tooth 12 was shown to be non-vital, but did not show any signs of discoloration. This tooth has not been treated endodontically. The distraction was completed (11 mm) and a Frialit II (Friadent, Mannheim, Germany) implant inserted at the time of distractor removal. It was noted at this procedure that the bucco-lingual dimension was inadequate. We performed an intra-oral bone-graft in the same sitting. The postoperative course has been uneventful.
between teeth 33 and 34 as well as between 43 and 44. There was hardly any interdental bone in these sites and the tooth 34 was loosened during the procedure. We applied a composite resin to the orthodontic appliance to fix the tooth. Due to the prominent rugae, excessive plate-bending was required for accurate and passive adaptation. This
Case 4. Metal fatigue and worsening of the anterior open-bite
An 18-year-old patient presented with severe mandibular hypoplasia, having already had distraction osteogenesis performed at the angles of the mandible some years previously5,32. A lateral radiograph (Fig. 4) and orthopantanogram (Fig. 5) show the patient at the time of presentation. We found an anterior open bite and insufficient archwidth to accommodate the dentition. We performed distraction osteogenesis
A 43-year-old patient presented with a necrotic bone transplant protruding through a loose implant and an associated mucosal perforation. The intention was to treat an edentulous space left after the loss of teeth 12–14. We removed the implant together with the necrotic bone and were able to achieve healing by secondary intention. An interim prosthesis was fitted. We performed distraction osteogenesis using a TRACK 1.5 mm distractor (Martin Medical, Tuttlingen, Germany). Distally, sufficient bone was present, however, mesially the defect reached almost to the piriform rim. A distance of 9 mm was distracted at the site where sufficient bone was available for attachment of the distractor plates and the patient is presently in retention. The proximal region remains deficient in bone quantity and soft-tissue and we plan to perform a bone-graft at the time of distractor removal and implant insertion. Discussion
Fig. 4. Lateral cephalometry of case 4 before treatment.
A review of 828 reported cases in the literature from 1966–1999 and attempted to assess the method of distraction osteogenesis as well as the complication rate33. M et al.23 attempted to analyse realistic experiences using anonymous questionnaires. Areas of controversy centre around possible differences between mono- and bicortical
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Suhr and Kreusch as 8 years although there may be problems with patient compliance. We therefore usually offer this treatment option to patients older than 10 years of age and in particular to patients who live close by. Forces acting on the distractor
Fig. 5. Orthopantanogram of case 4 before treatment.
osteotomy, rate and rhythm of distraction, and length of retention. We have attempted to objectively assess the problems we have had with the technique and present five illustrative cases. We have had for example to resort to additional bone-grafting for all our alveolar bone distraction osteogeneses although in the majority of cases these have needed to be quite small. Complication rate
The number of complications may be related to operator experience, as determining the indication, deciding on the type of distractor, the vector and rate of
distraction as well as determining the success of the distraction at the time of the removal or at the time of, for example, the implant-insertion are empirical variables. Four per cent of centres actively involved in performing DO can report having performed this technique in >100 cases23. The rest perform the technique on a sporadic basis and may therefore be expected to have a greater complication rate per case treated. We have had for example to resort to additional bone-grafting in all our alveolar bone distractions and count this as a complication. Efforts at trying to circumvent this problem in osteotomy line design and choice of distractor have not proven to be successful as yet. Distraction and patient age
Fig. 6. Lateral skull radiograph of case 4 after treatment.
Midline expansion is performed only after the age of 12 years33. Otherwise there appears to be no age-limit for the performance of the procedure4. Intra-oral devices for example in the treatment of mandibular hypoplasia have been inserted in patients as young
Movement of dentate bone or bone that is intended for dental rehabilitation is exposed to a multitude of forces which determine the final quantity and position9,20,22,27. Attached gingiva and periosteum is required, and the location of the incision should be chosen such that the final restoration may successfully be placed. Directional stability should be ensured in order to counteract soft-tissue forces26 which still seems to be a problem, even after the manufacturer has augmented the distractor with a vertical extension. This is assumed to be due to metal fatigue and an inability to overcome the forces. Expanding indications
If implants have been placed in the incorrect position, distraction may present a treatment option for their correction. DO may also be an option for retained teeth. Combinations of DO with other (cosmetic) surgery techniques such as onlay grafting may occasionally be required17,18,24. The screws must remain accessible throughout and the limits set by the distractor not be reached. The choice of distractor should be adequate to meet the treatment needs, and not be too large or too small. Continuous relief of interim prostheses where used should be performed in order to avoid mucosal perforation. Limits of distraction
Geniohyoid musculature can be lengthened to a maximum of 20% resting length. The inferior alveolar nerve may be able to be distracted14. Other than these two limitations, tissue expansion has shown the immense potential of skin and subcutaneous tissue for increasing surface area. The segment must remain attached to vital tissue. We are not aware of any other limits to date, and have not received reports of ischaemic (bone) necrosis after distraction osteogenesis. Duration of retention Fig. 7. Orthopantanogram of case 4 after treatment.
We routinely perform retention for 6 weeks, unless correction of an
Technical considerations in distraction osteogenesis incorrectly chosen vector is required. Retention may be longer in patients of the age-ranges 10–12 and 13–16 years33. Retention in the maxilla after rigid external distraction is only 2–4 weeks23 in some centres. Longer retention is recommended although this does not decrease the incidence of relapse. ‘Floating bone’
Errors in determining the vector may be corrected by the ‘floating bone concept’ as suggested by H13. Unsatisfactory positioning of the fragment should motivate the clinician to shorten the retention phase of the distractor to 3–4 weeks and continue distraction using elastic traction and the opposing dentition. The segment should be amenable to elastic traction by providing attachments for the elastics. We have applied this principle using intermaxillary elastic traction devices on fixed orthodontic appliances but have found it difficult to control the movement of the segments, resulting in sub-optimal treatment outcomes. We look forward to further developments in this field. Follow-up and relapse rate
Of mandibular DO only 26% patients were followed up for more than a year, with a 4% relapse-rate. No relapse was noted in alveolar bone DO group over a follow-up period of 13 months23. Nevertheless over-correction of alveolar segment distraction is recommended for the same reasons as apply in alveolar bone-grafting. M et al.23 reported a relapse-rate of up to 60% in the maxilla, which concurs with our clinical impression. Overcorrection is strongly recommended. General remarks
Reports are increasingly able to report bigger series10,11,20,22,28,34,37,38, pointing to an increasing acceptance of the procedure in routine clinical practice. DO is used sporadically in the majority of cases. The spectrum of indications and innovations is expanding17,18,19. An entire issue of the aesthetics journal ‘Annales Chirurgie Plastique et Esthetique’ (2001; 46(4) French) was devoted to the technique, yet consisted only of case reports. Representative articles are those of M et al.23 and S et al.33. In conclusion, the avoidance of undercuts, the movement of the segment into
the final planned position (and overcorrection) using the distractor at the time of insertion, avoidance of collateral damage and support of the patient throughout the procedure are prerequisites for the performance of this procedure. Clear advantages over conventional osteotomies and bone-grafting are still to be described. It is an unusually complex process which is reserved for the unusual patient to fulfil a complex requirement. DO is a continuous and fluid process which requires careful planning and close observation in order to detect errors early. There is a lack of evidence in support of the current method and the above should be seen as a consensus approach. It may be taken into the armamentarium of the treating surgeon as one way of obtaining bone quantity25,26 and movement of tooth- or implant-carrying bone34,39.
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References 1. A C, O OR, L HW. Shortening of mandibular linear distance with multivector distraction. J Craniofac Surg 2001: 12: 505–514. 2. C BC, S DP, P JW, B BS. Bimaxillary osteodistraction for the treatment of facial asymmetry in adults. Br J Plast Surg 2001: 54: 491–498. 3. C JY, H KG, B SH, L JH, K TW, K MJ, C YI. Original sagittal split osteotomy revisited for mandibular distraction. J Maxillofac Surg 2001: 29: 165–173. 4. D AD, T R, H PR, R RF. Mandibular distraction osteogenesis in very young patients to correct airway obstruction. Plast Reconstr Surg 2001: 108: 302–311. 5. G M, B WH, G CA, B PH, S ML. Positional changes and stability of bone segments during simultaneous bilateral mandibular lengthening and widening by distraction. Br J Oral Maxillofac Surg 2001: 39: 169–178. 6. G TW, P JW, F A, S BE. Changes in speech following maxillary distraction osteogenesis. Cleft Palate Craniofac J 2001: 38: 199–205. 7. H K, B Y, O K, E S. Maxillary distraction osteogenesis for cleft lip and palate children using an external, adjustable, rigid distraction device: A report of 2 cases. J Oral Maxillofac Surg 2001: 59: 1492–1496. 8. H TH, H A. A novel modular retention system for midfacial distraction osteogenesis. BJOMFS 2000: 38: 623–626. 9. H J, L F, Z¨ JE. Erste Ergebnisse bei der Distraktionsosteogenese des atrophischen Alveo-
16.
17.
18.
19.
20.
21.
22.
23.
24.
93
larkammes. Mund Kiefer Gesichtschir 1999: 3: 48. H T, P T, K¨ R, H H. Distraktionsosteogenese im Mittelgesichtsbereich. Quintessenz 2000: 51: 247–256. H T, K R, H A. Midfacial distraction osteogenesis without major osteotomies: a report on the first clinical application. Plast Reconstr Surg 2001: 108: 1667–1672. H T, H A. Endoscopically assisted intraoral mandibular distraction osteogenesis. Int J Oral Maxillofac Surg 2001: 30: 339–341. H B, M CH, W KD. The floating bone concept in intraoral mandibular distraction. J Craniomaxillofac Surg 1998: 26: S76. H J, T Z, W D, B MJ. Changes in the inferior alveolar nerve after mandibular lengthening with different rates of distraction. J Oral Maxillofac Surg 2001: 59: 1041–1045. I GA. The principles of the Ilizarov method. Bull Hosp Joint Dis Orthop Inst 1988: 48: 1. I GA. The tension-stress effect on the genesis and growth of tissues. Part II: The influence of the rate and frequency of distraction. Clin Orthop 1989: 239: 263. K DT, M CM, T V. Mandibular distraction combined with tongue-base traction for treatment of obstructive sleep apnea syndrome. Plast Reconstr Surg 2001: 108: 1673–1676. K CN, M-S GA, M W, W F, E R. Preprosthetic vertical distraction osteogenesis of the mandible using an L-shaped osteotomy and titanium membranes for guided bone regeneration. J Oral Maxillofac Surg 2001: 59: 1302–8. K M, C CP, R M, B M, R S. External distraction of the maxilla in patients with craniofacial dysplasia. J Craniofac Surg 2001: 12: 458–463. L PJ. Reflections on: distraction osteogenesis. Distraction osteogenesis. Br J Oral Maxillofac Surg 2001: 39: 181. M C, C P, R N. Mandibular distraction osteogenesis in unilateral craniofacial microsomia: preliminary report. J Med Assoc Thai 2001: 84: 811– 820. MC JG, S EJ, M BJ, L MT. Distraction osteogenesis of the craniofacial skeleton. Plast Reconstr Surg 2001: 108: 1501–1508. M MM, M PN, R BC, T AP, E JJ, V K CA. Craniofacial distraction osteogenesis: a review of 3278 cases. Plast Reconstr Surg 2001: 108: 1103–14. M MY, A JS, G H. Mandibular angle augmentation with the use of distraction and homologous lyophilized cartilage in a case of
94
25.
26.
27.
28.
29.
30.
Suhr and Kreusch morphing to Michael Jackson surgery. Ann Chir Plast Esthet 2001: 46: 336–340. P AR, D F, B E, G G, C D. Vertical alveolar distraction osteogenesis of the posterior edentulous mandible: a case report. Ann Chir Plast Esthet 2001: 46: 330–335. R GM, H K, V A. Vertical distraction of the severely resorbed mandible. The Groningen Distraction Device. Int J Oral Maxillofac Surg 2000: 29: 416–420. R A, M R, P M, L D. Intraoral distraction osteogenesis of the mandible in hemifacial microsomia. J Oral Maxillofac Surg 2001: 59: 728–733. R JP. Reflections on: distraction osteogenesis. Distraction osteogenesis— the future? Br J Oral Maxillofac Surg 2001: 39: 180–181. R J, J IT, T JS, A B. Traumatic cranial injury sustained from a fall on the rigid external distraction device. J Craniofac Surg 2001: 12: 237– 241. R-B P, V E, C A, N L, S J, M R,
31.
32.
33.
34.
35.
D-G FJ. Intraoral mandibular distraction osteogenesis: special attention to treatment planning. J Craniomaxillofac Surg 2001: 29: 254–262. S JD, S D, T B. Distraction osteogenesis of the mandible for airway obstruction in children. Laryngoscope 2001: 111: 1137– 1146. V S PJ, B KH, B AG, T DB. Condylar resorption following distraction osteogenesis: a case report. J Oral Maxillofac Surg 2001: 59: 1104–1107. S G, S H, D R, S H, M C. Craniofacial distraction osteogenesis: a review of the literature: Part 1: clinical studies. Int J Oral Maxillofac Surg 2001: 30: 89–103. V RL. Arch form and emerging treatment options. Int J Adult Orthodon Orthognath Surg 2001: 16: 5. V HL, P J, L N. Combined simultaneous distraction osteogenesis of the maxilla and mandible using a single distraction device in hemifacial microsomia. J Craniofac Surg 2001: 12: 253– 258.
36. W K, G H. [Der enorale Zugang bei Ilizarov Kallus-Distraktionenim Unterkiefer]. Dtsch Z Mund Kiefer Gesichts Chir 1995: 19: 303. 37. W K. [Distraction in mouth, jaw and facial surgery]. Mund Kiefer Gesichtschir 2000: 4: S226–236. 38. W D, R M, L P. Distraktionsosteogenese. Mund Kiefer Gesichtschir 2001: 5: 221–226. 39. Z W, B T, Z K, C A, W G. Multidimensional osteodistraction for correction of implant malposition in edentulous segments. Clin Oral Implant Res 2001: 12: 531–538.
Address: Mr Manfred A. A. Suhr Department of Oral and Maxillofacial Surgery Klinikum Nord Tangstedter Landstrasse 400 22417 Hamburg, Germany Tel.: 0049-40-5271-3760 Fax: 0049-40-5271-3767 E-mail: [email protected]