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Distraction osteogenesis of the jaws – pertinent papers 2002
British Journal of Oral and Maxillofacial Surgery 45 (2007) 87–89
Specialist Review
Distraction osteogenesis of the jaws – pertinent papers 2002 Maire Morton Available online 1 August 2005
Papers relating to distraction osteogenesis as applied to the maxillofacial region started to be published in the late 1980s and early 1990s. A Medline search of this title in the English language produced one paper in 1990 and by 2002 there were 91. As with all new technologies papers initially referred to animal work and case reports. Although some years have now passed there is still a lack of prospective case series of heterogeneous clinical material. Of the 91 papers that I reviewed for this article there was one prospective study with 5-year follow up. There were 21 animal studies of which just over half dealt with biological aspects of distraction. There were 19 retrospective case reports, 3 review articles, and 9 miscellaneous articles dealing mostly with aspects of healing or planning. Swennen G, Dempf R, Schliephake H. Craniofacial distraction osteogenesis: a review of the literature. Part II: Experimental studies. Int J Oral Maxillofac Surg 2002;31:123–35. The authors identified 120 articles about experimental craniofacial distraction between 1966 and 2000. The papers were divided into four groups dealing with mandibular, maxillary, midface, and cranial areas. Most (72%) dealt with the mandible. Seven different animal models were used and the authors attempted to define aspects of craniofacial distraction for each animal model. They pointed out that in much animal research in this field the extent of growth of the animals was not mentioned although this might make a material difference to the results. They made the case for this to be stated clearly in future. The authors then went on to look at the appropriateness of the various animal models based on phylogenic classification.
Comment This paper has 139 references and is a valuable resource. In particular the tables clearly show the areas where most animal research has concentrated and conversely the areas where there are gaps. The table showing the distraction variables for the various animal models is particularly helpful. Mommaerts MY, Nagy K. Is early osteodistraction a solution for the ascending ramus compartment in hemifacial microsomia? A literature study. J Craniomaxillofac Surg 2002;30:201–7. The authors examined the hypothesis that osteodistraction in hemifacial microsomia before skeletal maturity, induces generation of bone and soft tissue and renders conventional grafts of bone and soft tissue unnecessary. This early treatment has a beneficial effect on the ‘functional matrix’, promoting symmetrical vertical and sagittal expansion of the midface and the mandible. They examined eight published studies with follow up of distraction histogenesis in the ascending ramus, only two of which had more than 10 cases. The authors concluded that there is no evidence that osteodistraction produces better results and has a lower morbidity than conventional transplantation of growth centre and separate augmentation of soft tissue. They suggested future prospective multicentre studies of growth, and pointed to the importance in such a study of differentiating between the different Pruzansky–Kaban types of mandible and between reduced growth and collapse of newly generated bone. Comment This article is the first in the publications about distraction that preaches a word of caution in applying this new technology. Coming from authors with a deep appreciation of the
E-mail address: [email protected]. 0266-4356/$ – see front matter © 2005 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjoms.2005.06.017
88
M. Morton / British Journal of Oral and Maxillofacial Surgery 45 (2007) 87–89
complexity of the three dimensional problem, serious consideration must be given to their suggestions. Luchs JS, Stelnicki EJ, Rowe NM, Naijher NS, Grayson BH, McCarthy JG. Molding of the regenerate in mandibular distraction: Part 1: laboratory study. J Craniofac Surg 2002;13:205–11. In distraction osteogenesis for lengthening of the hypoplastic mandible the ideal occlusion is not always achieved and there is a need to mould the regenerate to achieve the ideal form. This study aimed to check the safety and efficiency of this manoeuvre in the laboratory. Four adult dogs had mandibular distraction and the vectors were set so that open bite developed. At the end of the distraction time the regenerate was moulded. In two dogs this was done in a single movement (acute moulding) and in the other two it was done gradually over 3 days (gradual moulding). The moulding was done by alteration to the distractor arm and when in the new position it was retained for 49 days. During that time the animals were assessed with cephalograms, and computed tomograms were taken before placement of the distractors and when the dogs were killed. The regenerate showed no sign of fibrous union and on histological examination there was bony union. Comment This paper provides support for the clinical practice of adjusting the bite, usually an anterior open bite, that often develops during mandibular distraction. In both cases the moulding was done at the end of the distraction period and as there was no difference in healing between the two groups the authors suggested that it could all be done at one sitting. They also suggested that the ability of the surgeon to fine-tune the occlusal position might shorten the orthodontic time. In this paper the moulding was done by adjusting the distractors but the authors suggested that elastics might be an alternative. However, the next paper suggested caution with elastics. Peltomaki T, Grayson BH, Vendittelli BL, Katzen T, Mccarthy JG. Moulding of the generate to control open bite during mandibular distraction osteogenesis. Eur J Orthod 2002;24:639–45. This paper looked at moulding the regenerate using intermaxillary elastics during active distraction in three patients. Three different anchorage systems were used (dental, orthopaedic, and skeletal). The results were monitored with lateral cephalograms. Anterior elastic fixation was used during distraction. The angle of the mandibular plane decreased in all cases but in the dental (orthodontic appliance) and orthopaedic (full arch splints) anchorage systems there were substantial dental movements including extrusion of the incisors. With skeletal anchorage (hook attached to bone screws and plates) there were no dental changes. Comment Although this paper comes from the university of Turku in Finland two of the authors are from the New York unit where
the previous paper was produced. The two go well together. In the first, the moulding was done manually and with the rigid external distractor arm. In the latter, it was done with the distractor in place but using elastics. It is difficult to see how the regenerate was moulded if the distractor was rigid. In the technique popularised by Hoffmeister, “the floating bone” concept, the distraction is completed and the distractor removed before the elastics are placed and then the jaw is held in elastics for healing to occur [Hoffmeister B, Marcks WKP. The floating bone concept in intraoral mandibular distraction. J Craniomaxillofac Surg 1998;26:76 (Abstract)]. Others remove the distractor, mould the regenerate, and then fix with a bone plate. Heavy elastics can cause undesirable dental movements. The weakness of this paper is the small number of patients who ranged in age from 7 to 15. There was only one patient in each anchorage group. However, it does indicate the need to be cautious about elastic traction. El-Bialy TH, Royston TJ, Magin RL, Evans CA, Zaki Ael-M, Frizzell LA. The effect of pulsed ultrasound on mandibular distraction. Ann Biomed Eng 2002;30:1251–61. This study evaluated the effect of pulsed ultrasound on tissue repair and bone growth during mandibular osteodistraction. Three groups, each of seven rabbits, were used. Animals in group 1 were given pulsed ultrasound on both sides of the mandible (alternating sides) on alternate days. Those in group 2 were given pulsed ultrasound on one side every day and those in group 3 were given none. The dose was 200 micros pulse of 1.5 MHz at a 1.1 kHz frequency of pulse repetition, 30 mW/cm2 . Bone formation was assessed by photodensitometry, a vibratory coherence test, a post-mortem 3-point bending mechanical stiffness test, and a post-mortem histological examination. Statistical analysis showed that pulsed ultrasound improved formation of bone at the distraction site with a high level of significance when assessed by the increase in photodensity of the new bone (p = 0.001), vibratory coherence (p = 0.001), mechanical stiffness (p = 0.003), and qualitative histological studies. Comment In this paper the distraction was carried out at a fast rate of 1.5 mm/12 h and the results are impressive. There is some work in orthopaedic publications about pulsed ultrasound that agree with these findings. There is a suggestion that this can help when there is less than optimum tissue or callus. Thurmuller P, Troulis M, O’Neill MJ, Kaban LB. Use of ultrasound to assess healing of a mandibular distraction wound. J Oral Maxillofac Surg 2002;60:1038–44. A standardised, non-invasive technique to assess healing of the mandibular distraction wound is not available. Current methods include clinical examination, plain radiography, and computed tomography. These imaging techniques are expensive and expose the patient to serial radiation. Anatom-
M. Morton / British Journal of Oral and Maxillofacial Surgery 45 (2007) 87–89
ical overlap and metal artefacts may obscure the distraction gap. In contract, ultrasound is a non-invasive, efficient, and inexpensive way to evaluate healing of bone. The purpose of this study was to test the feasibility of ultrasound to assess an experimental wound after mandibular distraction osteogenesis. The distractors were placed in 24 minipigs. There was 0 day latency and rates were 1, 2, or 4 mm a day for a 12 mm gap. The wounds were assessed in vivo at 0, 8, 16, and 24 days of neutral fixation. Ex vivo radiographs were used to estimate bone regeneration using a semiquantitive score. A semiquantitive ultrasound score was assigned, and the beam penetration depth was measured in mm. The plain radiographs showed that the distraction gap was achieved and maintained. The ultrasound score increased with duration of fixation and the beam penetration
89
depth decreased as expected. Ex vivo radiographs showed increasing bone fill score with time and paralleled the ultrasound score. The results of this feasibility study indicate that ultrasound is potentially useful for the assessment of bone formation in distraction osteogenesis wounds. Comment This paper was one of the first to apply ultrasound to the facial distraction wound, a technique that had been used by orthopaedic surgeons. The text is clear with easy-tounderstand illustrations for those of us not used to looking at ultrasound pictures. Future research will look at relating the ultrasound image to biomechanical strength and may lead to distractors being removed earlier.
Specialist Review
Distraction osteogenesis of the jaws – pertinent papers 2002 Maire Morton Available online 1 August 2005
Papers relating to distraction osteogenesis as applied to the maxillofacial region started to be published in the late 1980s and early 1990s. A Medline search of this title in the English language produced one paper in 1990 and by 2002 there were 91. As with all new technologies papers initially referred to animal work and case reports. Although some years have now passed there is still a lack of prospective case series of heterogeneous clinical material. Of the 91 papers that I reviewed for this article there was one prospective study with 5-year follow up. There were 21 animal studies of which just over half dealt with biological aspects of distraction. There were 19 retrospective case reports, 3 review articles, and 9 miscellaneous articles dealing mostly with aspects of healing or planning. Swennen G, Dempf R, Schliephake H. Craniofacial distraction osteogenesis: a review of the literature. Part II: Experimental studies. Int J Oral Maxillofac Surg 2002;31:123–35. The authors identified 120 articles about experimental craniofacial distraction between 1966 and 2000. The papers were divided into four groups dealing with mandibular, maxillary, midface, and cranial areas. Most (72%) dealt with the mandible. Seven different animal models were used and the authors attempted to define aspects of craniofacial distraction for each animal model. They pointed out that in much animal research in this field the extent of growth of the animals was not mentioned although this might make a material difference to the results. They made the case for this to be stated clearly in future. The authors then went on to look at the appropriateness of the various animal models based on phylogenic classification.
Comment This paper has 139 references and is a valuable resource. In particular the tables clearly show the areas where most animal research has concentrated and conversely the areas where there are gaps. The table showing the distraction variables for the various animal models is particularly helpful. Mommaerts MY, Nagy K. Is early osteodistraction a solution for the ascending ramus compartment in hemifacial microsomia? A literature study. J Craniomaxillofac Surg 2002;30:201–7. The authors examined the hypothesis that osteodistraction in hemifacial microsomia before skeletal maturity, induces generation of bone and soft tissue and renders conventional grafts of bone and soft tissue unnecessary. This early treatment has a beneficial effect on the ‘functional matrix’, promoting symmetrical vertical and sagittal expansion of the midface and the mandible. They examined eight published studies with follow up of distraction histogenesis in the ascending ramus, only two of which had more than 10 cases. The authors concluded that there is no evidence that osteodistraction produces better results and has a lower morbidity than conventional transplantation of growth centre and separate augmentation of soft tissue. They suggested future prospective multicentre studies of growth, and pointed to the importance in such a study of differentiating between the different Pruzansky–Kaban types of mandible and between reduced growth and collapse of newly generated bone. Comment This article is the first in the publications about distraction that preaches a word of caution in applying this new technology. Coming from authors with a deep appreciation of the
E-mail address: [email protected]. 0266-4356/$ – see front matter © 2005 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjoms.2005.06.017
88
M. Morton / British Journal of Oral and Maxillofacial Surgery 45 (2007) 87–89
complexity of the three dimensional problem, serious consideration must be given to their suggestions. Luchs JS, Stelnicki EJ, Rowe NM, Naijher NS, Grayson BH, McCarthy JG. Molding of the regenerate in mandibular distraction: Part 1: laboratory study. J Craniofac Surg 2002;13:205–11. In distraction osteogenesis for lengthening of the hypoplastic mandible the ideal occlusion is not always achieved and there is a need to mould the regenerate to achieve the ideal form. This study aimed to check the safety and efficiency of this manoeuvre in the laboratory. Four adult dogs had mandibular distraction and the vectors were set so that open bite developed. At the end of the distraction time the regenerate was moulded. In two dogs this was done in a single movement (acute moulding) and in the other two it was done gradually over 3 days (gradual moulding). The moulding was done by alteration to the distractor arm and when in the new position it was retained for 49 days. During that time the animals were assessed with cephalograms, and computed tomograms were taken before placement of the distractors and when the dogs were killed. The regenerate showed no sign of fibrous union and on histological examination there was bony union. Comment This paper provides support for the clinical practice of adjusting the bite, usually an anterior open bite, that often develops during mandibular distraction. In both cases the moulding was done at the end of the distraction period and as there was no difference in healing between the two groups the authors suggested that it could all be done at one sitting. They also suggested that the ability of the surgeon to fine-tune the occlusal position might shorten the orthodontic time. In this paper the moulding was done by adjusting the distractors but the authors suggested that elastics might be an alternative. However, the next paper suggested caution with elastics. Peltomaki T, Grayson BH, Vendittelli BL, Katzen T, Mccarthy JG. Moulding of the generate to control open bite during mandibular distraction osteogenesis. Eur J Orthod 2002;24:639–45. This paper looked at moulding the regenerate using intermaxillary elastics during active distraction in three patients. Three different anchorage systems were used (dental, orthopaedic, and skeletal). The results were monitored with lateral cephalograms. Anterior elastic fixation was used during distraction. The angle of the mandibular plane decreased in all cases but in the dental (orthodontic appliance) and orthopaedic (full arch splints) anchorage systems there were substantial dental movements including extrusion of the incisors. With skeletal anchorage (hook attached to bone screws and plates) there were no dental changes. Comment Although this paper comes from the university of Turku in Finland two of the authors are from the New York unit where
the previous paper was produced. The two go well together. In the first, the moulding was done manually and with the rigid external distractor arm. In the latter, it was done with the distractor in place but using elastics. It is difficult to see how the regenerate was moulded if the distractor was rigid. In the technique popularised by Hoffmeister, “the floating bone” concept, the distraction is completed and the distractor removed before the elastics are placed and then the jaw is held in elastics for healing to occur [Hoffmeister B, Marcks WKP. The floating bone concept in intraoral mandibular distraction. J Craniomaxillofac Surg 1998;26:76 (Abstract)]. Others remove the distractor, mould the regenerate, and then fix with a bone plate. Heavy elastics can cause undesirable dental movements. The weakness of this paper is the small number of patients who ranged in age from 7 to 15. There was only one patient in each anchorage group. However, it does indicate the need to be cautious about elastic traction. El-Bialy TH, Royston TJ, Magin RL, Evans CA, Zaki Ael-M, Frizzell LA. The effect of pulsed ultrasound on mandibular distraction. Ann Biomed Eng 2002;30:1251–61. This study evaluated the effect of pulsed ultrasound on tissue repair and bone growth during mandibular osteodistraction. Three groups, each of seven rabbits, were used. Animals in group 1 were given pulsed ultrasound on both sides of the mandible (alternating sides) on alternate days. Those in group 2 were given pulsed ultrasound on one side every day and those in group 3 were given none. The dose was 200 micros pulse of 1.5 MHz at a 1.1 kHz frequency of pulse repetition, 30 mW/cm2 . Bone formation was assessed by photodensitometry, a vibratory coherence test, a post-mortem 3-point bending mechanical stiffness test, and a post-mortem histological examination. Statistical analysis showed that pulsed ultrasound improved formation of bone at the distraction site with a high level of significance when assessed by the increase in photodensity of the new bone (p = 0.001), vibratory coherence (p = 0.001), mechanical stiffness (p = 0.003), and qualitative histological studies. Comment In this paper the distraction was carried out at a fast rate of 1.5 mm/12 h and the results are impressive. There is some work in orthopaedic publications about pulsed ultrasound that agree with these findings. There is a suggestion that this can help when there is less than optimum tissue or callus. Thurmuller P, Troulis M, O’Neill MJ, Kaban LB. Use of ultrasound to assess healing of a mandibular distraction wound. J Oral Maxillofac Surg 2002;60:1038–44. A standardised, non-invasive technique to assess healing of the mandibular distraction wound is not available. Current methods include clinical examination, plain radiography, and computed tomography. These imaging techniques are expensive and expose the patient to serial radiation. Anatom-
M. Morton / British Journal of Oral and Maxillofacial Surgery 45 (2007) 87–89
ical overlap and metal artefacts may obscure the distraction gap. In contract, ultrasound is a non-invasive, efficient, and inexpensive way to evaluate healing of bone. The purpose of this study was to test the feasibility of ultrasound to assess an experimental wound after mandibular distraction osteogenesis. The distractors were placed in 24 minipigs. There was 0 day latency and rates were 1, 2, or 4 mm a day for a 12 mm gap. The wounds were assessed in vivo at 0, 8, 16, and 24 days of neutral fixation. Ex vivo radiographs were used to estimate bone regeneration using a semiquantitive score. A semiquantitive ultrasound score was assigned, and the beam penetration depth was measured in mm. The plain radiographs showed that the distraction gap was achieved and maintained. The ultrasound score increased with duration of fixation and the beam penetration
89
depth decreased as expected. Ex vivo radiographs showed increasing bone fill score with time and paralleled the ultrasound score. The results of this feasibility study indicate that ultrasound is potentially useful for the assessment of bone formation in distraction osteogenesis wounds. Comment This paper was one of the first to apply ultrasound to the facial distraction wound, a technique that had been used by orthopaedic surgeons. The text is clear with easy-tounderstand illustrations for those of us not used to looking at ultrasound pictures. Future research will look at relating the ultrasound image to biomechanical strength and may lead to distractors being removed earlier.