- Email: [email protected]
Long-Term Stability After Craniofacial Distraction Osteogenesis
J Oral Maxillofac Surg 66:1812-1819, 2008
Long-Term Stability After Craniofacial Distraction Osteogenesis Saleh Al-Daghreer, BDS,* Carlos Flores-Mir, DDS, MSc, DSc, FRCD(c),† and Tarek El-Bialy, BDS, MSc Ortho, MSc OSci, PhD, FRCD(c)‡ Purpose: This study was conducted to systematically review long-term skeletal stability after cranio-
facial distraction osteogenesis. Materials and Methods: Several electronic databases (Old Medline, Medline, Medline In-Process and Other Non-Indexed Citations, Pubmed, Embase, Web of Science, and all EBM reviews [Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR]) were searched. Key words used in the search were “distraction,” “osteogenesis,” “craniofacial,” “maxillofacial,” “stability,” “relapse,” and “recurrence.” MeSH terms and truncations of these terms were selected with the help of a health science librarian. Abstracts that appeared to contain at least 3 years of postsurgical data were selected. The original articles were then retrieved and evaluated to ensure that they actually had 3 years of data after craniofacial distraction osteogenesis. The references were also hand-searched for possible missing articles that were not indexed in the searched databases. Results: A total of 118 abstracts were found in the electronic searches. After the first set of selection criteria was applied on these abstracts, 22 articles were retrieved. After the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. These 6 articles reported long-term stability after craniofacial distraction osteogenesis. Sample sizes were small, and the methodological quality of the studies was poor. Conclusions: Although, based on the selected studies, craniofacial bone distraction osteogenesis appeared to show long-term stability; limitations of the studies merit caution in interpreting these findings. Some early relapse occurred in the first 3 years postdistraction, but stability was maintained thereafter. Some methodologically sounder studies are needed to confirm the present findings. © 2008 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 66:1812-1819, 2008 Distraction osteogenesis (DO) is a biological process involving the formation of new bone between bone segments that are gradually separated by incremental traction. The traction generates tension that stimulates new bone formation parallel to the vector of distraction.1 The concept of applying DO to the treatment of craniofacial deformities was not conceived until 1972, when Snyder used a Swanson external
Received from the Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. *PhD Student. †Associate Professor. ‡Associate Professor. Address correspondence and reprint requests to Dr Flores-Mir: 4051 Dentistry/Pharmacy Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2N8; e-mail: [email protected] © 2008 American Association of Oral and Maxillofacial Surgeons
0278-2391/08/6609-0006$34.00/0 doi:10.1016/j.joms.2007.08.026
fixator to lengthen a canine mandible.2 Over the last 15 years, this procedure has become a popular technique to successfully treat craniofacial skeletal dysplasias in the sagittal and vertical dimensions.3-5 The patient population eligible for distraction now includes those with various craniofacial deficiencies, including craniofacial microsomia,6,7 Nager syndrome,8 Pierre-Robin syndrome,9 temporomandibular joint ankylosis,10 post-traumatic growth disturbances, postoncologic ablation,9 midface hypoplasias (maxillary deficiency, craniofacial synostosis),11 zygomatic deficiency (Treacher-Collins syndrome),8 craniofacial synostosis,12 and edentulous maxillary and mandibular alveoli.13 Distraction techniques have been used to correct craniofacial deformities that cannot be adequately addressed by conventional osteotomy. The benefits of distraction include the avoidance of bone grafting and donor site morbidity, its availability for use in surgery on younger patients, and concurrent expansion of the soft-tissue envelope.14 The unique feature of the distraction technique is that bone regeneration by DO is
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Table 1. DATABASE SEARCH AND RESULTS
Database PubMed
Medline and Old Medline
Medline In-Process and NonIndexed EMBASE
All EBM reviews
Web of Science
Selected for the Systematic Review
% of Total Selected Articles (7) Found by Database
Search Terms
Results
Abstracts Obtained
(1) distraction*; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction*; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9
111
58
6
85%
62
47
6
85%
0
0
0
0
75
24
1
15%
1
0
0
0
66
20
0
0
0
0
0
0
Hand search
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
accompanied by simultaneous expansion of the functional soft tissue matrix, including blood vessels, nerves, muscles, skin, mucosa, fascia, ligaments, cartilage, and periosteum. These adaptive changes of the surrounding soft tissues through the tension generated by the distraction forces applied on the bone is called distraction histogenesis.15-20 DO relapse is defined as the gradual recurrence of the abnormality for which distraction was performed. However, the regeneration in DO is subject to a number of external forces during consolidation, including those from the muscles of mastication and the soft tissue envelope. These external forces can alter the postdistracted position, size, and shape of bone.21 Little is known about differences in the relapse process between DO and conventional surgical procedures. A meta-analysis of cleft maxillary osteotomy and DO conducted by Cheung and Chua22 found no conclusive data on any differences in surgical relapse, velopharyngeal function, and speech between the 2
techniques. Both DO and conventional osteotomy can deliver a marked improvement in facial esthetics. Although many comprehensive reviews on the applications of craniofacial DO have been published,23-31 none has discussed long-term stability and relapse after craniofacial DO. Therefore, our goal was to systematically review the long-term skeletal stability after craniofacial DO.
Materials and Methods A computerized database search was conducted using Old Medline (1950 to 1965), Medline (1966 to week 1 of May 2007), Medline In-Process and Other Non-Indexed Citations (up to May 15, 2007), Pubmed (1966 to week 2 of May 2007), Embase (from 1988 to 2007, week 19), Web of Science (1945 to week 1 of May 2007), and all EBM reviews (Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR) up to May 15, 2007. Terms used in the litera-
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ture search were “distraction,” “osteogenesis,” “stability,” “recurrence,” “relapse,” “craniofacial,” and “maxillofacial.” The selection and specific use of each term with their respective truncation, if applicable, inside every database (Table 1) were done with the help of a senior librarian specializing in health sciences database searches. The following inclusion criteria were chosen to initially select potential articles from the published abstract information: ● ● ●
Human clinical trials or series of consecutively treated cases; no individual case reports Follow-up for 3 years or more No postsurgical complications
The selection process was followed independently by 3 researchers (SMA, CFM, and TAE), and their selection results were compared to settle discrepancies through discussion. If the abstract did not provide sufficient information on which to base a sound decision, then the actual article was obtained. Any abstracts that did not specifically mention the time of follow-up were automatically included at this stage as well. The articles ultimately selected were chosen with the following additional inclusion criteria applied to the full article: only cases in which measurements were taken soon after the surgery and then again 3 years or more after surgery. Because of the severity and limited number of cases treated with DO, randomization and blinding were considered unattainable. Almost certainly, all of the cases will likely include syndromic patients. Also in this regard, case reports were selected due to the high probability that higher methodological studies were lacking. Reference lists of the selected articles were also hand-searched for additional relevant publications that may have been missed in the database searches. In cases where specific data were necessary for the discussion and were not specified in the article, efforts were made to contact the authors to obtain the required extra information. A meta-analysis was planned only if the quality of the retrieved information warranted it.
Results From the database searches, a total of 116 abstracts were initially retrieved. The details for the searches, as well as the number of abstracts selected from each database produced, are given in Table 1. Of the 118 abstracts, only 22 articles were retrieved after the first set of selection criteria were applied. Once the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. No articles were found during the hand searches of the reference lists
Table 2. ARTICLES NOT SELECTED FROM THE INITIAL ABSTRACT SELECTION LIST AND REASONS FOR EXCLUSION
Article
Reason for Exclusion 22
Cheungc and Chua Gabbay et al32 Imai et al12 Rachmiel et al33 Alkan et al42 Fearon34 Wong and Padwa35 Figueroa et al36 Chiapasco et al37 Denny et al40 Iseri and Malkoc38 Heller et al8 Batra et al39 Swennen et al23 Kumar et al41 Nadjmi et al43
Meta-analysis Inadequate follow-up Inadequate follow-up Inadequate follow-up No follow-up of stability Inadequate follow-up Inadequate follow-up Inadequate follow-up Inadequate follow-up Follow-up time not indicated Inadequate follow-up Follow-up time not indicated Inadequate follow-up Literature review Follow-up time not indicated Inadequate reporting of data
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
of the selected articles that did not appear in the electronic database searches. Comparing the database results, Medline and PubMed had the greatest diversity of finally selected abstracts (85.7%). The other databases obtained significantly fewer finally selected abstracts (⬍15%). The different databases repeated most of the abstracts. At the final selection stage, from the 22 potential articles, 9 were excluded because of an inadequate follow-up period,12,32-39 3 because the follow-up time was not identified,8,40,41 1 because there was no follow up of stability,42 1 because it was a literature review,23 and 1 because it was a meta-analysis.22 One article did not provide sufficient data about the measurements;43 and we tried to contact the author to obtain more data but we did not get any response, so we excluded this potential study. Table 2 provides details about the reasons why these 16 articles were excluded at this stage. Finally, only 6 articles that met all of the inclusion criteria remained. Table 3 summarizes the sample size, follow-up period, and associated syndrome or condition for each. A methodological quality checklist developed to evaluate the selected articles is shown in Table 4, and an application of the methodological quality checklist is illustrated in Table 5. A flow diagram of the literature search is given in Figure 1. MIDFACE DISTRACTION
Three of the finally selected studies were on midface distraction in patients with a hypoplastic midface or maxilla.44-46 All of the studies used lateral cephalometric radiographs for evaluation, but the studies used different
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Table 3. FINALLY SELECTED STUDIES’ KEY METHODOLOGICAL INFORMATION
Measurement Error
Follow-Up (Average)
N/A
No
6.1 ⫾ 2.7 yrs
Cleft lip and palate Hemifacial microsomia
N/A Consecutive
Yes Yes
3 yrs 3 and 5 yrs
Cleft lip and palate
N/A Consecutive, Retrospective N/A
No
5 yrs
No No
5 and 10 yrs 61.6 mos
Study
Sample Size
Associated Syndrome
Meazzini et al44
Apert’s and Crouzon’s syndromes
Harada et al45 Meazzini et al47 Cho and Kyung46
10 7.3 ⫾ 2.6 yrs 8 (4 F, 4 M) 12.2 yrs ⫾ 11 mos 8 5.6 ⫾ 0.5 yrs 4 (1 F, 3 M) 15.25 yrs
Shetye et al7 Hollier et al48
12 (3 F, 9 M) 4.8 yrs 5 29.2 mos
Hemifacial microsomia Hemifacial microsomia, Nager
Selection
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
selected cephalometric landmarks, measurements, and follow-up periods. A point, U1, Wits appraisal, and Or were used as landmarks for detecting linear horizontal changes; ANB and SNA, for angular horizontal changes; ANS and PO (posterior occlusal), for vertical linear changes; and the maxillary occlusal, palatal, and mandibular planes for angular changes. Patients with Le Fort III distraction had a stable A point and Or (⫺2 to 1 mm) of growth 5 years postdistraction, along with variable vertical changes ranging from 0 to 5 mm of the ANS and 5 to 16 mm of the PO point and changes in the palatal plane of 3° to 8° and in the maximum occlusal plane of 0° to 7°.44 In 1 study, patients with Le Fort I distraction exhibited stable ANS and U1 after 3 years,45 but in another
Table 4. METHODOLOGICAL SCORE FOR CLINICAL TRIALS
I. Study design (8✓) A. Objective: objective clearly formulated (✓) B. Population: described (✓) C. Selection criteria: clearly described (✓); adequate (✓) D. Sample size: considered adequate (✓); estimated before collection of data (✓) E. Timing: prospective (✓) F. Randomization or consecutive selection: stated (✓) II. Study measurements (5✓) A. Measurement method: appropriate to the objective (✓) B. Blind measurement: blinding C. Reliability: described (✓), adequate level of agreement (✓) III. Statistical analysis (5✓) A. Dropouts: dropouts included in data analysis (✓) B. Statistical analysis: appropriate for data (✓); combined subgroup analysis (✓) C. Statistical significance level: P value stated (✓) NOTE: Maximum number of ✓s ⫽ 16. Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
study, angular changes of the SNA were stable for 5 years after the first 6 months relapse postdistraction.46 In addition, there was a gradual decrease in the overjet horizontally and the ANS and U1 vertically at 3 years postdistraction.45 MANDIBULAR DISTRACTION
The remaining 3 studies were on mandibular distraction. Two of these used PA cephalometric radiographs to evaluate the results of mandibular distraction,7,47 and the other used panoramic radiographs to measure the ratio between the affected and nonaffected sides.48 The patients who met the selection criteria in the 3 studies had hemifacial microsomia and underwent unilateral mandibular distraction. The studies used different anatomic landmarks and measurement methods. In unilateral mandibular distraction evaluated by the PA and panoramic radiographs, the antegonial plane and the ratio between the affected and nonaffected sides between the 3 and 5 years of follow-up was stable; most of the relapse in treatment results occurred in the first 3 years postdistraction.47 In patients with unilateral extraoral ramus distraction, the ratio of the affected and nonaffected rami and the occlusal plane cant were stable after relapse occurring in the first year in the data of 5 years of follow-up. The results were better in the 10-year follow-up, but there was a dropout of 7 patients of the 12 patients followed.7 In the third study, mean patient age at the time of surgery was 48 months; only 4 cases were followed for more than 36 months. The results showed a mean 15% relapse rate in the ratio between the 2 rami obtained by unilateral distraction after a 62-month mean follow-up.48
Discussion Despite the fact that conventional orthognathic surgery and craniofacial reconstruction have met with widespread success, several limitations are associated with these treatment modalities.49-51 One of these is the
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Table 5. METHODOLOGICAL SCORE OF SELECTED ARTICLES
Articles
A
B
C
D
E
F
G
H
I
J
K
L
Total Checks
% of Total
Meazzini et al44 Harada et al45 Meazzini et al47 Cho and Kyung46 Shetye et al7 Hollier et al48
✓ ⫽ ✓ ✓ ✓ ⫽
✓ ✓ ✓ ✓ ✓ ⫽
⫽⫽⫽ ✓✓ ⫽⫽⫽ ⫽-
⫽⫽ -✓ -✓ ⫽✓ ⫽⫽-
⫽ ✓ -
✓ ✓ -
✓ ⫽ ✓ ⫽ ✓ ✓
-
✓⫽ ✓⫽ ✓✓ --✓✓
-
-⫽⫽✓✓--
✓ -
6.5 6 10.5 7 6.5 5
40.6 37.5 65.6 43.75 40.6 31.25
NOTE: A to L: methodological criteria in Table 4. ✓: Satisfactorily fulfilled the methodological criteria (1 check). ⫽: Partially fulfilled the methodological criteria (0.5 checks). -: Did not fulfill the methodological criteria (0 checks). Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
inability of the muscles to be acutely stretched without the inherent risk of relapse.52,53 Moreover, many of the congenital deformities require such large musculoskeletal movements that the soft tissues simply will not accommodate the change, leading to compromised function and esthetics unless additional soft tissue procedures are performed.54-56 In addition, modern surgical intervention permits only acute changes in the spatial arrangement of bones with limited possibilities for new bone growth. It does not allow complete bone sculpting, that is, changing the shape and form of the bones to maximize the patient’s 3D structural, functional, and esthetic needs.25 DO offers unique benefits, such as a bone regeneration accompanied by simultaneous expansion of the functional soft tissue matrix, including blood vessels, nerves, muscles, skin, mucosa, fascia, ligaments, cartilage, and periosteum.15-20 Much information about the stability and growth after DO in the craniofacial area has not been yet published; however, most of the clinical trials and series of cases published to date have been summarized in comprehensive reviews, which focused more on the important parameters, such as age, rhythm, rate, latency period, contention period, devices, and surgical techniques.9,23-31 In addition, comparison of DO and conventional surgical osteotomies for advancing the maxilla in patients with cleft lip and palate were done by performing a meta-analysis on independent studies but on the basis of short-term results.22 Most of the follow-up studies were case reports or clinical trials of low quality due to small sample size, difficulty of randomization, lack of blinding, poor statistical analysis, and short follow-up, and did not provide sufficient data after more than 36 months.12,33,35-39,57-78 The results were controversial in terms of the stability of mandibular distraction, as summarized in the article by Batra et al.39 In our selected studies, there was variation in the anatomic landmarks used to evaluate the amount of distraction and duration of postsurgical growth fol-
low-up, which introduced more variability in the measurements. To evaluate maxillary skeletal changes, Harada et al45 used only 1 landmark, ANS; Cho and Kyung46 used only SNA, SNB, and ANB; and Nadjmi et al43 used Wit’s appraisal. In the mandibular distraction studies, the measurements were more comprehensive for measuring the distracted mandible or ramus and comparing it with the unaffected side.7,47,48 The statistical analysis and presentation of the data also were inadequate; the measurements were represented in terms of range,44 subjective assessments,45 individual cases,46,48 and in 2 studies as mean and standard deviation.7,47 Most of the studies were retrospective,7,43,45,46,48 which decreased the methodological quality. In the distraction of the craniofacial complex, few articles have been published on cranial distraction, as found by our systematic search.12,67,79 All of the studies that we found were excluded because they did not meet the selection criteria of our review. On the other hand, this technique is not popular due to its multiple limitations and critical complications.80
FIGURE 1. Flow diagram. Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
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AL-DAGHREER, FLORES-MIR, AND EL-BIALY
In the distraction of the midface, most relapse occurs in the first 6 months after distraction, as shown by the data in 2 of the selected studies.45,46 This also has been demonstrated in some short-term follow-up studies with results showing different amounts of relapse in the first 6 months or 1 year postdistraction33,35,36,43; however, other short-term follow-up studies have found minimal relapse to stable results in the first year.34,41 After long-term followup, the data in the selected studies demonstrate stable results of advanced maxilla, but in 2 of the studies the maxillomandibular relationship showed little growth of the maxilla after distraction in the long term due to decreased ANB or overjet.45,46 A properly designed clinical trial comparing the results of conventional osteotomy and DO in patients with midface deficiency would be very useful to confirm the assumed lower morbidities and differences in skeletal relapse between the 2 techniques in short-term and long-term follow-up. In regard to DO of the mandible, many studies support the stability of mandibular distraction results after short-term follow-up,4,71,81-84 but some studies have reported relapse in short-term follow-up.85-87 Our review apparently demonstrates that the mandibular distraction studies are of better methodological design, with consecutive case selection and comprehensive measurements provided in 2 of the 3 studies.7,47 The selected studies showed that most relapses occur in the first year7 or 3 years47 postdistraction, after which the results are stable in a better proportion between the 2 rami than the predistraction proportion. The same result has been found in younger patients with hemifacial microsomia who underwent DO before age 48 months.48 Based on our findings, we can draw the following conclusions from our analysis: ● ●
●
●
There are few published long-term studies on the stability of DO of the craniofacial complex. All of the selected studies are of poor methodological quality (ie, poor design, small sample size, insufficient presentation of sufficient anatomic landmarks). Based on the limited evidence found, it can be suggested that craniofacial DO shows long-term stability of results after early relapse in the first 3 years postdistraction. High-quality clinical trials are needed to obtain more conclusive results and evaluate the correlation between the long-term and short-term stability of craniofacial DO and the other variables such as associated syndromes, amount of distracted bone, patient age and gender, technique, and amount of distraction.
References 1. Ilizarov GA: Clinical application of the tension-stress effect for limb lengthening. Clin Orthop Relat Res 8:26, 1990 2. Snyder CC, Levine GA, Swanson HM, et al: Mandibular lengthening by gradual distraction: Preliminary report. Plast Reconstr Surg 51:506, 1973 3. McCarthy JG, Schreiber J, Karp N, et al: Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 89:1, 1992 4. Molina F, Ortiz Monasterio F: Mandibular elongation and remodeling by distraction: A farewell to major osteotomies. Plast Reconstr Surg 96:825, 1995 5. Polley JW, Figueroa AA: Management of severe maxillary deficiency in childhood and adolescence through distraction osteogenesis with an external, adjustable, rigid distraction device. J Craniofac Surg 8:181, 1997 6. Okumoto T, Nakajima H, Sakamoto T, et al: Simultaneous lengthening of both the mandible and maxilla by gradual distraction: Application to Murray’s type II hemifacial microsomia. Jpn J Plast Reconstr Surg 42:1145, 1999 [in Japanese] 7. Shetye PR, Grayson BH, Mackool RJ, et al: Long-term stability and growth following unilateral mandibular distraction in growing children with craniofacial microsomia. Plast Reconstr Surg 118:985, 2006 8. Heller JB, Gabbay JS, Kwan D, et al: Genioplasty distraction osteogenesis and hyoid advancement for correction of upper airway obstruction in patients with Treacher-Collins and Nager syndromes. Plast Reconstr Surg 117:2389, 2006 9. McCarthy JG, Stelnicki EJ, Mehrara BJ, et al: Distraction osteogenesis of the craniofacial skeleton. Plast Reconstr Surg 107: 1812, 2001 10. Ma YK, Shen GF, Lu XF, et al: Distraction osteogenesis for treatment of unilateral temporomandibular joint ankylosis and secondary OSAHS in children: Report of 4 cases. Shanghai Kou Qiang Yi Xue 15:19, 2006 [in Chinese]. 11. Cohen SR: Midface distraction. Semin Orthod 5:52, 1999 12. Imai K, Komune H, Toda C, et al: Cranial remodeling to treat craniosynostosis by gradual distraction using a new device. J Neurosurg 96:654, 2002 13. Papageorge MB: Distraction osteogenesis for augmentation of the deficient alveolar ridge. J Mass Dent Soc 51:24, 2002 14. Mofid MM, Manson PN, Robertson BC, et al: Craniofacial distraction osteogenesis: A review of 3278 cases. Plast Reconstr Surg 108:1103, 2001 15. Yasui N, Kojimoto H, Shimizu H, et al: The effect of distraction upon bone, muscle, and periosteum. Orthop Clin North Am 22:563, 1991 16. Shevtsov VI, Asonova SN, Yerofeyev SA: Morphological characteristics of angiogenesis in the myofascial tissues of a limb elongated by the Ilizarov method. Bull Hosp Jt Dis 54:76, 1995 17. Block MS, Daire J, Stover J, et al: Changes in the inferior alveolar nerve following mandibular lengthening in the dog using distraction osteogenesis. J Oral Maxillofac Surg 51:652, 1993 18. Schumacher B, Keller J, Hvid I: Distraction effects on muscle: Leg lengthening studied in rabbits. Acta Orthop Scand 65:647, 1994 19. Fisher E, Staffenberg DA, McCarthy JG, et al: Histopathologic and biochemical changes in the muscles affected by distraction osteogenesis of the mandible. Plast Reconstr Surg 99:366, 1997 20. Shevtsov VI, Asonova SN: Ultrastructural changes of articular cartilage following joint immobilization with the Ilizarov apparatus. Bull Hosp Jt Dis 54:69, 1995 21. McCarthy JG, Stelnicki EJ, Grayson BH: Distraction osteogenesis of the mandible: A ten-year experience. Semin Orthod 5:3, 1999 22. Cheung LK, Chua HD: A meta-analysis of cleft maxillary osteotomy and distraction osteogenesis. Int J Oral Maxillofac Surg 35:14, 2006 23. Swennen G, Schliephake H, Dempf R, et al: Craniofacial distraction osteogenesis: A review of the literature. Part 1: Clinical studies. Int J Oral Maxillofac Surg 30:89, 2001
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24. Aldegheri A, Blanc JL, Cheynet F, et al: Bone lengthening: Application to the mandible. Review of the literature. Rev Stomatol Chir Maxillofac 96:335, 1995 [in French] 25. Cope JB, Samchukov ML, Cherkashin AM: Mandibular distraction osteogenesis: A historic perspective and future directions. Am J Orthod Dentofacial Orthop 115:448, 1999 26. Davies J, Turner S, Sandy JR: Distraction osteogenesis: A review. Br Dent J 185:462, 1998. 27. Maull DJ: Review of devices for distraction osteogenesis of the craniofacial complex. Semin Orthod 5:64, 1999 28. Tavakoli K, Stewart KJ, Poole MD: Distraction osteogenesis in craniofacial surgery: A review. Ann Plast Surg 40:88, 1998 29. Taylor TD, Stal S: Applications of distraction osteogenesis: Part I. Clin Plast Surg 25:553, 1998 30. Troulis MJ, Padwa B, Kaban LB: Distraction osteogenesis: Past, present, and future. Facial Plast Surg 14:205, 1998 31. Yen SL: Distraction osteogenesis: Application to dentofacial orthopedics. Semin Orthod 3:275, 1997 32. Gabbay JS, Heller JB, Song YY, et al: Temporomandibular joint bony ankylosis: Comparison of treatment with transport distraction osteogenesis or the Matthews device arthroplasty. J Craniofac Surg 17:516, 2006 33. Rachmiel A, Aizenbud D, Peled M: Long-term results in maxillary deficiency using intraoral devices. Int J Oral Maxillofac Surg 34:473, 2005 34. Fearon JA: Halo distraction of the Le Fort III in syndromic craniosynostosis: A long-term assessment. Plast Reconstr Surg 115:1524, 2005 35. Wong GB, Padwa BL: Le Fort I soft tissue distraction: A hybrid technique. J Craniofac Surg 13:572, 2002 36. Figueroa AA, Polley JW, Friede H, et al: Long-term skeletal stability after maxillary advancement with distraction osteogenesis using a rigid external distraction device in cleft maxillary deformities. Plast Reconstr Surg 114:1382, 2004 37. Chiapasco M, Romeo E, Casentini P, et al: Alveolar distraction osteogenesis versus vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: A 1- to 3-year prospective study on humans. Clin Oral Implants Res 15:82, 2004 38. Iseri H, Malkoc S: Long-term skeletal effects of mandibular symphyseal distraction osteogenesis: An implant study. Eur J Orthod 27:512, 2005 39. Batra P, Ryan FS, Witherow H, et al: Long-term results of mandibular distraction. J Indian Soc Pedod Prev Dent 24:30, 2006 40. Denny AD, Kalantarian B, Hanson PR: Rotation advancement of the midface by distraction osteogenesis. Plast Reconstr Surg 111:1789, 2003 41. Kumar A, Gabbay JS, Nikjoo R, et al: Improved outcomes in cleft patients with severe maxillary deficiency after Le Fort I internal distraction. Plast Reconstr Surg 117:1499, 2006 42. Alkan A, Arici S, Sato S: Bite force and occlusal contact area changes following mandibular widening using distraction osteogenesis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 101:432, 2006 43. Nadjmi N, Schutyser F, Van Erum R: Trans-sinusal maxillary distraction for correction of midfacial hypoplasia: Long-term clinical results. Int J Oral Maxillofac Surg 35:885, 2006 44. Meazzini MC, Mazzoleni F, Caronni E, et al: Le Fort III advancement osteotomy in the growing child affected by Crouzon’s and Apert’s syndromes: Presurgical and postsurgical growth. J Craniofac Surg 16:369, 2005 45. Harada K, Sato M, Omura K: Long-term maxillomandibular skeletal and dental changes in children with cleft lip and palate after maxillary distraction. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 102:292, 2006 46. Cho BC, Kyung HM: Distraction osteogenesis of the hypoplastic midface using a rigid external distraction system: The results of a one- to six-year follow-up. Plast Reconstr Surg 118: 1201, 2006 47. Meazzini MC, Mazzoleni F, Gabriele C, et al: Mandibular distraction osteogenesis in hemifacial microsomia: Long-term follow-up. J Craniomaxillofac Surg 33:370, 2005
48. Hollier LH, Kim JH, Grayson B, et al: Mandibular growth after distraction in patients under 48 months of age. Plast Reconstr Surg 103:1361, 1999 49. Trauner R, Obwegeser H: The surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. I: Surgical procedures to correct mandibular prognathism and reshaping of the chin. Oral Surg Oral Med Oral Pathol 10:677, 1957 50. Converse JM, Horowitz SL: The surgical-orthodontic approach to the treatment of dentofacial deformities. Am J Orthod 55: 217, 1969 51. Cassidy DW Jr, Herbosa EG, Rotskoff KS, et al: A comparison of surgery and orthodontics in “borderline” adults with class II, division 1 malocclusions. Am J Orthod Dentofacial Orthop 104:455, 1993 52. Schendel SA, Epker BN: Results after mandibular advancement surgery: An analysis of 87 cases. J Oral Surg 38:265, 1980 53. Ellis E 3rd, Carlson DS: Stability two years after mandibular advancement with and without suprahyoid myotomy: An experimental study. J Oral Maxillofac Surg 41:426, 1983 54. Caldwell JB, Hayward JR, Lister RL: Correction of mandibular retrognathia by vertical L osteotomy: A new technique. J Oral Surg 26:259, 1968 55. Longaker MT, Siebert JW: Microsurgical correction of facial contour in congenital craniofacial malformations: The marriage of hard and soft tissue. Plast Reconstr Surg 98:942, 1996 56. Vargervik K, Ousterhout DK, Farias M: Factors affecting longterm results in hemifacial microsomia. Cleft Palate J 23(Suppl 1):53, 1986 57. Jayade CV, Ayoub AF, Khambay BS, et al: Skeletal stability after correction of maxillary hypoplasia by the Glasgow extra-oral distraction (GED) device. Br J Oral Maxillofac Surg 44:301, 2006 58. Bartlett SP, Losee JE, Quinn PD: Severe proliferative congenital temporomandibular joint ankylosis: A proposed treatment protocol utilizing distraction osteogenesis. J Craniofac Surg 17: 605, 2006 59. Gateno J, Engel ER, Teichgraeber JF, et al: A new Le Fort I internal distraction device in the treatment of severe maxillary hypoplasia. J Oral Maxillofac Surg 63:148, 2005 60. Suzuki EY, Motohashi N, Ohyama K: Longitudinal dento-skeletal changes in UCLP patients following maxillary distraction osteogenesis using RED system. J Med Dent Sci 51:27, 2004 61. Nadjmi N: Predictability of maxillary distraction with the transsinusoidal distractor [in French]. Rev Stomatol Chir Maxillofac 105:9, 2004 62. Walker DA: Management of severe mandibular retrognathia in the adult patient using distraction osteogenesis. J Oral Maxillofac Surg 60:1341, 2002 63. Wiltfang J, Kessler P: Endoscopically assisted Le Fort I osteotomy to correct transverse and sagittal discrepancies of the maxilla. J Oral Maxillofac Surg 60:1142, 2002 64. Fan H, Wang X, Lin Y, et al: Application of distraction osteogenesis in severe maxillary hypoplasia secondary to cleft palate. Zhonghua Yi Xue Za Zhi 82:699, 2002 [in Chinese] 65. Guimaraes-Ferreira J, Gewalli F, David L, et al: Calvarial bone distraction with a contractile bioresorbable polymer. Plast Reconstr Surg 109:1325, 2002 66. Imola MJ, Hamlar DD, Thatcher G, et al: The versatility of distraction osteogenesis in craniofacial surgery. Arch Facial Plast Surg 4:8, 2002 67. Sugawara Y, Tsuji N, Sunaga A, et al: Treating craniosynostosis with a multidirectional cranial distraction osteogenesis (MCDO) system. Jpn J Plast Reconstr Surg 48:1017, 2005 [in Japanese] 68. Akizuki T, Komuro Y, Kurakata M, et al: Midface distraction. Jpn J Plastic Reconst Surg 42:1155, 1999 [in Japanese] 69. Arnaud E, Marchac D, Renier D: Quadruple internal distraction with early frontal-facial advancement for faciocraniodysostosis. Rev Stomatol Chir Maxillofac 105:13, 2004 [in French] 70. Nadjmi V, Van Erum R, Schoenaers J, et al: Maxillary distraction using a trans-sinusal distractor: Technical note. Int J Oral Maxillofac Surg 32:553, 2003
AL-DAGHREER, FLORES-MIR, AND EL-BIALY 71. Ko EW, Hung KF, Huang CS, et al: Correction of facial asymmetry with multiplanar mandible distraction: A one-year follow-up study. Cleft Palate Craniofac J 41:5, 2004 72. Hierl T, Klisch N, Kloppel R, et al: Distraction osteogenesis in the treatment of severe midfacial hypoplasia. Mund Kiefer Gesichtschir 7:7, 2003 [in German] 73. Raghoebar GM, Heydenrijk K, Vissink A: Vertical distraction of the severely resorbed mandible: The Groningen distraction device. Int J Oral Maxillofac Surg 29:416, 2000 74. Hidding J, Zoller JE, Lazar F: Micro- and macrodistraction of the jaw: A sure method of adding new bone. Mund Kiefer Gesichtschir 4(Suppl 2):S432, 2000 [in German]. 75. Cohen SR, Boydston W, Hudgins R, et al: Monobloc and facial bipartition distraction with internal devices. J Craniofac Surg 10:244, 1999 76. Cedars MG, Linck DL 2nd, Chin M, et al: Advancement of the midface using distraction techniques. Plast Reconstr Surg 103:429, 1999 77. Harada K, Baba Y, Ohyama K, et al: Soft tissue profile changes of the midface in patients with cleft lip and palate following maxillary distraction osteogenesis: A preliminary study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 94:673, 2002 78. Kessler P, Kloss F, Hirschfelder U, et al: Distraction osteogenesis in the midface. Indications: Technique and first long-term results. Schweiz Monatsschr Zahnmed 113:677, 2003 79. Tung TH, Robertson BR, Winograd JM, et al: Successful distraction osteogenesis across a growing cranial suture without an osteotomy. Plast Reconstr Surg 103:362, 1999
1819 80. Yano H, Tanaka K, Sueyoshi O, et al: Cranial vault distraction: Its illusionary effect and limitation. Plast Reconstr Surg 117:193, 2006 81. Klein C, Howaldt HP: Mandibular micrognathism as a sequela of early childhood capitulum fractures and their treatment using distraction osteogenesis. Fortschr Kiefer Gesichtschir 41:147, 1996 [in German] 82. Grayson BH, Santiago PE: Treatment planning and biomechanics of distraction osteogenesis from an orthodontic perspective. Semin Orthod 5:9, 1999 83. Carls FR, Sailer HF: Seven years clinical experience with mandibular distraction in children. J Craniomaxillofac Surg 26:197, 1998 84. Kusnoto B, Figueroa AA, Polley JW: A longitudinal three-dimensional evaluation of the growth pattern in hemifacial microsomia treated by mandibular distraction osteogenesis: A preliminary report. J Craniofac Surg 10:480, 1999 85. Marquez IM, Fish LC, Stella JP: Two-year follow-up of distraction osteogenesis: Its effect on mandibular ramus height in hemifacial microsomia. Am J Orthod Dentofac Orthop 117: 130, 2000 86. Rachmiel A, Manor R, Peled M, et al: Intraoral distraction osteogenesis of the mandible in hemifacial microsomia. J Oral Maxillofac Surg 59:728, 2001 87. Huang CS, Ko WC, Lin WY, et al: Mandibular lengthening by distraction osteogenesis in children: A one-year follow-up study. Cleft Palate Craniofac J 36:269, 1999
Long-Term Stability After Craniofacial Distraction Osteogenesis Saleh Al-Daghreer, BDS,* Carlos Flores-Mir, DDS, MSc, DSc, FRCD(c),† and Tarek El-Bialy, BDS, MSc Ortho, MSc OSci, PhD, FRCD(c)‡ Purpose: This study was conducted to systematically review long-term skeletal stability after cranio-
facial distraction osteogenesis. Materials and Methods: Several electronic databases (Old Medline, Medline, Medline In-Process and Other Non-Indexed Citations, Pubmed, Embase, Web of Science, and all EBM reviews [Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR]) were searched. Key words used in the search were “distraction,” “osteogenesis,” “craniofacial,” “maxillofacial,” “stability,” “relapse,” and “recurrence.” MeSH terms and truncations of these terms were selected with the help of a health science librarian. Abstracts that appeared to contain at least 3 years of postsurgical data were selected. The original articles were then retrieved and evaluated to ensure that they actually had 3 years of data after craniofacial distraction osteogenesis. The references were also hand-searched for possible missing articles that were not indexed in the searched databases. Results: A total of 118 abstracts were found in the electronic searches. After the first set of selection criteria was applied on these abstracts, 22 articles were retrieved. After the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. These 6 articles reported long-term stability after craniofacial distraction osteogenesis. Sample sizes were small, and the methodological quality of the studies was poor. Conclusions: Although, based on the selected studies, craniofacial bone distraction osteogenesis appeared to show long-term stability; limitations of the studies merit caution in interpreting these findings. Some early relapse occurred in the first 3 years postdistraction, but stability was maintained thereafter. Some methodologically sounder studies are needed to confirm the present findings. © 2008 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 66:1812-1819, 2008 Distraction osteogenesis (DO) is a biological process involving the formation of new bone between bone segments that are gradually separated by incremental traction. The traction generates tension that stimulates new bone formation parallel to the vector of distraction.1 The concept of applying DO to the treatment of craniofacial deformities was not conceived until 1972, when Snyder used a Swanson external
Received from the Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. *PhD Student. †Associate Professor. ‡Associate Professor. Address correspondence and reprint requests to Dr Flores-Mir: 4051 Dentistry/Pharmacy Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2N8; e-mail: [email protected] © 2008 American Association of Oral and Maxillofacial Surgeons
0278-2391/08/6609-0006$34.00/0 doi:10.1016/j.joms.2007.08.026
fixator to lengthen a canine mandible.2 Over the last 15 years, this procedure has become a popular technique to successfully treat craniofacial skeletal dysplasias in the sagittal and vertical dimensions.3-5 The patient population eligible for distraction now includes those with various craniofacial deficiencies, including craniofacial microsomia,6,7 Nager syndrome,8 Pierre-Robin syndrome,9 temporomandibular joint ankylosis,10 post-traumatic growth disturbances, postoncologic ablation,9 midface hypoplasias (maxillary deficiency, craniofacial synostosis),11 zygomatic deficiency (Treacher-Collins syndrome),8 craniofacial synostosis,12 and edentulous maxillary and mandibular alveoli.13 Distraction techniques have been used to correct craniofacial deformities that cannot be adequately addressed by conventional osteotomy. The benefits of distraction include the avoidance of bone grafting and donor site morbidity, its availability for use in surgery on younger patients, and concurrent expansion of the soft-tissue envelope.14 The unique feature of the distraction technique is that bone regeneration by DO is
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AL-DAGHREER, FLORES-MIR, AND EL-BIALY
Table 1. DATABASE SEARCH AND RESULTS
Database PubMed
Medline and Old Medline
Medline In-Process and NonIndexed EMBASE
All EBM reviews
Web of Science
Selected for the Systematic Review
% of Total Selected Articles (7) Found by Database
Search Terms
Results
Abstracts Obtained
(1) distraction*; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction$; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9 (1) distraction*; (2) osteogenesis; (3) #1 AND #2; (4) craniofacial; (5) maxillofacial; (6) #4 OR #5; (7) stability; (8) relapse; (9) recurrence; (10) #7 OR #8 OR #9
111
58
6
85%
62
47
6
85%
0
0
0
0
75
24
1
15%
1
0
0
0
66
20
0
0
0
0
0
0
Hand search
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
accompanied by simultaneous expansion of the functional soft tissue matrix, including blood vessels, nerves, muscles, skin, mucosa, fascia, ligaments, cartilage, and periosteum. These adaptive changes of the surrounding soft tissues through the tension generated by the distraction forces applied on the bone is called distraction histogenesis.15-20 DO relapse is defined as the gradual recurrence of the abnormality for which distraction was performed. However, the regeneration in DO is subject to a number of external forces during consolidation, including those from the muscles of mastication and the soft tissue envelope. These external forces can alter the postdistracted position, size, and shape of bone.21 Little is known about differences in the relapse process between DO and conventional surgical procedures. A meta-analysis of cleft maxillary osteotomy and DO conducted by Cheung and Chua22 found no conclusive data on any differences in surgical relapse, velopharyngeal function, and speech between the 2
techniques. Both DO and conventional osteotomy can deliver a marked improvement in facial esthetics. Although many comprehensive reviews on the applications of craniofacial DO have been published,23-31 none has discussed long-term stability and relapse after craniofacial DO. Therefore, our goal was to systematically review the long-term skeletal stability after craniofacial DO.
Materials and Methods A computerized database search was conducted using Old Medline (1950 to 1965), Medline (1966 to week 1 of May 2007), Medline In-Process and Other Non-Indexed Citations (up to May 15, 2007), Pubmed (1966 to week 2 of May 2007), Embase (from 1988 to 2007, week 19), Web of Science (1945 to week 1 of May 2007), and all EBM reviews (Cochrane Database of Systematic Reviews, ACP Journal Club, DARE, and CCTR) up to May 15, 2007. Terms used in the litera-
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ture search were “distraction,” “osteogenesis,” “stability,” “recurrence,” “relapse,” “craniofacial,” and “maxillofacial.” The selection and specific use of each term with their respective truncation, if applicable, inside every database (Table 1) were done with the help of a senior librarian specializing in health sciences database searches. The following inclusion criteria were chosen to initially select potential articles from the published abstract information: ● ● ●
Human clinical trials or series of consecutively treated cases; no individual case reports Follow-up for 3 years or more No postsurgical complications
The selection process was followed independently by 3 researchers (SMA, CFM, and TAE), and their selection results were compared to settle discrepancies through discussion. If the abstract did not provide sufficient information on which to base a sound decision, then the actual article was obtained. Any abstracts that did not specifically mention the time of follow-up were automatically included at this stage as well. The articles ultimately selected were chosen with the following additional inclusion criteria applied to the full article: only cases in which measurements were taken soon after the surgery and then again 3 years or more after surgery. Because of the severity and limited number of cases treated with DO, randomization and blinding were considered unattainable. Almost certainly, all of the cases will likely include syndromic patients. Also in this regard, case reports were selected due to the high probability that higher methodological studies were lacking. Reference lists of the selected articles were also hand-searched for additional relevant publications that may have been missed in the database searches. In cases where specific data were necessary for the discussion and were not specified in the article, efforts were made to contact the authors to obtain the required extra information. A meta-analysis was planned only if the quality of the retrieved information warranted it.
Results From the database searches, a total of 116 abstracts were initially retrieved. The details for the searches, as well as the number of abstracts selected from each database produced, are given in Table 1. Of the 118 abstracts, only 22 articles were retrieved after the first set of selection criteria were applied. Once the final selection criteria were applied on these 22 articles, only 6 articles were finally selected. No articles were found during the hand searches of the reference lists
Table 2. ARTICLES NOT SELECTED FROM THE INITIAL ABSTRACT SELECTION LIST AND REASONS FOR EXCLUSION
Article
Reason for Exclusion 22
Cheungc and Chua Gabbay et al32 Imai et al12 Rachmiel et al33 Alkan et al42 Fearon34 Wong and Padwa35 Figueroa et al36 Chiapasco et al37 Denny et al40 Iseri and Malkoc38 Heller et al8 Batra et al39 Swennen et al23 Kumar et al41 Nadjmi et al43
Meta-analysis Inadequate follow-up Inadequate follow-up Inadequate follow-up No follow-up of stability Inadequate follow-up Inadequate follow-up Inadequate follow-up Inadequate follow-up Follow-up time not indicated Inadequate follow-up Follow-up time not indicated Inadequate follow-up Literature review Follow-up time not indicated Inadequate reporting of data
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
of the selected articles that did not appear in the electronic database searches. Comparing the database results, Medline and PubMed had the greatest diversity of finally selected abstracts (85.7%). The other databases obtained significantly fewer finally selected abstracts (⬍15%). The different databases repeated most of the abstracts. At the final selection stage, from the 22 potential articles, 9 were excluded because of an inadequate follow-up period,12,32-39 3 because the follow-up time was not identified,8,40,41 1 because there was no follow up of stability,42 1 because it was a literature review,23 and 1 because it was a meta-analysis.22 One article did not provide sufficient data about the measurements;43 and we tried to contact the author to obtain more data but we did not get any response, so we excluded this potential study. Table 2 provides details about the reasons why these 16 articles were excluded at this stage. Finally, only 6 articles that met all of the inclusion criteria remained. Table 3 summarizes the sample size, follow-up period, and associated syndrome or condition for each. A methodological quality checklist developed to evaluate the selected articles is shown in Table 4, and an application of the methodological quality checklist is illustrated in Table 5. A flow diagram of the literature search is given in Figure 1. MIDFACE DISTRACTION
Three of the finally selected studies were on midface distraction in patients with a hypoplastic midface or maxilla.44-46 All of the studies used lateral cephalometric radiographs for evaluation, but the studies used different
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Table 3. FINALLY SELECTED STUDIES’ KEY METHODOLOGICAL INFORMATION
Measurement Error
Follow-Up (Average)
N/A
No
6.1 ⫾ 2.7 yrs
Cleft lip and palate Hemifacial microsomia
N/A Consecutive
Yes Yes
3 yrs 3 and 5 yrs
Cleft lip and palate
N/A Consecutive, Retrospective N/A
No
5 yrs
No No
5 and 10 yrs 61.6 mos
Study
Sample Size
Associated Syndrome
Meazzini et al44
Apert’s and Crouzon’s syndromes
Harada et al45 Meazzini et al47 Cho and Kyung46
10 7.3 ⫾ 2.6 yrs 8 (4 F, 4 M) 12.2 yrs ⫾ 11 mos 8 5.6 ⫾ 0.5 yrs 4 (1 F, 3 M) 15.25 yrs
Shetye et al7 Hollier et al48
12 (3 F, 9 M) 4.8 yrs 5 29.2 mos
Hemifacial microsomia Hemifacial microsomia, Nager
Selection
Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
selected cephalometric landmarks, measurements, and follow-up periods. A point, U1, Wits appraisal, and Or were used as landmarks for detecting linear horizontal changes; ANB and SNA, for angular horizontal changes; ANS and PO (posterior occlusal), for vertical linear changes; and the maxillary occlusal, palatal, and mandibular planes for angular changes. Patients with Le Fort III distraction had a stable A point and Or (⫺2 to 1 mm) of growth 5 years postdistraction, along with variable vertical changes ranging from 0 to 5 mm of the ANS and 5 to 16 mm of the PO point and changes in the palatal plane of 3° to 8° and in the maximum occlusal plane of 0° to 7°.44 In 1 study, patients with Le Fort I distraction exhibited stable ANS and U1 after 3 years,45 but in another
Table 4. METHODOLOGICAL SCORE FOR CLINICAL TRIALS
I. Study design (8✓) A. Objective: objective clearly formulated (✓) B. Population: described (✓) C. Selection criteria: clearly described (✓); adequate (✓) D. Sample size: considered adequate (✓); estimated before collection of data (✓) E. Timing: prospective (✓) F. Randomization or consecutive selection: stated (✓) II. Study measurements (5✓) A. Measurement method: appropriate to the objective (✓) B. Blind measurement: blinding C. Reliability: described (✓), adequate level of agreement (✓) III. Statistical analysis (5✓) A. Dropouts: dropouts included in data analysis (✓) B. Statistical analysis: appropriate for data (✓); combined subgroup analysis (✓) C. Statistical significance level: P value stated (✓) NOTE: Maximum number of ✓s ⫽ 16. Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
study, angular changes of the SNA were stable for 5 years after the first 6 months relapse postdistraction.46 In addition, there was a gradual decrease in the overjet horizontally and the ANS and U1 vertically at 3 years postdistraction.45 MANDIBULAR DISTRACTION
The remaining 3 studies were on mandibular distraction. Two of these used PA cephalometric radiographs to evaluate the results of mandibular distraction,7,47 and the other used panoramic radiographs to measure the ratio between the affected and nonaffected sides.48 The patients who met the selection criteria in the 3 studies had hemifacial microsomia and underwent unilateral mandibular distraction. The studies used different anatomic landmarks and measurement methods. In unilateral mandibular distraction evaluated by the PA and panoramic radiographs, the antegonial plane and the ratio between the affected and nonaffected sides between the 3 and 5 years of follow-up was stable; most of the relapse in treatment results occurred in the first 3 years postdistraction.47 In patients with unilateral extraoral ramus distraction, the ratio of the affected and nonaffected rami and the occlusal plane cant were stable after relapse occurring in the first year in the data of 5 years of follow-up. The results were better in the 10-year follow-up, but there was a dropout of 7 patients of the 12 patients followed.7 In the third study, mean patient age at the time of surgery was 48 months; only 4 cases were followed for more than 36 months. The results showed a mean 15% relapse rate in the ratio between the 2 rami obtained by unilateral distraction after a 62-month mean follow-up.48
Discussion Despite the fact that conventional orthognathic surgery and craniofacial reconstruction have met with widespread success, several limitations are associated with these treatment modalities.49-51 One of these is the
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LONG-TERM STABILITY AFTER CRANIOFACIAL DISTRACTION OSTEOGENESIS
Table 5. METHODOLOGICAL SCORE OF SELECTED ARTICLES
Articles
A
B
C
D
E
F
G
H
I
J
K
L
Total Checks
% of Total
Meazzini et al44 Harada et al45 Meazzini et al47 Cho and Kyung46 Shetye et al7 Hollier et al48
✓ ⫽ ✓ ✓ ✓ ⫽
✓ ✓ ✓ ✓ ✓ ⫽
⫽⫽⫽ ✓✓ ⫽⫽⫽ ⫽-
⫽⫽ -✓ -✓ ⫽✓ ⫽⫽-
⫽ ✓ -
✓ ✓ -
✓ ⫽ ✓ ⫽ ✓ ✓
-
✓⫽ ✓⫽ ✓✓ --✓✓
-
-⫽⫽✓✓--
✓ -
6.5 6 10.5 7 6.5 5
40.6 37.5 65.6 43.75 40.6 31.25
NOTE: A to L: methodological criteria in Table 4. ✓: Satisfactorily fulfilled the methodological criteria (1 check). ⫽: Partially fulfilled the methodological criteria (0.5 checks). -: Did not fulfill the methodological criteria (0 checks). Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
inability of the muscles to be acutely stretched without the inherent risk of relapse.52,53 Moreover, many of the congenital deformities require such large musculoskeletal movements that the soft tissues simply will not accommodate the change, leading to compromised function and esthetics unless additional soft tissue procedures are performed.54-56 In addition, modern surgical intervention permits only acute changes in the spatial arrangement of bones with limited possibilities for new bone growth. It does not allow complete bone sculpting, that is, changing the shape and form of the bones to maximize the patient’s 3D structural, functional, and esthetic needs.25 DO offers unique benefits, such as a bone regeneration accompanied by simultaneous expansion of the functional soft tissue matrix, including blood vessels, nerves, muscles, skin, mucosa, fascia, ligaments, cartilage, and periosteum.15-20 Much information about the stability and growth after DO in the craniofacial area has not been yet published; however, most of the clinical trials and series of cases published to date have been summarized in comprehensive reviews, which focused more on the important parameters, such as age, rhythm, rate, latency period, contention period, devices, and surgical techniques.9,23-31 In addition, comparison of DO and conventional surgical osteotomies for advancing the maxilla in patients with cleft lip and palate were done by performing a meta-analysis on independent studies but on the basis of short-term results.22 Most of the follow-up studies were case reports or clinical trials of low quality due to small sample size, difficulty of randomization, lack of blinding, poor statistical analysis, and short follow-up, and did not provide sufficient data after more than 36 months.12,33,35-39,57-78 The results were controversial in terms of the stability of mandibular distraction, as summarized in the article by Batra et al.39 In our selected studies, there was variation in the anatomic landmarks used to evaluate the amount of distraction and duration of postsurgical growth fol-
low-up, which introduced more variability in the measurements. To evaluate maxillary skeletal changes, Harada et al45 used only 1 landmark, ANS; Cho and Kyung46 used only SNA, SNB, and ANB; and Nadjmi et al43 used Wit’s appraisal. In the mandibular distraction studies, the measurements were more comprehensive for measuring the distracted mandible or ramus and comparing it with the unaffected side.7,47,48 The statistical analysis and presentation of the data also were inadequate; the measurements were represented in terms of range,44 subjective assessments,45 individual cases,46,48 and in 2 studies as mean and standard deviation.7,47 Most of the studies were retrospective,7,43,45,46,48 which decreased the methodological quality. In the distraction of the craniofacial complex, few articles have been published on cranial distraction, as found by our systematic search.12,67,79 All of the studies that we found were excluded because they did not meet the selection criteria of our review. On the other hand, this technique is not popular due to its multiple limitations and critical complications.80
FIGURE 1. Flow diagram. Al-Daghreer, Flores-Mir, and El-Bialy. Long-Term Stability After Craniofacial Distraction Osteogenesis. J Oral Maxillofac Surg 2008.
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In the distraction of the midface, most relapse occurs in the first 6 months after distraction, as shown by the data in 2 of the selected studies.45,46 This also has been demonstrated in some short-term follow-up studies with results showing different amounts of relapse in the first 6 months or 1 year postdistraction33,35,36,43; however, other short-term follow-up studies have found minimal relapse to stable results in the first year.34,41 After long-term followup, the data in the selected studies demonstrate stable results of advanced maxilla, but in 2 of the studies the maxillomandibular relationship showed little growth of the maxilla after distraction in the long term due to decreased ANB or overjet.45,46 A properly designed clinical trial comparing the results of conventional osteotomy and DO in patients with midface deficiency would be very useful to confirm the assumed lower morbidities and differences in skeletal relapse between the 2 techniques in short-term and long-term follow-up. In regard to DO of the mandible, many studies support the stability of mandibular distraction results after short-term follow-up,4,71,81-84 but some studies have reported relapse in short-term follow-up.85-87 Our review apparently demonstrates that the mandibular distraction studies are of better methodological design, with consecutive case selection and comprehensive measurements provided in 2 of the 3 studies.7,47 The selected studies showed that most relapses occur in the first year7 or 3 years47 postdistraction, after which the results are stable in a better proportion between the 2 rami than the predistraction proportion. The same result has been found in younger patients with hemifacial microsomia who underwent DO before age 48 months.48 Based on our findings, we can draw the following conclusions from our analysis: ● ●
●
●
There are few published long-term studies on the stability of DO of the craniofacial complex. All of the selected studies are of poor methodological quality (ie, poor design, small sample size, insufficient presentation of sufficient anatomic landmarks). Based on the limited evidence found, it can be suggested that craniofacial DO shows long-term stability of results after early relapse in the first 3 years postdistraction. High-quality clinical trials are needed to obtain more conclusive results and evaluate the correlation between the long-term and short-term stability of craniofacial DO and the other variables such as associated syndromes, amount of distracted bone, patient age and gender, technique, and amount of distraction.
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