Craniofacial distraction with a modular internal distraction system: evolution of design and surgical techniques

Corrected Cephalometric Analysis to Determine the Distance and Vector of Distraction Osteogenesis for Syndromic Craniosynostosis

Background:

The purpose of this study was to confirm the utility of a corrected cephalometric analysis to facilitate the planning of distraction osteogenesis with Le Fort III osteotomy for syndromic craniosynostosis.

Methods:

This prospective study involved 4 male and 2 female patients (mean patient age, 8 years 9 months; age range, 4 years 6 months to 13 years 2 months) with Crouzon syndrome who were treated with Le Fort III maxillary distraction using our previously described system of analysis of a corrected cephalogram and who underwent clinical follow-up. Lateral cephalograms were obtained immediately after device removal.

Results:

Distraction of orbitale moved the vector downward to the adult profile, but there was slightly less elongation than the adult profile for the distraction distance. The desired and real mean angles after distraction of point A were 29.2 ± 7.9° and 6.1 ± 8.5°, respectively, and the desired and the real mean distances after distraction of point A were 30.6 ± 12.7 mm and 29.4 ± 4.1 mm, respectively.

Conclusions:

Using the corrected cephalometric analysis, the distance and vector of distraction osteogenesis with Le Fort III osteotomy could be determined in patients with syndromic craniosynostosis. The distraction system brought the patients' facial bones to the planned position using controlling devices.

Study of Distracted Bone in Maxilla: A Comparative Analysis

INTRODUCTION

Anterior maxillary distraction is one of the accepted modalities to treat hypoplastic maxilla. The study was undertaken to assess the maturation of the bone formed, which is measured by analyzing the amount of mineralization of the bone.

MATERIALS AND METHODS

For the study 29 patients were chosen, who were divided into three groups. First group consist of patients who had undergone distraction osteogenesis. Second group has cleft patients and third group is the control group. A bone biopsy using trephine drill is obtained from the subjects. This sample is subjected to Fourier transform infrared spectroscopy (FTIR).

RESULTS

From  the results a mineral to matrix ratio is obtained which is then compared between the three groups. There is a statistically significant difference between the mineralization of the three groups. The distracted bone shows the lowest mineralization while mineralization of the cleft bone is also less than the normal bone.

CONCLUSION

The study conclusively establishes that the distracted bone is not as mineralized as the normal bone. Although functionally the distracted bone is as good as the native bone and grafted bone as proved by the success rate of the implants placed. The study also highlights the use of FTIR for assessing the bone quality.

Management of Cleft Maxillary Hypoplasia with Anterior Maxillary Distraction: Our Experience

Maxillary hypoplasia is a common developmental problem in cleft lip and palate deformities. Since 1970s these deformities have traditionally been corrected by means of orthognathic surgery. Management of skeletal deformities in the maxillofacial region has been an important challenge for maxillofacial surgeons and orthodontists. Distraction osteogenesis is a surgical technique that uses body's own repairing mechanisms for optimal reconstruction of the tissues. We present four cases of anterior maxillary distraction osteogenesis with tooth borne distraction device-Hyrax, which were analyzed retrospectively for the efficacy of the tooth borne device-Hyrax and skeletal stability of distracted anterior maxillary segment.

Long-term results of surgically assisted maxillary protraction vs regular facemask

OBJECTIVE

To evaluate the short- and long-term treatment results of rapid maxillary expansion (RME) and surgical assistance during maxillary protraction with a facemask (FM).

MATERIALS AND METHODS

This study was carried out in 28 patients (12 male, 16 female) with maxillary retrognathism, anterior crossbite, and Class III skeletal and dental malocclusion characteristics. Seventeen patients (9 male, 8 female) with mild maxillary retrognathism were treated by RME and FM. The other 11 patients (8 female, 3 male), who had moderate to severe maxillary retrognathism, were treated with surgically assisted FM treatment. Patients treated with RME and FM were recalled after 5.64 years, and the surgically assisted FM group was recalled after 6.08 years. Cephalometric films taken before treatment (T0), right after maxillary protraction (T1), and at recall (T2) were used to evaluate and compare the results.

RESULTS

In the short term, good maxillary advancement and a shorter treatment period were achieved with surgically assisted FM therapy. However, in the long term, maxillary advancement and some soft tissue improvements were lost. On the other hand, in the RME and FM protraction group, maxillary advancement and soft tissue improvement were well maintained.

CONCLUSION

In the short term, statistically significant maxillary advancement was achieved with surgically assisted maxillary protraction. However, in the long term, these sagittal changes were not stable, whereas RME and FM provided stability.

A osteogenesis distraction device enabling control of vertical direction for syndromic craniosynostosis

Background:

We have developed a hybrid facial osteogenesis distraction system that combines the advantages of external and internal distraction devices to enable control of both the distraction distance and vector. However, when the advanced maxilla has excessive clockwise rotation and shifts more downward vertically than planned, it might be impossible to pull it up to correct it. We invented devices attached to external distraction systems that can control the vertical vector of distraction to resolve this problem. The purpose of this article is to describe the result of utilizing the distraction system for syndromic craniosynostosis.

Methods:

In addition to a previously reported hybrid facial distraction system, the devices for controlling the vertical direction of the advanced maxilla were attached to the external distraction device. The vertical direction of the advanced maxilla can be controlled by adjustment of the spindle units. This system was used for 2 patients with Crouzon and Apert syndrome.

Results:

The system enabled control of the vertical distance, with no complications during the procedures. As a result, the maxilla could be advanced into the planned position including overcorrection without excessive clockwise rotation of distraction.

Conclusion:

Our system can alter the cases and bring them into the planned position, by controlling the vertical vector of distraction. We believe that this system might be effective in infants with syndromic craniosynostosis as it involves 2 osteotomies and horizontal and vertical direction of elongation can be controlled.

Maxillary distraction osteogenesis at Le Fort-I level induces bone apposition at infraorbital rim

OBJECTIVE

The aim of this study is to evaluate whether there is any remodeling of bone at infraorbital rim following maxillary distraction osteogenesis (DO) at Le Fort-I level.

MATERIALS AND METHODS

Twelve adult subjects in the age range of 17-21 years with complete unilateral cleft lip and palate underwent advancement of the maxilla by DO. The effect of maxillary DO on the infraorbital rim remodeling was evaluated from lateral cephalograms recorded prior to the DO (T0), at the end of DO (T1), and at least 2-years after the DO (T2) by Walker's analysis. The ANOVA and two-tailed t test were used and probability value (P value) 0.05 was considered as statistically significant level.

RESULTS

There was anterior movement of maxilla by 9.22 ± 3.27 mm and 7.67 ± 3.99 mm at the end of immediate (T1) and long-term (T2) follow-up of maxillary DO, respectively. The Walker's analysis showed 1.49 ± 1.22 mm and 2.31 ± 1.81 mm anterior movement of the infraorbital margin (Orbitale point) at the end of T1 and T2, respectively (P < 0.01). This apposition of bone at the infraorbital rim region further improved the facial profile of these patients.

CONCLUSION

The advancement of maxilla by distraction osteogenesis at Le Fort-I level induced significant bone apposition at infraorbital rim.

CLINICAL RELEVANCE

Patients with mild midface hypoplasia who would otherwise may be candidates for osteotomy at Le Fort-II or Le Fort-III level may benefit from maxillary distraction at Le Fort-I level.

The role of distraction osteogenesis in the management of craniofacial syndromes

In patients with craniofacial syndromes, the skeletal discrepancy is often severe, and the ability to achieve the desired movement by immediate surgical repositioning is difficult because of restrictions of the soft-tissue envelope. The technique of distraction osteogenesis has provided an additional option for managing congenital and acquired craniofacial deformities. The use of distraction osteogenesis is, however, still within its infancy as a treatment modality. It is unlikely that the procedure will obviate the need for definitive orthognathic surgery at skeletal maturity in most patients with craniofacial anomalies. The role of distraction osteogenesis in craniofacial surgery will continue to evolve rapidly with increasing experience and technological advancement. Because distraction osteogenesis in the facial skeleton is a relatively new approach, analysis of the contemporary literature is imperative, and future long-term studies on the effects and outcome of distraction are essential.

A review of reconstructive materials for use in craniofacial surgery bone fixation materials, bone substitutes, and distractors

Over the last 40 years, craniofacial surgery, in general, and surgery for craniosynostosis, in particular, has witnessed the introduction of a number of new materials for use in operations involving the cranial vault. Some of these materials have proven quite useful over time, while others have failed to meet their stated objectives. In this review, the more popular implant materials are analyzed, and their relative merits and drawbacks are discussed. Craniofacial surgery in the pediatric population has its own unique limitations, quite different from the adult population and those issues are reviewed as well.

A novel craniofacial osteogenesis distraction system enabling control of distraction distance and vector for the treatment of syndromic craniosynostosis

BACKGROUND

Distraction osteogenesis is now an important clinical tool in craniofacial surgery. However, controlling the distance and vector of distraction in infants with syndromic craniosynostosis with good repeatability is a task that still proves difficult today. We have developed a new facial osteogenesis distraction system that combines the advantages of external and internal distraction devices to enable control of both the distraction distance and vector. This article describes the method and short-term results of this system.

METHODS

Our distraction system uses both a conventional external distraction device and a newly developed internal distraction device. Postoperative control of the distraction vector is performed using the external device, whereas control of distraction distance is done with the adjustable-angle internal device. This system was used for 2 patients with Crouzon syndrome.

RESULTS

The system enabled control of lengthening distance and vector, and no complications occurred during the procedures.

CONCLUSIONS

We developed a facial distraction system leveraging the advantages of external and internal distraction devices, which we then used to successfully control both lengthening distance and vector. The system would be particularly indicated in patients with severe scarring due to multiple follow-up surgeries and in patients requiring distraction of 20 mm or more. Aligning the periorbital profile at 5 to 6 years old caused the maxilla to rotate counterclockwise, and we consider that a procedure combining Le Fort III osteotomy with Le Fort I and II osteotomies is required to prevent these rotations.

Necrotizing soft tissue infection of the scalp after fronto-facial advancement by internal distraction in a 7-year old girl with Gorlin-Chaudhry-Moss syndrome--a case report

In 1960, Gorlin, Chaudhry and Moss described a syndrome consisting of craniofacial dysostosis in association with hypertrichosis, cardiac, genital, dental and ocular anomalies. Diagnosis is based on typical clinical findings and cannot be performed by molecular genetic analysis until now. There is little in the clinical literature concerning this rare craniofacial syndrome. For functional and psychosocial reasons, surgical correction of the complex craniofacial malformation in a 7-year old Hungarian girl with Gorlin-Chaudhry-Moss syndrome was performed by fronto-facial advancement using internal distraction devices. Postoperatively necrotizing soft tissue infection of the scalp developed leading to termination of the distraction process ahead of schedule and requiring aggressive surgical management. Typical physiological and clinical characteristics were observed both during the initial craniofacial correction as well as during the management of the infectious complication suggesting that the linking of different conditions (surgical trauma plus the selection of toxic microorganisms) has caused tissue destruction rather than the syndromal disorder or the surgical technique of distraction osteogenesis. Although skeletal improvement was achieved residual damage from the infectious complication must be considered as severe.

Correction of midface deficiency using intra-oral distraction device

A wide variety of disease processes produce alteration of midfacial skeletal growth, resulting in moderate-to-severe midface deficiency presenting as retrusion associated with Angle's class III malocclusion. Most cases of midface deficiency are seen in patients of cleft lip/palate. The surgical procedure to correct the clefts, undertaken over a long period of time from infancy to the teens tends to take its toll on the soft tissues over the midface. The scarring that is a feature in these conditions results in hampering of normal growth of the midface causing the deformity. Conventional procedures to correct the deformity by surgical advancement have been less than satisfactory in terms of success. This is where the concept of multidimensional growth using distraction proved useful. Today distraction has proved to be a versatile tool in the correction of midface deficiencies due to its various advantages. Six patients of cleft lip/palate were taken up for advancement of the hypoplastic midface using intra-oral distractors with successful and stable results.

Current practice of distraction osteogenesis for craniofacial anomalies in Europe: a web based survey

Aim of the study was to get more insight into the opinion of European surgeons and orthodontists on the use of distraction osteogenesis (DO) for patients with different diagnoses and treatment protocols. A web based survey was set up, showing records of four patients with different conditions: hemifacial microsomia (case 1), bilateral mandibular deficiency (case 2), cleft lip and palate (case 3) and Crouzon syndrome (case 4). Respondents from 181 Eurocleft centres were asked to fill out a questionnaire for each patient. Most of the respondents considered case 1 (80%), case 3 (81%) and case 4 (86%) suitable for DO, while only 31% were considering case 2 for DO. There was lack of consensus among the respondents about many aspects of DO. Out of six different treatment parameters, an acceptable degree of agreement was only seen in two: a latency period of 3-7 days and a distraction rate of 1mm per day. Furthermore, there was noticeable disagreement on the ideal age for treatment, surgical technique, distraction device, and retention period. Our results showed that there is a wide variety in treatment approaches for craniofacial anomalies in Europe. There is disagreement on essential steps in the distraction procedures.

Frontofacial monobloc advancement using gradual bone distraction method

For children with craniosynostosis presenting intracranial hypertension and facial hypoplasia, different techniques have been used. Commonly, an initial frontoorbital advancement to expand a tight cranium volume was followed by Le Fort III osteotomy to repair midface abnormalities several months later. The 2-stage surgeries were unified into a 1-step procedure to optimize treatment. We here report results of frontofacial monobloc advancement, applying gradual distraction by a rigid external distraction device. Three patients were treated with excellent functional and cosmetic outcome with high rate of patient satisfaction. There was no remarkable complication.

Modified bimaxillary distraction osteogenesis: A technique to correct facial asymmetry

AIM

To study the efficacy of modified simultaneous maxillary-mandibular distraction to correct facial asymmetry in patients with compensated occlusion and a canted occlusal plane.

PATIENTS AND METHODS

During the period January 1998-December 2003, 15 patients with facial asymmetry (8 male and 7 female, mean age 18 years) were treated using a modified technique of simultaneous maxillary-mandibular distraction. Their facial deformities were caused by hemicraniofacial microsomia (n=6) or ankylosis of the temporomandibular joint (TMJ) (n=9).

RESULTS

The mean (range) gain in mandibular height was 16 (13-22) mm, and increase in elongation 14 (11-18) mm achieved over 11-22 days. Predicted movement on cephalometric analysis correlated closely with the actual distraction (mean accuracy 0.4mm).

CONCLUSION

Simultaneous bimaxillary distraction osteogenesis is a robust technique that provides the surgeon with the ability to correct facial asymmetry in patients with hemicraniofacial microsomia and those with facial deformity after ankylosis of the TMJ. A cephalometric prediction tracing made before distraction is a reliable guide to the actual distraction needed to correct the facial deformities in these patients.

Trans-sinusal maxillary distraction for correction of midfacial hypoplasia: long-term clinical results

Maxillary distraction osteogenesis is indicated in severe angle class III malocclusions, and severe maxillary hypoplasia among some cleft patients and other craniofacial deformities. Twenty patients, aged 8-48 years (mean 17.8+/-10.5 SD) with maxillary and midfacial hypoplasia were treated. The follow-up period was 13-65 months (mean 35+/-16.3 SD). A trans-sinusal maxillary distractor was placed intraorally at each side of the maxilla. The distraction vector was predicted using specialist software, and was transferred to the patients using stereolithographic models and individual templates. A (high) Le Fort I type osteotomy was performed. The amount of activation varied from 8 to 17.5 mm (mean 13.1+/-2.9 SD). Soft and hard tissue formation resulted in complete healing across the distraction gaps. The distractors are almost completely submerged, and can be left in place as long as necessary to avoid relapse. Wit's appraisal was used to measure the stability of the long-term distraction results. Results up to 5 years after distraction showed considerable maxillary advancement with long-term stability. Ongoing growth of the facial skeleton must be considered when distraction osteogenesis is chosen in growing patients.

[Distraction osteogenesis in the treatment of facial and mandibular deformities]

<Zakljucak> Prikazani protokoli lecenja i kriterijumi uspesnosti svakako ce zahtevati dalje izmene i dopune, ali se mogu koristiti u buducim klinickim studijama u cilju obezbedjivanja objektivnih podataka. Buduci pravci razvoja kraniofacijalne OD ukljucuju: uticaj faktora rasta na OD, uticaj OD na kraniofacijalni skelet u procesu rasta, usavrsavanje tehnike osteotomije putem endoskopije, razvoj minijaturnih multidirekcionih distrakcionih uredjaja koji omogucavaju interceptivnu OD i modifikaciju i usavrsavanje protokola lecenja putem kraniofacijalne OD.

Combined push-pull distraction for correction of syndromic midfacial hypoplasia

PURPOSE

Gradual midfacial advancement, applying the principle of distraction osteogenesis, reduces the restriction of the soft tissues and results in bony consolidation without need for grafting. The midface can be distracted by either pushing it forward, using semiburied devices, or pulling it forward by a rigid external device. For each method there are inherent technical problems, such as controlling the vector of movement, symmetry of advancement, and differential movement of the upper/lower face. We have used a combination of the 2 methods, called "push-pull," in an effort to control the distraction process. The purpose of this paper is to describe our push-pull distraction technique and summarize our early experience.

MATERIALS AND METHODS

Ten patients (5 males and 5 females) with a mean age of 11 years 2 months underwent midfacial advancement using push-pull distraction. Two orthodontists, blinded for landmark identification, traced preoperative and postoperative cephalograms and determined linear and angular measurements of midfacial position. A Student t test was used to assess differences between the cephalometric measures on the 2 radiographs. Interexaminer reliability was calculated by an intraclass correlation coefficient.

RESULTS

Postdistraction cephalograms were taken a mean of 10 months (range, 3 to 20 months) after removal of the devices. Patients exhibited improvement at all levels of the midface after distraction. There was a statistically significant sagittal advancement from the infraorbital rim to dentoalveolus. The central midface was sufficiently advanced as shown by an improved convexity, nasolabial angle, and upper labial protrusion. There were no significant differences between examiners for any of the measurements in this study.

CONCLUSIONS

Push-pull distraction permits 1) equal movement at both the upper and lower facial levels, 2) advancement of the central midface, and 3) symmetric movement of the zygomaticomaxillary complexes. This method also provides a backup, in case one device malfunctions. In combination, the advantages of each device are additive; whereas the weaknesses are not. The push-pull technique is a practical method for midfacial distraction until a better single device is fabricated.

The effect of chitosan bead encapsulating calcium sulfate as an injectable bone substitute on consolidation in the mandibular distraction osteogenesis of a dog model

PURPOSE

The purpose of this project was to study the effect of chitosan bead encapsulating calcium sulfate, which provides a sustained release of chitosan and calcium sulfate after implantation, on early bony consolidation in distraction osteogenesis of a dog model.

MATERIALS AND METHODS

Forty-five dogs were used for this study. An external distraction device was applied to the mandibular body after a vertical osteotomy and mandibular distraction was initiated 5 days after the operation at a rate of 1 mm/day up to a 10-mm distraction. The experimental group was divided into a control group (I), hyaluronic acid group (II), chitosan group (III), calcium sulfate group (IV), and chitosan bead encapsulating calcium sulfate group (V). Normal saline was injected in group I. In group II, 1 mL of hyaluronic acid solution was injected into the distracted region. In group III, 1 mL of injectable solution of chitosan mixed with hyaluronic acid was implanted. In group IV, 1 mL of injectable solution of calcium sulfate mixed with hyaluronic acid was implanted. In group V, an injectable form of powdered chitosan bead encapsulating calcium sulfate mixed with 1 mL volume of hyaluronic acid was implanted.

RESULTS

Bone mineral density was 12% of the contralateral normal mandible at 3 weeks, 23.4% at 6 weeks in group I, 15% at 3 weeks, 29.1% at 6 weeks in group II, 16% at 3 weeks and 32% at 6 weeks in group III, 30.4% at 3 weeks and 52.8% at 6 weeks in group IV, and 33.6% at 3 weeks and 55% at 6 weeks in group V with statistical significance (P < .005). The mean 3-point failure load was compared with the intact contralateral mandible and noted to be 12% in the control group, 16% in group II, 18% in group III, 34.3% in group IV, and 31.7% in group V. Difference of mean percentages between one group and another was statistically significant (P < .005). In the histologic findings, new bone was generated in all groups. In groups IV and V, the formation of active woven bone was observed throughout the distracted region at 6 weeks. The amount of new bone formation in the distracted zone was in the order of group IV and V, III and II, and the control group.

CONCLUSIONS

These findings suggest that chitosan bead encapsulating calcium sulfate appears to facilitate early bony consolidation in distraction osteogenesis.

A meta-analysis of cleft maxillary osteotomy and distraction osteogenesis

This meta-analysis aims to provide evidence-based data to assist surgeons to make an informed choice between distraction osteogenesis or conventional osteotomy for cleft lip and palate patients. A PUBMED search of the National Library of Medicine from 1966 to December 2003 was conducted. Keywords used in the search were 'cleft', 'distraction', 'maxilla', 'maxillary', 'advancement', 'osteotomy', and 'orthognathic surgery'. This study concluded that distraction osteogenesis tends to be preferred to conventional osteotomy for younger CLP patients with more severe deformities. In such cases it was feasible to use distraction to correct moderate to large movement of the maxilla by either complete or incomplete Le Fort I osteotomy, and a concurrent mandibular osteotomy was less frequently required. Intra-operative and post-operative complications were uncommon with either technique, and some of the traditional ischemic complications related to conventional osteotomy were replaced by infection of the oral mucosa due to the prolonged retention of the distractors. There is still no conclusive data on any differences in surgical relapse, velopharyngeal function and speech between the two techniques. Both distraction osteogenesis and conventional osteotomy can deliver a marked improvement in facial aesthetics.

Prototype testing for a new bioabsorbable Le Fort III distraction device: A pilot study

PURPOSE

The goal of the study was to design and test prototypes for a new, internal resorbable Le Fort III distractor in the minipig model.

MATERIALS AND METHODS

Le Fort III osteotomies were performed on 3 juvenile minipigs, followed by implantation of the bioabsorbable distractors. After a 5-day latency period, the distraction progressed at a rate of 1 mm/day in 2 equal increments for 12 days. This was followed by a 6-week consolidation phase. Cephalometric radiographs were taken postoperatively, on completion of distraction and after the consolidation phase, to evaluate the amount of distraction that was obtained. Necropsy was performed at the completion of each experiment.

RESULTS

The first minipig was sacrificed at the end of the distraction period because of device failure. On necropsy, it was noted that the anterior footplate on either side had failed. The second minipig was sacrificed during the latency period because of severe pneumonia. On necropsy, it was noted that none of the footplates had failed but that the distraction barrels on either side had become dislodged from the anterior bioabsorbable footplates. The third minipig was sacrificed at the end of the distraction period because of device failure. On necropsy, it was noted that the posterior bioabsorbable footplates on either side were fractured across the posterior screw lines.

CONCLUSIONS

The bioabsorbable devices evaluated in this study could not withstand the forces generated during distraction osteogenesis in the minipig model. Experience with the prototypes may help in designing internal bioresorbable Le Fort III distraction devices.

A Reflectable Case of Obstructive Sleep Apnea in an Infant With Crouzon Syndrome

Obstructive sleep apnea has recently drawn attention as a cause of sudden death among infants. Life-threatening obstruction of the upper airway is encountered in patients with syndromic craniosynostosis. Early definitive management of obstructive sleep apnea can conquer this critical situation. Although early tracheostomy can solve the problem, successful early midfacial distraction has been reported. In this report, a reflectable case of sudden death caused by a severe obstructive sleep apnea attack at home just before the midfacial distraction, during the waiting period for the surgery of midfacial distraction, is described. The authors stress the importance of preoperative care of the upper airway and the early definitive treatment using distraction osteogenesis for midfacial hypoplasia in infantile syndromic craniosynostosis.

The bone regenerative effect of chitosan microsphere-encapsulated growth hormone on bony consolidation in mandibular distraction osteogenesis in a dog model

The purpose of this project was to study the effect of chitosan microsphere-encapsulated human growth hormone, which causes sustained release of chitosan and human growth hormone after implantation on early bony consolidation in distraction osteogenesis of a canine model. Forty-eight dogs were used for this study. An external distraction device was applied to the mandibular body after a vertical osteotomy, and the mandibular distraction was started 5 days after the operation at a rate of 1 mm/d up to a 10-mm distraction. The experimental group was divided into a control group (I), hyaluronic acid group (II), chitosan microsphere group (III), and chitosan microsphere-encapsulated human growth hormone group (IV). Normal saline was injected in group I. In group II, a 1-ml volume of hyaluronic acid solution was injected into the distracted area. In the group III, powder of chitosan microspheres and hGH were mixed with a 1-ml volume of hyaluronic acid to make an injectable form, and it was implanted into the distracted area. In group IV, powder of chitosan microsphere-encapsulated hGH was mixed with a 1-ml volume of hyaluronic acid. A total of 1-ml volume of the solution mix was implanted into the distracted area. Five dogs in each group (total of 20 dogs) were killed 3 weeks after completion of distraction. Twenty-eight dogs were killed at 6 weeks. Bone mineral density was 13.1% of the contralateral normal mandible at 3 weeks and 29.6% at 6 weeks in group I, 16.4% at 3 weeks and 40.4% at 6 weeks in group II, 16.6% at 3 weeks and 45.95% at 6 weeks in group III, and 29.6% at 3 weeks and 66.7% at 6 weeks in group IV. The mean three-point failure load was 16.1% in the control group, 34.7% in group II, 41.5% in group III, and 52.1% in group IV compared with the intact contralateral mandible, with statistical significance. In the histological findings, new bone was generated in all groups. In group IV, the formation of active woven bone was observed throughout the distracted area at 6 weeks. The amount of new bone formation in the distracted zone was in the order of group IV, group III, group II, and the control group. In conclusion, these findings suggest that chitosan microsphere-encapsulated hGH seems to be quite effective in early bone consolidation in distraction osteogenesis.

Fronto-facial Monobloc Advancement With Rigid External Distraction (RED-II) System

Fronto-facial monobloc advancement is one of the most rewarding procedures for upper and mid-face reconstruction in patients with craniosynostosis. However, it has challenging aspects. Epidural abscess and frontal bone necrosis after retrofrontal dead space is one of the major complications and has led many experienced surgeons not to continue with the procedure. Bone distraction can play a great role in preventing these problems. The Rigid External Distraction (RED-II) system is a external distraction device using the cranium as an anchorage point. In two craniosynostosis cases, fronto-facial monobloc advancement with the system was performed. Controllability of the monobloc segment increased significantly. Operative time and blood loss were lessened. No major complications were experienced.

Distraction Osteogenesis of the Cranial Vault for the Treatment of Craniofacial Synostosis

From January 2000 to December 2001, six patients with craniosynostosis were treated. Involved sutures were coronal sutures in three patients, coronal and metopic sutures in one patient, multiple sutures (brachycephaly and oxycephaly) in one patient, and multiple sutures with a cloverleaf skull deformity in one patient. The age distribution of the patients was 4 months to 3 years. Four were male, and two were female. A frontal craniotomy was performed in four patients with brachycephaly. In one patient with brachycephaly, the osteotomies were made across the nasofrontal junction, across the roof of the orbit, and along the lateral orbital wall. In one patient with a cloverleaf skull deformity, a frontal bone osteotomy was first performed 1 cm above the roof of the orbit. A supraorbital frontal bar was then made across the nasofrontal junction, across the roof of the orbit, and down to the lateral orbital wall. The frontal bone flap was repositioned to the supraorbital bar using absorbable miniplates and screws. Distraction was started 3 to 7 days after the operation at a distraction rate of 1 mm/d. The real duration of the first operation was 90 to 120 minutes, and the second operation to remove the device took 40 to 50 minutes to perform. The distracted length was 15 to 25 mm. The consolidation period was 3 to 5 weeks. The follow-up period was 6 months to 1 year. Postoperative three-dimensional computed tomography demonstrated reossification at the bone flap and advancement of the fronto-orbital area. After surgery, the cranial volume increased 22.7% on average compared with before surgery. The mean ratio of the anteroposterior length to the transverse length of the cranial vault was changed from 0.96 before surgery to 1.04 after surgery. In conclusion, the advantages of distraction osteogenesis of the cranial vault are that it offers a less invasive technique, a shorter operation time, easy care, and postoperative safety as a result of minimal dissection of the dura. Disadvantages are the limited possibility of initial reshaping and the necessity of one more operation for device removal.

Complications associated with gradual cranial vault distraction osteogenesis for the treatment of craniofacial synostosis

Distraction osteogenesis has become a standard technique for craniomaxillofacial reconstruction. The authors performed gradual cranial vault distraction osteogenesis in 19 patients with craniosynostosis to study the outcome and complications of this procedure. Postoperative infections developed around the shaft puncture wounds in four patients, including one who required surgical removal of the device. Advanced bone was deformed in one patient. In another, the expansion device was exposed, resulting in a postoperative scar. Despite these complications, the cranium was successfully expanded in all patients.

The bone regenerative effect of growth hormone on consolidation in mandibular distraction osteogenesis of a dog model

The purpose of this project was to study the effect of growth hormone on early bony consolidation in distraction osteogenesis of a dog model. Sixteen dogs were used for this study. The vertical osteotomy on the mandibular body was extended downward. An external distraction device was applied to the mandibular body and the mandibular distraction was started 5 days after the operation at a rate of 1 mm/d up to a 10-mm distraction. The experimental group was divided into a control group and growth hormone group. Dogs in the growth hormone group received a daily subcutaneous injection of 100 microg (1 IU) of recombinant human growth hormone per kilogram of body weight. The daily administration of growth hormone was performed from the day of the osteotomy through the whole distraction period to the sacrifice. Normal saline was injected in the control group. Eight dogs were allocated to each group. Two dogs in each group, a total of four dogs, were killed at 2 weeks after completion of distraction, four dogs were killed at 4 weeks, and the other eight dogs were killed at 6 weeks. The level of serum IGF-I in the growth hormone group was elevated and peaked between 8 days and 12 days after systemic administration of growth hormone. Bone mineral density was higher in the growth hormone group and lower in the control group for the whole period. Bone mechanical strength was 300% higher in the growth hormone group than in the control group. However, results were more suggestive than conclusive. On histological examination, the formation of a substantial amount of active woven bone was observed throughout the distracted zone at six weeks in the growth hormone group. In the control group, new bone was generated from the edge to the center of the distracted zone. In addition, most of the central area of the distracted zone was filled with fibrous tissue at six weeks. In conclusion, these findings suggest that growth hormone appears to be effective in early bony consolidation in distraction osteogenesis.

The role of hyaluronic acid, chitosan, and calcium sulfate and their combined effect on early bony consolidation in distraction osteogenesis of a canine model

The purpose of this project was to study the effect of hyaluronic acid, calcium sulfate, and chitosan on early bony consolidation in distraction osteogenesis of a canine model. Sixteen dogs were used for this study. The lateral surface of the mandibular body was exposed in the subperiosteal plane, and the vertical osteotomy on the mandibular body was extended downward. An external distraction device was applied to the mandibular body, and the mandibular distraction was started 5 days after the operation at a rate of 1 mm/d up to a 10-mm distraction. The experimental group was then divided into a control group, chitosan group, hyaluronic acid group, calcium sulfate combined with hyaluronic acid group, and calcium sulfate combined with chitosan group, depending on the type of implantation material in the distracted area. After completing the distraction, implantation material was injected into the distracted area, although no material was implanted into the distracted area of the control group. After implanting the materials, the distraction device was left in place for 6 weeks to allow for bony consolidation. Four dogs were allocated to each group. Two dogs in each group (total of 8 dogs) were killed 3 weeks after implantation of the material, and the other 8 dogs were killed after 6 weeks. New bone was generated in the distracted zone of all groups. In the calcium sulfate combined with chitosan group and calcium sulfate combined with hyaluronic acid group, the formation of active woven bone was observed throughout the distracted zone. Moreover, the new bone seemed to be nearly normal cortical bone at 6 weeks after implantation. In the chitosan group and hyaluronic acid group, the development of new bone was observed in the distracted zone at 6 weeks. The amount was less than that in the calcium sulfate combined with hyaluronic acid group and calcium sulfate combined with chitosan group. These findings suggest that calcium sulfate and its combined materials seem to be quite effective in early bony consolidation in distraction osteogenesis.

Single-stage craniofacial distraction using resorbable devices

We report on the use of a new type of internal bone distraction devices designed for craniofacial applications. These resorbable devices allow a single operative procedure for device placement, eliminating the need for a second open operative procedure for hardware removal. We report on three models of resorbable devices. The midface orbital frontal device was used for midface and monoblock advancement. The mandibular adolescent device was used in older children and adolescents. In neonates and young children, the mandibular infant device was used. Twenty-one patients (9 female, 12 male) aged 6 days to 15 years (mean = 53 months) underwent bony expansion of the craniofacial skeleton over a 2-year period. A total of 39 devices were implanted: 32 in the mandible, 3 in the maxilla alone, and 4 in the maxilla and frontal bones. Expansion distances ranged from 15 to 30 mm. Expansion took place at 1 to 2 mm/d. Latency periods ranged from 48 to 72 hours. There were no device structural failures and no major complications.

Role of BMP, betaig-h3, and chitosan in early bony consolidation in distraction osteogenesis in a dog model

The purpose of this investigation was to study the effect of bone morphogenetic protein (BMP), transforming growth factor beta-induced gene h3 (betaig-h3), and chitosan on early bony consolidation in distraction osteogenesis in a dog model. Sixteen dogs were used for this study. The lateral surface of the mandibular body was exposed in the subperiosteal plane and the vertical osteotomy on the mandibular body was extended downward. An external distraction device was applied to the mandibular body, and the mandibular distraction was started 5 days after the operation at a rate of 2 mm/day up to a 10-mm distraction after 5 days. The experimental group was then divided into a control group, a BMP group, a betaig-h3 group, and a chitosan group, depending on the type of implantation material used in the distracted area. On the same day after completing the distraction, BMP, betaig-h3, or chitosan was implanted into the distracted area. No material was implanted into the distracted area in the control group. After implanting the materials, the distraction device was left in place for 7 weeks to allow for bony consolidation. Four dogs were allocated to each group. Two dogs in each group, a total of eight dogs, were killed 4 weeks after completing the distraction and the other eight dogs were killed after 7 weeks. Serial radiographs were obtained every week after completing the distraction. New bone was generated in the distracted zone in all groups. In the BMP group, the formation of active woven bone was observed throughout the distracted zone, and the new bone appeared to be nearly normal cortical bone 7 weeks after implantation. In the betaig-h3 and chitosan groups, the development of new bone was observed in the distracted zone after 7 weeks; however, the amount was less than that in the BMP group. In the control group, the new bone was observed at the edges of the distracted zone. These findings suggest that BMP seems to be very effective in early bony consolidation in distraction osteogenesis.

Midface distraction following Le Fort III and monobloc osteotomies: problems and solutions

Distraction osteogenesis has been used increasingly for midfacial advancement in patients with syndromic craniosynostosis and in severe developmental hypoplasia of the midface. In these patients, the degree of advancement required is often so great that restriction of the adjacent soft tissues may preclude stable advancement in one stage. Whereas distraction is an ideal solution by which to gradually lengthen both the bones and the soft tissues, potential problems remain in translating the distraction forces to the midface. In these patients, severe developmental hypoplasia may be associated with weak union between the zygoma and the maxilla, increasing the chance of zygomaticomaxillary dysjunction when using internal devices that translate distraction force to the maxilla through the zygoma. Eight cases are reported in which either internal or external distraction systems were used for midface advancement following Le Fort III (n = 7) or monobloc (n = 1) osteotomies. Cases of patients in whom hypoplasia at the zygomaticomaxillary junction altered or impaired plans for midface distraction were reported from three host institutions. Seven patients had midface hypoplasia associated with syndromic craniosynostosis, and one patient had severe developmental midface hypoplasia. The distraction protocol was modified to successfully complete midface advancement in light of weakness at the zygomaticomaxillary junction in seven patients. Modifications included change from an internal to an external distraction system in two patients, rigid fixation and bone graft stabilization of the midface in one patient, and plate stabilization of a fractured or unstable zygomaticomaxillary junction followed by resumption of internal distraction in four patients. Previous infection and bone loss involving both malar complexes precluded one patient from being a candidate for an internal distraction system. Using a problem-based approach, successful advancement of the midface ranging from 9 to 26 mm at the occlusal level as measured by preoperative and postoperative cephalograms was undergone by all patients. Advantages and disadvantages of the respective distraction systems are reviewed to better understand unique patient characteristics leading to the successful use of these devices for correction of severe midface hypoplasia.

Clinical application of injectable calcium sulfate on early bony consolidation in distraction osteogenesis for the treatment of craniofacial microsomia

The purpose of this project was to study the effect of calcium sulfate on early bony consolidation in distraction osteogenesis. A total of eight patients with craniofacial microsomia were treated between April 2000 and February 2001. The age of the patients ranged from 2 to 40 years, and all were male. The follow-up period was 1 to 15 months. The operative procedure in adults was based on Ortiz Monasterio's simultaneous mandibular and maxillary distraction technique. In children, osteotomy of the mandible was performed for distraction. On the fifth day after the operation, distraction was performed at a rate of 1 mm/d in three adults. In children, distraction was performed at a rate of 1 mm/d in one patient and 2 mm/d in four patients without a latent period. On the day of completion of distraction, calcium sulfate was implanted into the distracted zone. Radiographs showed bony consolidation at 4 weeks in one child at a rate of 1 mm/d, at 5 to 7 weeks in four children at a rate of 2 mm/d, and at 5 weeks in three adults after implantation of the calcium sulfate. In conclusion, these findings suggest that calcium sulfate is effective for early bony consolidation in distraction osteogenesis and that it would shorten the whole treatment period.

External distraction of the maxilla in patients with craniofacial dysplasia

Patients with severe maxillary hypoplasia secondary to craniofacial dysplasia present a challenge to the craniofacial surgeon. Maxillary distraction presents a promising tool to treat these patients more successfully. Fifteen patients aged 12 to 20 years with craniofacial dysplasia and maxillary retrusion were treated with two different techniques after complete Le Fort I osteotomy: one group underwent face mask protraction (2 patients), and the other group underwent rigid external distraction (13 patients). Cephalometric evaluation was performed before and after distraction. Rigid external distraction appeared to be superior to face mask protraction. Maxillary retrusion was fully corrected in this group. The path of maxillary positioning was well controlled by changing the traction force vector. Distraction osteogenesis has certainly improved treatment of these patients.

Internal Le Fort III Distraction with Biodegradable Devices

Shortly after the initial application of distraction osteogenesis to the human mandible by McCarthy, distraction osteogenesis was used for gradual lengthening of the midface in children with syndromic craniosynostosis, cleft lip and palate, hemifacial microsomia, and midface hypoplasia from other causes. Both external and internal devices are available for midface distraction. In spite of the many advantages of internal metallic distraction devices, they can be more difficult to remove. By substituting the metallic fixation plates of the Stryker-Leibinger Modular Internal Distraction system, with resorbable MacroPore fixation mesh, only the distractor screw and cable drive need to be removed. Moreover, by using a resorbable stabilizer, the screw and cable components are not needed for the consolidation phase, and can be removed at the completion of active distraction. In this case report of a 4-year-old girl with Crouzon's syndrome, contouring of the resorbable distraction devices was performed using a sterilizable model, 20 mm of distraction was achieved, and 4 days later the distractor screw was replaced with a resorbable stabilizer, resulting in an excellent correction of her midface hypoplasia.