after ilizarov first reported successful distraction osteogenesis of the long bone , there was a report by mccarthy et al .
( 1 ) who were the first to perform a distraction osteogenesis of the human craniofacial mandible bone .
thereafter numerous studies reported on craniofacial bone expansion . in order to successfully perform distraction osteogenesis in a craniofacial bone , both external and internal devices developed .
( 2 ) , who managed infant patients with craniofacial distraction by the direct application of helmets , which later gradually progressed to distraction techniques ( 3 ) .
advantages of the external type device are that the direction of distraction can be determined 3 dimensionally even after surgery , and that it is easy to remove ( 4 )
. drawbacks of this method include the difficulty in maintaining the stability of the osteotomized segment , difficulty in applying it to a patient of less than 2 yr of age who has a thin calvarium , difficulty in activating , and the most problematic of all is the inability to maintain this device for a sustained period of time due to the bizarre morphological appearance of the patient ( 5 ) .
the internal device was first utilized as a custom - made distractor since its first introduction in the mid-1990s , which was easier to apply as a modular type ( 6 , 7 ) .
recently , a biodegradable or a device with a bendable plate has been introduced ( 8) .
disadvantages of this device are the difficulty in determining the distraction direction , the inability to change the direction after surgical application , and the necessity of a secondary surgery for removal of the device ( 5 , 9 ) .
to solve the problem of the lack of intracranial and intraorbital space during craniofacial dysostosis , fronto - orbital monoblock advancement with lefort iii osteotomy has been developed to simultaneously expand the frontal skull and mid - face bones .
the combination of this technique with distraction osteogenesis further enhances the efficacy of the procedure . in our opinion , the application of either an external or internal device will both afford favorable results when combined with fronto - orbital monoblock advancement with lefort iii osteotomy , and although the internal device method is technically more difficult to employ , it may be applied for a longer period of time , and therefore seems to be advantageous in terms of osteogenesis and bone fusion .
in korea , numerous reports have described the utilization of external devices for management of craniofacial dysostosis to date , but studies on the application of internal devices are not yet available ( 10 ) .
we herein report the first case of a 7-yr - old male patient with pfeiffer syndrome in whom craniofacial monoblock distraction was successfully performed with an internal device .
a 7-yr - old boy presented to our surgical center with a broad big toe and thumb , bulging skull on the anterior fontanelle , underdevelopment of the frontal bone , exophthalmos , small face , tongue protrusion , malocclusion with midfacial retrusion , mild respiratory difficulty due to minor upper airway obstruction , and developmental delay .
physical examination showed that his head circumference was 55 cm ( more than 97th percentile )   in spite of the low body weight ( 10th percentile ) , and short height ( 3th percentile ) .
he also demonstrated a low intelligence quotient ( korea wechsler preschool primary scale of intelligence ) of 70 , and anthrophobia with passive characteristics .
we planned monoblock distraction osteogenesis to decrease the intracranial and intraorbital pressures , and to increase the nasal and pharyngeal airway spaces . using a bicoronal incision ,
a standard fronto - orbital osteotomy was performed . after separating the frontal bone flap ,
a forceful forward protrusion of the frontal lobe was noticed suggesting high intracranial pressure from the craniosynostosis .
thereafter , the orbital bandeau was also separated with a pneumatic saw , and a lefort iii - osteotomy was performed .
the osteotomy line ran across the zygomatic arch , from the sphenozygomatic suture along the floor of the orbit , behind the nasolacrimal duct , along the lacrimomaxillary suture to the nasal bone .
the nasal septum was separated from the perpendicular plate of the ethmoid bone with a straight osteotome .
the pterygoid plates were separated with a chisel placed into the pterygomaxillary fissure . the viscerocranium was mobilized .
downward rotation of the facial skeleton was also possible when using rowe 's forceps for disjunction of the mid - face from the cranial base .
the frontal bone flap and orbital bandeau were fixed into a fronto - maxillary monoblock bone flap with three micro - plates , and two modular midfacial distractors were fixed posteriorly to the temporal bone and anteriorly to the malar eminence of the zygomatic arch .
bilateral activation cables were brought through a stab wound posterior to the coronal incision and anterior to the ear .
the coronal incision was closed with continuous monofilament sutures subcutaneously , and staples in the skin .
the total operating time was 380 min , and 740 ml of packed red cells was infused .
the patient was kept on a mechanical ventilator for 10 hr , decannulated on the next morning after surgery , and stayed 1 day in the intensive care unit .
postoperatively , a distance of approximately 1 cm appeared between the skull flap and the parietal skull resulting in increased intracranial volume , which was almost completely filled by expansion of the brain .
we distracted the fronto - maxillary monoblock bone flap 1.0 mm everyday for 20 days beginning 1 week after the operation .
the distractors were kept for 3 months of the consolidation phase to a final 20 mm displacement .
follow - up 3-dimensional computed tomogram ( ct ) scans at 2 and 4 months after surgery showed increased intracranial space and sufficient expansion of the underlying brain with   only a small free epidural space , and the patient also showed stable forward advancement of the fronto - orbito - maxillary faciocranial monoblock , resulting in improved bilateral eye and mouth closing and occlusion motions ( fig . 2 , 3 ) .
we removed the two distraction bars 4 months after the initial establishment of the distraction system . at 12 months after surgery , the follow - up 3-dimensional ct scans showed proper ossification in the distracted area ( fig .
the patient showed good cranial contours aesthetically , with upward elevation and forward displacement of the preoperatively depressed fronto - facial contour .
he also showed a slightly increased intellectual quotient of 80 , and his character changed from passive to active , resulting in improved learning and rehabilitation exercise without any unexpected postoperative complications .
surgical management by lefort iii osteotomy for children with craniofacial dysostosis syndrome was first reported by gillies in 1950 , after which this procedure was firmly established as the primary mode of treatment by tessier ( 11 ) .
( 12 ) developed the monoblock advancement with lefort iii osteotomy method whereby the fronto - orbital segment and the midface counterpart are advanced simultaneously . in the 1990s , this technique further advanced to distraction osteogenesis ( 13 , 14 )
. advantages of distraction osteogenesis are that distraction is less invasive since it is performed without a bone graft and therefore less blood loss occurs , the operative time is shorter , bone union is superior leading to longer bone formation or growth , the induced bone growth shows good bone fusion that is comparable to previous methods in terms of bone thickness and strength , and finally , favorable skin and subcutaneous soft tissue expansion allows repeat surgery ( 15 ) .
the first operation for treatment of craniofacial dysostosis syndrome is usually necessary within months or within one year of birth , and additional surgery may be required at 2 - 3 yr of age .
the age 5 - 6 yr , at which adenoid infections most commonly occurs and develop to further narrow the passageway leading to obstructive sleep apnea syndrome , is considered to be the optimum age for timing of the primary surgery of the mid - face ( 16 , 17 ) .
additional craniofacial surgery is performed at 15 yr of age according to the status of the skull and facial bones .
as our patient did not receive craniosynostosis surgery during the infancy , the increased intracranial pressure resulted in the horn - like central bony elevation of the anterior fontanelle , and the maxilla was underdeveloped leading to eyeball protrusion , malocclusion , and respiratory difficulty .
therefore , the skull and maxilla were simultaneously expanded with distraction . in cases where the cranium and midface needs to be advanced simultaneously ,
it is advantageous to perform the monoblock advancement in which the midfacial segment and the fronto - orbital segment are advanced together , thus reducing the number of procedures to a single procedure .
however , there exists a major drawback such as possible severe and fatal infection of the opened nasal cavity and frontal skull base ( 18 ) . in a recent study
, it was suggested that since advancement for distraction osteogenesis is performed after nasal mucosal healing , opening the nasal cavity and frontal skull base would significantly decrease the possibility of a severe infection ( 19 ) .
common and difficult problems when applying an internal device is the determination of the direction of the device and the inability to change the direction once it has been applied ( 5 , 9 ) .
exceptional advancement employing an internal device during craniofacial monoblock distraction with lefort iii osteotomy frequently results in the soft tissue tension casing caudal rotation of the midfacial segment , which in turn displaces the zygomaticomaxillary complex more anteriorly than the dentoalveolus ( 20 ) .
furthermore , lateral advancement forces leads to midline advancement , resulting in possible fractures of the zygomaticomaxillary junction , and worsening of the facial concavity ( 20 ) . to overcome these problems ,
authors expect that the zygomaticomaxillary complex balance with internal device distraction will prevent rotation , and also that sufficient bone separation during surgery will markedly decrease any lateral distraction of the zygomaticomaxillary complex . despite such inherent limitations of the internal device ,
the reason for this is that the external type is cosmetically unfavorable and uncomfortable for long - term application ( 21 , 22 ) . for bone formation induction and consolidation to take place after distraction osteogenesis
, the distraction device needs to be in place for at least 1 - 3 months , which is very difficult with a poor patient 's compliance .
hence , a shorter consolidation period ensues and the bone fusion rate decreases , and subsequently there is an increased chance of relapse .
a review of previous reports showed that during the postoperative period , a latency period was applied for 0 - 7 days , the activation rate was 0.5 - 1.5 mm / day , and the activation period was 14 - 30 days ( 5 , 7 , 14 - 16 , 22 - 26 ) .
also , the total distance of advancement has been reported to be 14 - 30 mm for cranial distraction , and 8 - 23 mm for facial distraction .
the recommended consolidation period ranges from 3 weeks to 6 months ( 5 , 7 , 14 - 16 , 19 , 23 - 26 ) .
as yet , there have been no definite conclusive statistical data in the literature that suggest which method is superior to the others , but it is generally recommended that activation and follow - up radiological studies such as 3-dimensional ct be conducted to assess bone fusion during the consolidation phase .
 a 7-yr - old boy visited our surgical center with pfeiffer syndrome type 1 , presenting with macrocrania , broad big toe and thumb , exophthalmos , tongue protrusion , malocclusion with midfacial retrusion , mild respiratory difficulty due to minor upper airway obstruction , and developmental delay . 
 he also exhibited anthrophobia with a passive character . 
 the patient was treated with internal monoblock distraction osteogenesis to increase the intracranial and intraorbital volumes , and the nasal and pharyngeal airway spaces using two modular mid - facial internal distractors . for distraction , 
 the latency period was 1 week , the daily activation of 1.0 mm was 20 days ( total advancement 20 mm at the midline ) , and the consolidation period was 3 months . 
 the follow - up computed tomography 12 months after surgery showed expansion of the brain and proper ossification in the distracted area . 
 the patient also showed aesthetically good cranial contours , improved tongue and eyeball protrusion , no respiratory difficulty , and improved learning . 
 we suggest that the internal distraction may last longer than an external type , resulting in a better bone fusion rate and successful expansion of craniofacial bones . 
INTRODUCTION
CASE REPORT
DISCUSSION