Transport distraction osteogenesis: a new method to heal adult calvarial defects

Cranial Bone Transport Promotes Angiogenesis, Neurogenesis, and Modulates Meningeal Lymphatic Function in Middle Cerebral Artery Occlusion Rats

BACKGROUND

Ischemic stroke is a leading cause of death and disability worldwide. However, the time window for quickly dissolving clots and restoring cerebral blood flow, using tissue plasminogen activator treatment is rather limited, resulting in many patients experiencing long-term functional impairments if not death. This study aims to determine the roles of cranial bone transport (CBT), a novel, effective, and simple surgical technique, in the recovery of ischemic stroke using middle cerebral artery occlusion (MCAO) rat model.

METHODS

CBT was performed by slowly sliding a bone segment in skull with a special frame and a speed of 0.25 mm/12 hours for 10 days following MCAO. Morris water maze, rotarod test, and catwalk gait analysis were used to study the neurological behaviors, and infarct area and cerebral flow were evaluated during CBT process. Immunofluorescence staining of CD31 and Nestin/Sox2 (sex determining region Y box 2) was performed to study the angiogenesis and neurogenesis. OVA-A647 (ovalbumin-Alexa Fluor 647) was intracisterna magna injected to evaluate the meningeal lymphatic drainage function.

RESULTS

CBT treatment has significantly reduced the ischemic lesions areas and improved the neurological deficits in MCAO rats compared with the rats in the control groups. CBT treatment significantly promoted angiogenesis and neurogenesis in the brain of MCAO rats. The drainage function of meningeal lymphatic vessels in MCAO rats was significantly impaired compared with normal rats. Ablation of meningeal lymphatic drainage led to increased neuroinflammation and aggravated neurological deficits and ischemic injury in MCAO rats. CBT treatment significantly improved the meningeal lymphatic drainage function and alleviated T-cell infiltration in MCAO rats.

CONCLUSIONS

This study provided evidence for the possible mechanisms on how CBT attenuates ischemic stroke injury and facilitates rapid neuronal function recovery, suggesting that CBT may be an alternative treatment strategy for managing ischemic stroke.

Unusual Craniofacial Distraction

A retrospective Institutional Review Board-approved review was performed at the Institute of Reconstructive Plastic Surgery, NYU Langone Medical Center, of patients undergoing craniofacial distraction osteogenesis procedures using the rigid external distractor device between 2000 and 2010. Three particularly challenging cases were identified and are presented here.

Versatility of Distraction Osteogenesis for the Craniofacial Skeleton

Malformations of the craniofacial skeleton are common. Restoration of anatomic shape, size, and position has been traditionally accomplished using autologous bone grafting to fill gaps created by surgery and segmental movement. The authors present their practice using distraction in many different ages and settings over 20 years. A retrospective review was performed of all craniofacial patients treated using distraction osteogenesis for mandible, midface, and calvarium. The authors identified 205 patient. Mandible: 112 patients were treated at an average age of 3.4 years. 18.8% of patients required repeat distraction. There was no difference in the neonatal versus older group (P = 0.71). There were significantly higher reoperation rates in syndromic children (P < 0.01). Midface: 58 patients underwent Lefort III distraction at an average age of 13.6 years. One (1.7%) required repeat distraction (Miller syndrome). Five (8.6%) patients underwent subsequent Lefort I advancement for occlusal changes. Calvarium: 33 patients were treated at an average age of 4.7 years. No repeat distractions were performed. One patient required an additional advancement procedure. Distraction demonstrates successful long-term correction of defects in the craniofacial skeleton with the versatility and control needed to treat the wide spectrum of deformity.

Treatment of large calvarial defects with bone transport osteogenesis: a preclinical sheep model

BACKGROUND

Bone transport osteogenesis (BTO), distraction of a free portion of bone across a defect, offers an autologous solution to large cranial defects that may allow treatment without permanent hardware implantation. This study establishes a sheep model to evaluate the feasibility and distraction kinetics of BTO.

METHODS

Subtotal cranial defects (3.5 × 3.5 cm) were created in 10 young adult sheep and a transport segment (3.5 × 2 cm) traversed the defect at varying distraction rates (0, 0.5, 1.0, and 1.5 mm/day) using semi-buried cranial distractors. After a 6-week consolidation period, sheep were euthanized and the resultant bone was analyzed by CT, histology, and mechanical testing.

RESULTS

Gross examination, histology, and 3D CT revealed that control animals had fibrous nonunion whereas distraction animals had ossified defects with fibrous nonunion at the distal docking site. There was one premature consolidation in the 0.5 mm/day group. The volume of bony regenerate in the 0.5, 1.0, and 1.5 mm/day distraction rate groups was statistically indistinct (P = 0.16). The mean flexural moduli (MPa) of non-decalcified samples from the control cranium, transport segment, and bone regenerate were found to be 4.50 ± 4.9, 6.17 ± 2.1, and 4.14 ± 4.8, respectively (P = 0.24).

CONCLUSIONS

This experiment provides proof of concept for BTO for large calvarial defects in a sheep model. Distraction at a rate of 0.5 mm per day may place individuals at higher risk for premature consolidation, but distraction rates did not have significant effects on regenerate quantity or quality. Future work will include the use of curvilinear distraction devices for 3-dimensional contour.

Transport distraction osteogenesis with recombinant human bone morphogenic protein-2 for large calvarial defect reconstruction

BACKGROUND

Transport distraction osteogenesis (TDO) has been used in attempts to treat large calvarial defects but has, until now, lacked consistency and reliability. To achieve sufficient bone formation, the effect of TDO was compared to the effect of TDO combined with recombinant human bone morphogenic protein-2 (rhBMP-2).

METHODS

Fourteen dogs were divided into 2 groups; 6 animals in the control group received TDO only, and 8 received TDO combined with rhBMP-2. A calvarial defect 33 × 35 mm in size was generated, and the drug-delivering internal distractor was applied. After a 5-day latency period, distraction with rhBMP-2 at 10 μg/day was initiated at a rate of 2 mm/day. This was followed by a consolidation period of 3 months, after which areas of osteogenesis and strength were measured and histologic examinations were conducted.

RESULTS

The average area of osteogenesis was higher in the experimental group (P < 0.01). Regenerated bone of the experimental group showed increased strength (P < 0.05). Histological examination showed typical mature bone in the experimental group. Prominent osteoblastic rimming was observed in the bone marrow of the experimental group.

CONCLUSIONS

TDO with an internal distraction device delivering rhBMP-2 can enhance bone regeneration of large calvarial defects in a dog model. These results suggest the potential for human clinical testing of TDO combined with rhBMP-2.

Comparing calvarial transport distraction with and without radiation and fat grafting

The purpose of this study is to: a) assess transport distraction to reconstruct cranial defects in radiated and non-radiated fields b) examine adipose grafting's effect on the bony regenerate and overlying wound, and c) elucidate sources of bone formation during transport distraction osteogenesis. Twenty-three male New Zealand white rabbits (3 months; 3.5 kg) were used, 10 non-irradiated and 13 irradiated (17 treatment, 6 control) with a one-time fraction of 35 Gy. A 16 × 16 mm defect was abutted by a 10 × 16 mm transport disc 5 weeks after irradiation, and 11 animals were fat grafted at the distraction site. Latency (1 day), distraction (1.5 mm/day), and consolidation (4 weeks) followed. Fluorochromes were injected subcutaneously and microCT, fluorescence, and histology assessed. In distracted animals without fat grafting, bone density measured 701.87 mgHA/ccm and 2271.95 mgHA/ccm in irradiated and non-irradiated animals. In distracted animals with fat grafting, bone density measured 703.23 mgHA/ccm and 2254.27 mgHA/ccm in irradiated and non-irradiated animals. Fluorescence revealed ossification emanating from the dura, periosteum, and transport segment with decreased formation in irradiated animals. Transport distraction is possible for cranial reconstruction in irradiated fields but short-term osseous fill is significantly diminished. Adipose grafting enhances wound healing in previously irradiated fields but does not enhance ossification.

Evaluation of inferior alveolar nerve regeneration by bifocal distraction osteogenesis with retrograde transportation of horseradish peroxidase in dogs

Background

Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing segmental mandibular defects. However, there are few reports regarding the occurrence of inferior alveolar nerve regeneration during the process of distraction. Previously, we reported inferior alveolar nerve regeneration after distraction, and evaluated the regenerated nerve using histological and electrophysiological methods. In the present study, we investigated axons regenerated by bifocal distraction osteogenesis using retrograde transportation of horseradish peroxidase in the mandibles of dogs to determine their type and function.

Methods and Findings

Using a bifocal distraction osteogenesis method, we produced a 10-mm mandibular defect, including a nerve defect, in 11 dogs and distracted using a transport disk at a rate of 1 mm/day. The regenerated inferior alveolar nerve was evaluated by retrograde transportation of HRP in all dogs at 3 and 6 months after the first operation. At 3 and 6 months, HRP-labeled neurons were observed in the trigeminal ganglion. The number of HRP-labeled neurons in each section increased, while the cell body diameter of HRP-labeled neurons was reduced over time.

Conclusions

We found that the inferior alveolar nerve after bifocal distraction osteogenesis successfully recovered until peripheral tissue began to function. Although our research is still at the stage of animal experiments, it is considered that it will be possible to apply this method in the future to humans who have the mandibular defects.

Electrophysiologic evaluation of inferior alveolar nerve regenerated by bifocal distraction osteogenesis in dogs

BACKGROUND

Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, there are no reports regarding inferior alveolar nerve regeneration during bifocal distraction. In the present study, the authors evaluated the function of inferior alveolar nerve regenerated by bifocal distraction after segmental resection in the mandibles of dogs.

METHODS

Using a bifocal distraction osteogenesis method, the authors produced a 10-mm mandibular defect and distracted the transport disk at a rate of 1 mm/day. The regenerated inferior alveolar nerve was evaluated by electrophysiologic analysis that was performed on all dogs after euthanasia at 3, 6, and 12 months after the first operation.

RESULTS

At 6 and 12 months, stable evoked potential measurements were obtained from the nerves throughout the study on electrophysiologic analyses.

CONCLUSIONS

The authors' results indicate that the inferior alveolar nerve regenerated by bifocal distraction osteogenesis functioned electrophysiologically at 6 months after the first operation. Although our research is still at the stage of animal experiments, future application in humans is considered to be possible.

Inferior alveolar nerve regeneration after bifocal distraction osteogenesis in dogs

PURPOSE

Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, no reports have been published regarding inferior alveolar nerve regeneration during this procedure. We assumed that the nerve could regenerate with the bone regeneration during bifocal distraction, if the nerve had been saved at a mesial site of the transport disc. In the present study, we investigated that possibility in dogs.

MATERIALS AND METHODS

Using a bifocal distraction osteogenesis method, we produced a 10-mm mandibular defect, including the nerve defect, and distracted the transport disc at a rate of 1 mm/day in 12 dogs. The nerve was saved at the mesial site of the transport disc. The regenerated nerve was evaluated by a jaw opening reflex examination performed once daily. Histologic examinations with hematoxylin-eosin and immunohistochemical staining with neurofilament and S-100 antibody were also performed on all dogs after death at 3, 6, and 12 months after the first operation.

RESULTS

The jaw opening reflex had recovered in all dogs. The average period of recovery was 109.5 ± 24.7 days. On histologic examination, although consecutive nerves were observed in all areas, cellular nerve fascicles were seen, consistent with wallerian degeneration at 3 and 6 months in the nerve connection area on the distal side of the transport disc.

CONCLUSIONS

Our results have indicated that inferior alveolar nerve regeneration after bifocal distraction osteogenesis is successful in dogs. Although our research is still at the stage of animal experiments, future application in humans can be considered to be possible.

Trifocal distraction osteogenesis for reconstruction of skull defect

OBJECTIVE

To apply trifocal distraction osteogenesis in canine model of skull segmental defects and to provide reference for clinical treatment.

METHODS

Six labrador dogs were selected in this study and divided into observation group and control group randomly. Each group contained 3 dogs. Skull segmental defects models were established by surgery, and dogs in bservation group received trifocal distraction osteogenesis treatment. Bone density was observed and compared between two groups during treatment.

RESULTS

There were no significant difference in bone density between two groups on th 1st day (P>0.05). The bone density of observation group on the 30th day, and 60th day were higher than that of control group (P<0.01).

CONCLUSIONS

Trifocal distraction osteogenesis has significant clinical effect, and it would be widely used in clinical treatment.

Trifocal biplanar distraction-compression osteosynthesis: a new method for three-dimensional reconstruction of the calvarial defects

Surgical treatment of calvarial defects and deformities has some drawbacks such as donor site morbidity or use of allogenic materials. In this experimental study, we presented a three-dimensional reconstruction of cranial defects by using trifocal biplanar distraction-compression osteosynthesis (TBDCO).Eight sheep with a mean age of 2 years were divided into 2 groups as the control (n = 3) and distraction groups (n = 5). All the animals were operated on under general anesthesia, and 80 x 50-mm full-thickness calvarial defects were created. In the control group, no treatment was performed. In the distraction group, TBDCO was performed with a custom-made distraction device with 2 transport segments. After 5 days of latency period, the anterior transport segment was distracted to a posterior and superior direction (0.7 and 0.3 mm, respectively) and the posterior transport segment was distracted obliquely to an anterior and superior direction (0.7 and 0.3 mm, respectively) with a resulting total vectorial movement of 0.75 mm/d. Active distraction was approximately 29 days, and the consolidation period was 60 days.No major complications were seen during the whole procedure. In the control group, the bone defects remained unhealed. In the distraction group, defects healed and the reconstructed calvarium was dome shaped. Preoperative and postoperative cranial volume measurements of the distraction group animals revealed an increase in cranial volume (P < 0.05). Histologic evaluation showed inductive bone regeneration and mature bone structure development within the distraction zone. Trifocal biplanar distraction-compression osteosynthesis is an effective and safe technique for three-dimensional closure of the cranial defects. In clinical practice, it could provide several advantages over currently available reconstructive procedures.

Calvarial reshaping using bifocal bidirectional transport distraction osteogenesis

PURPOSE

The aim of this study is to assess 3-dimensional reconstruction of cranial defects by use of bifocal bidirectional transport distraction osteogenesis (BBTDO).

MATERIALS AND METHODS

This study was performed on 8 sheep, divided into a control group (n = 3) and treatment group (n = 5). Full-thickness cranial defects (50 x 40 mm) were created on calvaria. In the control group only the skin was closed. In the treatment group BBTDO was performed. Distraction was performed with a custom-made distraction device with a transport segment of 40 x 20 mm. After a 5-day period of latency, distraction was applied to the transport segment. During the first 20 days of distraction, the transport segment was distracted 1 mm in the forward direction and 0.5 mm in the upward direction. After the next 20 days of distraction, the transport segment was distracted 1 mm forward and 0.5 downward. After a total of 40 days' distraction, a 30-day consolidation period was applied. Macroscopic, radiologic (computed tomography with volume measurements), and histologic evaluations were done.

RESULTS

No major complications were seen during the whole study period. In the control group the bone defects remained unhealed at the end of the study period. The same-sized defects in the treatment group healed with a convexity like the calvaria. Preoperative and postoperative cranial volume measurements of the treatment group animals showed an increase in cranial volume (P < .05). Histologic evaluation showed inductive bone regeneration and mature bone structure development within the distraction zone.

CONCLUSION

The BBTDO is an effective and safe technique for 3-dimensional closure of cranial defects.

Transport distraction osteogenesis for closing full-thickness calvarial defects in sheep

OBJECTIVE

To prove the hypothesis that transport distraction osteogenesis can be applied to the skull to close critical-size calvarial defects.

DESIGN

A sheep model was developed to investigate this hypothesis. In four sheep, bilateral parietal bone windows were created and adjacent osteotomies performed. On the tested side, an adjacent bone segment was transported into the defect. The contralateral side was left untreated as a control.

MAIN OUTCOME MEASURES

After completion of the distraction and consolidation period, a computed tomography study was performed, and the animals were sacrificed. The newly formed bone was examined macroscopically and histologically.

RESULTS

A successful closure of the defect with transport distraction was achieved in all of the animals. The control side healed spontaneously in one (younger) sheep but did not heal in the other three animals. The closure of the bony defect with transport distraction was evident macroscopically as well as on the computerized tomography. Microscopic examination showed new healthy bone formation on the treated side.

CONCLUSION

We conclude that transport distraction is an effective tool in closing full-thickness calvarial defects in adult sheep. Further investigation is needed before applying this promising technique in humans.

Experimental application of a biomaterial in bifocal transport osteogenesis for craniofacial reconstruction

PURPOSE

Bifocal transport osteogenesis is an alternative technique of callus distraction, in which movement of a transport segment results in the formation of new bone in order to close a continuity defect. The aim of this experimental pilot study was to replace a bone graft by a biomaterial as a transport segment.

MATERIAL AND METHODS

Critical size defects of the calvaria in four adult sheep were treated with transport segments consisting either of an autogenous free bone graft of the calvaria (n=2) or of the biomaterial (deproteinized bovine cancellous bone; n=2). Latency period was 5 days; the rate of distraction was 1mm per day and was planned for 40 days. The consolidation period was 28 days. Specimens were investigated by conventional radiography, CT-scans and histologically, including immunofluorescence.

RESULTS

In both groups, transport osteogenesis resulted in a "de novo" formation of bone, indicating that this biomaterial may contribute successfully to bone formation in bifocal transport osteogenesis. However, volume and thickness of the newly formed bone at the defect site were smaller when using the biomaterial than when using autogenous bone grafts.

CONCLUSION

The application of a biomaterial as transport segments in bifocal transport osteogenesis in cranial critical size defects resulted in the formation of new bone thus excluding bone graft donor site morbidity.

Calvarial bone healing under spring distension at continuous forces

The aim of the present study was to evaluate in young animals the dynamics of calvarial bone healing when exposing a bone defect to continuous forces for up to 13 weeks. Six-week-old rabbits after a sagittal suture strip craniectomy were randomized for either of the following protocols: (1) no spring was applied (n = 7); (2) a titanium-molybdenum alloy (TMA) lower-force spring was inserted across the craniectomy gap (n = 9); (3) a stainless steel (SS) higher-force spring was applied (n = 8), or (4) sham operation (n = 8). Results showed that the surgically created calvarial bone gap was after 3 weeks kept widened both when a spring of lower force (TMA) and when a spring exerting a higher force (SS) was applied. At 6 weeks, none of the rabbits of the spring-exposed (2 and 3) groups had any bone bridging the gap, while bone bridging was visible in animals of the 2 groups (1 and 4) lacking springs. Strikingly enough, in both spring-treated groups, the surgically created defect was still after 13 weeks incompletely bridged by bone, interposed by connective tissue, most evidently in those exposed to higher forces (SS). In contrast, a normal sagittal suture enclosed by lamellar bone was seen in both the sham and the strip groups. We conclude that exposing a surgically created calvarial bone defect to continuous mechanical forces delayed the bridging of the bone defect by at least 13 weeks, even if the force exerted by either spring was very low. In any case, when a higher force (SS group) was applied, the bone reunion was efficiently prevented. No side effects were recognized.

Distraction osteogenesis

The treatment of bone loss resulting from acute trauma has traditionally been a complex surgical problem. Numerous procedures have been devised to reconstitute bone stock, obtain fracture union, and provide a stable functional limb. Traditional internal bone transport has been used successfully for bony reconstruction for both acute and reconstructive bone loss. Potential complications are primarily related to the complexity of the external device, prolonged time in the frame, and nonunion of the docking and regenerate segments. Recent advances in fixator and pin design have reduced the complexity of these devices as well as the incidence of pin- and frame-related complications. Gradual shortening, rapid distraction using autodistractors, transporting over intramedullary devices, and using orthobiologic and adjuvant techniques to assist in the consolidation of regenerate and docking sites are now being combined to decrease the morbidity and excessive frame time required to complete these reconstructions.

Reconstruction of Mandibular Condyle by Transport Distraction Osteogenesis: Experimental Study in Rhesus Monkey

PURPOSE

This study investigated histomorphologic changes in the newly formed condyle reconstructed by transport distraction osteogenesis through a nonhuman primate model.

MATERIALS AND METHODS

Six adult rhesus monkeys were used in this study. Bilateral condyles and articular discs were extirpated, and the technique of transport distraction osteogenesis was carried out to reconstruct the condyles. X-ray and 3-dimensional (3D) computed tomography (CT) scanning films were taken at various intervals. Two monkeys were killed respectively at 4, 12, and 24 weeks after completion of distraction; the transport segments and the distracted calluses were harvested and processed for histologic examination. The original condyles removed at surgery served as normal control.

RESULTS

Open bite was seen in all animals postoperatively and diminished at the end of distraction. Bone regeneration was perfect in the distraction gap between the transport disc and the pre-existing mandible. The bony transport disc gradually remodeled to a neocondyle that was similar to the original condyle in the appearances and structures. The head of neocondyle was covered with a fibrous cap, which might play the role of an articular disc.

CONCLUSION

A neocondyle with functional shape can be created by transport distraction osteogenesis. This suggests that this technique is an alternative method for reconstruction of the mandibular condyle.

Ortho- and heterotopic bone grafts in bifocal transport osteogenesis for craniofacial reconstruction--an experimental study in sheep

Bifocal transport osteogenesis (BTO) is a promising technique for the reconstruction of extended osseous craniofacial defects. Aim of this study was to determine the potential of this technique related to various donor sites of the transport segment. In 10 adult sheep critical size defects of the calvaria were treated by gradual movement of a transport segment consisting either of autogenous regional free calvarial bone grafts (n=5) or autogenous illiac free bone grafts (n=5). Latency period was 5 days; the rate of distraction was 1mm per day and extended approximately 40 days. The consolidation period was 28 days. After harvesting, specimens were investigated by conventional radiography, CT-scans, histologically and by fluorescence. In both groups transport osteogenesis resulted in a complete closure of the critical size defect. Membranous bone formation and remodeling occurred during the entire period of distraction and consolidation. The volumes and thickness of newly formed bone at the defect site were increased significantly when calvarial bone grafts were used (P<0.05). Iliac bone grafts became progrediently smaller during distraction, while the volume of calvarial grafts remained relatively constant (P<0.05). In conclusion, transport segments consisting of calvarial and iliac bone resulted in a reliable closure of craniofacial critical size defects in adult organisms; the application of calvarial bone grafts resulted in an increased extend of bone formation.

Craniofacial reconstruction by transport distraction osteogenesis: corticotomy versus osteotomy--an experimental study

Transport osteogenesis is a modified technique of callus distraction appropriate for the reconstruction of extended osseous defects of long or flat bones. The aim of this study was to determine the regenerative potential of this technique related to the degree of mobilization of the transport segment. In 10 adult sheep, critically sized defects of the calvaria were treated by gradual movement of a transport segment consisting of calvarial bone. The transport segments were either corticotomized (n = 5) or osteotomized (n = 5). The latency period was 5 days; the rate of distraction was 1 mm/d, extended for approximately 40 days. The consolidation period was 28 days. Specimens were investigated by conventional radiography, computed tomography scans, immunofluorescence, and histological examination. In both groups, transport osteogenesis resulted in a complete closure of the defect. The volume and thickness of newly formed bone at the defect site did not differ significantly between the groups, nor did the extent of vascularization. Bone formation and remodeling occurred during the entire period of distraction and consolidation. Osteotomized transport segments became smaller during distraction, whereas the volume of corticotomized segments remained relatively constant. In conclusion, transport osteogenesis resulted in reliable closure of extended skull defects in adult organisms; corticotomy and osteotomy of the transport segment led to a similar extent of bone formation.

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.