Distraction Osteogenesis Group Research Articles

D157. Using Orthodontic Elastic Traction During the Active Period of Distraction Osteogenesis to Increase the Effective Vertical Extension of Hemifacial Microsomia Patients: A Multi-center Randomized Clinical Trial

PURPOSE: In this study, the aim was to assess whether using elastic traction during the active period of distraction osteogenesis could effectively increase the vertical extension. METHODS: Patients with Pruzansky-Kaban Type II mandibular deformity were recruited and randomly assigned into Elastic traction + Distraction Osteogenesis group or Distraction Osteogenesis group, respectively. During the active period, the experimental group received orthodontic elastic traction 3 days after distraction osteogenesis implantation, while the control group received no treatment. All the participants underwent computed tomography (CT) examination before surgery, at the end of the active period, 6 months and 2 years after distraction osteogenesis tractor implantation. The primary outcome was the effective vertical extension rate of the mandible from the baseline to the end of the active period after operations, and there were 7 secondary outcomes used. RESULTS: 70 patients were included. The effective vertical extension rates were 85.021% ± 7.432% and 68.811% ± 9.510% in the experimental and control groups, respectively (P = 0.001). The average distances between the lower middle incisor point to the sagittal plane at the end of the active period were 2.485 ± 1.411 mm and 3.938 ± 2.293 mm in the experimental and control groups, respectively (P = 0.026). At the end of the active period of distraction osteogenesis, the average values of the mandibular occlusal plane canting were -4.887 ± 3.126 mm and -0.177 ± 4.029 mm in the experimental and control groups, respectively (P = 0.026). CONCLUSION: Elastic traction-assisted distraction osteogenesis could improve traction efficiency and facial symmetry.

Using orthodontic elastic traction during the active period of distraction osteogenesis to increase the effective vertical extension of hemifacial microsomia patients: A multi-center randomized clinical trial

In this study, the aim was to assess whether using elastic traction during the active period of distraction osteogenesis could effectively increase the vertical extension.Patients with Pruzansky-Kaban Type II mandibular deformity were recruited and randomly assigned into Elastic traction + Distraction Osteogenesis group or Distraction Osteogenesis group, respectively. During the active period, the experimental group received orthodontic elastic traction 3 days after distraction osteogenesis implantation, while the control group received no treatment. All the participants underwent computed tomography (CT) examination before surgery, at the end of the active period, 6 months and 2 years after distraction osteogenesis tractor implantation. The primary outcome was the effective vertical extension rate of the mandible from the baseline to the end of the active period after operations, and there were 7 secondary outcomes used.70 patients were included. The effective vertical extension rates were 85.021% ± 7.432% (mean ± SD) and 68.811% ± 9.510% (mean ± SD) in the experimental and control groups, respectively (P = 0.001). The average distances between the lower middle incisor point to the sagittal plane at the end of the active period were 2.485 ± 1.411 mm and 3.938 ± 2.293 mm in the experimental and control groups, respectively (P = 0.026). At the end of the active period of distraction osteogenesis, the average values of the mandibular occlusal plane canting were −4.887 ± 3.126 mm and −0.177 ± 4.029 mm in the experimental and control groups, respectively (P = 0.026).Elastic traction-assisted distraction osteogenesis could improve traction efficiency and facial symmetry.

The Influence of the First-Stage DO Treatment of Palate Defect on Growth of Maxilla.

To study the influence of distraction osteogenesis (DO) on the maxillary growth as first-stage treatment of palatal defect. The uniform palate defect experimental animal models (21 miniature pigs) were established surgically. Then animals were randomly divided into negative control group (A, n = 6), conventional surgery group (B, n = 6), and distraction osteogenesis group (C, n = 9) respectively. The group A underwent none treatment as control group, the group B were undergoing a conventional defect repair surgery, and the group C were undergoing a distraction osteogenesis treatment. Cone beam computed tomography examination was performed monthly to analyze the growth of maxilla for 6 months. One pig of group C was randomly sacrificed at 2, 4, and 8 weeks after the completion of DO and the tissue of distraction gap was stained with hematoxylin-eosin and Masson staining. At the end of 6th months, all pigs were sacrificed and tissues of the surgical area were stained as previous described. The palate defect was repaired by the distraction osteogenesis with the successful bone formation on the distraction gap. Group A and group C kept a similar growth rate, but that of group B was relatively slow. Distraction osteogenesis is efficient and successful for closing the defect of palate and there is no significant disturbance on the subsequent growth of the maxilla.

Maxillary distraction osteogenesis versus orthognathic surgery for cleft lip and palate patients.

Cleft lip and palate is one of the most common birth defects and can cause difficulties with feeding, speech and hearing, as well as psychosocial problems. Treatment of orofacial clefts is prolonged; it typically commences after birth and lasts until the child reaches adulthood or even into adulthood. Residual deformities, functional disturbances, or both, are frequently seen in adults with a repaired cleft. Conventional orthognathic surgery, such as Le Fort I osteotomy, is often performed for the correction of maxillary hypoplasia. An alternative intervention is distraction osteogenesis, which achieves bone lengthening by gradual mechanical distraction. This review is an update of the original version that was published in 2016. To provide evidence regarding the effects and long-term results of maxillary distraction osteogenesis compared to orthognathic surgery for the treatment of hypoplastic maxilla in people with cleft lip and palate. Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 15 May 2018), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2018, Issue 4), MEDLINE Ovid (1946 to 15 May 2018), Embase Ovid (1980 to 15 May 2018), and LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; from 1982 to 15 May 2018). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We included randomised controlled trials (RCTs) comparing maxillary distraction osteogenesis to conventional Le Fort I osteotomy for the correction of cleft lip and palate maxillary hypoplasia in non-syndromic cleft patients aged 15 years or older. Two review authors assessed studies for eligibility. Two review authors independently extracted data and assessed the risk of bias in the included studies. We contacted trial authors for clarification or missing information whenever possible. All standard methodological procedures expected by Cochrane were used. We found six publications involving a total of 47 participants requiring maxillary advancement of 4 mm to 10 mm. All of them related to a single trial performed between 2002 and 2008 at the University of Hong Kong, but not all of the publications reported outcomes from all 47 participants. The study compared maxillary distraction osteogenesis with orthognathic surgery, and included participants from 13 to 45 years of age.Results and conclusions should be interpreted with caution given the fact that this was a single trial at high risk of bias, with a small sample size.The main outcomes assessed were hard and soft tissue changes, skeletal relapse, effects on speech and velopharyngeal function, psychological status, and clinical morbidities.Both interventions produced notable hard and soft tissue improvements. Nevertheless, the distraction group demonstrated a greater maxillary advancement, evaluated as the advancement of Subspinale A-point: a mean difference of 4.40 mm (95% CI 0.24 to 8.56) was recorded two years postoperatively.Horizontal relapse of the maxilla was significantly less in the distraction osteogenesis group five years after surgery. A total forward movement of A-point of 2.27 mm was noted for the distraction group, whereas a backward movement of 2.53 mm was recorded for the osteotomy group (mean difference 4.8 mm, 95% CI 0.41 to 9.19).No statistically significant differences could be detected between the groups in speech outcomes, when evaluated through resonance (hypernasality) at 17 months postoperatively (RR 0.11, 95% CI 0.01 to 1.85) and nasal emissions at 17 months postoperatively (RR 3.00, 95% CI 0.14 to 66.53), or in velopharyngeal function at the same time point (RR 1.28, 95% CI 0.65 to 2.52).Maxillary distraction initially lowered social self-esteem at least until the distractors were removed, at three months postoperatively, compared to the osteotomy group, but this improved over time and the distraction group had higher satisfaction with life in the long term (two years after surgery) (MD 2.95, 95% CI 014 to 5.76).Adverse effects, in terms of clinical morbidities, included mainly occlusal relapse and mucosal infection, with the frequency being similar between groups (3/15 participants in the distraction osteogenesis group and 3/14 participants in the osteotomy group). There was no severe harm to any participant. This review found only one small randomised controlled trial concerning the effectiveness of distraction osteogenesis compared to conventional orthognathic surgery. The available evidence is of very low quality, which indicates that further research is likely to change the estimate of the effect. Based on measured outcomes, distraction osteogenesis may produce more satisfactory results; however, further prospective research comprising assessment of a larger sample size with participants with different facial characteristics is required to confirm possible true differences between interventions.

Relationship of distraction rate with inferior alveolar nerve degeneration-regeneration shift.

Distraction osteogenesis is an important technique for the treatment of maxillofacial abnormities and defects. However, distraction osteogenesis may cause the injury of the inferior alveolar nerve. The relationship between distraction rate and nerve degeneration-regeneration shift remains poorly understood. In this study, 24 rabbits were randomly divided into four groups. To establish the rabbit mandibular distraction osteogenesis model, the mandibles of rabbits in distraction osteogenesis groups were subjected to continuous osteogenesis distraction at a rate of 1.0, 1.5 and 2.0 mm/d, respectively, by controlling rounds of screwing each day in the distractors. In the sham group, mandible osteotomy was performed without distraction. Pin-prick test with a 10 g blunt pin on the labium, histological and histomorphometric analyses with methylene blue staining, Bodian's silver staining, transmission electron microscopy and myelinated fiber density of inferior alveolar nerve cross-sections were performed to assess inferior alveolar nerve conditions. At 28 days after model establishment, in the pin-prick test, the inferior alveolar nerve showed no response in the labium to a pin pricks in the 2 mm/d group, indicating a severe dysfunction. Histological and histomorphometric analyses indicated that the inferior alveolar nerve suffered more degeneration and injuries at a high distraction rate (2 mm/d). Importantly, the nerve regeneration, indicated by newborn Schwann cells and axons, was more abundant in 1.0 and 1.5 mm/d groups than in 2.0 mm/d group. We concluded that the distraction rate was strongly associated with the inferior alveolar nerve function, and the distraction rates of 1.0 and 1.5 mm/d had regenerative effects on the inferior alveolar nerve. This study provides an experimental basis for the relationship between distraction rate and nerve degeneration-regeneration shift during distraction osteogenesis, and may facilitate reducing nerve complications during distraction osteogenesis.

Gastrostomy Placement Rates in Infants with Pierre Robin Sequence: A Comparison of Tongue-Lip Adhesion and Mandibular Distraction Osteogenesis

This study was conducted to compare the gastrostomy rates in infants with Pierre Robin sequence treated with tongue-lip adhesion or mandibular distraction osteogenesis. This was a retrospective study of symptomatic plastic and reconstructive surgery patients treated over an 8-year period. The primary predictor variable was surgical intervention (tongue-lip adhesion or distraction osteogenesis). Secondary predictor variables were categorized as demographic and clinical factors. The primary outcome was the need for gastrostomy tube placement. Secondary outcomes were complication rates, costs, and length of stay. Thirty-one tongue-lip adhesion and 30 distraction osteogenesis patients were included in the study. The groups were statistically comparable with regard to demographic and clinical factors (p > 0.18). Gastrostomy rates were higher in patients who underwent tongue-lip adhesion (48 percent) versus those who underwent distraction osteogenesis (16.7 percent; p = 0.008). In an adjusted model, subjects undergoing tongue-lip adhesion were more likely to require gastrostomy tube for nutritional support (OR, 6.5; 95 percent CI, 1.7 to 25.2; p = 0.007). There were two major complications in the tongue-lip adhesion group and none in the distraction osteogenesis group. There were three minor complications in the tongue-lip adhesion group and five in the distraction osteogenesis group. Total operating room costs were higher for distraction osteogenesis (p = 0.05), and total hospital costs and length of stay were higher for tongue-lip adhesion (p < 0.05). Among infants with symptomatic Pierre Robin sequence, treatment by distraction osteogenesis is associated with a lower risk for gastrostomy placement for nutritional support. Hospital costs are higher for tongue-lip adhesion. Therapeutic, III.

Maxillary distraction osteogenesis versus orthognathic surgery for cleft lip and palate patients.

Cleft lip and palate is one of the most common birth defects and can cause difficulties with feeding, speech and hearing, as well as psychosocial problems. Treatment of orofacial clefts is prolonged; it typically commences after birth and lasts until the child reaches adulthood or even into adulthood. Residual deformities, functional disturbances, or both, are frequently seen in adults with a repaired cleft. Conventional orthognathic surgery, such as Le Fort I osteotomy, is often performed for the correction of maxillary hypoplasia. An alternative intervention is distraction osteogenesis, which achieves bone lengthening by gradual mechanical distraction. To provide evidence regarding the effects and long-term results of maxillary distraction osteogenesis compared to orthognathic surgery for the treatment of hypoplastic maxilla in people with cleft lip and palate. We searched the following electronic databases: Cochrane Oral Health's Trials Register (to 16 February 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 1), MEDLINE Ovid (1946 to 16 February 2016), Embase Ovid (1980 to 16 February 2016), LILACS BIREME (1982 to 16 February 2016), the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) (to 16 February 2016), and the World Health Organization (WHO) International Clinical Trials Registry Platform (to 16 February 2016). There were no restrictions regarding language or date of publication in the electronic searches. We performed handsearching of six speciality journals and we checked the reference lists of all trials identified for further studies. We included randomised controlled trials (RCTs) comparing maxillary distraction osteogenesis to conventional Le Fort I osteotomy for the correction of cleft lip and palate maxillary hypoplasia in non-syndromic cleft patients aged 15 years or older. Two review authors assessed studies for eligibility. Two review authors independently extracted data and assessed the risk of bias in the included studies. We contacted trial authors for clarification or missing information whenever possible. All standard methodological procedures expected by Cochrane were used. We found six publications involving a total of 47 participants requiring maxillary advancement of 4 mm to 10 mm. All of them related to a single trial performed between 2002 and 2008 at the University of Hong Kong, but not all of the publications reported outcomes from all 47 participants. The study compared maxillary distraction osteogenesis with orthognathic surgery, and included participants from 13 to 45 years of age.Results and conclusions should be interpreted with caution given the fact that this was a single trial at high risk of bias, with a small sample size.The main outcomes assessed were hard and soft tissue changes, skeletal relapse, effects on speech and velopharyngeal function, psychological status, and clinical morbidities.Both interventions produced notable hard and soft tissue improvements. Nevertheless, the distraction group demonstrated a greater maxillary advancement, evaluated as the advancement of Subspinale A-point: a mean difference of 4.40 mm (95% CI 0.24 to 8.56) was recorded two years postoperatively.Horizontal relapse of the maxilla was significantly less in the distraction osteogenesis group five years after surgery. A total forward movement of A-point of 2.27 mm was noted for the distraction group, whereas a backward movement of 2.53 mm was recorded for the osteotomy group (mean difference 4.8 mm, 95% CI 0.41 to 9.19).No statistically significant differences could be detected between the groups in speech outcomes, when evaluated through resonance (hypernasality) at 17 months postoperatively (RR 0.11, 95% CI 0.01 to 1.85) and nasal emissions at 17 months postoperatively (RR 3.00, 95% CI 0.14 to 66.53), or in velopharyngeal function at the same time point (RR 1.28, 95% CI 0.65 to 2.52).Maxillary distraction initially lowered social self-esteem at least until the distractors were removed, at three months postoperatively, compared to the osteotomy group, but this improved over time and the distraction group had higher satisfaction with life in the long term (two years after surgery) (MD 2.95, 95% CI 014 to 5.76).Adverse effects, in terms of clinical morbidities, included mainly occlusal relapse and mucosal infection, with the frequency being similar between groups (3/15 participants in the distraction osteogenesis group and 3/14 participants in the osteotomy group). There was no severe harm to any participant. This review found only one small randomised controlled trial concerning the effectiveness of distraction osteogenesis compared to conventional orthognathic surgery. The available evidence is of very low quality, which indicates that further research is likely to change the estimate of the effect. Based on measured outcomes, distraction osteogenesis may produce more satisfactory results; however, further prospective research comprising assessment of a larger sample size with participants with different facial characteristics is required to confirm possible true differences between interventions.

Long-Term Results of Mandibular Distraction Osteogenesis with a Resorbable Device in Infants with Robin Sequence: Effects on Developing Molars and Mandibular Growth.

Mandibular distraction osteogenesis with a unidirectional resorbable device is an effective treatment option for severe upper airway obstruction in infants with Robin sequence. Long-term effects, especially with regard to tooth development and mandibular outgrowth, are not known. Robin sequence infants with a follow-up of greater than or equal to 5 years were included. Baseline characteristics were extracted from medical records. Panoramic and lateral cephalometric radiographs were analyzed and patients were recalled for physical examination. Ten infants underwent mandibular distraction osteogenesis at a mean age of 3.7 months (median, 19 months; range, 11 days to 27 months). Mean length of follow-up was 6.8 years (range, 5.0 to 7.9 years). Ten Robin sequence infants without mandibular distraction osteogenesis (mean length of follow-up, 7.4 years; range, 6.7 to 8.9 years) were the controls. Shape anomalies, positional changes, and root malformations of molars were seen significantly more often than in the control group (p = 0.007, p = 0.009, and p = 0.043, respectively). Mandibular length was shorter (p = 0.030), but mandibular ramus height was comparable (p = 0.838) with that of the non-mandibular distraction osteogenesis group. Compared with healthy controls, all Robin sequence infants had a significantly shorter mandible. Mandibular distraction osteogenesis with a resorbable system reveals overall good short- and long-term results, but the effects on developing molars and mandibular outgrowth likely necessitate secondary procedures. This factor should be considered when deciding on treatment options and counseling of parents. Therapeutic, III.

Stability after Cleft Maxillary Distraction Osteogenesis or Conventional Orthognathic Surgery.

ABSTRACTObjectivesTo compare stability of maxillary advancements in patients with cleft lip and palate following distraction osteogenesis or orthognathic surgery.Material and MethodsInclusion criteria: 1) cleft lip and palate, 2) advancement > 8 mm. Eleven patients comprised the distraction osteogenesis group (DOG). Seven patients comprised the orthognathic treatment group (CONVG). Skeletal and soft tissue points were traced on lateral cephalograms: T1 (preoperatively), T2 (after surgery), T3 (follow-up). Group differences were analyzed using Students t-test.ResultsAt T1-T2, advancement of 6.98 mm (P = 0.002) was observed in DOG. Horizontal overjet increased 11.62 mm (P = 0.001). A point-nasion-B point (ANB) angle increased 8.82° (P = 0.001). Aesthetic plane to upper lip was reduced 5.44 mm (P = 0.017) and the naso-labial angle increased 16.6° (P = 0.001). Vertical overbite (VOB) increased 2.27 mm (P = 0.021). In T2-T3, no significant changes were observed in DOG. In T1-T2, horizontal overjet increased 8.45 mm (P = 0.02). The ANB angle, 9.33° (P = 0.009) in CONVG. At T2-T3, VOB increased, 2.35 mm (P = 0.046), and the ANB angle reduced, 3.83° (P = 0.003). In T2-T3, no parameters changed in CONVG.At follow-up (T3), VOB increased in CONVG compared with DOG, (P = 0.01). Vertical position of A point differed between the groups (P = 0.04). No significant intergroup differences between soft tissue parameters occurred.ConclusionsDistraction osteogenesis resulted in a stable position of the maxilla and movement upwards in vertical plane, however in case of orthognathic treatment sagittal relapse and a continued postoperatively downward movement was registered.

Effects of Platelet-Rich Plasma and Recombinant Human Bone Morphogenetic Protein-2 on Suture Distraction Osteogenesis

Growth factors contained in platelet-rich plasma (PRP) have been reported to induce osteoblast differentiation in certain studies, while in others, osteogenesis has not been shown clinically. The aim of the present study was to verify the effect of PRP and its combination with rhBMP-2 as a controlled delivery system during sagittal suture distraction osteogenesis. Thirty-six-week male New Zealand white rabbits were randomly assigned to sagittal suture distraction osteogenesis groups treated with (1) PRP gel alone; and (2) PRP gel mixed with 10 μg rhBMP-2 (PRP/rhBMP-2), and a control group untreated. A heavy 200-g continuous mechanical force was applied for 33 days using a nickel titanium open spring to distract the suture between 2 miniscrew implants. The suture morphology was evaluated radiographically and histologically after sacrifice. The amount of suture separation in the control group and the PRP gel group were statistically greater (P < 0.05) than in the PRP/rhBMP-2 gel group. Compared to the control group, the micro-CT and histologic analysis showed that the local application of PRP gel not only stimulates the new bone formation between the suture gap but accelerates the suture wound healing during distraction without suture fusion. There was a percent of total suture height 15.3 ± 9.5% fusion in PRP/rhBMP-2 gel group and the average thickness of cranium bone in the PRP/rhBMP-2 gel group was statistically greater (P < 0.05) than in the control group and the PRP gel group. In this animal model, both PRP gel and PRP/rhBMP-2 gel are effective in improving new bone formation in suture distraction osteogenesis. PRP gel induces suture bone formation without suture fusion and accelerates the suture wound healing, while the PRP/rhBMP-2 gel group, in which the sutures fused prematurely, showed powerful bone formation ability aided by rhBMP-2. PRP can be alternatively use as a controlled release system for rhBMP-2, but caution should be used before proceeding with the application of high-dose growth factors around the growing craniofacial sutures.

Neonatal Outcomes of Pierre Robin Sequence: An Institutional Experience

The aim of this study was to characterize the outcomes of one institute's experience regarding upper airway and feeding management in Pierre Robin sequence (PRS) neonates. A retrospective review of 33 neonates was performed. Average daily weight gain for all patients and average length of stay for each group was calculated and the results were compared using Student's t test. Average daily weight gain was 16.5 g in the mandibular distraction osteogenesis (MDO) group (MDO; N = 12) and 5.6 g in the nonsurgical intervention (NSI) group (N = 18; P = .043). Average length of stay was longer in the MDO group (P = .01). In all, 67% of MDO patients were discharged with total PO (per os) feeds compared with 22% of NSI patients. Neonates with PRS who do not require surgical airway intervention are more likely to require assisted feeding, have slower weight gain, and a shorter average hospital stay compared to neonates undergoing mandibular MDO.

Trigeminal Nitric Oxide Synthase Expression Correlates with New Bone Formation During Distraction Osteogenesis

Nitric oxide synthase (NOS) has been reported to be involved with both bone healing and bone metabolism. The aim of this study was to test the null hypothesis that there is no correlation between new bone formation during mandibular distraction osteogenesis and NOS expression in the trigeminal ganglion of rats. Newly formed tissue during distraction osteogenesis and trigeminal NOS expression measured by the NADPH-diaphorase (NADPH-d) reaction were evaluated in 72 male Wistar rats by histomorphometric and histochemical methods. In animals submitted to 0.5 mm/day distraction osteogenesis, the percentage of bone tissue was higher in the basal area of the mandibles compared with the center and significantly increased through the experimental periods (P < 0.05). At the sixth postoperative week, the difference in bone formation between the continuous and acute distraction osteogenesis groups was the highest. Significant correlation between new bone formation by distraction osteogenesis and NADPH-d-reactive neurons was found, varying according to neuronal cell size (r = -0.6, P = 0.005, small cells strongly stained; r = 0.5, P = 0.018, large cells moderately stained). The results suggest that NOS may play a role in the bone healing process via neurogenic pathways, and the phenomenon seems to be neuronal cell morphotype-dependent. Further studies are now warranted to investigate the mechanistic link between the expression of trigeminal NOS and mandibular new bone formation by distraction osteogenesis.

Treatment of lower limb deformities and limb-length discrepancies with the external fixator in Ollier’s disease

BackgroundIn this study, we addressed two questions on the treatment for Ollier’s disease: (1) how much callus formation occurs when an osteotomy is performed intralesionally and (2) how is the stability of the wires and half-pins that are inserted intralesionally. MethodsFour children with Ollier’s disease underwent treatment of 12 lower limb segments using distraction osteogenesis until completion of their growth. All osteotomies were performed at the centers of the deformities, resulting in a total of seven osteotomies performed intralesionally. ResultsFull correction of the deformity and full restoration of length were achieved in all cases, but a residual limb-length discrepancy of <10 mm remained. The mean external fixation index in the intralesional distraction osteogenesis group was 39.7 days/cm versus 30.8 days/cm in the extralesional distraction osteogenesis group. Conversion from abnormal cartilage to normal regenerate bone was seen in only one segment. Although approximately two-thirds of the wires and half-pins were inserted intralesionally, in all but one case (in which an iatrogenic fracture occurred) the wires and half-pins were well stabilized throughout the external fixation period. ConclusionsAlthough deformity and limb-length discrepancies due to Ollier’s disease were successfully resolved by distraction osteogenesis, enchondroma may arise in distracted calluses when osteotomized intralesionally. However, the stability of the external fixator was sufficient to lengthen limbs and correct deformities even when wires and half-pins were inserted intralesionally.

Comparison of Treatment Outcome and Stability Between Distraction Osteogenesis and LeFort I Osteotomy in Cleft Patients With Maxillary Hypoplasia

The purpose of this study was to compare treatment outcome and relapse between maxillary advancement surgery with LeFort I osteotomy and maxillary distraction osteogenesis in patients with cleft lip and palate with maxillary hypoplasia. The sample consisted of a maxillary advancement surgery with LeFort I osteotomy group (group 1, N= 14, mean age, 21.7 years) and a maxillary distraction osteogenesis group (group 2, N = 11, mean age, 16.3 years). Lateral cephalograms were taken and traced at presurgery (T0), postsurgery (T1), and postretention (T2). Nine hard and four soft tissue cephalometric variables were measured. Differences in measurements at each stage, treatment outcome (T1-T0), and relapse (T2-T1) were compared between groups with independent t test. Because the amount of surgical movement could affect the amount of relapse, a difference in relapse between two groups was compared by analysis of covariance with the amount of surgical movement as a covariant. Although the amounts of forward movements of A point (P < 0.01), upper incisor (P < 0.001), and upper lip (P < 0.001) during T1-T0 were greater in group 2, there were no significant differences in the amounts of relapse (T2-T1) between the two groups. During T1-T0, counterclockwise rotation of the palatal plane was observed in group 2 as a result of downward movement of posterior nasal spine (PNS) at T1, whereas group 1 had clockwise rotation of palatal plane at T1 because of downward movement of anterior nasal spine (ANS). The amounts of relapse (T2-T1) in vertical movements of PNS and upper incisor were significantly different between the two groups (P < 0.05). The amount of required maxillary advancement, vector control of palatal plane, and vertical position of upper incisor would be important factors when planning a surgical treatment in patients with cleft lip and palate with midface hypoplasia.

Stem Cells and Distraction Osteogenesis: Endothelial Progenitor Cells Home to the Ischemic Generate in Activation and Consolidation

Ischemia is a limiting factor during distraction osteogenesis. The authors sought to determine the extent of ischemia in the distraction zone and whether endothelial progenitor cells home to the distraction zone and participate in local vasculogenesis. Laser Doppler imaging was used to assess the extent of blood flow in the distraction zone in gradually distracted, immediately distracted, and osteotomized rat mandibles during activation and consolidation. Animals (n = 50; 25 rats with unilateral gradual distraction and contralateral osteotomy as an internal control, and 25 rats with unilateral immediate distraction) were examined on postoperative days 4, 6, and 8 of activation, and after 1 and 2 weeks of consolidation. Endothelial progenitor cells isolated from human peripheral blood were labeled with fluorescent DiI dye, and 0.5 x 10 cells were injected intra-arterially under direct vision into each carotid artery at the start of activation in nude rats (n = 18) that then underwent the distraction protocol outlined above. Doppler flow analysis demonstrated relative ischemia during the activation period in the distraction osteogenesis group and increased blood flow in the osteotomized control group as compared with flow in a normal hemimandible [normal, 1 (standardized); distraction osteogenesis, 0.58 +/- 0.05; control, 2.58 +/- 0.21; p < 0.05 for both results]. We observed a significantly increased endothelial progenitor cell population at the generate site versus controls at midactivation and at 1 and 2 weeks of consolidation [25 +/- 1.9 versus 1 +/- 0.3 DiI-positive cells per high-power field (p < 0.05), 124 +/- 21 versus 8 +/- 4 DiI-positive cells per high-power field (p < 0.05), and 106 +/- 18 versus 9 +/- 3 DiI-positive cells per high-power field (p < 0.05), respectively]. These data suggest that the distraction zone becomes relatively ischemic during activation and that endothelial progenitor cells home to the ischemic generate site during the activation phase and remain during the consolidation phase. Selective expansion of these stem cells may be useful in overcoming ischemic limitations of distraction osteogenesis. Moreover, their homing capability may be used to effect site-specific transgene delivery to the generate.

Sustained proliferation accompanies distraction osteogenesis in the rat.

These studies were conducted to compare the local cellular proliferation patterns in the rat tibia during distraction osteogenesis with those during nondistracted fracture healing. Bone specimens from distraction osteogenesis and nondistracted fracture groups were analyzed 2, 10, and 20 days after surgery. Proliferation was determined by metabolic labeling with [3H]thymidine and by immunocytochemistry with an antibody to proliferating cell nuclear antigen. Videomicroscopy was used to count the cells staining positively within specified regions. The number of cells incorporating [3H]thymidine was positively correlated (r2 = 0.78) with the number of proliferating cell nuclear antigen positive cells on alternating serial slides. At day 2, the latter cells were largely confined to the bone marrow and periosteum in both groups, and the cell numbers per mm2 were also equivalent. At days 10 and 20, the proliferating cell nuclear antigen positive cells predominated in both the proximal and distal primary matrix front zones in the distraction osteogenesis group. In contrast, the proliferating cell nuclear antigen positive cells in the nondistracted fracture group were scattered throughout the healing area. Significantly more of these cells were in the primary matrix front zones than in any location within the nondistracted fracture-healing area. The number of these cells in the bone marrow adjacent to the surgical area declined from day 2 to day 10 in both groups. The results suggest that (a) proliferating cell nuclear antigen immunostaining is a reliable indicator of cycling cells; (b) by day 10, distraction osteogenesis is characterized by a zone-specific pattern of proliferating cells; and (c) distraction osteogenesis prolongs the stimulation of proliferation within the gap after fracture.