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Orthognathic surgery in osteogenesis imperfecta: a case report with management considerations.

Osteogenesis imperfecta is a disease of connective tissues with additional metabolic defects. It is associated with recognisable facial disproportion and sometimes warrants surgical intervention for aesthetic, functional and psychological reasons. A severe case of osteogenesis imperfecta type 3 is presented to illustrate the feasibility of bimaxillary surgery using a mandibular body step osteotomy and maxillary down grafting at the Le Fort I level. The medical, anaesthetic, surgical and specific maxillofacial implications of surgery in these patients are discussed.

Adult↗

Trifocal distraction osteogenesis for segmental mandibular defect: a technical innovation.

Distraction osteogenesis in the mandible is a promising method, not only for correction of mandibular hypoplasia such as hemifacial microsomia, but also for reconstruction of segmental bone defects in the mandible. The authors report a case in which a mandibular segmental defect, about 60 mm in length, was reconstructed by distraction osteogenesis. The patient was a 45-year-old man who had been treated for an oral floor cancer. After preoperative chemotherapy and irradiation therapy, the mandible had been resected from the second incisor on the right side to the first molar on the left side, and had been reconstructed with a titanium plate and a vascularized rectus-abdominis compound flap. However, an infection developed around the titanium plate and this plate had to be removed. Therefore, trifocal distraction using an original three-dimensional distractor was performed, at the rate of 1 mm per day (0.5 mm in the morning and 0.5 mm in the evening). During the distraction period, the skin flap was pushed out from the bone defect. Although small free bone transplants were needed for complete continuity, the segmental bone defect was almost filled by the regenerated bone with the lengthened gingiva. Radiographic observation showed successful new bone formation in the lengthened area.

Bone Plates↗

Scanning electron microscopy of teeth in osteogenesis imperfecta type I.

Opalescent teeth from five patients and nonopalescent teeth from six patients with osteogenesis imperfecta type I were examined with the scanning electron microscope and their appearances compared with those of teeth from normal persons. In opalescent teeth the main findings were a reduction in the number and variation in the size of the dentinal tubules that were irregularly embedded within the disturbed dentinal matrix and an abnormally smooth enamel-dentinal junction. Similar less marked dentinal abnormalities were found in the nonopalescent teeth from three patients. No abnormality was found in the enamel in any of the teeth examined. These findings suggest that in osteogenesis imperfecta teeth that appear normal may have defective dentine. This relevant to the current clinical classification of the disorder into subgroups according to the clinical presence or absence of affected teeth.

Adult↗

Osteogenesis imperfecta: lifelong management is imperative and feasible.

Osteogenesis imperfecta is a group of inherited diseases responsible for varying degrees of skeletal fragility. Minimal trauma is sufficient to cause fractures and bone deformities. The classification of osteogenesis imperfecta has recently been improved by the inclusion of additional clinical and histomorphometric data. The diagnosis is often readily made in infancy; some cases, however, go unrecognized until adulthood. Lifelong multidisciplinary management is imperative. Pamidronate therapy in childhood is the most extensively studied treatment and has been proved beneficial. Other bisphosphonates are being evaluated, particularly in adults. Prevention of vitamin D and calcium deficiency is essential throughout life. Pain is common and should be given adequate attention.

Adult↗

Effect of cyclical intravenous pamidronate therapy in children with osteogenesis imperfecta. Open-label study in seven patients.

OBJECTIVES: To evaluate the efficacy of pamidronate in protecting against fractures, increasing bone mineral density (BMD), and decreasing bone remodeling marker levels in children with osteogenesis imperFecta. PATIENTS AND METHODS: Seven children (two girls and five boys; mean age, 8.5 years) were given cyclical intravenous pamidronate (Aredia) for 1 to 7 years, with a mean cycle duration of 6 months and a mean dose of 1.86 mg/kg/cycle. Four patients had type III and three type IV disease according to the Sillence classification scheme. RESULTS: A trend toward a decrease in the fracture rate as compared to the pretreatment period was found, but the difference was not significant in this small sample (P = 0.09). Lumbar spine BMD showed a significant annual increase (+26.7%, P = 0.03) far greater than the expected mean annual increase related to growth. No significant decreases in bone remodeling markers were noted. CONCLUSION: Pamidronate seems useful in the treatment of osteogenesis imperfecta in children, since it increases BMD and reduces the fracture rate, in keeping with the findings from the larger series studied by Glorieux. Pamidronate is a symptomatic, noncurative treatment that does not correct the genetic abnormalities responsible for the histological bone alterations.

Adolescent↗

New uses of bisphosphonates: osteogenesis imperfecta.

Osteogenesis imperfecta is a heterogeneous group of inherited disorders chiefly affecting type I collagen, resulting in bone fragility responsible for a host of recurrent fractures. Limb and spine deformities, growth failure and restricted mobility are the end-result in severe cases. Cyclical intermittent intravenous infusions of pamidronate, a potent inhibitor of bone resorption, have yielded substantial improvement in chronic pain, bone mineral density, fracture rate and mobility without significant side effects. The role of growth hormone and bone marrow transplantation in the treatment of osteogenesis imperfecta is still unresolved. Newer, theoretically more potent bisphosphonates are currently being tested in this potentially crippling condition.

Bone Density↗

Effects of locally applied transforming growth factor-beta1 on distraction osteogenesis in a rabbit limb-lengthening model.

In this study we tested the effect of locally applied transforming growth factor-beta1 (TGF-beta1) on distraction osteogenesis in rabbits. A total of 61 rabbits were studied. Seven days after tibial osteotomy, distraction was started at a rate of 0.25 mm/12 h for 3 weeks. Starting with distraction, TGF-beta1 was applied in four different dosages (0, 10, 20, and 40 ng/day) at the site of osteotomy through a catheter connected to a subcutaneously implanted miniosmotic pump. Rabbits were killed at the end of the distraction period or 3 weeks later, and histological, densitometric, and biomechanical parameters were assessed. TGF-beta1 treatment had no detectable effect on bone mineral density or histologically determined bone volume in the distraction gap but it increased the amount of fibrous tissue in the callus region. Load to failure in uniaxial tension tended to be lower in TGF-beta1-treated animals. In conclusion, TGF-beta1 treatment during distraction osteogenesis did not have a beneficial effect in this model.

Absorptiometry, Photon↗

Recombinant species-specific growth hormone increases hard callus formation in distraction osteogenesis.

The effect of growth hormone (GH) on secondary fracture healing and callus formation has been demonstrated in several previously investigated animal models. The aim of this study was to investigate and quantify the effects of GH on bone regenerates in a distraction osteogenesis model. In 20 mature female Yucatan micropigs, the tibia and fibula were osteotomized, stabilized with an external fixator, and distracted at 2 mm/day for 10 days after a 4 day latency period. The regenerates were allowed to consolidate for 10 days. Micropigs in the study group (ten animals) received a daily injection of 100 microg per kilogram body weight of recombinant porcine growth hormone (r-pGH). Micropigs in the control group (ten animals) received sodium chloride as placebo. After killing on day 25, a quantitative histomorphometrical analysis of the formed callus and the adjacent cortical bone was performed and the results of polychrome in vivo labeling were assessed. The regenerates of the r-pGH-treated animals showed a significantly larger callus area but no change in callus structure. We found islands of cartilage tissue in the regenerates of both groups; the calli from the control group exhibited a higher fraction of cartilage compared with the r-pGH group, but this was not significant. Quantification of the fluorescent in vivo labeling revealed that the distraction gap in GH-treated group showed significant ossification even during distraction. These results demonstrate that growth hormone can accelerate the maturation of the regenerate in distraction osteogenesis without changing the callus microstructure. This may prove to be a useful clinical tool for shortening the healing time in limb lengthening and bone segment transport.

Animals↗

Osteogenesis imperfecta type VII maps to the short arm of chromosome 3.

We have identified a novel form of autosomal recessive osteogenesis imperfecta (OI) in a small First Nations community from northern Quebec. Mutation screening of the COL1A1/COL1A2 genes revealed no detectable mutations, and type I collagen protein analyses were also normal. By linkage analysis, we mapped this unique autosomal recessive variant of osteogenesis imperfecta to chromosome 3p22-24.1. Based on the assumption of a founder effect, genome-wide screening was performed on a DNA sample pooled from seven affected individuals. Familial as well as historical recombinations identified within an extended haplotype of 19 markers localized the disease between markers D3S2324 and D3S1561, separated by <5 cM. Based on chromosomal localization to 3p22-24.1, the transforming growth factor-beta receptor 2 gene and the parathyroid hormone/parathyroid hormone-related peptide receptor were tested, but were excluded as being associated with the phenotype. This study excludes type I collagen mutations in the pathogenesis of the disease and assigns this form of OI to a locus other than the ones containing the type I collagen genes.

Chromosome Mapping↗

Immunohistochemical localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias in rats.

Type I collagen, fibronectin and tenascin C play an important role in regulating early osteoblast differentiation, but the temporal and spatial relationship of their localization during embryonic osteogenesis in vivo is notknown. The present study was designed to localize these three molecules in the dentary of mandibles and tibias in rat embryos using immunohistochemistry. Serial paraffin sections were cut and adjacent sections were processed for von Kossa staining or immunohistochemistry for type I collagen, fibronectin and tenascin C. In the dentary, tenascin C was localized within and around the mesenchymal cell condensation in embryos at 14 days in utero. The bone matrix at 15 days showed immunoreactivity for both type I collagen and fibronectin. The immunoreactivity of type I collagen was persistent, whereas that of fibronectin decreased with age of embryos. In tibias, tenascin C was localized in the perichondral mesenchymal tissue at 17 days. Immunoreactivity for type I collagen was persistent in the bone matrix, whereas the tibial bone showed little immunoreactivity for fibronectin at any embryonic age examined. The present study demonstrated characteristic localization of type I collagen, fibronectin and tenascin C during embryonic osteogenesis in the dentary of mandibles and tibias.

Animals↗

Retrovirally transduced bone marrow stromal cells isolated from a mouse model of human osteogenesis imperfecta (oim) persist in bone and retain the ability to form cartilage and bone after extended passaging.

Bone marrow stromal cells isolated from a model of osteogenesis imperfecta (oim) mice, were transduced with a retrovirus (BAG) carrying the LacZ and neor genes after passage 21. The transduced cells retained the ability to express alkaline phosphatase activity in vitro when treated with recombinant human bone morphogenetic protein two (rhBMP-2), formed cartilage in vitro in aggregate cultures and formed bone in ceramic cubes after 6 weeks of implantation in nude mice. X-gal staining of ceramic cubes seeded with the transduced cells demonstrated the presence of LacZ-positive cells on the edges of bone and also in the lacunae of the newly formed bone 6 weeks after implantation. After infusion into femurs of oim mice, the transduced cells were detected in the marrow cavity and on the edges of the trabecular bone of the injected and contralateral femurs by X-gal staining and PCR analysis at 4, 10, 20, 30 and 40 days after injection. The LacZ gene was also detected in the lung and liver of the recipient mice at 4 and 10 days after injection but not at later time-periods. The present findings suggest that long-term cultured bone marrow stromal cells from osteogenesis imperfecta (OI) animals have the potential to traffic through the circulatory system, home to bone, form bone and continue to express exogenous genes. These findings open the possibility of using these cells as vehicles to deliver normal genes to bone as an alternative approach for the treatment of some forms of OI and certain other bone acquired and genetic diseases.

Alkaline Phosphatase↗

Premaxillary distraction osteogenesis with an individual tooth-borne appliance.

Distraction osteogenesis defines a technique of bone generation and osteosynthesis by the distraction of native preexisting bone. The technique offers a promising treatment alternative for patients with maxillary hypoplasia and a retrognathic mandible. In this case report, the steps in the treatment of an 18.2-year-old girl with premaxillary hypoplasia and anterior crossbite are described. The patient was treated with a distraction osteogenesis technique, and premaxillary advancement was performed using an individual tooth-borne distraction device. The surgical operation consisted of a classical segmental maxillary osteotomy carefully respecting the palatal periosteum. The distractor was cemented in the mouth after the surgical procedures. The patient was observed during a seven-day latency period, after which the device was activated 0.5 mm every 12 hours. The anterior crossbite was eliminated in one week, and the treatment was finished with fixed orthodontic appliances.

Adolescent↗

Mandibular distraction osteogenesis and maxillary osteotomy in a class II division 1 patient with chronic juvenile arthritis.

A patient with juvenile chronic arthritis presented with a malocclusion characterized by mandibular hypoplasia, symphysial deficiency, and an increased mandibular occlusal plane angle. Correction of the mandibular defect required both the horizontal advancement of the mandible and a counterclockwise rotation of the proximal segment to reduce the mandibular occlusal plane angle. This was achieved by a combination of distraction osteogenesis to horizontally advance the mandible (14 mm), followed by manipulation of the postdistraction regenerate to reduce the mandibular occlusal plane and increase the symphysial projection. The counterclockwise rotation of the mandibular body resulted in the creation of a posterior open bite. After a three-month period to allow consolidation of the mandibular distraction osteogenesis, secondary maxillary surgery at the Le Fort 1 level was performed to reestablish maxillary occlusal contact at the new mandibular occlusal plane. A genioplasty was also performed to improve chin projection.

Adolescent↗

An unusual manifestation of bleeding diathesis in a patient with osteogenesis imperfecta.

We present the anaesthetic and surgical management, and post-operative course of a patient with osteogenesis imperfecta which exemplifies the problems associated with this condition. The observed petechial haemorrhagic rash is not characteristic of the bleeding tendency in osteogenesis imperfecta nor characteristic of acute disseminated intravascular coagulation. Despite potential life-threatening complications the patient made a good recovery and was discharged 3 weeks after surgery.

Adult↗

Type I and type III procollagen propeptides in amniotic fluid of normal pregnancies and in a case of mild osteogenesis imperfecta.

BACKGROUND: The propeptides derived from type I and III procollagens, PICP, PINP and PIIINP, indicate the synthesis of the corresponding collagens. Their circulating concentrations reflect the growth velocity in infants and children METHODS: We measured these propeptides in 145 samples of amniotic fluid of normal pregnancy. In addition, we have analysed an amniotic fluid and serum sample from a mother with osteogenesis imperfecta, and later the infant's serum sample was also collected for procollagen propeptide analysis. RESULTS: High concentrations of propeptides, 100-1000 times higher than those in adult serum, were found in early second trimester, decreasing significantly towards term, reflecting the decreased foetal growth rate. Interestingly, the amino-terminal propeptide of type I procollagen, PINP, decreased more that the corresponding carboxy-terminal propeptide, PICP, although both are in principle derived from the same protein. At both stages of pregnancy, the discrepant ratio of PICP to PINP indicated a molar excess of PINP. Abnormally low concentrations of PICP and PINP with normal PIIINP concentrations measured in amniotic fluid and in the serum indicated decreased synthesis of type I procollagen in a foetus/infant with mild osteogenesis imperfecta. CONCLUSIONS: Our data show a decrease in collagen synthesis with the stage of pregnancy and lower values of type I procollagen propeptides in a case of OI.

Adult↗

Laryngomalacia causing sleep apnea in an osteogenesis imperfecta patient.

Obstructive sleep apnea is rarely caused by laryngomalacia in adult patients. To our knowledge, laryngomalacia secondary to osteogenesis imperfecta inducing obstructive sleep apnea has not been reported. We present an adult osteogenesis imperfecta patient with obstructive sleep apnea. Oral examination demonstrated an extremely long epiglottis in the oral cavity. Fiberoptic nasopharyngoscopy revealed that the epiglottis and redundant mucosa of the arytenoids were drawn into the laryngeal inlet during inspiration. Supraglottoplasty with intraoral and laryngoscopic approach was carried out and resulted in marked decreases in snoring, sleep apnea, and daytime sleepiness. In this report, we describe a unique laryngeal manifestation inducing obstructive sleep apnea in an adult with brittle bone disease. The anomaly of laryngeal structure can be corrected by surgical intervention with good response in the sleep-disordered breathing.

Adult↗

Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.

PURPOSE: Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation. MATERIALS AND METHODS: Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA). RESULTS: Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%). CONCLUSIONS: The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.

Animals↗

Distraction osteogenesis after membranous bone onlay grafting in a dog model.

PURPOSE: The purpose of this experiment was to study the possibility of distraction osteogenesis in a membranous bone onlay graft to the mandible and to clarify the histology of the bone repair. MATERIALS AND METHODS: Four dogs, 5 months of age at the beginning of the experiment, were used for this study. The zygomatic arch was exposed in the subperiosteal plane, and a 3-cm long, full-thickness portion of the arch was harvested. The lateral surface of the mandibular body was exposed in the subperiosteal plane, and the bone was fixed to the lateral surface as a membranous onlay graft using screws. A vertical osteotomy through the graft and underlying mandibular body was done postoperatively at week 1 in dog 1, week 2 in dog 2, week 3 in dog 3, and week 4 in dog 4. An external distraction device was applied to the mandibular body, and distraction was started 7 days after the operation at a rate of 1 mm/d for 10 days. After completion of distraction, the device was left in place for 6 weeks to allow for bony consolidation. Radiographs were carried out at 2, 4, and 6 weeks postdistraction. All dogs were killed 6 weeks after distraction. RESULTS: New bone between the native underlying mandibular segments was generated in the distraction zone in all dogs. New bone was not generated between the segments of the membranous bone onlay graft in dog 1, but was generated in dog 2, dog 3, and dog 4. However, in dogs 2 and 3, the new bone between the segments was less firm, with more fibrous tissue, than the bone between the native underlying mandibular segments. Histologically, the distraction gap between the segments of the membranous bone onlay graft in dogs 2 and 3 was composed of considerable fibrous tissue in the central zone and activated osteoblastic cells forming new bone in the margins. In dog 4, there was much more osteoblastic activity in the distraction gap, and the new bone had the appearance of almost normal cortical bone. CONCLUSION: These findings show that distraction osteogenesis is possible in a membranous bone onlay graft and suggest that the distraction should be performed at least 4 weeks after the onlay grafting.

Animals↗