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Cephalometric analysis of the consolidation phase following bilateral pediatric mandibular distraction.

OBJECTIVE: The goal of the consolidation phase of mandible distraction is to maintain the improvement in maxillomandibular form and relationship while the generated tissue ossifies. During this period, external deforming forces can act on the healing generated bone. The purpose of this study was to describe the potential cephalometric changes that occur following pediatric bilateral mandibular distraction using external devices. DESIGN: Retrospective lateral superimposition cephalometric analyses. PARTICIPANTS: Thirty-five cases of pediatric mandible distraction were reviewed. Seven of these cases were included in the study after exclusion criteria were applied. These cases represented a group with severe congenital dysmorphology and a mean device activation of 26.5 mm. MAIN OUTCOME MEASURES: Changes in pogonion position, symphyseal plane rotation, mandible length, and mandible length relative to maxillary length during the 18 to 36 days of activation, the eight weeks of consolidation, and the 1-year period following removal of the distraction device were measured. RESULTS: All patients demonstrated variable changes in position of the mandible during the consolidation phase. The most common were retrusion of pogonion, a decrease in mandible length, and a clockwise rotation of the symphyseal plane. In some cases the changes that occurred during consolidation were greater than those that occurred on 1-year follow-up. CONCLUSIONS: The consolidation phase of distraction osteogenesis is a dynamic phase and should not be assumed to be static. Multicenter use of this cephalometric technique would help to identify potential risk factors associated with postactivation changes.

Cephalometry↗

Use of orthopedic finger distractor for facial asymmetry correction.

Facial asymmetry after unilateral ankylosis results due to the loss of the condylar growth center on the ankylosed side. This results in the skeletal midline deviating to the affected side, a lack of vertical growth on the same side produces a cant of the occlusal plane and mandibular retrognathism is seen as a result of the hypoplasia. The lower border of the mandibular corpus and angle on the contra lateral side is usually flattened. We report a case of facial asymmetry following unilateral ankylosis, which was treated by a combined approach with distraction osteogenesis and orthodontics. Inexpensive orthopedic finger distractors were used. The facial changes were analyzed using the Grummons facial asymmetry analysis.

Ankylosis↗

Functional outcome following bone transport reconstruction of distal tibial defects.

BACKGROUND: Little has been written about the functional outcome of patients treated with bone transport to reconstruct a distal tibial defect. The aim of this study was to investigate the functional capabilities of patients who had undergone reconstruction with distraction osteogenesis for the treatment of a distal tibial defect in one lower limb. METHODS: At least eighteen months after completion of treatment, eight patients who had no pain and were able to walk and climb stairs without difficulty performed isometric ankle plantar flexion maximum voluntary contractions while the electromyographic activity of the tibialis anterior and triceps surae muscles was simultaneously recorded. Seven of the patients also underwent gait analysis. Data for the involved limb were compared with those collected for the contralateral limb. RESULTS: During gait, stance time (p = 0.01), the plantar flexion angular displacement and peak moment developed during the second half of stance (p < 0.046), and the amount of ankle power generated (p = 0.02) were significantly decreased in the involved limb compared with the contralateral limb. Similar decreases were observed in the plantar flexion (p = 0.01) and dorsiflexion (p = 0.01) maximum voluntary contractions and the corresponding electromyographic activity (p = 0.01). CONCLUSIONS: These results suggest that adaptive changes had occurred at the level of the transported muscles, which affected both routine and maximal effort capabilities. These findings contribute to our understanding of the functional limitations of patients who have undergone bone transport with its obligatory shortening of muscle length.

Adult↗

[Current trends and problems in the measurement of limb loading parameters during transosseous osteosynthesis using external fixation devices].

The problem in question is whether it is reasonable to equip a conventional limb external fixation apparatus with means for the diagnosis of loading parameters: the forces and displacement of the opposite supporting elements of the apparatus. It is assumed that during distraction osteogenesis it is expedient to apply load to the limb by the load rate only at the initial stage of callus regeneration (the plastic or slightly elastic mechanical state) while the most effective way to do so is to act force at later stages. A number of functions derived from the modified parameters which might aid a physician to choose the optimum limb loading parameters at different stages of treatment were considered by using as example a hypothetical ring-type apparatus equipped with means for continuous measurement of current forces applied to the apparatus and current displacements of opposite ring blocks. Specifications for the measuring system of loading parameters were defined by using an Ilizarov apparatus as an example and why possible rough measurement errors may occur is revealed. The paper shows it necessary to develop methods for calculation of parasitic deformations, i.e. those of the loaded elements of the apparatus for the evaluation of the reciprocal displacement of bone fragments.

Biomechanical Phenomena↗

Comparison of two systems for tibial external fixation in rabbits.

BACKGROUND AND PURPOSE: Use of rabbits in orthopedic investigations is common. In this study, focus is on factors that influence bone healing and on distraction osteogenesis. Biomechanical characteristics of two external fixator systems (Orthofix device and Hoffmann device) for long bones were tested. METHODS: Twelve freshly dissected tibiae were obtained from six skeletally mature New Zealand White rabbits, and four-point bending stiffness in two planes (90 and 180 degrees to the fixator pins) and torsional stiffness and strength of the bone-fixator complex were evaluated by use of a material testing machine. RESULTS: In four-point bending, Orthofix device had higher stiffness and strength, compared with Hoffmann device. When the load was applied 180 degrees to the pins, both devices had higher stiffness, compared with that at 90 degrees. In torsional testing, Orthofix device had significantly higher stiffness and strength. CONCLUSIONS: Significant differences in structural properties between the two systems were evident. Loading direction and gap conditions were important factors in determining properties of the systems. Therefore, type of external fixation system and fixation technique should be considered when designing experiments, using the rabbit long bone model.

Animals↗

The use of bone grafts and substitutes in the craniomaxillofacial region.

Craniomaxillofacial defects arise from congenital abnormalities or are acquired following trauma or ablative surgery. Various bone grafting techniques have been developed for application in the facial skeleton to assist in the reconstruction of small alveolar deficiencies to more complex, extensive bony defects. Autogenous grafts from different sites vary in volume, stability and contour characteristics. The introduction of allogeneic grafts has further increased the possibilities for hard tissue replacement as have alloplastic substitutes which have been used successfully. Recent advances in bone regeneration in the maxillofacial region using distraction osteogenesis and the recent advent of cell culture techniques have introduced new therapeutic approaches that will provide the foundation for a significant shift in the approach to reconstructive surgery of the facial skeleton.

Biomedical Engineering↗

Complications following orthognathic surgery that required early surgical intervention: fifteen years' experience.

The aim of this study was to assess complications following various orthognathic surgical procedures that required early surgical intervention. This study was carried out on 821 patients who had undergone surgical treatment for correction of dentofacial deformities between 1985 and 2000. Only patients who required a second procedure to deal with immediate or early postoperative complications (i.e., those occurring within 4 weeks of surgery) were investigated in this study. Twelve patients underwent a second surgical procedure; 9 had undergone conventional osteotomy surgery, and 3 had undergone distraction osteogenesis. Three Le Fort I cases had to be further impacted and repositioned, and 4 vertical subsigmoid osteotomies had to be reexplored. The details of the complications are presented, and possible methods by which these problems could be reduced and/or prevented are discussed.

Adolescent↗

Refinement of facial reconstructive surgery by stereo-model planning.

The development of rapid prototyping has evolved from crude milled models to laser polymerized stereolithographic models of excellent accuracy. The technology was advanced further with the recent introduction of fused deposition modelling and a three-dimensional ink-jet printing technique in stereo-model fabrication. The concept of using a three-dimensional model in planning the operation has amazed maxillofacial surgeons since its first application in grafting a skull defect in 1995. It was followed by many bright ideas for applications in the field of facial reconstructive surgery. Stereo-models may assist in diagnosis of facial fractures, joint ankylosis and even impacted teeth. The surgery can be simulated prior the operation of complex craniofacial syndromes, facial asymmetry and distraction osteogenesis. The stereo-model can be used for preparation of reconstructive plate or joint prostheses. It is of enormous value for educational teaching and as a patient information tool when obtaining the consent for surgery.

Ankylosis↗

[Repair of mandibular defects by dosed distraction. Part I. Distraction of the callus for osteoplasty of the mandible by local tissues].

During the war in Afghanistan the author repaired gunshot defects in the mandible using a compression-distraction device (CDD) which he designed in cooperation with A. Kh. Shamsudinov. Osteoplasty of the mandible is based on the distraction osteogenesis phenomenon. Proceeding from this phenomenon, the author developed several variants of mandibular osteoplasty in 1982-1983, one of these variants being osteoplasty with local tissues, permitting bloodless repair of mandibular defects of up to 5 cm long. Osteoplasty with local tissues can be used not only for repair of mandibular defects of any origin, but for enlarging the mandible in congenital or acquired abnormalities as well.

Bony Callus↗

Molecular biology and its applications in orthodontics and oral and maxillofacial surgery.

Molecular biology is an exciting, rapidly expanding field, which has enabled enormously greater understanding of the biology of diseases and malfunctions in many fields. It chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interrelationship of DNA, RNA and protein synthesis and how these interactions are regulated. Since the introduction of molecular biology into modern science, numerous other fields have been enabled to go "molecular". Advanced molecular biological techniques showed us new avenue towards finding answers to the questions asked for decades. The first part of this article described the history of molecular biology. It started as a joined discipline of other areas of biology, i.e. genetics and biochemistry in the 1930s and 1940s, and enjoyed its classical period and became institutionalized in the 1950s and 1960s. Major molecular techniques manipulating proteins, DNA and RNA were introduced and their mechanisms were concisely illustrated. The current knowledge of molecular biology and their applications in orthodontic and oral and maxillofacial surgery, i.e. osteoclast differentiation and function, regulation of tooth movement, mechanotransduction/cell-signalling, bone fracture healing, oral cancer as well as craniofacial/dental anomalies and distraction osteogenesis were discussed. Although the problems of introducing molecular technologies are still substantial, it is anticipated that the future of medicine/dentistry will be "molecular": molecular prevention, molecular diagnosis and molecular therapy.

Humans↗

Treatment protocol for unilateral cleft lip and palate patients: questioned by two case reports.

BACKGROUND: The types and severity of clefts as well as palatal development and growth in children with repaired cleft lip and palate deformities can vary greatly. Independent of the technique used surgery produces scar tissue, which restricts palatal growth so that by the second decade many patients have an underdeveloped maxilla. Experience has shown that the maxillary retrognathism found in many cleft patients is not amenable to nonsurgical correction. Few long-term studies have evaluated the procedures, sequencing and timing of the treatment methods found to give the best results. This lack of reliable information means there is a serious gap in our ability to assess the value of different treatment modalities. AIMS AND METHODS: From the viewpoint of orthodontics, this article describes the treatment protocol used by the cleft lip and palate team at the University Hospitals of the KU Leuven. The present treatment protocol is illustrated and questioned by two cases. The roles of prediction of facial growth and distraction osteogenesis are discussed.

Alveoloplasty↗

Distraction osteogensis: a surgical option for restoring missing tissue in the anterior esthetic zone.

Common causes of alveolar defects include bone resorption due to loss of teeth, infection, or trauma. There is often insufficient height or width of residual bone, and ridge augmentation may be required prior to implant placement. These defects range from small alveolar deficiencies to more complex, extensive bony defects. Various techniques are available for reconstructing alveolar ridges. Without augmentation, dental implants may have to be placed in anatomically unfavorable positions or have adverse angulations. These position/angulation compromises can lead to esthetic dissatisfaction, mechanical overload, and possibly implant loss. Both bone grafting and distraction osteogenesis are predictable methods for restoring missing tissue.

Adolescent↗

The efficacy of various bone augmentation procedures for dental implants: a Cochrane systematic review of randomized controlled clinical trials.

PURPOSE: To test (a) whether and when bone augmentation procedures are necessary and (b) which is the most effective augmentation technique for specific clinical indications. Trials were divided into 3 categories: (1) major vertical or horizontal bone augmentation (or both); (2) implants placed in extraction sockets; (3) fenestrated implants. MATERIALS AND METHODS: An exhaustive search was conducted for all randomized controlled clinical trials (RCTs) comparing different techniques and materials for augmenting bone for implant treatment reporting the outcome of implant therapy at least to abutment connection. No language restriction was applied. The last electronic search was conducted on October 1, 2005. RESULTS: Thirteen RCTs of 30 potentially eligible trials reporting the outcome of 332 patients were suitable for inclusion. Six trials evaluated techniques for vertical and/or horizontal bone augmentation. Four trials evaluated techniques of bone grafting for implants placed in extraction sockets, and 3 trials evaluated techniques to treat fenestrated implants. CONCLUSIONS: Major bone grafting procedures of extremely resorbed mandibles may not be justified. Bone substitutes may replace autogenous bone for sinus lift procedures of extremely atrophic sinuses. Both guided bone regeneration procedures and distraction osteogenesis can be used to augment bone vertically, but it is unclear which is the most efficient. It is unclear whether augmentation procedures are needed at immediate single implants placed in fresh extraction sockets; however, sites treated with barrier + Bio-Oss showed a higher position of the gingival margin than sites treated with barriers alone. More bone was regenerated around fenestrated implants with nonresorbable barriers than without barriers; however, it remains unclear whether such bone is of benefit to the patient. Bone morphogenetic proteins may enhance bone formation around implants grafted with Bio-Oss, but there was no reliable evidence supporting the efficacy of other active agents, such as platelet-rich plasma, in conjunction with implant treatment.

Alveolar Ridge Augmentation↗

Deformity correction by external fixation and/or intramedullary nailing in hypophosphatemic rickets.

BACKGROUND: There are many modalities of treatment for complex lower extremity deformity in hypophosphatemic rickets. We evaluated the outcomes of deformity correction using an external fixation and/or intramedullary nailing in hypophosphatemic rickets. PATIENTS AND METHODS: 55 segmental deformities (20 femora, 35 tibiae) from 20 patients were examined retrospectively. There were 9 children and 11 adults. Distraction osteogenesis was used in 28 segments and acute deformity correction in 27. External fixation was applied in 24 segments, intramedullary nailing in 6, and external fixation and intramedullary nailing in 25. RESULTS: There were 18 major and 13 minor complications in 26 of 28 segments with distraction osteogenesis, and 13 major and 10 minor complications in 19 of 27 segments with acute correction. Recurrent deformity or refracture occurred in 10 of 21 segments with distraction osteogenesis by external fixation only, 4 of 6 with acute correction by intramedullary nailing, and 1 of 25 with distraction osteogenesis or acute correction by external fixation and intramedullary nailing. Nail-related complications occurred in 3 of 6 with intramedullary nailing and 2 of 25 with external fixation and intramedullary nailing. INTERPRETATION: External fixation and intramedullary nailing can be recommended to prevent complications during or after deformity correction in hypophosphatemic rickets.

Adolescent↗

Intracranial migration of halo fixation pins: a complication of using an extraoral distraction device.

OBJECTIVE: Distraction osteogenesis is a well-accepted technique in the treatment of patients with hypoplastic craniofacial components. Complications of distraction osteogenesis are well described in the literature. We describe a complication of using an external distraction device in a 9-year-old girl with Pfeiffer. INTERVENTION AND RESULTS: A modified Lefort III osteotomy was performed for maxillary hypoplasia with application of an external distraction halo device by a pediatric neurosurgeon. A postoperative computed tomography (CT) scan showed 0.5-cm skull penetration of the cranial pins. The pins were repositioned and the patient was followed up on a regular basis until discharge from the hospital. At 3-week follow-up, a CT scan of the head showed migration of the pins 1.5 cm intracranially. The halo was removed and repositioned at a different site. No detectable neurological sequelae from the pin penetration were noted. The patient developed cellulitis at the site of the penetration and was admitted to the hospital for a course of intravenous antibiotics. There were no other complications, and the rest of her treatment course proceeded as planned. A review of the literature on complications of halo usage as well as suggestions for their management in association with distraction osteogenesis is described.

Acrocephalosyndactylia↗

Long term results of mandibular distraction.

Mandibular distraction osteogenesis has become a popular surgical modality due to its many advantages over conventional orthognathic surgical procedures. However, in spite of the technique having been used for over 15 years, no concrete long term results are available regarding the stability of results. We discuss the various studies which have reported either in favour or against the stablility of results after distraction. We report a series of 6 cases (3 unilateral and 3 bilateral distraction) where distraction was carried out before puberty and followed them up to seven years after removal of distractors. This case series shows that results achieved by distraction osteogenesis are unstable or best unpredictable with respect to producing a permanent size increase in the mandible. The role of the distraction osteogenesis in overcoming the pterygomassetric sling is questionable. We suggest a multicenter study with adequate patient numbers treated with a similar protocol and documented after growth cessation to have meaningful conclusions on the debate of distraction osteogenesis versus orthognathic surgery.

Adolescent↗

The use of internal maxillary distraction for maxillary hypoplasia: a preliminary report.

PURPOSE: Distraction osteogenesis is a useful alternative to advance the maxilla in complicated cases of maxillary hypoplasia. The purpose of this article is to review the workup, experience, and preliminary results with the use of internal distraction osteogenesis for maxillary hypoplasia at one teaching institution. PATIENTS AND MATERIALS: Over a 5-year period, more than 300 patients with craniofacial and dentofacial defects have undergone oral and maxillofacial surgery at our center to correct their skeletal discrepancies. Of these, 10 have had maxillary distraction osteogenesis done with internal distractors. Follow-up of 6 months or more was available for 8 patients. Stereolithographic models were used to bend distractors prior to surgery in 6 patients. RESULTS: Latency prior to the start of distraction was 3 to 7 days and varied with the age of the patient. Distraction occurred at approximately 1 mm per day with an average distraction length of 8.5 mm (range, 6-10 mm). Excellent occlusal results were obtained in 5 patients. Major complications including nonunion and failure to achieve acceptable occlusal results were observed in 3 patients. Minor complications including pain and loosening of the distracter devices were observed in 2 patients, but did not appear to affect the esthetic and functional results. CONCLUSIONS: Distraction osteogenesis is a useful alternative to traditional orthognathic surgery to treat maxillary hypoplasia. Internal distractions are attractive to patients, but are more difficult to place and can cause discomfort to patients when trying to achieve an ideal primary vector of distraction. Stereolithographic models can help with placement of the device. Changes in design of distractors may help with patient discomfort.

Adolescent↗

Functional and esthetic rehabilitation after mandibular resection in a child using a tooth/implant-supported distraction device: a case report.

After resection and autogenous bone grafting in infancy and childhood, hypotrophy of the concerned jaw can often be observed. A 6-year-old male patient with osteogenic sarcoma was treated with partial resection of the mandible from the left first molar to the right first premolar. The aim was to rehabilitate the patient functionally and esthetically as he grew. At the age of 16, after the placement of 4 Brånemark System implants in the consolidated autogeneous bone graft, the patient was treated with horizontal distraction osteogenesis. A new and unconventional type of individual tooth/implant-supported distraction device was used to lengthen the mandible by 16 mm. The implants placed to support the device were later used for prosthodontic rehabilitation. Progress in bone reconstruction, plastic coverage, and implant dentistry, as well as distraction osteogenesis, have enabled the compensation of functional and esthetic impairments caused by resection, especially in infants and young children.

Child↗