An analysis of the stability of craniofacial fracture fixation using a mandibular model

This thesis aims to investigate the differences in mechanical properties of major miniplating systems used for non compression miniplate osteosynthesis of mandibular fractures, and to determine whether these properties influence treatment outcome. The study was conducted in three parts. Six of the major miniplate systems currently used at the Royal Adelaide Hospital were subjected to bending tests at the University of Adelaide Engineering Department to quantify the relative stiffness of each plate. A wide variation in the mechanical properties of the individual plating systems was identified. In addition the properties of the materials, their biocompatibilty and CT compatibility are discussed. In the second part of the study, patients with recent mandibular fractures were treated using internal fixation with miniplates that were the least stiff as identified earlier. These patients then had a load applied across the fracture, and cephalometric radiographs were taken to detect any deformation of the fracture. No deformation was detected a tolerable loads, suggesting that the pain response protected these patients from a bite force which would deform the malleable miniplates. In the third part of the study, a prospective sample of patients presenting with mandibular fractures was analysed. These patients were treated with a variety of the miniplating systems. The results of treatment as a whole rü/ere compared to identiff any direct benefit consequent on the miniplate selected. Whilst significant differences in stiffness existed between the plating systems and the cost of the miniplates, no significant differences in treatment outcome were identified,red between the noncompression miniplates employed. As no observable benefits have been identified by choice of miniplate, selection should be based on surgical preference, biocompatibility, CT compatibility, and unit cost. Due to the variations in materials, design, properties, CT compatibility and unit costs, it is important not to regard all miniplates as equal and interchangeable.Thesis (M.S.)--University of Adelaide, Dept. of Plastic and Reconstructive Surgery at the R.A.H. and The Australian Craniofacial Unit, 199

Fixation of Bio-Resorbable and Titanium Miniplates in Mandibular Fractures: A Comparative Study

This comparative study of mandibular fractures fixation between titanium and bioresorbable miniplates was conducted in the Department of Oral and Maxillofacial surgery, Sri Ramakrishna Dental College and Hospital, Coimbatore. This study evaluated mandibular fractures under various parameters such as Age, Sex, Etiology, Time elapsed, Anatomic site fractured, fixation of titanium and bioresorbable miniplates and its Complications, Bite force measurement after fixation. 32 patients who had sustained injuries to Mandible over a period of two years were studied. (2009-2011). In our study, mandibular trauma predominantly affected males commonly involving the second and third decades of life pointing out towards the active period of life when they tend to be more energetic and thus involve themselves in high-speed transportation related injuries, which are the leading causes of maxillofacial trauma. Causes of mandibular fractures are constantly changing with changes in life style, industrialization, transportation and legislative measures. There appears to be a shift in the trend of the cause of mandibular trauma from Traffic accidents to violence in most developed countries; on the contrary, our study indicates that Road traffic accidents related injuries to be the primary cause in the patients treated in the unit for mandibular fractures. The issue of time lapse from the moment of injury to the initialization of the treatment could be due to transportation difficulties, socioeconomic conditions and delay due to treatment of associated injuries by various specialties. Mandible, being a mobile bone and having fractures, which are usually of compound types, communicate intraorally, are prone for infections. Majority of cases (66%) referred to our unit were seen within a week following trauma and rest of the patients reported a week later. The reason was that the patients were being treated for their concomitant injuries while a few were unaware of the treatment facilities offered. The most common fracture site involved in the mandible region was the parasymphyseal region (63%) followed by the condylar region (38%) and which were commonly seen with road traffic accidents with the impact occurring at the chin region with forces that were transmitted poster superiorly. Goals in treatment of mandible fractures include restoration of normal function and achievement of normal occlusion with adequate union of fracture segments, maintaining facial symmetry, and an aesthetic balance of the face. The treatment outcome depends on many factors such as type, the location of fractures, single or comminuted fractures, as well as general and local systemic conditions. In our study all the cases were treated as open reduction with titanium and bioresorbable miniplates. Pain, paraesthesia, oedema, occlusion, mouth opening, infection, step deformity and malunion were evaluated during the 1st week, 1st month and after 6 months postoperatively. Oedema and malocclusion were seen more common during the 1st postoperative week in bioresorbable plate fixation than when compared to titanium miniplate fixation. Bite force were evaluated in parasymphysis fractures by using indigenous bite force equipment in anteriors, canines, molars (5 bite point) and no significant change in bite force was noted among bioresorbable, titanium and control group. Complication rate was reduced to 4.1 % in patients with titanium miniplates and 6.3% in those with bioresorbable miniplates during the 6 months follow up period, but the difference was not significant. This comparative study concluded that both titanium and bioresorbable miniplates has both its own advantages and disadvantages. The disadvantages of biodegradable materials include cost, breakage of screws, difficult intraoperative handling, and swelling of the plate during degradation. In case of titanium miniplate fixation there is a potential risk of removing the titanium plates at a later stage resulting in additional cost, time, and a relatively high morbidity. In some places titanium plates are removed routinely, in which case these drawbacks cannot be considered. However the question of long-term titanium toxicity should be borne in mind

Functional evaluation of the behavior of masticatory muscles in zygomaticomaxillary complex fracture

BACKGROUND: The purpose of this study is to functionally evaluate the behaviour of the masticatory muscles (Masseter and Temporalis) following Zygomaticomaxillary Complex fractures by assessing bite force, electromyography and mandibular movements. MATERIALS AND METHODS: Group I consisted of twenty patients with unilateral Zygomatico Maxillary Complex fractures who were treated surgically with one, two or three point fixations at the frontozygomatic, infra orbital or zygomatico maxillary buttress region as per clinical and radiological assessments. Group II control group included twenty normal patients. The muscle activity was functionally evaluated before and after the surgery for a period of six months. The evaluation consisted of bite force measurement, EMG analysis and measurements of mandibular movements. RESULTS: There was an increase in bite force and EMG activity throughout the evaluated post-operative period but at the end of six months, majority of the patients were still below the control levels. Maximum mouth opening increased considerably after the surgery. The number of fixation points (one, two or three point fixation) did not influence the muscle activity. CONCLUSION: The masticatory musculature, according to bite force and EMG returned to near normal levels by the third month after the surgery. The study supports the current clinical concept of minimized fixation in treating Zygomatico Maxillary Complex fractures

Finite element study of fractured mandible in human and sheep

Osteosynthesis is one of the most discussed and investigated subjects in the orthopaedic literature. Mandible fractures are reported as one of the main causes of facial injury and their impact on patient life may bring serious consequences, compromising masticatory function, speech and facial aesthetics. Current treatments for mandibular simple fractures include the use of load-sharing devices such as titanium miniplates and screws, which have the role of fixing the fracture ends and restore the facial continuity. Fixation systems ultimately aim to generate the optimum mechanical strains within the fracture region, which will promote the bone healing process. However, there is not a clear understanding of the influence of fixation stability on the biomechanics of stabilized mandibular fractures, particularly when using biomaterials different from titanium. The aim of this study is to investigate the biomechanical response of fractured mandible using traditional titanium miniplates and alternative fixation systems made of magnesium alloys. With a view on future preclinical evaluation of these new devices, both human and sheep models are investigated

Factors Influencing Fixation of Plates in Fracture Mandible: A Clinical and Biomechanical study

AIM : The symphysis and angle region are the most frequent sites for mandibular fractures. Direct application of 2.0mm conventional and locking titanium miniplates are the most commonly used intraoral open reduction and internal fixation technique today. Anatomic and biomechanical limitations continue to make this application technically challenging with a considerable complication rate. Such incongruences are analysed with respect to the complex biomechanical behaviour of the mandible. METHODOLOGY : Individual human mandible geometry, the specific bone density distribution, and the position and orientation of the masticatory muscles were evaluated by performing computed tomography scan of the cadaveric human mandible. Dimensional changes in the holes of the 2.0mm (Orthomax, Leforte and Synthes) titanium conventional and locking miniplates/screws were evaluated using RAPID-I Precision Vision Measuring System (VMS) pre and post adaptation to angle and symphysis region. The average bite forces of 15 patients who were operated for symphysis and angle fractures were measured using AXPERT electronic bite force gauge at 5 bite points viz right molars, right premolars, left molars, left premolars and anteriors. Three Dimensional Finite Element Analysis (3D FEA) was performed for symphysis and angle fracture sites with Temporomandibular Joint remaining static. Deflection, stability, mechanical stress over bone, maximal stress over miniplate, fracture gap and direction of displacement evaluated for loading conditions. RESULTS : Symphysis fracture fixation showed maximum deflection of 6.05196mm with Orthomax conventional and least of 2.50747mm with Leforte locking miniplates. Maximum stress over bone was 98.6587 Mpa with Orthomax conventional and least was with Synthes locking of about 78.476 MPa. Stress over plate was more of about 75.4011 MPa in Orthomax conventional and least of about 61.2447 MPa in Synthes locking. Fracture gap was more of about 0.86241mm in Orthomax conventional and least of about 0.01804mm with Leforte locking. Angle fracture fixation showed maximum deflection of 5.93459mm with Orthomax conventional and least of about 3.00287mm with Synthes locking plates. Maximum stress over bone was more of about 379.81 Mpa for Orthomax conventional and least of about 309.63 MPa for Synthes locking plates. Stress over plate was more of about 2114.62 MPa in Orthomax conventional and least of about 833.457 MPa in Synthes locking. Fracture gap was more of about 2.2708mm in Orthomax conventional and least of about 1.86241mm with Leforte locking. CONCLUSION : Consecutive rapid failure of the miniplates could not be prevented when the angle and symphysis region are loaded with vertical bite forces. The more stable plate is Synthes locking plate followed by Leforte locking plate for the symphysis region and angle region. The static yield limit of titanium exceeds, when geometry and dimension of the miniplates get altered, while adapted to angle and symphysis region. Hence, the dimensional changes in the holes of miniplates occurring during adaptation of the plate to the fracture site are also a factor to be considered for stability of the plate

Analysis of the Outcome of Mandible Fracture Management

Facial injury is the most common cause of disfigurement. The most frequently injured facial bone is mandible after nasal bone because it is the most mobile and prominent facial bone .The mandibular fractures outnumbers zygomatic and maxillary fractures by a ratio of 6:2:1 respectively. Fractures of mandible invariably produce malocclusion if not treated properly. Restoration of the occlusion usually indicates anatomic reduction and proper positioning of the mandible and facial bones. Various techniques that are advocated in the literature to manage mandibular fractures vary ranging from bandages and external appliances, extra oral and intraoral appliances, mono maxillary wiring, intermaxillary wiring, plates and screws. Aim of the project is to analyze the outcome of mandibular fracture fixation with eyelets, arch bars, miniplates and screws and assess the stability of the fixation, occlusion after fixation comparing the jaw dysfunction before and after treatment and post operative sequalae – such as post operative pain, bony and soft tissue infections, nonunion, nerve injury, osteomyelitis, malocclusion and malunion. This study was conducted in the Department of Plastic and Reconstructive Surgery, Coimbatore Medical college and Hospital ,Coimbatore on 67 patients who reported to the trauma ward and the department of plastic and reconstructive surgery for the treatment of fracture mandible from December 2012 to December 2014. Before starting the study, ethical clearance was obtained from the Ethical committee of the Coimbatore Medical College and Hospital, Coimbatore. Informations were collected from the clinical and surgical notes of each of the patients. The demographic variables such as age, gender, and residence were assessed. Clinical informations such as diagnosis, etiology, and anatomical distribution of mandibular fractures was assessed. INCLUSION CRITERIA : All adult patients between 25 to 55 years, patients reporting within first 7-10 days from the day of trauma, dentulous / partially dentulous patients and patients giving consent for the follow up period of 3 months post operatively were included in the study. EXCLUSION CRITERIA : Compound fractures, patients with other facial bone fractures, patients with systemic / debilitating diseases and patients with head injury were excluded. During the clinical evaluation, history of incident, swelling, laceration, malocclusion, sublingual hematoma, deformity and trismus, step deformity, tenderness, Paresthesia / dysaesthesia /anesthesia of mental nerve and TMJ examination were assessed. All patients with suspected mandible fracture were subjected to OPG (Orthopantomogram) & CT facial bones. The mandibular fractures were classified according to the site such as Ramus, Condyle, Symphysis, Body, Parasymphysis and Angle. Out of 67 patients,15 patients who had undisplaced fractures, Condylar & Subcondylar fractures were treated conservatively with arch bars, eyelets and Maxillomandibular fixation (MMF) for 4-6 weeks. Post MMF OPG was taken to assess the reduction. The remaining 52 displaced, unfavorable and Communited fractures were treated surgically. Arch bars and MMF were done preoperatively for all the cases to achieve conclusion. Extra oral approach (Risdon) was used for the angle fracture. Intra oral approach (gingivobuccal sulcal approach) was used for the Symphysis, Parasymphysis and body the fractures. Conventional non locking miniplates (2mm) and screws (2x8mm) were used. In cases where 2 miniplates were used, MMF was removed soon after the surgery. In cases where single plate was used, MMF retained for 2 wks. Arch bars maintained for 4 more wks. In fractures with combinations like Parasymphysis and Subcondyle, plating was done only for the Parasymphysis and the Subcondyle treated conservatively with MMF for 2-3 weeks. Those for whom MMF was removed they were advised to take liquid diet for 2 days and thereafter on a soft diet for 4 to 6 weeks. Those who were advised to maintain MMF, continued liquid diet for 2-3 weeks. The patients were asked to maintain oral hygiene with mouth wash. Sutures were removed on the 5th postoperative day for patients who had underwent extra oral approach. At the end of second post operative week they were started on gentle physiotherapy. Follow up was performed weekly during the first 6 weeks and thereafter monthly for 4 to 6 months. During the follow up the following parameters were recorded. 1. Resolution of facial edema, 2. Healing of surgical sites, 3. Sensory , motor disturbances, 4. Visual analog score for pain 5. Visual analog score for chewing ability, 6. Angle criteria for occlusion, 7. Mouth opening. In single fracture, the results both in the surgical and conservative groups are equal. Conservative group took longer time for improvement than surgical group, since we maintain MMF for 4-6 Weeks. In double and segmental fracture, surgical management had good outcome with double plate fixation