Choice of internal rigid fixation materials in the treatment of facial fractures

Titanium versus plasma electrolytic oxidation surface-modified magnesium miniplates in a forehead secondary fracture healing model in sheep

Magnesium as a biodegradable material offers promising results in recent studies of different maxillo-facial fracture models. To overcome adverse effects caused by the fast corrosion of pure magnesium in fluid surroundings, various alloys, and surface modifications are tested in animal models. In specified cases, magnesium screws already appeared for clinical use in maxillofacial surgery. The present study aims to compare the bone healing outcome in a non-load-bearing fracture scenario of the forehead in sheep when fixed with standard-sized WE43 magnesium fixation plates and screws with plasma electrolytic oxidation (PEO) surface modification in contrast to titanium osteosynthesis. Surgery was performed on 24 merino mix sheep. The plates and screws were explanted en-bloc with the surrounding tissue after four and twelve weeks. The outcome of bone healing was investigated with micro-computed tomography, histological, immunohistological, and fluorescence analysis. There was no significant difference between groups concerning the bone volume, bone volume/ total volume, and newly formed bone in volumetric and histological analysis at both times of investigation. The fluorescence analysis revealed a significantly lower signal in the magnesium group after one week, although there was no difference in the number of osteoclasts per mm2. The magnesium group had significantly fewer vessels per mm2 in the healing tissue. In conclusion, the non-inferiority of WE43-based magnesium implants with PEO surface modification was verified concerning fracture healing under non-load-bearing conditions in a defect model. STATEMENT OF SIGNIFICANCE: Titanium implants, the current gold standard of fracture fixation, can lead to adverse effects linked to the implant material and often require surgical removal. Therefore, degradable metals like the magnesium alloy WE43 with plasma electrolytic oxidation (PEO) surface modification gained interest. Yet, miniplates of this alloy with PEO surface modification have not been examined in a fracture defect model of the facial skeleton in a large animal model. This study shows, for the first time, the non-inferiority of magnesium miniplates compared to titanium miniplates. In radiological and histological analysis, bone healing was undisturbed. Magnesium miniplates can reduce the number of interventions for implant removal, thus reducing the risk for the patient and minimizing the costs.

Management of mandibular angle and body fractures using miniplates and 3D plates

Mandibular angle fractures have the greatest recorded rate of postoperative complications of any mandibular location and hence they present an especially difficult task for surgeons. Therefore, it is of interest to compare the conventional miniplates and three dimensional (3D) plates in management of mandibular angle fracture and body fractures.60 patients with isolated non-comminuted mandibular angle fractures and body fractures were randomly assigned into two groups by lottery. Utilizing Champy's osteosynthesis standards, group one (n = 30) received treatment with 2-mm standard miniplate and group two (n = 30) had treatment with open reduction and internal fixation utilizing 2-mm 3D locking stainless steel plates. The mean operative time was greater in conventional miniplate category as compared to three dimensional plates. Need for postoperative occlusion correction was lesser n 3 dimensional plate category. The incidence of postoperative infection was comparable in both categories. Incidental tooth damage was lesser in three-dimensional plate's category three-dimensional locking plates are an alternate strategy that has a comparable result profile to miniplates.

BoneTape: A novel osteosynthetic device for the stabilization of zygomatic fractures

BACKGROUND

The study aims to assess the safety and effectiveness of BoneTape™, a new resorbable bone fixation device, using a zygomatic fracture model in rabbits.

METHODS

The study followed BoneTape™ samples and control (sham) groups over 2-, 6-, and 12-week periods post-zygomaticomaxillary (ZM) osteotomy and zygomaticofrontal (ZF) disarticulation. The osteotomized segments were analyzed for bone healing, inflammatory response, and tissue healing. µCT imaging and histological analysis were used to examine the axial alignment, offset, and quality of new bone formation.

RESULTS

BoneTape™ samples demonstrated enhanced maintenance of the initial intraoperative positioning, reduced axial offset, and better alignment when compared with the control group, enabling stable bone healing under physiological loading conditions. Complete union was observed at 12-weeks in both groups. The BoneTape™ group experienced minimal immune and tissue reactions, classically associated with wound healing, and showed an increased number of giant cells at 6 and 12-weeks.

CONCLUSION

BoneTape™ represents a promising advancement in osteosynthesis, demonstrating efficacy in maintaining stable zygomatic reconstruction and eliciting minimal immune response in a rabbit model. This study introduces BoneTape™ as a disruptive solution specifically designed for clinical application in cranio-maxillofacial fracture fixation, with the potential to eliminate the use of over-engineered solutions while offering benefits such as ease of application and fewer biologically disruptive steps.

Engineering innovations in medicine and biology: Revolutionizing patient care through mechanical solutions

The overlap between mechanical engineering and medicine is expanding more and more over the years. Engineers are now using their expertise to design and create functional biomaterials and are continually collaborating with physicians to improve patient health. In this review, we explore the state of scientific knowledge in the areas of biomaterials, biomechanics, nanomechanics, and computational fluid dynamics (CFD) in relation to the pharmaceutical and medical industry. Focusing on current research and breakthroughs, we provide an overview of how these fields are being used to create new technologies for medical treatments of human patients. Barriers and constraints in these fields, as well as ways to overcome them, are also described in this review. Finally, the potential for future advances in biomaterials to fundamentally change the current approach to medicine and biology is also discussed.

Rigid Fixation of the Pediatric Facial Skeleton

Pediatric facial fractures are uncommon, and fortunately, the majority can be managed with conservative measures. Rigid fixation of the pediatric facial skeleton can potentially be associated with delayed hardware issues and growth inhibition. When appropriate, resorbable fixation is most commonly used for this purpose. Titanium plates and screws are advantageous when rigid fixation is a priority because properly placed hardware that respects natural suture lines is not thought to significantly inhibit growth. Furthermore, titanium fixation may be removed following healing.

Cost Burden of Rigid Internal Fixation in Craniomaxillofacial Trauma Care in Low- and Middle-Income Countries

Fractures of the craniomaxillofacial (CMF) skeleton cause significant morbidity and mortality in low- and middle-income countries (LMICs). Despite this, quality CMF trauma care is lacking for the majority of the world's population. There is a paucity of literature describing the costs of standard-of-care open reduction internal fixation (ORIF) for CMF fractures in LMICs. We consider the cost of a six-hole plate with six screws (SHPS), standard materials used in ORIF for CMF fractures, as a percentage of gross domestic product (GDP) per capita to ascertain the cost burden to patients. Hospital pricing catalog data at 14 LMIC institutions were queried. On average, the SHPS cost represented 10.2% of the GDP per capita in sampled LMICs. We highlight manufacturing costs, import taxes, and lack of subsidized health care as factors contributing to the significant cost burden of ORIF in these areas. Future work should characterize additional financial and socioeconomic barriers to optimal CMF care.

Synthesis of Novel Antimicrobial CHX-CaCl2 Coatings on Maxillofacial Fixatures for Infection Prevention

Maxillofacial surgery placement of fixatures (Leonard Buttons, LB) at close proximity to surgical incisions provides a potential reservoir as a secondary local factor to advanced periodontal disease, with bacterial formation around failed fixatures implicating plaque. To address infection rates, we aimed to surface coat LB and Titanium (Ti) discs using a novel form of chlorhexidine (CHX), CHX-CaCl₂ and 0.2% CHX digluconate mouthwash as a comparison. CHX-CaCl₂ coated, double-coated and mouthwash coated LB and Ti discs were transferred to 1 mL artificial saliva (AS) at specified time points, and UV-Visible spectroscopy (254 nm) was used to measure CHX release. The zone of inhibition (ZOI) was measured using collected aliquots against bacterial strains. Specimens were characterized using Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). SEM displayed copious dendritic crystals on LB/ Ti disc surfaces. Drug release from double-coated CHX-CaCl₂ was 14 days (Ti discs) and 6 days (LB) above MIC, compared to the comparison group (20 min). The ZOI for the CHX-CaCl₂ coated groups was significantly different within groups (p < 0.05). CHX-CaCl₂ surface crystallization is a new drug technology for controlled and sustained CHX release; its antibacterial effectiveness makes this drug an ideal adjunct following clinical and surgical procedures to maintain oral hygiene and prevent surgical site infections.

Biomechanical Comparison of WE43-Based Magnesium vs. Titanium Miniplates in a Mandible Fracture Model in Sheep

In fractures of the mandible, osteosynthesis with titanium plates is considered the gold standard. Titanium is an established and reliable material, its main disadvantages being metal artefacts and the need for removal in case of osteosynthesis complications. Magnesium, as a resorbable material with an elastic modulus close to cortical bone, offers a resorbable alternative osteosynthesis material, yet mechanical studies in mandible fracture fixation are still missing. The hypothesis of this study was that magnesium miniplates show no significant difference in the mechanical integrity provided for fracture fixation in mandible fractures under load-sharing indications. In a non-inferiority test, a continuous load was applied to a sheep mandible fracture model with osteosynthesis using either titanium miniplates of 1.0 mm thickness (Ti1.0), magnesium plates of 1.75 mm (Mg1.75), or magnesium plates of 1.5 mm thickness (Mg1.5). No significant difference (p > 0.05) was found in the peak force at failure, stiffness, or force at vertical displacement of 1.0 mm between Mg1.75, Mg1.5, and Ti1.0. This study shows the non-inferiority of WE43 magnesium miniplates compared to the clinical gold standard titanium miniplates.

Quantifying Aerosol Generation in Maxillofacial Trauma Repair Techniques

Study Design

Cadaveric simulation study.

Objective

The novel coronavirus (COVID-19), which can be transmitted via aerosolized viral particles, has directed focus on protection of healthcare workers during procedures involving the upper aerodigestive tract, including maxillofacial trauma repair. This study evaluates particle generation at different distances from open reduction and internal fixation (ORIF) of maxillofacial injuries in the intraoperative setting to reduce the risk of contracting airborne diseases such as COVID-19.

Methods

Two cadaveric specimens in a simulated operating room underwent ORIF of midface and mandible fractures via intraoral incisions as well as maxillomandibular fixation (MMF) using hybrid arch bars. ORIF was performed with both self-drilling screws and with the use of a power drill for creating guide holes. Real-time aerosol concentration was measured throughout each procedure using 3 particle counters placed 0.45, 1.68, and 3.81 m (1.5, 5.5, and 12.5 feet, respectively) from the operative site.

Results

There was a significant decrease in particle concentration in all procedures at 1.68 m compared to 0.45 m, but only 2 of the 5 procedures showed further significant decrease in particle concentration when going from 1.68 to 3.81 m from the operative site. There was significantly less particle concentration generated at all distances when using self-drilling techniques compared to power drilling for ORIF.

Conclusions

Consideration of using self-drilling screwing techniques as well as maintaining physical distancing protocols may decrease risk of transmission of airborne diseases such as COVID-19 while in the intraoperative setting.

A Narrative Review of u-HA/PLLA, a Bioactive Resorbable Reconstruction Material: Applications in Oral and Maxillofacial Surgery

The advent of bioresorbable materials to overcome limitations and replace traditional bone-reconstruction titanium-plate systems for bone fixation, thus achieving greater efficiency and safety in medical and dental applications, has ushered in a new era in biomaterial development. Because of its bioactive osteoconductive ability and biocompatibility, the forged composite of uncalcined/unsintered hydroxyapatite and poly L-lactic acid (u-HA/PLLA) has attracted considerable interest from researchers in bone tissue engineering, as well as from clinicians, particularly for applications in maxillofacial reconstructive surgery. Thus, various in vitro studies, in vivo studies, and clinical trials have been conducted to investigate the feasibility and weaknesses of this biomaterial in oral and maxillofacial surgery. Various technical improvements have been proposed to optimize its advantages and limit its disadvantages. This narrative review presents an up-to-date, comprehensive review of u-HA/PLLA, a bioactive osteoconductive and bioresorbable bone-reconstruction and -fixation material, in the context of oral and maxillofacial surgery, notably maxillofacial trauma, orthognathic surgery, and maxillofacial reconstruction. It simultaneously introduces new trends in the development of bioresorbable materials that could used in this field. Various studies have shown the superiority of u-HA/PLLA, a third-generation bioresorbable biomaterial with high mechanical strength, biocompatibility, and bioactive osteoconductivity, compared to other bioresorbable materials. Future developments may focus on controlling its bioactivity and biodegradation rate and enhancing its mechanical strength.

In silico modelling of the corrosion of biodegradable magnesium-based biomaterials: modelling approaches, validation and future perspectives

Metallic biomedical implants based on magnesium, zinc and iron alloys have emerged as bioresorbable alternatives to permanent orthopaedic implants over the last two decades. The corrosion rate of biodegradable metals plays a critical role in controlling the compatibility and functionality of the device in vivo. The broader adoption of biodegradable metals in orthopaedic applications depends on developing in vitro methods that accurately predict the biodegradation behaviour in vivo. However, the physiological environment is a highly complex corrosion environment to replicate in the laboratory, making the in vitro-to-in vivo translation of results very challenging. Accordingly, the results from in vitro corrosion tests fail to provide a complete schema of the biodegradation behaviour of the metal in vivo. In silico approach based on computer simulations aim to bridge the observed differences between experiments performed in vitro and vivo. A critical review of the state-of-the-art of computational modelling techniques for predicting the corrosion behaviour of magnesium alloy as a biodegradable metal is presented.

Long-term evaluation of treatment protocols for isolated midfacial fractures in a German nation-wide craniomaxillofacial trauma center 2007-2017

An update on the trends in maxillofacial traumatology provides additional information on the actual and changing needs. This retrospective study aimed to review all patient records of patients treated for isolated midface fractures in the Department of Cranial- and Maxillofacial Surgery at the Dortmund General Hospital between 2007 and 2017. The patient radiographs and patient files were reviewed. The safety and efficacy of the applied methods were controlled by assessing complications based on the Clavien-Dindo classification system. The statistical analysis included descriptive methods including regression analysis and χ2-test. In eleven years, 3474 isolated midface fracture sites have been identified in 2868 patients. The yearly trend is slightly increasing, in elderly clearly worsening, in children and youth decreasing. The male-to-female ratio was 2.16:1 for the whole study population, in the age group 18-25 y.o. 6.95:1 while in elderly above 80 y.o. 1:2.51, the age group specific incidence reflects this result, too. The most common fractures were nasal bone fractures (1405), zygomatic fractures (832) and orbital floor fractures (700). The average hospital stay was 2.7 days, the most fractures were operated within 24 h. The complication rate was 2.02% (Clavien-Dindo class II-V). The incidence of midfacial fractures is increasing in the total population and especially in elderly, but decreasing in children. Development of injury prevention measures is needed in this population. The diagnostic and therapeutic procedures are appropriate, as there is a low complication rate and short inpatient stay observed.

Biomaterials in Craniomaxillofacial Reconstruction: Past, Present, and Future

ABSTRACT

Deformity and tissue loss involving the craniomaxillofacial region occurs frequently as a result of trauma, oncologic resection, or a congenital malformation. In order to maximize the patient's quality of life, reconstruction of the craniomaxillofacial skeleton must seek to restore aesthetics as well as function. Advances in diagnostic technology, surgical technique, instrumentation, and innovative biomaterials used have transformed the way reconstructive surgeons approach their patients' needs. From the advent of alloplastic reconstruction, surgeons have sought the ideal material for use in craniomaxillofacial surgery. Substances such as metals, ceramics, glasses, and more recently resorbable polymers and bioactive materials have all been utilized.While autologous bone has remained widely-favored and the gold standard, synthetic alternatives remain a necessity when autologous reconstruction is not readily available. Today, alloplastic material, autografting via microvascular tissue transfer, hormone and growth factor-induced bone formation, and computer-aided design and manufacturing of biocompatible implants represent only a fraction of a wide range of options used in the reconstruction of the craniomaxillofacial skeleton. We present a brief review of the materials used in the repair of deformities of the craniomaxillofacial skeleton as well as a look into the potential future direction of the field.

Comparative study of outcomes between locking plates and three-dimensional plates in mandibular fractures

Objectives

The objective was to compare the efficiency and assess postoperative complications of 2.00 mm unicortical locking plates and three-dimensional (3D) plates in surgical correction of uncomplicated mandibular fracture.

Materials and Methods

A prospective cohort study of twenty patients of uncomplicated mandibular fractures, who were operated either by noncompression unicortical 2-mm locking mini-plate or by noncompression unicortical 2-mm 3D mini-plate, were enrolled and followed up for the study outcomes such as operative time, postoperative infection, and postoperative occlusion.

Results

Majority of the patients (90%) were male who had road traffic accident. In 80% of cases, mandibular fracture site was parasymphysis. The mean operating time for 3D plates (43.20 min) was significantly lower than that for locking plates (54.82 min), P < 0.001. All cases operated by 3D plates compared to 60% by locking mini-plates did not need intermaxillary fixation, P = 0.025. The 80% of cases operated by 3D plates did not require postoperative occlusion correction compared to 30% in another group, P = 0.01. For other parameters such as postoperative sensory disturbance, postoperative infection, incidence tooth damage, vertical displacement of mandible, feeling of plate after platting, and chewing efficiency after 1 week, there were no statistical significant differences between the two groups.

Conclusions

The outcome of 2.0mm 3D mini-plate is better in terms of operating time required, post-operative need of intermaxillary fixation and occlusal correction. While the outcome is similar to the use of non-compression unicortical 2.00mm locking miniplate in parameters like infection rate and incidence of tooth damage etc.

Biomechanical evaluation of unilateral subcondylar fracture of the mandible on the varying materials: A finite element analysis

Fixation materials used in the surgical treatment of subcondylar fractures contribute to successful clinical outcomes. In this study, we simulated the mechanical properties of four fixation materials [titanium (Ti), magnesium alloy (Mg alloy), poly-L-lactic acid (PLLA), and hydroxyapatite/poly-L-lactide (HA-PLLA)] in a finite-element analysis model of subcondylar fracture. Two four-hole plates were fixed on the anterior and posterior surfaces of the subcondyle of the mandible. In the simulation model of a subcondylar fracture, we evaluated the stress distribution and mechanical deformation of fixation materials. The stress distribution conspicuously appeared on the condylar neck of the non-fractured side and the center of the anterior plate for all materials. More stress distribution to the biologic component appeared with HA-PLLA than with Ti or Mg alloy, but its effects were less prominent than that of PLLA. The largest deformation was observed with PLLA, followed by HA-PLLA, Mg alloy, and Ti. The results of the present study imply the clinical potential of the HA-PLLA fixation material for open reduction of subcondylar fractures.

Do mandibular miniplates increase the risk of complex fracture in facial trauma recurrence? Case series

Whether to conserve or remove miniplates, widely used in oral and maxillofacial surgery, has not been agreed on in the literature. Complications such as pain, infection, and screw exposure or loosening have already been largely described. We present the consequences of a trauma recurrence on a mandible with miniplates. The data of 13 patients who had a mandibular fracture previously surgically treated with miniplates (ten mandibular fractures and three mandibular osteotomies) were analysed. All the patients were male; the average age was 32 years (range, 20-64 years). The mechanism of the second trauma was assault in most of the cases. The average time between the first osteosynthesis and the new fracture was 35 months (range, 6-128 months). The fractures occurred at a distance from the miniplates in all the cases except two. No plate fracture was reported. We hypothesised that miniplates reinforced the underlying bone, protecting it from fractures, and transmitted the forces to areas anterior or posterior to the miniplates or to the condyle. Thus, the risk of mandible trauma recurrence should be taken into account in the indication of plate removal, and the biomechanical consequences of the conservation of the miniplates should be studied.

Clinical Outcomes of Intramedullary and Extramedullary Fixation in Unstable Intertrochanteric Fractures: A Randomized Clinical Trial

Background

The best method for repairing intertrochanteric fractures is still controversial. The fixation methods include extramedullary (EM) and intramedullary (IM). Studies that compare IM and EM fixations for unstable hip fractures are rare. In this study, our goal was to compare the efficacy of EM and IM fixation in treatment of unstable intertrochanteric fractures.

Methods

A total of 113 patients with unstable intertrochanteric were randomized in this cohort study between March 2016 and June 2018 in trauma center of Kashani and Alzahra Hospitals, Isfahan, Iran. The patients were followed for a period of 12 months with sequential clinical and imaging evaluations. Baseline data were recorded at the time of injury. Radiographs were evaluated immediately post-operatively and at the scheduled follow-up intervals.

Results

A total of 20 of patients were excluded during the study and finally 93 patients (43 males and 50 females) with mean age of 62.74±16.4 completed the follow-up sessions. Mann-Whitney test indicated a significant difference in tip-apex distance between the two groups. While the two groups were homogeneous in the baseline LEM score, it was not significantly different between two groups after 1 and 3 months of surgery as well. However, the LEM score was significantly higher in IM group after 6 and 12 months of surgery.

Conclusion

According to our findings, IM nails (such as the cephalomedullary nail) afforded more advantages over EM devices (such as the DHS and DCS) in the treatment of unstable intertrochanteric fractures. Our results indicated that the final LEM scores as well as the time to union were better in IM fixation group.

Ti-15Mo Alloy Decreases the Stress Concentration in Mandibular Angle Fracture Internal Fixation Hardware

Objectives

Comparison of the mechanical stability of 2.0 plates made of commercially pure titanium (cpTi) and a titanium-molybdenum (Ti-15Mo) alloy and two methods of internal fixation employed mandibular angle fractures, using 3D finite element analysis.

Materials and Methods

Four groups were evaluated. For the cpTi: group Eng 1P, one 4-hole plate and 4 screws 6 mm long, in the tension zone of the mandible; group Eng 2P, two 4-hole plates, one in the tension zone of the mandible and the other in the compression zone, both were fixed with 8 screws 6 mm long. The same groups were created for the Ti-15Mo alloy. A 100 N compressive load was applied to the occlusal surface of the mandibular first molar on the plated side.

Results

When considering the von Mises equivalent stress (σ _vM) values for the comparison between both groups with one plate, a decrease of 10.5% in the plate and a decrease of 29.0% in the screws for the Ti-15Mo group was observed. Comparing the same groups with two plates, a decrease of 28.5% in the screws was shown for the Ti-15Mo alloy group. No significant differences were observed when considering maximum and minimum principal stresses (σ _max, σ _min), and maximum principal strain (ε _max) to the mandibular bone. The Ti-15Mo alloy plates substantially decreased the stress concentration in the screws for both internal fixation techniques and in the plate for the Ti-15Mo 1 plate group.

Conclusion

From a clinical standpoint, the use of Ti-Mo alloy with reduced stiffness will decrease the stress shielding between the hardware and bone, influencing the outcome of the treatment.

Nasolacrimal Obstruction Following the Placement of Maxillofacial Hardware

Purpose

This article reviews cases of nasolacrimal obstruction (NLO) secondary to maxillofacial hardware placement.

Methods

A retrospective review was performed at a single institution from 2012 to 2017 of patients with NLO following maxillofacial reconstruction. The study was approved by the Institutional Review Board of the University of California, San Francisco, adhered to the tenets of the Declaration of Helsinki, and was Health Insurance Portability and Accountability Act compliant. Patients were included if external dacryocystorhinostomy (DCR) confirmed previously placed maxillofacial hardware as the primary contributor to lacrimal outflow obstruction and had at least 3 months of follow-up.

Results

Of 420 patients who underwent external DCR, 6 cases of implant-related NLO were identified. The mean age was 47.3 ± 9.6 years and 66.7% of patients were male. All patients presented with epiphora and 50% also had chronic dacryocystitis. Patients had prior maxillofacial hardware placement for paranasal sinus tumors (66.7%) or facial fractures (33.3%). In addition to external DCR, all patients had revision or removal of implants that were impeding lacrimal outflow by 2 mechanisms: (1) an orbital implant impinging the lacrimal sac or nasolacrimal duct (NLD) and/or (2) maxillofacial screws placed into the bony NLD or nasolacrimal fossa. Five of the 6 patients (83.3%) had complete resolution of symptoms and patency of the nasolacrimal system at their last follow-up visit (range 3-30 months).

Conclusion

NLO secondary to hardware placement, though infrequent, is underreported. Two mechanisms of hardware-induced NLO were encountered in this case series. Specific attention to nasolacrimal anatomy at the time of maxillofacial reconstruction may help minimize implant-induced NLO.

Thermomechanical and in vitro biological characterization of injection-molded PLGA craniofacial plates

PURPOSE:

To evaluate the thermomechanical and in vitro biological response of poly(lactic-co-glycolic acid) (PLGA) plates for craniofacial reconstructive surgery.

METHODS:

PLGA 85/15 craniofacial plates were produced by injection molding by testing two different temperatures (i.e., 240°C, PLGA_lowT, and 280°C, PLGA_highT). The mechanical properties of the produced plates were characterized by three-point bending tests, dynamic mechanical analysis, and residual stress. Crystallinity and thermal transitions were investigated by differential scanning calorimetry. Finally, in vitro cell interaction was evaluated by using SAOS-2 as cell model. Indirect cytotoxicity tests (ISO 10-993) were performed to prove the absence of cytotoxic release. Cells were then directly seeded on the plates and their viability, morphology, and functionality (ALP) checked up to 21 days of culture.

RESULTS:

A similar performance of PLGA_lowT and PLGA_highT plates was verified in the three-point bending test and dynamic mechanical analyses. Also, the two processing temperatures did not influence the in vitro cell interaction. Cytotoxicity and ALP activity were similar for the PLGA plates and control. Cell results demonstrated that the PLGA plates supported cell attachment and proliferation. Furthermore, energy-dispersive X-ray spectroscopy revealed the presence of sub-micron particles, which were identified as inorganic mineral deposits resulting from osteoblast activity.

CONCLUSION:

The present work demonstrated that the selected processing temperatures did not affect the material performance. PLGA plates showed good mechanical properties for application in craniofacial reconstructive surgery and adequate biological properties.

A novel soft tissue prediction methodology for orthognathic surgery based on probabilistic finite element modelling

Repositioning of the maxilla in orthognathic surgery is carried out for functional and aesthetic purposes. Pre-surgical planning tools can predict 3D facial appearance by computing the response of the soft tissue to the changes to the underlying skeleton. The clinical use of commercial prediction software remains controversial, likely due to the deterministic nature of these computational predictions. A novel probabilistic finite element model (FEM) for the prediction of postoperative facial soft tissues is proposed in this paper. A probabilistic FEM was developed and validated on a cohort of eight patients who underwent maxillary repositioning and had pre- and postoperative cone beam computed tomography (CBCT) scans taken. Firstly, a variables correlation assessed various modelling parameters. Secondly, a design of experiments (DOE) provided a range of potential outcomes based on uniformly distributed input parameters, followed by an optimisation. Lastly, the second DOE iteration provided optimised predictions with a probability range. A range of 3D predictions was obtained using the probabilistic FEM and validated using reconstructed soft tissue surfaces from the postoperative CBCT data. The predictions in the nose and upper lip areas accurately include the true postoperative position, whereas the prediction under-estimates the position of the cheeks and lower lip. A probabilistic FEM has been developed and validated for the prediction of the facial appearance following orthognathic surgery. This method shows how inaccuracies in the modelling and uncertainties in executing surgical planning influence the soft tissue prediction and it provides a range of predictions including a minimum and maximum, which may be helpful for patients in understanding the impact of surgery on the face.

Metals used in maxillofacial surgery

The goal of maxillofacial surgery is to restore the shape and functionality of maxillofacial region. In the past years, there has been a tremendous progress in this field because of significant advances in biotechnology that provided innovative biomaterials to efficiently reconstruct the maxillofacial injured region. By using appropriate selection of the implant biomaterial, it is possible to reconstruct the native tissue, both in form and function. The ideal biomaterial should mimic native tissues regarding density, strength, and modulus of elasticity. Autografts are currently the gold standard for replacement of missing tissues, but synthetic biomaterials have been widely used because they eliminate the discomfort to take the replacement tissue from the donor site. Among synthetic biomaterials, different metals may be utilized to efficiently reconstruct the maxillofacial injured region. This article makes an effort to summarize the most important metals in use in maxillofacial surgery, and point out advantages and disadvantage of each type.

Increased Osteoid Formation in BMP-2-Loaded Silk-Based Screws

BACKGROUND

Resorbable osteosynthesis systems are used to treat craniofacial fractures. However, conventional synthetic polyester materials are potentially associated with inflammatory reaction and negative host response and may result in incomplete bone remodeling. The authors have developed a resorbable silk fibroin-based osteosynthesis system and propose that silk screws loaded with bone morphogenetic protein-2 (BMP-2) may exhibit biocompatibility and promote bone remodeling.

METHODS

Resorbable silk screws were prepared and loaded with BMP-2. The BMP-2-loaded and nonloaded silk screws were inserted into the distal femora in 15 Sprague-Dawley rats by self-tapping, similar to conventional metal systems. Animals were euthanized after 1, 3, and 6 months. The femora were explanted at the designated time points, dissected for histologic evaluation, and compared regarding osteoid formation and inflammatory response.

RESULTS

Increasing organization of newly formed bone tissue was observed over time in both groups. No appreciable difference in inflammation was noted between the BMP-2-loaded and nonloaded silk screws. Notably, mineralized collagen around the periphery of the screw appears to be greatest and more organized in the BMP-2-loaded samples. There was greater recruitment of osteoclasts and osteoblasts around the perimeter of the BMP-2-loaded screws at 3 and 6 months.

CONCLUSIONS

The BMP-2-loaded silk-based fixation device in this study exhibited characteristics comparable to the current nonloaded silk screws with regard to integration and biocompatibility. However, functionalization of silk screws with BMP-2 appeared to allow for more organized collagen and osteoid deposition after 3 and 6 months and may increase the potential of successful remodeling.

CT of facial fracture fixation: an experimental study of artefact reducing methods

OBJECTIVES

This study aimed to determine the optimal post-operative CT imaging method that enables best visualization of facial bony structures in the vicinity of osteosynthesis material.

METHODS

Conducted at Töölö Hospital (Helsinki, Finland), this study relied on scanning a phantom with CBCT, 64-slice CT and high-definition multislice CT with dual-energy scan (providing monochromatic images of 70-, 100-, 120- and 140-keV energy levels) and iterative reconstruction (IR) methods. Two radiologists assessed the image quality, and the assessments were analyzed. In addition, a physicist performed a semi-quantitative analysis of the metal-induced artefacts.

RESULTS

The three subjects most easily assessed were the loose screw and both the bone structure and the fracture further away from the screw and the plate. Soft tissues adjacent to the screw and the plate remained more difficult for assessment. Both image interpreters agreed that the artefacts disturbed their assessments under dual energy. Metal artefacts disturbed the least under multislice CT with IR [adaptive statistical iterative reconstruction (ASiR) and VEO]. Neither interpreter found metal suppression helpful in CBCT.

CONCLUSIONS

CBCT with or without a metal artefact reduction algorithm was not optimal for post-operative facial imaging compared with multislice CT with IR. Multislice CT with ASiR filtering offered good image quality performance with fast image volume reconstruction, representing the current sweet spot in post-operative maxillofacial imaging.

Development of a methacrylate-terminated PLGA copolymer for potential use in craniomaxillofacial fracture plates

We synthesised methacrylate-terminated PLGA (HT-PLGA, 85:15 LA:GA, 169kDa), for potential use as an adhesively attached craniomaxillofacial fracture fixation plate. The in vitro degradation of molecular weight, pH and flexural modulus were measured over 6weeks storage in PBS at 37°C, with commercially available high (225kDa, H-PLGA) and low (116kDa, L-PLGA) molecular weight 85:15 PLGAs used as comparators. Molecular weights of the materials reduced over 6weeks, HT-PLGA by 48%, H-PLGA by 23% and L-PLGA by 81%. HT-PLGA and H-PLGA exhibited a near constant pH (7.35) and had average flexural moduli in excess of 6GPa when produced, similar to that of the mandible. After 1week storage both exhibited a significant reduction in average modulus, however, from weeks 1-6 no further significant changes were observed, the average modulus never dropped significantly below 5.5GPa. In contrast, the L-PLGA caused a pH drop to below 7.3 by week 6 and an average modulus drop to 0.6 from an initial 4.6GPa. Cell culture using rat bone marrow stromal cells, revealed all materials were cytocompatible and exhibited no osteogenic potential. We conclude that our functionalised PLGA retains mechanical properties which are suitable for use in craniofacial fixation plates.

Juvenile Swine Surgical Alveolar Cleft Model to Test Novel Autologous Stem Cell Therapies

Reconstruction of craniofacial congenital bone defects has historically relied on autologous bone grafts. Engineered bone using mesenchymal stem cells from the umbilical cord on electrospun nanomicrofiber scaffolds offers an alternative to current treatments. This preclinical study presents the development of a juvenile swine model with a surgically created maxillary cleft defect for future testing of tissue-engineered implants for bone generation. Five-week-old pigs (n=6) underwent surgically created maxillary (alveolar) defects to determine critical-sized defect and the quality of treatment outcomes with rib, iliac crest cancellous bone, and tissue-engineered scaffolds. Pigs were sacrificed at 1 month. Computed tomography scans were obtained at days 0 and 30, at the time of euthanasia. Histological evaluation was performed on newly formed bone within the surgical defect. A 1 cm surgically created defect healed with no treatment, the 2 cm defect did not heal. A subsequently created 1.7 cm defect, physiologically similar to a congenitally occurring alveolar cleft in humans, from the central incisor to the canine, similarly did not heal. Rib graft treatment did not incorporate into adjacent normal bone; cancellous bone and the tissue-engineered graft healed the critical-sized defect. This work establishes a juvenile swine alveolar cleft model with critical-sized defect approaching 1.7 cm. Both cancellous bone and tissue engineered graft generated bridging bone formation in the surgically created alveolar cleft defect.

Current management of facial fractures in the preadolescent

PURPOSE OF REVIEW

This article reviews the trends in management of preadolescent facial fractures - a challenging population because of the need to consider growth, dynamic changes in dentition, and evolving fracture patterns.

RECENT FINDINGS

Recent findings are a more thorough understanding of fracture patterns and distribution because of recent comprehensive studies isolating the preadolescent age cohort; the role of rigid internal fixation for significantly displaced fractures; and the potential applications and indications for the use of resorbable hardware for fracture fixation in the preadolescent.

SUMMARY

As preadolescent fractures occur in a period of growth and evolving dentition in the facial skeleton, it is mandatory for the treating surgeon to have a thorough knowledge of standard and alternative treatment options to optimally manage these patients.

Study of Efficacy and the Comparison Between 2.0 mm Locking Plating System and 2.0 mm Standard Plating System in Mandibular Fractures

PURPOSE

The purpose of this study was to evaluate the efficacy and comparison between 2.0 mm locking plate system and 2.0 mm Champy's titanium mini plating system in mandible fractures.

MATERIALS AND METHODS

A total of 20 patients with mandibular fractures were selected and divided into two groups A and B on randomized basis. Group A was treated with open reduction internal fixation using 2.0 mm locking plates and group B with 2.0 mm Champy's titanium miniplates. All patients were followed up for 12 weeks postoperatively.

RESULTS

Results of the study show less screw loosening, less precision in plate adaptation and less alteration of the osseous or occlusal relationship upon screw tightening in group A. Chi square test was applied to compare the results between the two groups. Statistical analysis did not show significant difference of incidence of malocclusion between the two groups (p value = 0.606). Statistical analysis using un-paired t test showed significant difference of working time between the two groups (p value = 0.00296). When comparing the overall complication rates according to plates used, the χ(2) test showed no statistically significant difference between the locking and nonlocking plates (p > 0.05).

CONCLUSION

It is observed in our study that the locking plate/screw system offers significant advantages over the conventional plating system. The precise adaptation required for using conventional plates is not needed when this locking plate/screw system is used. Locking plate/screw system provides better stability than the conventional plate/screw system.

Retained broken implants in the craniomaxillofacial skeleton

Facial fracture patients are seen in a Level 1 trauma hospital. In our institution, we manage many patients with facial fractures and carry out more than 150 surgical procedures every year. Open reduction and internal fixation is our management of choice. All surgical procedures involve drilling of bone and implant insertion to keep the fractured bones in an anatomically reduced position to aid healing. Occasionally, drill bits used to create the pilot hole break and are embedded in the bone. We present a situation in which such an incident occurred and review the literature on retained broken implants and devices.

In vitro and in vivo corrosion, cytocompatibility and mechanical properties of biodegradable Mg-Y-Ca-Zr alloys as implant materials

This study introduces a class of biodegradable Mg-Y-Ca-Zr alloys novel to biological applications and presents evaluations for orthopedic and craniofacial implant applications. Mg-Y-Ca-Zr alloys were processed using conventional melting and casting techniques. The effects of increasing Y content from 1 to 4 wt.% as well as the effects of T4 solution treatment were assessed. Basic material phase characterization was conducted using X-ray diffraction, optical microscopy and scanning electron microscopy. Compressive and tensile tests allowed for the comparison of mechanical properties of the as-cast and T4-treated Mg-Y-Ca-Zr alloys to pure Mg and as-drawn AZ31. Potentiodynamic polarization tests and mass loss immersion tests were used to evaluate the corrosion behavior of the alloys. In vitro cytocompatibility tests on MC3T3-E1 pre-osteoblast cells were also conducted. Finally, alloy pellets were implanted into murine subcutaneous tissue to observe in vivo corrosion as well as local host response through H&E staining. SEM/EDS analysis showed that secondary phase intermetallics rich in yttrium were observed along the grain boundaries, with the T4 solution treatment diffusing the secondary phases into the matrix while increasing the grain size. The alloys demonstrated marked improvement in mechanical properties over pure Mg. Increasing the Y content contributed to improved corrosion resistance, while solution-treated alloys resulted in lower strength and compressive strain compared to as-cast alloys. The Mg-Y-Ca-Zr alloys demonstrated excellent in vitro cytocompatibility and normal in vivo host response. The mechanical, corrosion and biological evaluations performed in this study demonstrated that Mg-Y-Ca-Zr alloys, especially with the 4 wt.% Y content, would perform well as orthopedic and craniofacial implant biomaterials.