Resorbable poly(L-lactide) plates and screws for the fixation of zygomatic fractures

Redefining Surgical Materials: Applications of Silk Fibroin in Osteofixation and Fracture Repair

Silk and silk derivatives have emerged as a possible alternative in surgical device development, offering mechanical strength, biocompatibility, and environmental sustainability. Through a systematic review following PRISMA guidelines, this study evaluated silk fibroin's application across pre-clinical and clinical settings, focusing on its role as screws and plates for osteofixation. A comprehensive search yielded 245 studies, with 33 subjected to full-text review and 15 ultimately included for qualitative analysis. The findings underscore silk fibroin's superior properties, including its tunable degradation rates and ability to be functionalized with therapeutic agents. In vivo and in vitro studies demonstrated its efficacy in enhancing bone healing, offering improved outcomes in osteofixation, particularly for craniofacial defects. Silk fibroin's remarkable attributes in biodegradation and drug release capabilities underscore its potential to enhance patient care. Ultimately, silk fibroin's integration into surgical practices promises a revolution in patient outcomes and environmental sustainability. Its versatility, coupled with the continuous progress in fabrication techniques, signals a promising horizon for its widespread acceptance in the medical field, potentially establishing a new benchmark in surgical treatment. Further research is expected to solidify the transition of silk products from basic science to patient care, paving the way for widespread use in various surgical applications.

Molybdenum as a Potential Biocompatible and Resorbable Material for Osteosynthesis in Craniomaxillofacial Surgery-An In Vitro Study

Titanium and stainless steel are commonly known as osteosynthesis materials with high strength and good biocompatibility. However, they have the big disadvantage that a second operation for hardware removal is necessary. Although resorbable systems made of polymers or magnesium are increasingly used, they show some severe adverse foreign body reactions or unsatisfying degradation behavior. Therefore, we started to investigate molybdenum as a potential new biodegradable material for osteosynthesis in craniomaxillofacial surgery. To characterize molybdenum as a biocompatible material, we performed in vitro assays in accordance with ISO Norm 10993-5. In four different experimental setups, we showed that pure molybdenum and molybdenum rhenium alloys do not lead to cytotoxicity in human and mouse fibroblasts. We also examined the degradation behavior of molybdenum by carrying out long-term immersion tests (up to 6 months) with molybdenum sheet metal. We showed that molybdenum has sufficient mechanical stability over at least 6 months for implants on the one hand and is subject to very uniform degradation on the other. The results of our experiments are very promising for the development of new resorbable osteosynthesis materials for craniomaxillofacial surgery based on molybdenum.

Experience with resorbable plates for fixation of mandible fracture. A prospective study of 10 cases

Aim:

This study aims to evaluate the efficacy of resorbable plates for the fixation of mandible fracture.

Materials and Methods:

10 cases of fracture mandible were treated with resorbable plates using the Inion CPS system. Patients were evaluated during their entire hospital stay and recalled on 1^st, 4^th, and 8^th postoperative weeks. A thorough evaluation was done at the recall visits for any surgical and postoperative complications such as infection, malocclusion, neural abnormalities, wound or suture dehiscence, segmental mobility, foreign body reaction, and pain on biting. Bite force measurements were taken to evaluate the return of function.

Results:

Clinical union of the fracture was noted at the 8^th week follow-up examination for all cases. There were swelling and pain at the operated site at 8^th week follow-up for one patient, which was managed conservatively. The mean bite force was recorded for different regions and it increased over the entire follow-up period progressively.

Conclusion:

These plates and screws are an essential tool in the treatment of mandibular fractures owing to benefits such as biodegradability, biocompatibility, and the ability to be eliminated via the body's natural processes.

The Modified Hedgehog Technique to Repair Pure Chondral Shear-off Lesions in the Pediatric Knee

OBJECTIVE

The paediatric knee is prone to pure chondral shear-off lesions due to the developing osteochondral unit. Refixation of the chondral fragment is commonly done using metalwork or absorbable biomaterials. Both fixation methods come with biomaterial-related drawbacks. Earlier work on chondral allografts for cartilage repair in adults has shown successful osteochondral integration when the chondral allograft is treated with multiple incisions and then glued to the subchondral bone using fibrin glue. This is commonly referred to as the "hedgehog technique." This study investigates the feasibility of a modification of the hedgehog technique in autologous cartilage to repair shear-off lesions in children.

DESIGN

Three consecutive patients (aged 11, 12, and 14 years) with shear-off chondral fragments of 2, 5, and 8 cm² were treated using this modified hedgehog technique. The calcified side of the chondral fragments were multiply incised and trimmed obliquely for an interlocking fit in the defect site. Fibrin glue and, if indicated sutures, were applied to fix the fragment to the defect. In 1 patient, an anterior cruciate ligament (ACL) repair was also performed. Patients were evaluated clinically and by magnetic resonance imaging (MRI) up to 12 months postoperatively.

RESULTS

Twelve months after surgery, all patients reported no pain and showed complete return to sport and full range of motion. MRI showed no signs of fragment loosening.

CONCLUSIONS

The modified hedgehog technique is a feasible treatment option to repair pure chondral shear-off lesions in the paediatric knee. This was the first time this technique was used in autografting.

Bioabsorbable System-Related Subcutaneous Swelling After Craniofacial Surgery

BACKGROUND

Bioabsorbable systems have been commonly used in pediatric patients for primary cranioplasty and other related surgeries. However, subcutaneous swelling, a unique complication related to bioabsorbable osteosynthesis, is a concern. Differences in the incidence of subcutaneous swelling, depending on the bioabsorbable material used to construct the plate, are still unknown.

METHODS

The authors retrospectively reviewed all incidences of subcutaneous swelling related to resorbable systems used during primary cranioplasty for patients with craniosynostosis at their hospital between 2014 and 2018 during a 12-month follow-up period. Furthermore, the authors reviewed all published English-language articles (since 1995) on subcutaneous swelling in bioabsorbable systems used for craniosynostosis.

RESULTS

The most common resorbable systems used in the literature were divided into 2 groups: mixtures of poly D-lactic acid and polyglycolic acid, and mixtures of poly D- and L-lactic acid. In patients for whom poly D-lactic acid and polyglycolic acid were used, the incidence of subcutaneous swelling during resorption was 0% to 4.2% between 3 and 9 months of follow-up. In patients for whom poly D- and L-lactic acid was used, subcutaneous swelling during resorption occurred in 5% to 16.7% of these patients between 6 and 12 months of follow-up. All cases resolved spontaneously after complete absorption of the plate.

CONCLUSIONS

It was difficult to determine which system had the lowest incidence of subcutaneous swelling. The thickness of each resorbable system and the thickness of the infants' scalps were different in each study. However, subcutaneous swelling occurred in every resorbable system. Therefore, preoperative counseling and careful follow-up are necessary.

Rheological characterization, compression, and injection molding of hydroxyapatite-silk fibroin composites

Traditional bone fixation devices made from inert metal alloys provide structural strength for bone repair but are limited in their ability to actively promote bone healing. Although several naturally derived bioactive materials have been developed to promote ossification in bone defects, it is difficult to translate small-scale benchtop fabrication of these materials to high-output manufacturing. Standard industrial molding processes, such as injection and compression molding, have typically been limited to use with synthetic polymers since most biopolymers cannot withstand the harsh processing conditions involved in these techniques. Here we demonstrate injection and compression molding of a bioceramic composite comprised of hydroxyapatite (HA) and silk fibroin (SF) from Bombyx mori silkworm cocoons. Both the molding behavior of the HA-SF slurry and final scaffold mechanics can be controlled by modulating SF protein molecular weight, SF content, and powder-to-liquid ratio. HA-SF composites with up to 20 weight percent SF were successfully molded into stable three-dimensional structures using high pressure molding techniques. The unique durability of silk fibroin enables application of common molding techniques to fabricate composite silk-ceramic scaffolds. This work demonstrates the potential to move bone tissue engineering one step closer to large-scale manufacturing of natural protein-based resorbable bone grafts and fixation devices.

Deterioration of the Mechanical Properties of FFF 3D-Printed PLA Structures

Poly(lactic acid) (PLA) is a biodegradable polymer material used for the fabrication of objects by fused filament fabrication (FFF) 3D printing. FFF 3D printing technology has been quickly spreading over the past few years. An FFF-3D-printed object is formed from melted polymer extruded from a nozzle layer-by-layer. The mechanical properties of the object, and the changes in those properties as the object degrades, differ from the properties and changes observed in bulk objects. In this study we evaluated FFF-3D-printed objects by uniaxial tensile tests and four-point flexural tests to characterize the changes of three mechanical properties, namely, the maximum stress, elastic modulus, and breaking energy. Eight types of test pieces printed directly by an FFF 3D printer using two scan patterns and two interior fill percentages (IFPs) were tested by the aforesaid methods. The test pieces were immersed in saline and kept in an incubator at 37 °C for 30, 60, or 90 days before the mechanical testing. The changes in the mechanical properties differed largely between the test piece types. In some of the test pieces, transient increases in strength were observed before the immersion degraded the strength. Several of the test piece types were found to have superior specific strength in the tests. The results obtained in this research will be helpful for the design of PLA structures fabricated by FFF 3D printing.

Bioabsorbable Osteofixation Materials for Maxillofacial Bone Surgery: A Review on Polymers and Magnesium-Based Materials

Clinical application of osteofixation materials is essential in performing maxillofacial surgeries requiring rigid fixation of bone such as trauma surgery, orthognathic surgery, and skeletal reconstruction. In addition to the use of titanium plates and screws, clinical applications and attempts using bioabsorbable materials for osteofixation surgery are increasing with demands to avoid secondary surgery for the removal of plates and screws. Synthetic polymeric plates and screws were developed, reaching satisfactory physical properties comparable to those made with titanium. Although these polymeric materials are actively used in clinical practice, there remain some limitations to be improved. Due to questionable physical strength and cumbersome molding procedures, interests in resorbable metal materials for osteofixation emerged. Magnesium (Mg) gained attention again in the last decade as a new metallic alternative, and numerous animal studies to evaluate the possibility of clinical application of Mg-based materials are being conducted. Thanks to these researches and studies, vascular application of Mg-based biomaterials was successful; however, further studies are required for the clinical application of Mg-based biomaterials for osteofixation, especially in the facial skeleton. The review provides an overview of bioabsorbable osteofixation materials in maxillofacial bone surgery from polymer to Mg.

Efficacy of Altered Two-Point Fixation in Zygomaticomaxillary Complex Fracture

PURPOSE

To reconstruct a zygomaticomaxillary complex (ZMC) fracture, zygomaticofrontal (ZF) suture is the most reliable site to assess anatomical alignment and to secure rigidity. It has been chosen primary site to be fixed, but approach through the lateral eyebrow incision may leave a visible scar. This study suggests altered two-point fixation of ZMC fracture without accessing the ZF suture.

METHODS

In the retrospective study, a total of 40 patients with ZMC fracture were divided into two groups (group 1, two-point fixation and group 2, three-point fixation). Patient demographics and follow-up were evaluated, and degree of reduction including cortical gaps of ZF and inferior orbital (IO) area, protruding difference of zygoma, and malar difference using asymmetry index were measured through preoperative and postoperative CT.

RESULTS

Preoperatively, the means of ZF displacement, IO displacement, protruding difference of zygoma, and facial asymmetry index between the groups were not statistically different. The result was the same after the operation. However, all variables were significantly different before and after surgery within each group. Moreover, mean operation time was significantly different between groups (P value = 0.026).

CONCLUSION

Altered two-point fixation in ZMC fracture excluding incision approaching the ZF provides surgical efficacy and similar surgical outcomes to three-point fixation but offers reduced operation time and fewer complications.

Short phosphate glass fiber - PLLA composite to promote bone mineralization

The clinical application of composites seeks to exploit the mechanical and chemical properties of materials which make up the composite, and in researching polymer composites for biomedical applications the aim is usually to enhance the bioactivity of the polymer, while maintaining the mechanical properties. To that end, in this study medical grade Poly(L-lactic) acid (PLLA) has been reinforced with short phosphate-based glass fibers (PGF). The materials were initially mixed by melting PLLA granules with the short fibers, before being extruded to form a homogenous filament, which was pelletized and used as feedstock for compression moulding. As made the composite materials had a bending strength of 51 MPa ± 5, and over the course of eight weeks in PBS the average strength of the composite material was in the range 20-50 MPa. Human mesenchymal stromal cells were cultured on the surfaces of scaffolds, and the metabolic activity, alkaline phosphatase production and mineralization monitored over a three week period. The short fiber filler made no significant difference to cell proliferation or differentiation, but had a clear and immediate osteoinductive effect, promoting mineralization by cells at the material surface. It is concluded that the PLLA/PGF composite material offers a material with both the mechanical and biological properties for potential application to bone implants and fixation, particularly where an osteoinductive effect would be valuable.

Evaluation of the Deterioration of the Mechanical Properties of Poly(lactic acid) Structures Fabricated by a Fused Filament Fabrication 3D Printer

A fused filament fabrication (FFF) 3D printer is a simple device capable of manufacturing three-dimensional structures in a series of easy steps. Commercial-level FFF 3D printers have spread rapidly in many fields in recent years. Poly(lactic acid) (PLA) is a biodegradable thermoplastic polymer used as a typical printing medium for FFF 3D printers. The FFF printer constructs an object with melted polymer extruded from a tiny scanning nozzle. The mechanical properties of FFF 3D structures printed with different scan patterns can therefore vary in accordance with the directions from which forces act upon them. The nozzle scan pattern also influences the deterioration of the mechanical properties of the structures in accordance with the degradation caused by the hydrolysis of PLA. In this study we conducted tensile tests to evaluate the strength characteristics of 3D printed test pieces formed from PLA using four different scan patterns: parallel, vertical, parallel-and-vertical, and cross-hatched at opposing diagonal angles to the tensile direction. We also formed test pieces by an injection molding method using the same material, for further comparison. We evaluated the deterioration of the test pieces after immersing them in saline for certain periods. After the test pieces formed by different nozzle scan patterns were immersed, they exhibited differences in the rates by which their maximum tensile stresses deteriorated and their masses increased through water uptake. The influences of the scan patterns could be classified into two types: the unidirectional scan pattern influence and bidirectional scan pattern influence. The data obtained in this research will be applied to structural design when the FFF 3D printer is employed for the fabrication of structures with PLA filament.

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.

Foreign-Body Reaction to Bioabsorbable Plate and Screw in Craniofacial Surgery

Hydroxyapatite and poly-L-lactide plates are often used for maxillofacial surgery. These plates take 3 to 4 years to resorb completely, leading to the possibility of a foreign-body reaction. A 20-year-old woman who developed a foreign-body reaction to the plates was reported. Based on review of the relevant literature, foreign-body reactions have often been reported with this plate. Long-term follow-up is warranted to evaluate patients using this plate in maxillofacial surgery.

Comparisons among four types of absorbable plates used for internal fixation of zygomaticomaxillary complex fractures

IMPORTANCE

Conventional plating systems include titanium plates for the fixation of facial bone fractures. However, titanium plates result in artifacts on computed tomography images and appear unstable on magnetic resonance images. Therefore, absorbable plates have been widely used for the fixation of facial bone fractures of late in Asia.

OBJECTIVE

To compare stability and symmetry among four different absorbable plates used for internal fixation of zygomaticomaxillary complex fractures.

PARTICIPANTS

The subjects were patients with zygomaticomaxillary complex fractures that were diagnosed and treated by internal fixation with absorbable plates between January 2012 and April 2018. Patients aged ≤14 years and ≥76 years were excluded. Patients with other fracture types were also excluded. All patients underwent surgery within 2 weeks of the injury.

INTERVENTION

Internal fixation was performed with one of four types of absorbable plates, namely Inion^®, Polymax^®, Osteotrans^®, and Biosorb^®.

MAIN OUTCOME MEASURES

The stability of the four plates was investigated by evaluation of the orbital height ratio (A'/A), zygoma angle (a'/a), distance (b'/b) from the midline, and gap (c) of the temporal process on three-dimensional facial computed tomography images obtained before, 3 weeks after, and 3-6 months after surgery. Any plate-associated complications were recorded.

RESULTS

In total, 400 patients were enrolled, and there were 100 patients in each of the four groups. There were no significant differences with regard to postoperative stability and relapse among the four plates. Moreover, facial symmetry showed no changes over time in any group. Complications such as infection and sensory disturbance were not frequent. All plates except Biosorb^® were palpable for more than 6 months after surgery, with Osteotrans^® remaining palpable for several years.

CONCLUSIONS AND RELEVANCE

Our findings suggest that all four types of absorbable plates are useful for treating isolated zygomaticomaxillary complex fractures. While Biosorb^® is unsuitable for severe comminuted fractures. Polymax^® and Inion^® are not bendable at room temperature. It is important to select an appropriate absorbable plate according to each patient's condition and the fracture severity.

Does fixation method affects temporomandibular joints after mandibular advancement?

PURPOSE

Sagittal split ramus osteotomy (SSRO) is a standard procedure in which miniplates and screws are used to achieve stabilization. Although the titanium plate and screw fixation system is stable, resorbable fixation systems are also used. There is currently no consensus on the ideal fixation technique for SSRO procedures and its effect on the condyle. We aimed to evaluate the stress distribution on temporomandibular joints (TMJ).

METHODS

A 3D finite element model of a hemimandible was designed and 5 mm advancement was simulated on a computer model. Four different fixation techniques were applied: inverted-L shaped bicortical screws, L-shaped bicortical screws, miniplate with monocortical screws, and miniplate with monocortical screws and bicortical screw. Computer models were prepared twice for resorbable and titanium material. Load of 600N and muscle forces were applied. In the finite element analysis, computer models simulated and analyzed stress distribution of bone, fixation materials and condyle.

RESULTS

Bicortical screws increase the total stress on TMJ, and the stress is located more on the posterior part than the anterior. Miniplates decrease the stress, and the forces are located more on the anterior aspect of the TMJ.

CONCLUSION

According to our analysis, the use of bicortical screws increases the stress amount on the condyle. For the patients with a tendency toward temporomandibular disorders, using miniplate fixation techniques may decrease the forces around the condyle. These findings should be useful for oral surgeons when deciding on the most appropriate fixation technique in patients with a tendency toward temporomandibular joint disorders.

Overview of innovative advances in bioresorbable plate systems for oral and maxillofacial surgery

Maxillofacial osteosynthetic surgeries require stable fixation for uneventful boney healing and optimal remodeling. Although conventional titanium plates and screws for osteofixation are considered the gold standard for rigid fixation in maxillofacial surgeries, bioresorbable implants of plates and screw systems are commonly used for various maxillofacial osteosynthetic surgeries such as orthognathic surgery, maxillofacial fractures, and reconstructive surgery. Titanium plates are limited by their palpability, mutagenic effects, and interference with imaging, which may lead to the need for subsequent removal; the use of a biologically resorbable osteofixation system could potentially address these limitations. However, several problems remain including fundamental issues involving decreased mechanical strength and stability, slow biodegradation, complex procedures, and the available bioresorbable implant materials. Major advances in bioresorbable plate systems have been made with the use of bioactive/resorbable osteoconductive materials and an accelerator of bioresorption, such as polyglycolic acid. This report presents an overview of currently available resorbable implant materials and their applications, with a focus on recent innovative advances and new developments in this field.

Biodegradable Piezoelectric Force Sensor

Measuring vital physiological pressures is important for monitoring health status, preventing the buildup of dangerous internal forces in impaired organs, and enabling novel approaches of using mechanical stimulation for tissue regeneration. Pressure sensors are often required to be implanted and directly integrated with native soft biological systems. Therefore, the devices should be flexible and at the same time biodegradable to avoid invasive removal surgery that can damage directly interfaced tissues. Despite recent achievements in degradable electronic devices, there is still a tremendous need to develop a force sensor which only relies on safe medical materials and requires no complex fabrication process to provide accurate information on important biophysiological forces. Here, we present a strategy for material processing, electromechanical analysis, device fabrication, and assessment of a piezoelectric Poly-l-lactide (PLLA) polymer to create a biodegradable, biocompatible piezoelectric force sensor, which only employs medical materials used commonly in Food and Drug Administration-approved implants, for the monitoring of biological forces. We show the sensor can precisely measure pressures in a wide range of 0-18 kPa and sustain a reliable performance for a period of 4 d in an aqueous environment. We also demonstrate this PLLA piezoelectric sensor can be implanted inside the abdominal cavity of a mouse to monitor the pressure of diaphragmatic contraction. This piezoelectric sensor offers an appealing alternative to present biodegradable electronic devices for the monitoring of intraorgan pressures. The sensor can be integrated with tissues and organs, forming self-sensing bionic systems to enable many exciting applications in regenerative medicine, drug delivery, and medical devices.

Surgical treatment of isolated zygomatic fracture: Outcome comparison between titanium plate and bioabsorbable plate

BACKGROUND

Zygoma fracture is of clinical importance because malar prominence plays an essential role in facial appearance. Traditionally, most maxillofacial surgeons perform osteosynthesis with titanium plates and screws for rigid fixation. However, this procedure has certain disadvantages that include the possibility of implant exposure, palpability or loosening of the screws, painful irritation, temperature sensitization, and radiographic artifacts. In this study, we compared the function and satisfaction outcome between Bonamates^® bioabsorbable implant and Leibinger titanium implant.

METHOD

Consecutively 53 patients with isolated unilateral zygomatic fracture that were treated with the Bonamates^® bioabsorbable plate system, n = 53 were compared to patients with the titanium plate system, n = 55 in the period between 2009 and 2013. All patients were followed-up at least 6 months. Preoperative and postoperative facial computed tomography (CT) scans were performed and scored from 0 to 2 in the 5 areas of zygoma. A score of 2 indicated the most severely displaced fracture in one of the areas. A visual analogue scale ranging from 0 to 10 was used to assess the postoperative aesthetic and functional satisfactions.

RESULT

The mean ages of the patients in the bioabsorbable and titanium plate groups were 33 years and 30 years, respectively. The male to female ratios were 1.2:1 (bioabsorbable plate group) and 1.1:1 (titanium plate group). The average preoperative CT scan scores of the bioabsorbable and titanium plate groups were 5.7 and 5.1, respectively. The postoperative CT scan scores of the bioabsorbable and titanium plate groups were 1.3 and 1.1, respectively. The implant cost of the bioabsorbable group was approximately 6-fold higher than that of the titanium plate group. The complication rate was similar in both groups and included complications such as palpable implant, skin irritation, and hypersensitive cheek. The patients in both groups attained similar mouth-opening function and a satisfactory score at 6 months after operation.

CONCLUSION

This study revealed that the bioabsorbable plate outcome was similar to the titanium plate outcome for patients with isolated unilateral zygomatic fracture. The bioabsorbable implant system provides another option for internal fixation devices in the treatment of zygomatic fractures and avoids implant removal surgery; however, the implant cost of bioabsorbable plates is higher than that of titanium plates in Taiwan.

[Biodegradable fixation systems in pediatric craniofacial surgery: 10-year experience with 324 patients]

INTRODUCTION

Over the past 15 years, resorbable materials have been successfully used for osteosynthesis, but their high cost prevents widespread application. However, the use of resorbable systems could be a method of choice, especially in treatment of children in the active growth period. Obviously, biodegradable materials not only are highly competitive with known metal constructs in terms of fixation rigidity, biocompatibility, and a low risk of infection but also have an undeniable advantage, such as gradual resorption allowing quick return of damaged bones to the physiological conditions of functioning. A special feature of bioresorbable systems is that they can be assembled using ultrasonic welding, which greatly facilitates the fixation process and also provides necessary rigidity, even in cases of joining very thin bones when reliable fixation with screws is impossible.

MATERIAL AND METHODS

Over the past 10 years, we have used biodegradable systems in 324 patients. In 244 of them, we used traditional (plate/screw) systems; in 80 cases, an ultrasonic welding system was chosen for osteosynthesis.

RESULTS

In the present work, we discuss, based on clinical evidence, the advantages and disadvantages of both fixation systems for reconstructive craniofacial surgery in children.

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.

Efficacy of Resorbable Plates for Reduction and Stabilization of Laryngeal Fractures

We evaluated the efficacy of resorbable reconstruction plates (polylactic acid copolymer) for the open reduction and stabilization of displaced laryngeal fractures. Both MacroPore and Leibinger reconstruction plates were used with equal ease of application in 3 adult male patients. We found the plating system to be especially effective for the reduction of comminuted cricoid fractures. Adequate skeletal stabilization allowed early resumption of phonatory and respiratory function without long-term intraluminal stenting for skeletal support. No complications of hematoma, seroma, or infection were experienced. Resorbable plates appear to be relatively safe and useful for internal fixation of both cartilaginous and ossified parts of the larynx, allowing rapid rehabilitation and return of function.

Are Biodegradable Osteosyntheses Still an Option for Midface Trauma? Longitudinal Evaluation of Three Different PLA-Based Materials

The aim was to evaluate three different biodegradable polylactic acid- (PLA-) based osteosynthesis materials (OM). These OM (BioSorb, LactoSorb, and Delta) were used in 64 patients of whom 55 (85.9%) had fractures of the zygoma, five (7.8%) in the LeFort II level, two of the frontal bone (3.1%), and two of the maxillary sinus wall (3.1%). In addition to routine follow-up (FU) at 3, 6, and 12 months (m) (T1, T2, and T3) all patients were finally evaluated at a mean FU after 14.1 m for minor (e.g., nerve disturbances, swelling, and pain) and major (e.g., infections and occlusal disturbances) complications. Out of all 64 patients 38 presented with complications; of these 28 were minor (43.8%) and 10 major (15.6%) resulting in an overall rate of 59.4%. Differences in minor complications regarding sensibility disturbance at T1 and T3 were statistically significant (P = 0.04). Differences between the OM were not statistically significant. Apart from sufficient mechanical stability for clinical use of all tested OM complications mostly involved pain and swelling probably mainly related to the initial bulk reaction attributable to the drop of pH value during the degradation process. This paper includes a review of the current aspects of biodegradable OM.

The management of pediatric type 1 nasoorbitoethmoidal fractures with resorbable fixation

Nasoorbitoethmoid (NOE) fractures are rare in the pediatric population. A recent study reported that NOE fractures account for 1% to 8% of all pediatric craniofacial fractures based on the National Trauma Data Bank. Although infrequent, NOE fractures must be appropriately identified and treated because of potential severe esthetic and functional complications. In this report, we discuss our experience treating the uncommon case of a 9-year-old girl who was involved in a motor vehicle accident and had traumatic injuries to the midface, including a type 1 NOE fracture. We elected to use biodegradable plates to treat her left type 1 NOE fracture because of concerns of facial growth disturbances with the use of conventional rigid fixation techniques at her young age. At 1-year follow-up, the patient demonstrated an acceptable outcome with no functional problems reported. We have also incorporated in this article a thorough review of the literature relating the evolution of biodegradable plates for the treatment of pediatric facial fractures.

Aesthetic recovery of alveolar atrophy following autogenous onlay bone grafting using interconnected porous hydroxyapatite ceramics (IP-CHA) and resorbable poly-L-lactic/polyglycolic acid screws: case report

Background

Onlay bone grafting techniques have some problems related to the limited volume of autogenous grafted bone and need for surgery to remove bone fixing screws. Here, we report a case of horizontal alveolar ridge atrophy following resection of a maxillary bone cyst, in which autogenous onlay bone grafting with interconnected porous hydroxyapatite ceramics (IP-CHA) and bioresorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) screws was utilized.

Case presentation

A 51-year-old man had aesthetic complications related to alveolar atrophy following maxillary bone cyst extraction. We performed onlay grafting for aesthetic alveolar bone recovery using IP-CHA to provide adequate horizontal bone volume and PLLA-PGA screws for bone fixing to avoid later damage to host bone during surgical removal. During the operation, an autogenous cortical bone block was collected from the ramus mandibular and fixed to the alveolar ridge with PLLA-PGA screws, then the gap between the bone block and recipient bone was filled with a granular type of IP-CHA. Post-surgery orthopantomograph and CT scan findings showed no abnormal resorption of the grafted bone, and increased radiopacity, which indicated new bone formation in the area implanted with IP-CHA.

Conclusion

Our results show that IP-CHA and resorbable PLLA-PGA screws are useful materials for autogenous onlay bone grafting.

Use of bioresorbable plating systems in paediatric mandible fractures

AIM

The aim of this study is to retrospectively evaluate the use of bioresorbable plating systems in the rigid fixation of paediatric mandible fractures.

PATIENTS AND METHODS

Our series consists of fifteen paediatric patients (11 male, 4 female, average age 8.13 years) with mandible fractures of varying severity treated with bioresorbable plates over a 54-month period at our institution. Fractures of the ramus, body, parasymphysis, and symphysis were treated by one surgeon with open reduction and internal fixation with 1.5 mm and 2 mm resorbable plates and monocortical screws, using 3 different plating systems, each with differing polymer concentrations of polyglycolic and poly-L-lactic acid. The patients were followed with respect to the following clinical categories: fracture location, postoperative occlusion, maximum interincisal opening (MIO), segmental mobility at the fracture site, and any abnormal swelling at the operative site.

RESULTS

Our data shows a stable occlusion and maximum interincisal opening of thirty millimetres or greater was achieved in 14 of 15 patients seen in follow up, with 8 patients having an MIO of 40 mm or greater. No segmental mobility noted at any of the fracture sites. Thirteen patients had no postoperative sequelae or implant related complications. Two patients developed a seroma-like collection at the operative site. Postoperative films starting at 1 year showed significant bony osseous fill where the previous screw sites were located.

CONCLUSIONS

In our case series we found that the use of resorbable polyglycolic and poly-L-lactic acid plating systems when combined with a brief postoperative period of intermaxillary fixation is an effective method of internal fixation for mandibular fractures in the paediatric population.

Bone plate composed of a ternary nano-hydroxyapatite/polyamide 66/glass fiber composite: biomechanical properties and biocompatibility

An ideal bone plate for internal fixation of bone fractures should have good biomechanical properties and biocompatibility. In this study, we prepared a new nondegradable bone plate composed of a ternary nano-hydroxyapatite/polyamide 66/glass fiber (n-HA/PA66/GF) composite. A breakage area on the n-HA/PA66/GF plate surface was characterized by scanning electron microscopy. Its mechanical properties were investigated using bone-plate constructs and biocompatibility was evaluated in vitro using bone marrow-derived mesenchymal stem cells. The results confirmed that adhesion between the n-HA/PA66 matrix and the glass fibers was strong, with only a few fibers pulled out at the site of breakage. Fractures fixed by the n-HA/PA66/GF plate showed lower stiffness and had satisfactory strength compared with rigid fixation using a titanium plate. Moreover, the results with regard to mesenchymal stem cell morphology, MTT assay, Alizarin Red S staining, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction for alkaline phosphatase and osteocalcin showed that the n-HA/PA66/GF composite was suitable for attachment and proliferation of mesenchymal stem cells, and did not have a negative influence on matrix mineralization or osteogenic differentiation of mesenchymal stem cells. These observations indicate that the n-HA/PA66/GF plate has good biomechanical properties and biocompatibility, and may be considered a new option for internal fixation in orthopedic surgery.

The use of silk-based devices for fracture fixation

Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.

Bioabsorbable fixation devices in trauma and bone surgery: current clinical standing

Bioabsorbable fixation devices are increasingly used in trauma, orthopedic and craniomaxillofacial surgery. The devices are essentially made of polylactic acid and/or polyglycolic acid polymers. Ultra-high-strength implants are manufactured from such polymers using self-reinforcing techniques. Implants are available for stabilization of fractures, osteotomies, bone grafts and fusions, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures. As these implants are completely absorbed, the need for a removal operation is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided. The risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced. Implants do not interfere with clinical imaging. Current clinical use of bioabsorbable devices is reviewed.

Skeletal stability after mandibular setback surgery: comparison between the hybrid technique for fixation and the conventional plate fixation using an absorbable plate and screws

PURPOSE

The purpose of this study was to compare the temporal changes in condylar long axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with the hybrid fixation technique and the conventional plate fixation.

PATIENTS AND METHODS

Of 44 Japanese patients diagnosed with mandibular prognathism, 22 underwent SSRO with the conventional plate fixation (1 u-HA/PLLA plate and 4 monocortical screws in each side) and 22 underwent SSRO with a hybrid fixation technique (1 u-HA/PLLA plate and 4 monocortical screws and bicortical screw in each side). The temporal changes in condylar long axis and skeletal stability were assessed by axial, frontal, and lateral cephalograms. After surgery, breakage of the plate and screws was checked by 3-dimensional computed tomography (3DCT).

RESULTS

Although there was a significant difference between the groups regarding Me-Ag in T1 (P = 0.0138), there were no significant differences between the groups for the other measurements in lateral, frontal and axial cephalometric analysis in each time interval. In two cases, 4 sides in the conventional plate fixation group, failure of the absorbable plate was found by 3DCT. However, there was no breakage in the hybrid fixation group.

CONCLUSION

This study suggested that there were no significant differences in the postoperative temporal changes between the two groups in mandibular setback surgery.

Complications of absorbable fixation in maxillofacial surgery: a meta-analysis

BACKGROUND

The use of titanium during maxillofacial fixation is limited due to its palpability, mutagenic effects and interference with imaging, which lead to the requirement for subsequent removal. The use of a biologically absorbable fixation material will potentially eliminate these limitations. In this meta-analysis, we analyzed the complications of absorbable fixation in maxillofacial surgery.

METHODS

We performed a systematic search of PubMed, Embase, Cochrane Central Register of Systematic Reviews and Cochrane Central Register of Controlled Trials for trials published through December 2012. Data extracted from literature were analyzed with Review manager 5.0.24.

RESULTS

Relevant data was extracted from 20 studies (1673 participants) and revealed that patients in the absorbable group had significantly more complications than those in the titanium group (RR = 1.20; 95% CI: 1.02-1.42; P = 0.03) in all enrolled maxillofacial surgeries. For bimaxillary operation subgroup, the absorbable fixation group did not have a significant increase in complications when compared with the titanium group (RR = 1.89; 95% CI: 0.85-4.22; P = 0.12). There was no significant difference observed between the absorbable and titanium groups receiving a bilateral sagittal split ramus osteotomy (BSSRO) (RR = 1.45; 95% CI: 0.84-2.48; P = 0.18) and Le Fort I osteotomy (RR = 0.65; 95% CI: 0.34-1.23; P = 0.18). The combined results of the five trials revealed that the absorbable group had a significantly lower rate of complications compared to the titanium group (RR = 0.71; 95% CI: 0.52-0.97; P = 0.03) in fracture fixation.

CONCLUSION

This meta-analysis shows that absorbable fixation systems used for fixation in maxillofacial surgery do not have adequate safety profiles. Subgroup indicated the safety of absorbable fixation systems was superior during fracture fixation. The absorbable fixation systems tend to have a similar favorable safety profile as titanium fixation during Le Fort I, bimaxillary operation and BSSRO.

Biomaterials for reconstruction of the internal orbit

Orbital floor injuries, alone or combination with other facial fractures, are one of the most commonly encountered midface fractures. Techniques for orbital reconstruction have migrated away from autogenous bone grafts to well-tolerated alloplasts, such as titanium and Medpor. Material for reconstructing the orbit can then be selected based on requirements of the defect matched to the mechanical properties of the material. Material selection is largely and ultimately dependent upon surgeon preference.

Surgical treatment of facial fracture by using unsintered hydroxyapatite particles/poly l-lactide composite device (OSTEOTRANS MX(®)): a clinical study on 17 cases

BACKGROUND

In Japan we currently use absorption properties for facial fractures. OSTEOTRANS MX(®) (Takiron co., ltd, Japan) is an absorption device, which is called Super FIXSORB MX(®) in Japan. This absorbable osteosynthetic device constitutes unsintered hydroxyapatite particles/poly l-lactide (u-HA/PLLA) composites. This study focuses on reporting clinical cases of using OSTEOTRANS MX(®).

MATERIALS AND METHODS

Seventeen patients (16 men and 1 woman) aged 10-80 years (mean: 39.9 years, SD: ±20.7) with 86 fracture sites were treated. In all cases we used 1.0 mm plates and 5 mm or 7 mm screws. The postoperative observation period was 6-60 months (mean: 21.8 months, SD: ±14.5).

RESULTS

The fracture site recovered in all cases. Complications included one bone excess on the forehead and one foreign-body reaction on the frontozygomatic suture, but the fracture sites were recovered and had no problems. In the case with the longest observation time 60 months, the plate was almost fully absorbed. However, in other cases the plate was not fully absorbed because of a shorter observation time.

CONCLUSION

OSTEOTRANS MX(®) is a useful device because of its suitable intensity, thinness, radiopaque, and few complications. A longer observation time is required for a plate to be absorbed completely.

Setbacks of bio-resorbable plates and screws in the management of condylar fractures: our experience

PURPOSE

Fractures of the condyle can be managed by open or by closed reduction. This study was designed to mention the complications of the bio-resorbable material we had experienced while using them in the management of condylar fractures.

METHODS

Fifteen (11 men and four women) patients with subcondylar fractures were included in the study. Resorbable poly-l-lactide plates and screws were used for the fracture fixation. Patients were followed up clinically and radiographically for a period of 2 years.

RESULTS

Seven patients had a satisfactory reduction following the placement of bio-resorbable plates. Three patients had developed a swelling in the pre-auricular region, extending till the angle. Two patients had a screw breakage whereby leading to malunion and three other patients had bone resorption, at the fractured site that was appreciated radiographically.

CONCLUSION

Inspite of the advantages of these materials, certain complications has been experienced in our study with regard to the resorption and degradation of the material which has been mentioned and explained in our article.

Comparative study of bone repair in mandibular body osteotomy between metallic and absorbable 2.0 mm internal fixation systems. Histological and histometric analysis in dogs: a pilot study

The objective of this study was to compare the bone repair along a mandibular body osteotomy stabilized with 2.0 mm absorbable and metallic systems. 12 male, adult mongrel dogs were divided into two groups (metallic and absorbable) and subjected to unilateral osteotomy between the mandibular third and fourth premolars, which was stabilized by applying two 4-hole plates. At 2 and 18 weeks, three dogs from each group were killed and the osteotomy sites were removed and divided equally into three parts: the upper part was labelled the tension third (TT), the lower part the compression third (CT), and the part between the TT and CT the intermediary third (IT). Regardless of the treatment system, union between the fragments was observed at 18 weeks and the CT showed more advanced stages of bone repair than the TT. Histometric analysis did not reveal any significant differences among the 3 parts or systems in the distance between bone fragments at 2 weeks. Although at 18 weeks the proportions of newly formed bone did not differ among TT, IT and CT, significantly enhanced bone formation was observed in all sections for the metallic group. The patterns of repair were distinct between treatments.

Subdermal implants of poly(L-lactic acid) with plasticizer: an ultrastructural study in rats

Poly(L-lactic acid) (PLLA) membranes containing 7% triethylcitrate plasticizer were implanted in the subcutaneous tissue of rats, and the cellular reaction was evaluated over a period of 2-180 days. The samples were processed for conventional transmission electron microscopy. Polymorphonuclear-type cells and a fibrin network were seen within membrane pores 2 days after implantation. In subsequent samples, there was cellular infiltration, which consisted mainly of fibroblasts, macrophages and multinuclear giant cells embedded in an abundant extracellular matrix containing a network of collagen fibers and blood vessels. At 90 and 180 days after implantation, a high density of voluminous phagocytic cells with a large number of endocytic polymer fragments within their cytoplasm was seen. These results show that PLLA membranes can support connective tissue proliferation and remodeling, which are important properties for successful bio-protheses.

TISSUE ENGINEERING APPROACH TO OSTEOCHONDRAL REPAIR AND REGENERATION

Repair of osteochondral lesions remains difficult in current clinical medicine. This is due to the lack of self-reparatory capacity in adult cartilage to respond to injuries. Furthermore, current surgical based treatment is unable to achieve long-term satisfactory results. Cell therapies combined with scaffolds has become a promising tissue engineering approach for osteochondral regeneration. This article briefly outlines the approaches and limitations in osteochondral tissue engineering from three key aspects, namely: (1) Cells and Cell Source; (2) Biomaterials and Scaffold design and fabrication; and (3) Mechanical and Biochemical Stimulus. Current optimal candidate cells for tissue engineering include bone marrow and adipose tissue derived mesenchymal stem cells. As for scaffolds, the structural design and biomaterials used should support cell growth and the organization of new functional tissue formation. Using Fused Deposition Modeling (FDM) technique, the authors developed a novel polycaprolactone osteochondral scaffold which was shown to have the ability to recruit mesenchymal stem cells and the potential for repairing defects in vivo. The article also discussed mechanical and biological stimulus for enhancing in vitro growth of tissue-engineered constructs. The final challenge is the integration of the tissue-engineered tissues into a living system as a functional device.

Biological effect of resorbable plates on normal osteoblasts and osteoblasts derived from Pfeiffer syndrome

Biodegradable fixation devices made of the polymers polylactide, polyglycolide and their copolymers are used routinely during maxillofacial, craniofacial, and orthopedic reconstructive surgical procedures, thanks to their property of biodegradation that avoid the need for implant removal. In particular, they are used in the treatment of craniosynostosis in pediatric patients affected by Pfeiffer syndrome, where the resorption time of 1 year or less does not interfere with the normal growth of the skull. To study the mechanism how polylactide-polyglycolide (PLPG) acid plates can induce osteoblast differentiation and proliferation in normal osteoblasts and in osteoblasts derived from a patient with Pfeiffer syndrome, the expression levels of bone-related genes were analyzed using real-time reverse transcription-polymerase chain reaction. Osteoblasts grown on the PLPG acid plates resulted in significant upregulation of mRNA expression of many genes related to osteodifferentiation during the treatment, indicating that polylactide, polyglycolide biopolymers enhance proliferation, differentiation, and deposition of matrix in osteoblasts. This study also revealed some differences in gene expression between normal osteoblasts and osteoblasts derived from patients with Pfeiffer syndrome, cultivated on PLPG acid plates.

Feasibility of absorbable plates and screws for fixation in reduction malarplasty with L-shaped osteotomy

Reduction malarplasty with L-shaped osteotomy has been widely applied to correct malar prominence because of its simple manipulation, satisfactory outcome, and few complications in east Asians. Secondary surgery for the removal of titanium miniplates or microplates and screws is often needed because of the drawbacks of implants. To overcome the disadvantage, the authors applied absorbable plates and screws instead of titanium fixation system and evaluated the feasibility of them. A total of 47 women (mean age, 26.8 y) diagnosed with malar prominence were randomly selected and received L-shaped osteotomy for malar reduction from January 2008 to December 2009. Of these, 22 patients (group A) received absorbable plates and screws (Fixsorb-MX, Takiron, Japan) for fixation and 25 patients received titanium fixation system as control (group B). The outcomes were evaluated by photographs and x-ray films. The distance of the anterior protrusive point of the bilateral zygoma (Zv-Zv), the distance from the paries anterior of acoustic duct (P) to the anterior protrusive point of zygoma (P-Zv), and the angle formed by the nasion-Zv line and the P-Zv line (∠NZP) were analyzed through posteroanterior and lateral cephalograms preoperatively, 10 days postoperatively, and at 6 to 12 months of follow-up, respectively. In group A, 20 patients (90.9%) were satisfied with the outcomes compared with 92.0% in group B. No zygomatic nonunion and other complications occurred after surgery in both groups. In group A, the values of Zv-Zv and P-Zv were 88.4±1.6 and 68.6±6.8 mm at 10 days after surgery, which increased to 90.6±1.5 and 70.7±3.0 mm at 6 to 12 months of follow-up. The value of ∠NZP was 105.0±4.3 degrees at 10 days after surgery and 103.2±3.6 degrees at 6 to 12 months after surgery. In group B, the values of distance and degree maintained almost the same at different time points after surgery. The results had no significant difference between groups A and B (P>0.05). The findings of the study suggested that the application of absorbable plate system in reduction malarplasty with L-shaped osteotomy is feasible. The absorbable fixation system would have a wider application in craniofacial surgery.

Skeletal stability after mandibular setback surgery: comparisons among unsintered hydroxyapatite/poly-L-lactic acid plate, poly-L-lactic acid plate, and titanium plate

PURPOSE

The purpose of this study is to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with an unsintered hydroxyapatite (u-HA)/poly-L-lactic acid (PLLA) plate, PLLA plate, or titanium plate.

PATIENTS AND METHODS

Of 60 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with a u-HA/PLLA plate system, 20 underwent SSRO with a PLLA plate system, and 20 underwent SSRO with a conventional titanium plate system. The time-course changes in condylar long-axis and skeletal stability were assessed by use of axial, frontal, and lateral cephalograms.

RESULTS

Compared with the u-HA/PLLA group, the titanium group showed a significantly greater change in the right condyle angle between initially and 1 month (P = .0105) and intercondylar axes angle between 1 and 3 months (P = .0013). The PLLA group showed a significantly greater change than the titanium group (P = .0043) and u-HA/PLLA group (P = .0002) in terms of ramus inclination between 1 and 3 months; however, there were no significant differences among the 3 groups in the other measurements for each time interval.

CONCLUSION

This study suggests that there are no significant differences in postoperative time-course changes among a u-HA/PLLA plate system, PLLA plate system, and conventional titanium plate system.