Successful Use of Biosorb Osteofixation Devices in 165 Cranial and Maxillofacial Cases: A Multicenter Report

High Boron Content Enhances Bioactive Glass Biodegradation

Derived Hench bioactive glass (BaG) containing boron (B) is explored in this work as it plays an important role in bone development and regeneration. B was also found to enhance BaG dissociation. However, it is only possible to incorporate a limited amount of B. To increase the amount of B in BaG, bioactive borosilicate glasses (BaG-B_x) were fabricated based on the use of the solution-gelation process (sol-gel). In this work, a high B content (20 wt.%) in BaG, respecting the conditions of bioactivity and biodegradability required by Hench, was achieved for the first time. The capability of BaG-B_x to form an apatite phase was assessed in vitro by immersion in simulated body fluid (SBF). Then, the chemical structure and the morphological changes in the fabricated BaG-B_x (x = 0, 5, 10 and 20) were studied. The formation of hydroxyapatite (HAp) layer was observed with X-ray diffraction (XRD) and infrared (IR) spectroscopy. The presence of HAp layer was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Enhanced bioactivity and chemical stability of BaG-B_x were evaluated with an ion exchange study based on Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and energy dispersive spectroscopy (EDS). Results indicate that by increasing the concentration of B in BaG-Bx, the crystallization rate and the quality of the newly formed HAp layer on BaG-B_x surfaces can be improved. The presence of B also leads to enhanced degradation of BaGs in SBF. Accordingly, BAG-B_x can be used for bone regeneration, especially in children, because of its faster degradation as compared to B-free glass.

Infants With Trigonocephaly Treated With Fronto-Orbital Remodelling and Endocortical Positioning of Resorbable Plates-A Retrospective Cohort Study Including 101 Patients

PURPOSE

Fronto-orbital remodeling is the gold standard for surgical treatment of metopic synostosis in many craniofacial centers. For fixation, resorbable materials are widely used. Because of swelling during resorption, the positioning of the plates can be relevant. Therefore, the goal of this study was to investigate whether there are limitations to endocortical positioning of resorbable plates.

METHODS

In this retrospective study, all patients with metopic craniosynostosis resulting in trigonocephaly, who were treated with a standardized fronto-orbital remodeling and endocortical positioning of resorbable plates, between February 2012 and December 2019 were included. The endpoint of this study was the postoperative complications that can be attributed to the material used.

RESULTS

A total of 101 patients, who were treated at our unit, could be included with a male predominance, 81 (80.2%) boys versus 20 (19.8%) girls. Surgery was performed at a median age of 9 months (±2.56). No complications were seen related to resorbable plates. All patients of our study population were categorized as Whitaker classification I and II.

CONCLUSION

This study shows that the risk level in using endocortical resorbable plates positioned on the inner surface of the bone is low. From an aesthetic point of view, we could not detect any disadvantage.

Bioresorbable plate fracture after cranioplasty caused by head injury: a pediatric case

Background

Recently, bone fixation materials have been developed as surgical materials. Bioabsorbable materials offer several advantages over other materials and are widely used. We report a rare case of the fracture of bioresorbable plates caused by head injury and describe some considerations.

Case description

A 6-year-old boy suffered from consciousness disturbance. He was admitted to our hospital and diagnosed with left frontal subcortical hemorrhage due to ruptured arteriovenous malformation (AVM). He received the surgery of removal of the AVM with decompressive craniectomy. He was discharged without any neurologic deficit and underwent the cranioplasty 4 months after the initial surgery. Two months after the last treatment, he was fallen and hit his left frontal head. The next day, he noticed an abnormal bulge in the injured area. We diagnosed the bulging as cerebrospinal fluid leakage because of the dural tear. The repairment of dural tear was performed. We found that two bioresorbable plates used by cranioplasty were both cracked, and the dura mater beneath them was torn. We repaired the damaged dura with an artificial dura mater. After surgery, cerebrospinal fluid leakage did not occur.

Conclusion

It has been reported that the durability of bioresorbable plates is no less than that of titanium plates. We experienced a relatively rare case in which bioabsorbable plate used for bone fixation was damaged due to head trauma. After craniotomy or cranioplasty using bioresorbable plates, special attention should be paid to head trauma that involves bone flap sinking force and side bending stress.

The Effect of Diclofenac Sodium-Loaded PLGA Rods on Bone Healing and Inflammation: A Histological and Histomorphometric Study in the Femur of Rats

Implants made of poly(lactide-co-glycolide) (PLGA) are biodegradable and frequently provoke foreign body reactions (FBR) in the host tissue. In order to modulate the inflammatory response of the host tissue, PLGA implants can be loaded with anti-inflammatory drugs. The aim of this study was to analyze the impact of PLGA 80/20 rods loaded with the diclofenac sodium (DS) on local tissue reactions in the femur of rats. Special emphasis was put on bone regeneration and the presence of multinucleated giant cells (MGCs) associated with FBR. PLGA 80/20 alone and PLGA 80/20 combined with DS was extruded into rods. PLGA rods loaded with DS (PLGA+DS) were implanted into the femora of 18 rats. Eighteen control rats received unloaded PLGA rods. The follow-up period was of 3, 6 and 12 weeks. Each group comprised of six rats. Peri-implant tissue reactions were histologically and histomorphometrically evaluated. The implantation of PLGA and PLGA+DS8 rods induced the formation of a layer of newly formed bone islands parallel to the contour of the implants. PLGA+DS rods tended to reduce the presence of multi-nucleated giant cells (MGCs) at the implant surface. Although it is known that the systemic administration of DS is associated with compromised bone healing, the local release of DS via PLGA rods did not have negative effects on bone regeneration in the femora of rats throughout 12 weeks.

Ultrasound-Activated Bioresorbable Osteosynthesis in the Treatment of Craniosynostosis

ABSTRACT

The purpose of this study is to estimate the incidence of fixation-related complications following ultrasound-activated biodegradable osteosynthesis (UBO) in the treatment of craniosynostosis. The authors searched MEDLINE, PubMed, Embase, Google Scholar, and Cochrane Library from January 2005 to January 2020 for clinical studies reporting the use of UBO for fixation in the treatment of craniosynostosis. The primary outcome was the incidence of fixation-related complications, including unstable fixation; swelling, plate visibility, or palpability; infection; inflammation, sinus formation, and discharge; implant exposure; reoperation or implant removal. The pooled incidence rates were estimated using random-effects models. Of 155 studies identified, 10 were included, representing 371 patients. Forty-six (12.4%) patients presented fixation-related complications. The incidence rates of swelling/visibility/palpability, infection, and reoperation/implant removal were pooled based on the available data. The pooled incidence rate of chronic swelling/visibility/palpability was 0.21 (95% confidence interval [CI], 0.05-0.43). Sensitivity analysis by omitting the outlier study demonstrates that the incidence of swelling/visibility/palpability was 0.07 (95% CI, 0.04-0.11). The pooled incidence rate of infection and reoperation/implant removal was 0.07 (95% CI, 0.01-0.16) and 0.04 (95% CI, 0.01-0.09), respectively. Results show that although UBO can provide stable fixation, chronic swelling/visibility/palpability, infection, and reoperation for removal are not uncommon. Based on the literature, the authors recommend judicious use of UBO in patients with large frontorbital advancement and in the area of the coronal suture or other sites with thin overlying skin/subcutaneous tissue. The high possibility of chronic swelling/palpability/visibility during degradation, needs to be discussed preoperatively.

Stability of bioresorbable plates following reduction of mandibular body fracture: Three-dimensional analysis

PURPOSE

The recent development of bioresorbable bone plates and screws allows plates to be applied to the load-bearing regions of the mandible and to remain in place over time without the need for removal. We hypothesized that the stability of composite plates and screws forged from unsintered hydroxyapatite particles and poly-l-lactide (u-HA/PLLA) is comparable to that of standard titanium fixation systems for the reduction of fractures of load-bearing regions of the mandibular body.

MATERIALS AND METHODS

40 patients underwent open reduction and internal fixation of the fractured mandibular body with either a titanium or u-HA/PLLA bone plate. Cone-beam CT images were obtained immediately postoperatively and at 6-month follow-up, and were analyzed for positional changes of the affected mandible.

RESULTS

There were no significant differences in the postoperative positional changes of reference points between the titanium and u-HA/PLLA miniplates, except for that for the coronoid process (p-value = 0.03). Multivariate regression analysis revealed no significant differences in spatial changes between the immediate postoperative and 6-month follow-up images, after adjusting for age and sex.

CONCLUSION

The stability of bioresorbable u-HA/PLLA miniplates and screws was comparable to that of titanium miniplates and screws immediately postoperatively and at 6-month follow-up, following surgical reduction of fractures of load-bearing regions of the mandibular body. Bioresorbable osteosynthesis can be considered a viable alternative to titanium osteosynthesis.

Tissue repair in neonatal and paediatric surgery: Analysis of infection in surgical implantation of synthetic resorbable biomaterials

BACKGROUND

There has been increased interest in the use of biomaterials that resorb completely leaving only the patient's native tissue. Synthetic materials are advantageous for tissue repair because they are highly customisable. The infection rate of using resorbable natural materials in paediatric surgery has recently been outlined, but there has not yet been a review of the use of synthetic resorbable materials in paediatric surgery.

OBJECTIVES

This systematic review analyses the risk of infection after implantation of fully resorbable synthetic biomaterials in paediatric cases.

METHODS

The literature was searched from January 1970 to January 2018 (inclusive), specifically searching for paediatric cases (0-18 years old), use of synthetic resorbable materials and infection.

RESULTS

The infection rate in 3573 cases of synthetic resorbable material implantation was 1.1% (41 cases). A Chi-squared test for independence found infection rate to vary among materials. Of the many biomaterials identified in this review, the highest infection rates were seen in Suprathel's use in burns injuries (12.1%).

CONCLUSIONS

This review found a low infection rate in synthetic resorbable materials used in paediatric surgery, with particularly strong evidence for low infection risk in LactoSorb® use.

Evaluation of Fronto-Orbital Advancement Using Titanium-Based Internal Fixation for Corrective Pediatric Craniofacial Surgery

BACKGROUND

For successful reshaping of the cranial vault in terms of corrective fronto-orbital advancement (FOA) efficient and reliable internal fixation systems for stabilization of bone fragments are indispensable. The rate of complications and feasibility of corrective FOA with the usage of titanium-based rigid fixation systems is rarely analyzed and discussed.

METHODS

The authors retrospectively reviewed the medical records of 42 patients who received corrective FOA with the implementation of titanium internal rigid fixation and consecutive secondary surgery for removal. The reliability of the fixation system was judged by the outcome of the FOA as evaluated by the Whitaker score, esthetic outcome as well as by the complication rate of the secondary intervention, necessary for removal of the fixation system.

RESULTS

All patients were categorized as Whitaker I (no further treatment desirable). Esthetic outcome was excellent in all patients as judged by surgeon and parents. Mean age at the time of FOA was 9.3 months. Time to removal, duration of the second hospital stay for removal of the fixation system, and duration of surgical drains were on average 5 months, 2 days, and 1.7 days, respectively. Mean duration of the secondary surgery was 63 min. No complications occurred.

CONCLUSION

Our investigation supports the usage of titanium internal rigid fixation systems in pediatric craniofacial surgery, thereby providing a reliable alternative to avoid the well-documented problems of bio-absorbable plate fixation systems.

Efficacy and Safety of Biodegradable Osteofixation Devices in Oral and Maxillofacial Surgery: a Systematic Review

The use of osteofixation devices should be evidence-based if uncomplicated bone healing is to be achieved. Numerous studies describe and claim the advantages of biodegradable over titanium devices as a bone fixation method. Here, we systematically review the available literature to determine the clinical efficacy and safety of biodegradable devices compared with titanium devices in oral and maxillofacial surgery. In addition, related general aspects of bone surgery are discussed. We conducted a highly sensitive search in the databases of MEDLINE (1966–2005), EMBASE (1989–2005), and CENTRAL (1800–2005) to identify eligible studies. Eligible studies were independently evaluated by two assessors using a quality assessment scale. The study selection procedure revealed four methodologically ‘acceptable’ articles. Owing to the different outcome measures used in the studies, it was impossible to perform a meta-analysis. Therefore, the major effects regarding the stability and morbidity of fracture fixation using titanium and biodegradable fixation systems were qualitatively described. Any firm conclusions regarding the fixation of traumatically fractured bone segments cannot be drawn, due to the lack of controlled clinical trials. Regarding the fixation of bone segments in orthognathic surgery, only a few controlled clinical studies are available. There does not appear to be a significant short-term difference between titanium and biodegradable fixation systems regarding stability and morbidity. However, definite conclusions, especially with respect to the long-term performance of biodegradable fixation devices used in maxillofacial surgery, cannot be drawn. Abbreviations: CENTRAL, Cochrane Central Register of Controlled Trials; MeSH, Medical Subject Heading; VAS, Visual Analogue Scale; and W, weight.

The Role of Resorbable Mesh as a Fixation Device in Craniosynostosis

The purpose of the study was to present our experience with endocranial fixation using the Resorb-X mesh (KLS Martin, Jacksonville, FL) in frontoorbital reconstruction. A retrospective review of all patients underwent frontoorbital advancement at our institution from 2003 to 2012 was performed. Inclusion criterion included: pediatric patients who underwent frontoorbital advancement for craniosynostosis; patients underwent treatment of the craniosynostosis only at our center; resorbable fixation devises were applied only endocranially; and follow-up was ≥ 2 years. Patients' evaluation included demographic information, postoperative complications, surgical outcomes, and postoperative computed tomographic imaging if accessible. Thirty-nine patients met the inclusion criteria. Resorbable plates were used in 16 patients and Resorb-X mesh in 23 patients. Observed complications were unrelated to the fixation system used. Resorption of fixation devices was evident in all patients after 20 months following reconstruction. There were no incidents of local reaction to the fixation system. Frontoorbital area contour was deemed good in 24 patients and excellent in 15 patients by both families and attending surgeon. There was a statistical significant difference (P = 0.030) between patients ≤ 12 months and >12 months regarding the complications rate. Endocranial fixation using the Resorb-X mesh is easily applicable, avoids material palpability, and provides stable and secure fixation. This technique is superior to the conventional endocranial osseous fixation with absorbable plates, as it avoids some of its possible complications while providing all the benefits of resorbable fixation.

Frontal cranial modeling using endocranial resorbable plate fixation in 27 consecutive plagiocephaly and trigonocephaly patients

INTRODUCTION

Premature ossification of coronal and metopic sutures is treated by fronto-orbital remodeling. Such operations require stable fixation of the reshaped cranial bones. Currently, biodegradable plating systems are used to provide sufficient stability over the time that takes for the osteotomies to ossify. Plates that are placed traditionally on the outer surface of the cranium are often palpable and even visible through the thin overlying skin, compromising the cosmetic results of these operations. Improved aesthetics could be achieved by placing the plates endocranially.

PURPOSE

This study aimed to evaluate endocranial resorbable plate fixation and its clinical and radiographic results in frontal remodeling cranioplasty for plagiocephaly and trigonocephaly patients with follow-up sufficiently long for the plates to have been completely resorbed.

METHODS

A poly(lactide-co-glycolide) (PLGA) resorbable plating system was used on the inner aspect of frontal bone in 27 patients treated for coronal and metopic craniosynostoses. The outcome was evaluated at follow-up visits. The mean follow-up was 79.2 months.

RESULTS

Three patients had complications that required reoperations. None of these complications were related to the endocranial location of the plates. There were no problems with ossification of the osteotomy sites. All but one patient's outcome was judged as good or excellent.

CONCLUSION

Placement of resorbable fixation on the endocranial surface of the calvarial bones is safe, stable, and results in satisfactory aesthetics without interfering with the ossification of the cranial bones.

Resorbable osteosynthetic devices in pediatric traumatology: a prospective series of 24 cases

Bioresorbable devices are commonly used in traumatology. The biomechanical stability of these materials has improved in the past decade, and they have proven to be biologically non-hazardous, while their main advantage is that their use avoids reintervention for removal of the device. A prospective monocentric study was conducted: 24 patients presenting with a fracture that was amenable to osteosynthesis by small-diameter screws were included. These comprised ten tibial spine fractures, four osteochondritis dissecans of the distal femur, eight fractures of the medial epicondyle of the distal humerus, and two distal tibial apophyseal fractures. One or more screws were used that were made of a copolymer of poly-L-lactide-poly-D-lactide acid and trimethylene carbonate with a diameter of 2.8 mm. All patients were immobilized with a cast. Clinical and radiographic monitoring was conducted every month. The entire follow-up protocol had a duration of 24 months. One patient with osteochondritis dissecans presented with joint effusion. Joint stiffness at the time of cast removal resolved completely after 4 months, except for with three children (one epicondyle fracture, two tibial spine fractures). No subjective or objective instability could be detected by clinical examination. Radiographic follow-up revealed no secondary displacement, and all of the fractures had healed. No osteolysis was seen around the screws. No growth disturbances were noticed. Bioresorbable materials thus appear to be a suitable alternative approach for certain pediatric fractures. Their use resulted in outcomes similar to traditional techniques in terms of functional properties and bone healing. Although initial costs are presumably slightly higher, by avoiding a removal operation the total financial burden is most likely reduced.

LEVEL OF EVIDENCE

III.

Cyanoacrylate Adhesive as an Alternative Tool for Membrane Fixation in Guided Tissue Regeneration

AIM

To report a well succeeded use of cyanoacrylate adhesive for fixating a resorbable membrane during a guided tissue regeneration procedure (GTR).

BACKGROUND

The immobilization of membranes in GTR is essential for establishing proper environment for cell differentiation and tissue regeneration. However, some membranes are very difficult to be kept in position by sutures and its fixation by mini screws or pins may be time consuming and expensive.

CASE DESCRIPTION

A 47-year-old woman presenting a vertical bone defect at the palatal aspect of the left central incisor was treated by GTR using particulate autogenous bone graft associated to a collagen membrane. The membrane was glued to the bone surrounding the defect and to the tooth surface with cyanoacrylate adhesive. The postoperative period was uneventful and 4 years later, excellent results in terms of radiographic filling of the defect and reduction of the probing depth were seen. For illustrative purposes, histological findings obtained during a previous experiment in calvaria of guinea pigs is shown, characterizing a foreign body granuloma and proving that the cyanoacrylate adhesive is a safe tool in GTR.

CONCLUSION

The use of a membrane glued with cyanoacrylate to immobilize membranes in GTR is viable and safe from both technical and biological standpoints and may be advantageous for clinical and research purposes.

CLINICAL SIGNIFICANCE

The alternative method for membrane fixation shown in this case report can contribute to simplify the technique in GTR procedures.

The "in situ molding technique: " an accurate and simple way to fix resorbable plates to the facial skeleton

Bioabsorbable plates developed for use in the facial skeleton have become an integral part of the craniomaxillofacial surgeon's reconstructive armamentarium. They avoid the problems associated with the retention of metal plates and can be easily contoured when heated in a thermobath. The technical process of molding and securing these devices, often through small access incisions, to achieve rigid fixation of facial fractures can be difficult. In this article, we describe a simple, novel technique that we have developed, using hot water suction irrigation, to achieve in situ molding of resorbable plates during facial fracture fixation. We used this technique to fix 123 facial fractures in 110 patients over a 4-year period. No complications secondary to the use of hot water suction irrigation were encountered.

Biomaterials for craniofacial reconstruction

Biomaterials for reconstruction of bony defects of the skull comprise of osteosynthetic materials applied after osteotomies or traumatic fractures and materials to fill bony defects which result from malformation, trauma or tumor resections. Other applications concern functional augmentations for dental implants or aesthetic augmentations in the facial region. For ostheosynthesis, mini- and microplates made from titanium alloys provide major advantages concerning biocompatibility, stability and individual fitting to the implant bed. The necessity of removing asymptomatic plates and screws after fracture healing is still a controversial issue. Risks and costs of secondary surgery for removal face a low rate of complications (due to corrosion products) when the material remains in situ. Resorbable osteosynthesis systems have similar mechanical stability and are especially useful in the growing skull. The huge variety of biomaterials for the reconstruction of bony defects makes it difficult to decide which material is adequate for which indication and for which site. The optimal biomaterial that meets every requirement (e.g. biocompatibility, stability, intraoperative fitting, product safety, low costs etc.) does not exist. The different material types are (autogenic) bone and many alloplastics such as metals (mainly titanium), ceramics, plastics and composites. Future developments aim to improve physical and biological properties, especially regarding surface interactions. To date, tissue engineered bone is far from routine clinical application.

A retrospective follow-up of ankle fracture patients treated with a biodegradable plate and screws

BACKGROUND

Biodegradable fixation implants have been developed to avoid secondary hardware removal. The aim of this study was to retrospectively follow-up ankle fracture patients treated with a biodegradable plate and screws, and to evaluate the clinical outcome and occurrence of complications.

METHODS

Fifty-seven ankle fracture patients treated with biodegradable implants were invited, and a total of 50 were available to participate in this study. The follow-up included a review of each patient's medical records, evaluation of radiographs, fracture reduction classification, and functional scoring.

RESULTS

There were 36 lateral malleolar and 14 bimalleolar fractures. No perioperative complications occurred. Average follow-up time was 17 months. All fractures healed. Fracture alignment was classified as anatomical in 49 patients and good in 1 case. The mean Olerud and Molander functional ankle score at final follow-up was 86. Eight patients had postoperative complications. These included delayed wound healing in 1 case, 3 cases of deep-vein thrombosis, and 4 soft tissue reactions.

CONCLUSIONS

According to the results of this retrospective study, the biodegradable implants used yielded fracture healing and functional results comparable to those previously reported after conventional metal fixation.

Bioabsorbable instrumentation for single-level cervical degenerative disc disease: a radiological and clinical outcome study

Object

The authors present the radiological and clinical outcome data obtained in patients who underwent single-level anterior cervical discectomy and fusion (ACDF) for cervical spondylosis and/or disc herniation; bioabsorbable plates were used for instrumentation. The use of metallic plates in ACDF has gained acceptance as a stabilizing part of the procedure to increase fusion rates, but when complications occur with these devices, the overall effectiveness of the procedure is compromised. As a possible solution, bioabsorbable implants for ACDF have been developed. This study investigates the feasibility and radiological and clinical outcomes of the bioabsorbable plates for ACDF.

Methods

The radiological and clinical outcomes of 30 patients were investigated retrospectively. All patients presented with cervical radiculopathy or myelopathy and underwent single-level ACDF in which a bioabsorbable anterior cervical plate and an allograft bone spacer were placed at a level between C-3 and C-7. Radiological outcome was assessed based on the fusion rate, subsidence, and Cobb angle of the surgical level. Clinical outcome was determined by using a visual analog scale, the Neck Disability Index, and the Odom criteria.

Results

There were no intraoperative complications, and no hardware failure was observed. No signs or symptoms of adverse tissue reaction caused by the implant were seen. Two reoperations were necessary due to postoperative blood collections. The overall complication rate was 16.7%. After 6 months, radiographic fusion was seen in 92.3% of patients. Subsidence at 11.3 ± 7.2 months was 3.1 ± 5.8 mm (an 8.2% change over the immediately postoperative results), and the change in the sagittal curvature was –2.7 ± 2.7°. The visual analog scale score for neck and arm pain and Neck Disability Index improved significantly after surgery (p < 0.001). Overall at 19.5 months postoperatively, 83% of the patients had favorable outcomes based on the Odom criteria.

Conclusions

Absorbable instrumentation provides better stability than the absence of a plate but graft subsidence and deformity rates may be higher than those associated with metal implants. There were no device-related complications, but adverse late effects cannot be excluded. The fusion rate and outcome are comparable to the results achieved with metallic plates. The authors were satisfied with the use of bioabsorbable plates as a reasonable alternative to metal, avoiding the need for lifelong metallic implants.

Biodegradable Polymers in Bone Tissue Engineering

The use of degradable polymers in medicine largely started around the mid 20^th century with their initial use as in vivo resorbing sutures. Thorough knowledge on this topic as been gained since then and the potential applications for these polymers were, and still are, rapidly expanding. After improving the properties of lactic acid-based polymers, these were no longer studied only from a scientific point of view, but also for their use in bone surgery in the 1990s. Unfortunately, after implanting these polymers, different foreign body reactions ranging from the presence of white blood cells to sterile sinuses with resorption of the original tissue were observed. This led to the misconception that degradable polymers would, in all cases, lead to inflammation and/or osteolysis at the implantation site. Nowadays, we have accumulated substantial knowledge on the issue of biocompatibility of biodegradable polymers and are able to tailor these polymers for specific applications and thereby strongly reduce the occurrence of adverse tissue reactions. However, the major issue of biofunctionality, when mechanical adaptation is taken into account, has hitherto been largely unrecognized. A thorough understanding of how to improve the biofunctionality, comprising biomechanical stability, but also visualization and sterilization of the material, together with the avoidance of fibrotic tissue formation and foreign body reactions, may greatly enhance the applicability and safety of degradable polymers in a wide area of tissue engineering applications. This review will address our current understanding of these biofunctionality factors, and will subsequently discuss the pitfalls remaining and potential solutions to solve these problems.

Focus session on the changing "epidemiology" of craniosynostosis (comparing two quinquennia: 1985-1989 and 2003-2007) and its impact on the daily clinical practice: a review from Necker Enfants Malades

INTRODUCTION

The aim of this study was to evaluate the evolution in craniosynostosis in terms of incidence and management in the last 20 years and to discuss the clinical implications and future perspectives with regards to the practical organization of daily practice.

METHODS

The relative incidence and management modalities of craniosynostosis hospitalized at the Craniofacial Unit of Necker, French National Referral Center for Faciocraniosynostosis, in two different quinquennia: 1985-1989 (group A) and 2003-2007 (group B) were reviewed.

RESULTS

A total of 1,286 children were included in our study; group A 472, group B 814, that is an overall increase of 1.7-fold in the second period of the study. Sagittal synostosis remained the most frequent type (45% of cases in both groups). Conversely, the number of cases of Pfeiffer syndrome increased from seven patients to 20 (x2.8) and metopic synostosis cases increased from 49 to 193 (x3.9). Mean age at surgery in group A was 22.5 months and 13 months in group B.

DISCUSSION

The comparison of the two quinquennia shows that there has been a change in the incidence of the different types of synostosis. The timing for surgery has also changed with the treatment of younger children in group B compared to group A. The principles of the surgical treatment of monosutural craniosynostosis have remained unmodified in our center. However, there has been an evolution in the techniques due to the introduction of new tools such as internal and external distractions, springs, and resorbable plates.

Biomechanical in vitro evaluation of the effect of cyclic loading on the postoperative fixation stability and degradation of a biodegradable ankle plate

The effect of cyclic loading on the postoperative fixation stability of a biodegradable ankle plate was tested biomechanically during 12 weeks of hydrolytic degradation. Fracture of the lateral malleolus was simulated, and the parameters of cyclic loading were chosen to represent the physiological conditions during the healing period. Additionally, the effect of cyclic loading on degradation was investigated by measuring the inherent viscosities. In Group I, the cyclic loading was conducted in four phases with gradual increases in estimated walking distance and speed during the healing period. In Group II, cyclic loading was conducted after 12 weeks. Group III was used as a control for inherent viscosity measurements. None of the specimens failed under cyclic loading. No significant differences were found between the loaded groups in any of the parameters measured. Additionally, no significant difference was found in inherent viscosities at 12 weeks. The initial fixation stability provided by the biodegradable ankle plate remains biomechanically unchanged over 12 weeks. Cyclic loading, applied either during or after 12 weeks of hydrolytic degradation, does not seem to have any clinically relevant effect on the fixation stability or the degradation properties.

Effective correction of frontal cranial deformities using biodegradable fixation on the inner surface of the cranial bones during infancy

PURPOSE

Fixation of cranial bones in pediatric craniofacial surgery with biodegradable materials has developed into an accepted method. However, placing the fixation material on the outer surface of the cranial bone at the frontal cranium in infants can result in suboptimal cosmetic outcomes, as the plates and screws can be palpable. The placement of resorbable fixation devices on the inner surface of the skull would allow for less obvious fixation beneath the skin with a potentially superior cosmetic result. The authors report the use of such resorbable fixation devices on the inner or endocranial aspect of the cranium which appears to be novel.

MATERIALS AND METHODS

Ten patients with the mean age of 14 months (range 7-35 months) were treated with cranial remodeling using poly(lactide-co-glycolide) (PLGA) biodegradable fixation on the inner surface of the cranial bones. Five patients had trigonocephaly, four plagiocephaly, and one brachycephaly. All patients had 3D computed tomography (CT) and clinical photographs done preoperatively and postoperatively at follow-up. The outcome was judged at follow-up by clinical evaluation, photographs, 3D CT, and interview of the parents. The mean follow-up time was 3.5 years (range 0.5-6 years).

RESULTS

The primary recovery was uneventful in all cases. No wound infection occurred, but one patient had a minor skin necrosis which required a single revision operation to correct. The cosmetic outcome was scored as excellent, good, fair, or poor. There was no case with delayed union. Seven out of ten cases were judged as excellent and three as good, none as fair or poor.

CONCLUSIONS

The use of resorbable PLGA fixation devices on the inner aspect of the skull appears to provide a satisfactory cosmetic result in this small preliminary group of pediatric patients. Further long-term study of these materials in this specific location in a larger patient group is needed.

Maximizing results in craniofacial surgery with bioresorbable fixation devices

The resorbable plating system allows the infant's skull to grow once the system is resorbed, thus not inhibiting the necessary developmental growth seen with the titanium system. Despite marked improvements in long-term outcomes, there are still technical points that can be followed to maximize outcome while reducing and possibly eliminating minor complications such as plate palpability and visibility through the skin as well as skin breakdown over the plate. A retrospective electronic chart review was performed on the pediatric patient population who underwent craniofacial surgery with the use of resorbable fixation devices by the senior author (LG). Fifty-two patients underwent surgical correction for craniosynostosis with resorbable material (Craniosorb, Lactosorb, or Biosorb PDX). This series included patients with brachycephaly (17), anterior plagiocephaly (unilateral coronal synostosis; 16), trigonocephaly (11), multisuture craniosynostosis (7), and Cohen's craniotelencephalic dysplasia (1). The mean age at the time of the operation was 8 months and the mean follow up was 17 months. Eight patients experienced complications related to the resorbable material. Seven of the eight had complete resolution of symptoms after conservative treatment and one patient had complete resolution of the skin infection after plate removal. The purpose of this study was to evaluate the risks and complications with the use of resorbable material to establish guidelines for avoidance of surgical pitfalls that lead to increased risk of morbidity with the use of this material, particularly as it relates to plate visibility under the skin, plate palpability, skin breakdown, and skin infections over the plating system.

Biomechanical stability of bioabsorbable screws for fixation of acetabular osteotomies

The purpose of this study was to compare the biomechanical stability of triple innominate osteotomies fixed with either bioabsorbable or stainless steel screws. Triple innominate osteotomies were performed on composite hemipelves and fixed with either three 4.5-mm bioabsorbable screws or three stainless steel 4.5-mm screws. Two screws were placed from the iliac wing into the acetabular fragment, and 1 screw was placed from below the acetabular fragment into the iliac wing. Eight specimens for each screw type were biomechanically tested in an anatomical position (replicating weight bearing) and in a flexed and abducted position (replicating spica cast positioning). Specimens were cyclically loaded between 10 and 450 N to simulate the hip contact force in this population. Lower screws were then removed, and specimens were tested under identical conditions. Fragment displacement (mm) and construct stiffness (N/mm) were compared with a 2-way analysis of variance (P < 0.05). There were no significant differences between materials for fragment displacement or construct stiffness. Anatomical position showed significantly less displacement than spica position for both materials. Initial displacement in the spica position was significantly less during lower loads for stainless steel fixation. Bioabsorbable screws demonstrate comparable biomechanical stability to stainless steel screws in anatomical and spica positions at physiological loads. Flexion and abduction of the femur adversely affect the stability of the construct for both materials. Bioabsorbable screws behave similarly to steel screws when stabilizing triple innominate osteotomies and would have the advantage of not requiring a second surgery for screw removal. Confirmation of biocompatibility should be completed before widespread clinical application.

Bioabsorbable implants

Absorbable implants have become the hottest implant material, overtaking titanium as the future. Absorbable devices have moved beyond orthopedics and maxillofacial surgery to spine, vascular, plastics and general surgery. This chapter outlines the experiences of many specialties.

The Effect of High Temperature Intraoperative Molding on Bioabsorbable PLLA-PGA Craniofacial Fixation

Bioabsorbable internal fixation has become an established part of the surgeons' armamentarium. There are several unique aspects of bioabsorbable polymers that can enhance their versatility. One of these is the application of heat to adapt the implant. Hot-tip cautery has been used for years to cut and otherwise customize bioabsorbable implants intraoperatively. As the tips of these devices can reach temperatures of over 1,000 degrees C, there is the potential that such practice can modify the degradation properties of these polymers. This study was performed to better understand the extent to which this potential exists. Screw heads of an 82:18 poly-L-lactic acid and poly-glycolic acid copolymer were modified by repeated passage of a hot-tip cautery wire, deforming the hex geometry to that of a ball. There was no significant difference between the glass transition temperature (approximately 59 degrees C) and inherent viscosity (approximately 1.45 dL/g) of treated and untreated screw heads, indicating no overall change in these properties throughout the mass of the screw head. Additionally, these properties were measured and comparisons made between the treated screw heads and untreated plates made of the same polymer during 28-day exposure to an in vitro bath (pH 7.4, 37 degrees C). The glass transition temperature and inherent viscosity exhibited declines during this period, with no significant differences between the two groups. Collectively, these results suggest that hot-tip cautery results in no substantial changes in the degradation characteristics of this polymer.

Self-Reinforced Ciprofloxacin-Releasing Polylactide-Co-Glycolide 80/20 Inhibits Attachment and Biofilm Formation by Staphylococcus Epidermidis

We have observed the efficiency of antibiotic-releasing polylactide-co-glycolide (PLGA) 80/20 in preventing Staphylococcus epidermidis attachment and biofilm formation in vitro. The aim of the present study was to evaluate the effect of self-reinforced (SR) implants with enhanced antibiotic release on bacterial attachment and biofilm formation rates, and also on growth inhibition of Staphylococcus epidermidis. Cylindrical SR-PLGA+AB specimens (length 30 mm, diameter 3 mm) were examined by scanning electron microscopy (SEM) for attachment of S. epidermidis ATCC 35989 on biomaterial surface and formation of biofilm, after incubating with bacterial suspension of ca. 10 cfu/mL for 1, 3, 7, 14 and 21 days. SR-PLGA and SR-PLGA+AB implants were tested on agar plates by measuring the inhibition distance around implants. On the surface of SR-PLGA+AB, at days 1, 3, 7, 14 and 21, the percentage of areas with not a single bacteria attached, was 88.6%, 71.1%, 73.7%, 73.7%, and 68.4%, respectively. On the areas where bacteria were detected, the number of bacterial cells remained low during whole study period, and no significant increase by time was seen. There was no biofilm observed on 97-99% of the examined areas during the whole study period on SR-PLGA+AB. In agar plates, the SR-PLGA+AB showed inhibition of bacterial growth, with (mean) 53.2 mm diameter of inhibition area with peeled implants and 50.5 mm with non-peeled implants. There was no inhibition seen around implants without ciprofloxacin. Bioabsorbable ciprofloxacin-releasing self-reinforced PLGA (SR-PLGA+AB) was superior to plain SR-PLGA in preventing bacterial attachment, biofilm formation, and also the growth of Staphylococcus epidermidis.

Effect of FGF and Polylactide Scaffolds on Calvarial Bone Healing With Growth Factor on Biodegradable Polymer Scaffolds

Repair of bone defects remains a major concern in reconstructive surgery. Synthetic biodegradable polymers have been used as scaffolds for guided bone regeneration. Fibroblast growth factors (FGFs) promote cell growth, differentiation, and tissue maintenance factors. They can stimulate the proliferation of osteogenic cells and chondrocytes, and also promote angiogenesis. Acidic and basic fibroblast growth factors (FGF-1 and FGF-2, respectively) are the best known members of this protein family. To evaluate the healing of experimental bone defects using poly-L/D-lactide (PLDLA) 96/4 scaffolds and FGF-1, 18 adult rats were operated on. A 6-mm diameter critical size defect (CSD) was made in the calvarial bone of each rat. The animals were divided into three treatment groups: 1) Neither scaffold nor FGF was used (control group); 2) scaffold only; and 3) scaffold with FGF-1. Follow-up time was eight weeks. Samples were embedded in methylmethacrylate and 5-microm thick sections from the middle of each specimen were stained with modified Masson-Goldner method. The shape and size of defects were evaluated radiologically. New bone formation was measured histologically and histomorphometrically. Radiologically, in the control group the shape of the defects changed from round to oval and edges were blunt. In the other groups the defects were round with sharp edges. Histomorphometrically, mean surface area of bone trabeculae was 1.05 mm (SD +/- 0.25) in group 1 (no implant), 1.35 mm (SD +/- 0.52) in group 2 (implant) and 0.79 mm (SD +/- 0.34) in group 3 (implant and FGF-1). Histological examinations revealed no or little osteoid in the groups 1 and 2, whereas in the group 3 samples had little or moderate new bone formation. Accordingly, no clear benefit of using knitted PLDLA scaffolds combined with FGF-1 on the healing of calvarial critical size defects in rats could be demonstrated.

Maxillary and mandibular osteosyntheses with PLGA and P(L/DL)LA implants: a 5-year inpatient biocompatibility and degradation experience

BACKGROUND

This study consists of a 5-year experience with 413 maxillary and mandibular resorbable plate osteosyntheses focusing on clinically apparent foreign body reaction (i.e., swelling, osteolyses, and fistulation), indirect implant degradation (i.e., palpability and radiographic reossification), and direct implant degradation (i.e., molecular weight and crystallinity of explants).

METHODS

Eighty fracture and reconstruction cases (32 female and 48 male patients, aged 1 to 83 years) were osteofixated with poly(L-lactide-co-glycolide) (PLGA) copolymer (n = 20) (139 PLGA osteosyntheses) or poly(L-lactide-co-DL-lactide) [P(L/DL)LA] (n = 60) [274 P(L/DL)LA osteosyntheses]. Local revisions (n = 30) were performed during secondary operations at 3, 6, 12, 18, or 24 months. Average clinical and radiographic follow-up lasted 29 months (range, 6 to 63 months).

RESULTS

Five patients (6 percent) had apparent foreign body reactions, whereas 75 (94 percent) did not. One P(L/DL)LA mild reaction was effectively treated with cold packs and analgesics, one PLGA and three P(L/DL)LA medium severe reactions were treated with curettage, and one local osteolysis disappeared at 6 months. Implant palpability lasted 12 (PLGA) or 24 months [P(L/DL)LA]. The difference was significant (p < 0.000001). Burr holes reossified at 24 (PLGA) and 36 months [P(L/DL)LA] (p < 0.05). The 85:15 PLGA explants' initial 44,600 molecular weight decreased to 11,000 at 6 months; and scarce powdering granular residuals, too small for molecular weight assessment, were encountered at 12 months. The 70:30 P(L/DL)LA initial molecular weight of 45,000 decreased to 25,000 at 6 months and 8,000 at 18 months and to similar granules at 24 months (p < 0.02). Histology showed macrophages, giant cells, lymphocyte infiltration, little granulocytic infiltration, and minimal bleeding residuals.

CONCLUSIONS

Both copolymers showed reliable biocompatibility and disintegration. Overall, 6 percent clinically apparent foreign body reactions were controlled conservatively and by local curettage; 85:15 PLGA degraded within 12 months and 70:30 P(L/DL)LA within 24 months, leaving powdering residual granules. Burr holes reossified 12 months later.

A Resorbable Rivet System for Pediatric Craniofacial Surgery: Biomechanical Testing and Clinical Experience

The use of a new method of bone fixation for pediatric craniofacial surgery was evaluated by both biomechanical tests and clinical use. A "pull-back" rivet composed of 82% poly-L-lactic acid and 18% polyglycolic acid (LactoSorb) for use with resorbable plates was developed to obviate the traditional hand-tapping technique used for the placement of resorbable screws. In in vitro testing, the average failure load of the rivets in uniaxial pullout was nearly 50 kg and approximately 75 kg in shear. Approximately two thirds of their initial strength was retained by 6 weeks. In clinical testing, 10 patients undergoing cranial vault reconstruction were treated by 1.5-mm resorbable plates secured by rivets. Although postoperative clinical outcomes were unaffected, good engagement of the devices with secure plate fixation was obtained in only about 70% of the rivets fired. Although the novel approach of a pull-back rivet was encouraging in both design and in vitro testing, its clinical use is impaired by the sensitivity of the device to the thickness of the bone into which it is placed, as well as its larger diameter compared with resorbable screws.

Bioabsorbable fixation in foot and ankle

Bioabsorbable implants are playing an increasing role in the surgical management of foot and ankle pathologies. Current technology allows implants to have acceptably comparable strength and pull-out characteristics to metallic implants. The advantages include elimination of secondary surgeries, biodegradability of implants placed across mobile articular surfaces, as well as acceptable biocompatibility and resorption properties to limit historical complication concerns.