Are there any complications with bioabsorbable fixation devices? A 10 year review in orthognathic surgery

Behavioral toxicity and neurotoxic mechanisms of PLA-PBAT biodegradable microplastics in zebrafish

Escalation of ecological concern due to biodegradable plastics has attracted the attention of many contemporary researchers. This study searched to investigate the acute and sub-chronic toxicity of polylactic acid (PLA) and polybutyleneadipate-co-terephthalate (PLA-PBAT) bio-microplastics on 3-month-old zebrafish to elucidate their potential toxic mechanisms. Acute toxicity assessments revealed 96 h-LC50 value of 12.69 mg/L for PLA-PBAT. Sub-chronic exposure of over 21 days revealed deviations in critical behavioral patterns and physiological indicators. In treated groups, weight gain and specific growth rates were significantly lower than those obtained for the control group, such that high doses induced significant reductions in total organ coefficient (p < 0.05). A positive correlation was observed between zebrafish mortality and increased doses. Detailed behavioral evaluations revealed a dose-dependent decrease in the speed and range of swimming, along with modifications in shoaling behavior, anxiety-like responses, and avoidance behaviors. Brain tissues transcriptomic analyses revealed the molecular responses underlying sub-chronic exposure to PLA-PBAT. Totally 702 DEGs and 5 KEGG pathways were significantly identified in low-dose group, with the top 2 significant pathways being ribosome pathway and cytokine-cytokine receptor interaction pathway. Totally 650 DEGs and 5 KEGG pathways were significantly identified in medium-dose group, with the top 2 significant pathways being Herpes simplex virus 1 infection pathway and complement and coagulation cascades pathway. Totally 1778 DEGs and 16 KEGG pathways were significantly identified in high-dose group, with the top 2 significant pathways being metabolism of xenobiotics by cytochrome P450 and drug metabolism - cytochrome P450 pathway. Most significantly enriched pathways are associated with immune responses. The validation of key gene in cytokine-cytokine receptor interaction pathway also confirmed its high correlation with behavioral indicators. These results indicate that PLA-PBAT is likely to cause behavioral abnormalities in zebrafish by triggering immune dysregulation in the brain.

Polylactide Degradation Activates Immune Cells by Metabolic Reprogramming

Polylactide (PLA) is the most widely utilized biopolymer in medicine. However, chronic inflammation and excessive fibrosis resulting from its degradation remain significant obstacles to extended clinical use. Immune cell activation has been correlated to the acidity of breakdown products, yet methods to neutralize the pH have not significantly reduced adverse responses. Using a bioenergetic model, delayed cellular changes were observed that are not apparent in the short-term. Amorphous and semi-crystalline PLA degradation products, including monomeric l-lactic acid, mechanistically remodel metabolism in cells leading to a reactive immune microenvironment characterized by elevated proinflammatory cytokines. Selective inhibition of metabolic reprogramming and altered bioenergetics both reduce these undesirable high cytokine levels and stimulate anti-inflammatory signals. The results present a new biocompatibility paradigm by identifying metabolism as a target for immunomodulation to increase tolerance to biomaterials, ensuring safe clinical application of PLA-based implants for soft- and hard-tissue regeneration, and advancing nanomedicine and drug delivery.

High Adherence of Oral Streptococcus to Polylactic Acid Might Explain Implant Infections Associated with PLA Mesh Implantation

The aim of this study was to evaluate and compare the biofilm formation properties of common pathogens associated with implant-related infections on two different implant material types. Bacterial strains tested in this study were Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Escherichia coli. Implant materials tested and compared were PLA Resorb × polymer of Poly DL-lactide (PDLLA) comprising 50% poly-L-lactic acid and 50% poly-D-lactic acid) and Ti grade 2 (tooled with a Planmeca CAD-CAM milling device). Biofilm assays were done with and without saliva treatment to evaluate the effect of saliva on bacterial adhesion and to mimic the intraoral and extraoral surgical routes of implant placement, respectively. Five specimens of each implant type were tested for each bacterial strain. Autoclaved material specimens were first treated with 1:1 saliva-PBS solution for 30 min, followed by washing of specimens and the addition of bacterial suspension. Specimens with bacterial suspension were incubated for 24 h at 37 °C for biofilm formation. After 24 h, non-adhered bacteria were removed, and specimens were washed, followed by removal and calculation of adhered bacterial biofilm. S. aureus and E. faecalis showed more attachment to Ti grade 2, whereas S. mutans showed higher adherence to PLA in a statistically significant manner. The salivary coating of specimens enhanced the bacterial attachment by all the bacterial strains tested. In conclusion, both implant materials showed significant levels of bacterial adhesion, but saliva treatment played a vital role in bacterial attachment, therefore, saliva contamination of the implant materials should be minimized and considered when placing implant materials inside the body.

Efficacy of bioresorbable plating system in the treatment of pediatric maxillary fractures: A short clinical study

Aim

The aim of this study was to evaluate the efficacy, stability, and clinical outcomes of a bioresorbable plating system in the treatment of pediatric maxillary fractures.

Materials and Methods

Twenty pediatric patients with maxillary fractures (13 males and 7 females) were included in this study. The 1.5- and 2.0-mm resorbable plates were used and secured with monocortical resorbable screws 6 mm and 7 mm in length. All patients were followed up for 6 months. Clinical parameters, such as pain, swelling, soft-tissue infection, malocclusion, nerve injury, and bite force for stability, were prospectively assessed.

Results

Fall from height (50%) was the most common cause of etiology, followed by road traffic accidents (35%). Maxillary alveolar # (40) was the most common fracture site, followed by nasal complex # (25%) and zygomatic complex # (25%). Appropriate fixation and adequate primary bone healing was achieved in 100% of the cases. Few minor complications were observed: (1) soft-tissue infection (5%) and (2) paresthesia (10%). There was a significant increase in bite force in the incisor and molar regions. Observation in clinical parameters shows that there was a significant reduction in postoperative pain and swelling at different follow-up periods.

Conclusion

Bioresorbable plating system is used as a load-sharing plate in a semirigid fixation technique after anatomic fracture reduction. Although its high costs limit its feasibility for use low infection rates, minimized second surgery for implant removal attracts its use. 1.5- and 2-mm resorbable plating system along is a good treatment modality for moderately displaced maxillary fractures in pediatric patients. Larger sample size and longer follow-up studies are required for conclusive results.

Investigation and Characterisation of New Eco-Friendly Cosmetic Ingredients Based on Probiotic Bacteria Ferment Filtrates in Combination with Alginite Mineral

In light of the fact that three of the five healthiest meals on earth are fermented, fermentation came into focus of both customers, product developers, and researchers all around the world. Even in the cosmetics industry, fermented cosmetics have been increasingly introduced, creating a market emphasising the positive image that healthy fermented substances are environment-friendly and that it also aids skin health. Moreover, discovering usages for various naturally occurring organo-mineral rocks is a growing area of research. Thus, this study’s aim was to combine the benefits of alginite and Lactobacilli (LAB) for cosmetic applications and investigate their combined effect on the skin considering the fermentation parameters as well, such as biomass and lactic acid concentration. The examined LAB strains were Lactobacillus rhamnosus, Lactobacillus acidophilus, Limosilactobacillus reuteri, and Lactococcus lactis, and a non-LAB probiotic strain Bifidobacterium adolescentis was also studied for the same purposes. The cell-free broth, also called as “filtrates”, of the fermentations—both those that included alginite and those that did not—were tested for skin moisturising with a corneometer and for antioxidant activity with DPPH scavenging, as well as for skin-whitening properties with the inhibition of mushroom tyrosinase. The findings suggest that the combination of alginite and Limosilactobacillus reuteri is a potential novel cosmeceutical component with skin tanning capabilities. This result may help create more readily available, environmentally friendly, natural, and sustainable cosmetic ingredients.

Comparative Study of Morphology and Distribution of Valves in Human Retromandibular Vein

The objective of this study was to analyze the distribution and morphology of the valves in the human retromandibular vein. The retromandibular, internal thoracic, azygos, femoral, and brachial veins were harvested from 46 cadavers donated to the Department of Anatomy at Tokyo Dental College for dissection. The frequency of the valves in each vein, the length of the cusps, and the thickness of the vein itself were measured. Valves were present at high frequency (92.1%) in the veins of the limbs and had cusps at least twice as long as the internal diameter of the vein. Veins in the trunk contained a lower frequency of valves, with cusps that tended to be shorter (1.60±0.77) than those of the venous valves in the limbs (2.12±0.60). The valves of the retromandibular vein tended to resemble venous valves in the trunk in terms of both frequency and morphology. The main function of venous valves in the limbs is to prevent retrograde flow. Conversely, valves in the veins of the trunk and retromandibular vein play a role in retaining blood in the veins, and their relationship to other veins means that they can cause major hemorrhage.

Prognosis of Patient With Resorbable Plates and Screws Under the Incision Site

Various resorbable plates and screws were used for facial bone fractures because of several strengths. However, there are few studies on their clinical course and long-term follow-up concerning their degradation and resorption time. The authors present rare case of long term follow-up of resorbable plates and screws under the incision site.

Comparison of the long-term clinical performance of a biodegradable and a titanium fixation system in maxillofacial surgery: A multicenter randomized controlled trial

BACKGROUND

Biodegradable fixation systems could reduce or eliminate problems associated with titanium removal of implants in a second operation.

AIM

The aim of this study was to compare the long-term (i.e. >5 years postoperatively) clinical performance of a titanium and a biodegradable system in oral and maxillofacial surgery.

MATERIALS AND METHODS

The present multicenter Randomized Controlled Trial (RCT) was performed in four hospitals in the Netherlands. Patients treated with a bilateral sagittal split osteotomy (BSSO) and/or a Le Fort-I osteotomy, and those treated for fractures of the mandible, maxilla, or zygoma were included from December 2006 to July 2009. The patients were randomly assigned to either a titanium (KLS Martin) or a biodegradable group (Inion CPS).

RESULTS

After >5 years postoperatively, plate removal was performed in 22 of the 134 (16.4%) patients treated with titanium and in 23 of the 87 (26.4%) patients treated with the biodegradable system (P = 0.036, hazard ratio (HR) biodegradable (95% CI) = 2.0 (1.05-3.8), HR titanium = 1). Occlusion, VAS pain scores, and MFIQ showed good and (almost) pain free mandibular function in both groups.

CONCLUSION

In conclusion, the performance of the Inion CPS biodegradable system was inferior compared to the KLS Martin titanium system regarding plate/screws removal in the abovementioned surgical procedures.

TRIAL REGISTRATION

http://controlled-trials.com ISRCTN44212338.

Postpolymerization Modifications of Alkene-Functional Polycarbonates for the Development of Advanced Materials Biomaterials

Functional aliphatic polycarbonates have attracted significant attention as materials for use as biomedical polymers in recent years. The incorporation of pendent functionality offers a facile method of modifying materials postpolymerization, thus enabling functionalities not compatible with ring-opening polymerization (ROP) to be introduced into the polymer. In particular, polycarbonates bearing alkene-terminated functional groups have generated considerable interest as a result of their ease of synthesis, and the wide range of materials that can be obtained by performing simple postpolymerization modifications on this functionality, for example, through radical thiol-ene addition, Michael addition, and epoxidation reactions. This review presents an in-depth appraisal of the methods used to modify alkene-functional polycarbonates postpolymerization, and the diversity of practical applications for which these materials and their derivatives have been used.

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.

Tissue response after implantation of pure titanium and bioresorbable screws in scapula with postoperative irradiation: an experimental study on rats

OBJECTIVE

The study focuses on the comparison of tissue reaction to titanium and bioresorbable implants with and without postoperative irradiation on an animal model.

MATERIALS AND METHODS

Thirty-nine LEW/W rats were randomly assigned to experimental or control groups. One titanium and one bioresorbable screw (poly-L-lactide [PLLA] and L- and D-lactide poly-L/D-lactide [PDLLA]) were implanted into the left scapulas of 24 rats. Half of them received 30 Gy to the operation site and the other half received 42 Gy. In the control groups, 3 rats received 30 Gy, and 6 rats received 42 Gy to the scapula area without operation; and 6 rats had implants inserted as in the experimental group, but received no postoperative irradiation. The scapulas were removed 14 or 30 days after irradiation and a histologic analysis was performed.

RESULTS

The host tissue reaction to titanium and PLLA-PDLLA screws without postoperative irradiation was of similar intensity. In irradiated animals, the inflammatory tissue reaction was more evident around the titanium screws than around the bioresorbable screws, irrespective of the radiation dose and of the time that elapsed from the irradiation. The reaction was more evident on the 14th day than on the 30th day after the last radiation dose (70 and 86 days after surgery, respectively). The intensity of the inflammatory tissue reaction, irrespective of the implant type, was more intense in the group irradiated with 42 Gy.

CONCLUSIONS

PLLA-PDLLA implants appear to cause less tissue reaction after irradiation and could be safer reconstructive devices than titanium implants for patients undergoing surgery and adjuvant radiotherapy for cancer.

Cost-Effectiveness of a Biodegradable Compared to a Titanium Fixation System in Maxillofacial Surgery: A Multicenter Randomized Controlled Trial

Background

Biodegradable fixation systems could reduce/delete the problems associated with titanium plate removal. This means less surgical discomfort, and a reduction in costs.

Aim

The aim of the present study was to compare the cost-effectiveness between a biodegradable and a titanium system in Maxillofacial surgery.

Materials and Methods

This multicenter RCT was performed in the Netherlands from December 2006 to July 2009. Included were 230 patients who underwent a bilateral sagittal split osteotomy (BSSO), a Le Fort-I osteotomy, or a bi-maxillary osteotomy and those treated for fractures of the mandible, maxilla, or zygoma. The patients were randomly assigned to a titanium group (KLS Martin) or to a biodegradable group (Inion CPS). Costs were assessed from a societal perspective. Health outcomes in the incremental cost-effectiveness ratio (ICER) were bone healing (8 weeks) and plate removal (2 years).

Results

In 25 out of the 117 patients who were randomized to the biodegradable group, the maxillofacial surgeon made the decision to switch to the titanium system intra-operatively. This resulted in an Intention-To-Treat (ITT-)analysis and a Treatment-Received (TR-) analysis. Both analyses indicated that operations performed with titanium plates and screws had better health outcomes. In the TR-analysis the costs were lower in the biodegradable group, in the ITT-analysis costs were lower in the titanium group.

Conclusion and Discussion

The difference in costs between the ITT and the TR analyses can be explained by the intra-operative switches: In the TR-analysis the switches were analysed in the titanium group. In the ITT-analysis they were analysed in the biodegradable group. Considering the cost-effectiveness the titanium system is preferable to the biodegradable system in the regular treatment spectrum of mandibular, Le Fort-I, and zygomatic fractures, and BSSO’s, Le Fort-I osteotomies and bimaxillary osteotomies.

Trial Registration

Controlled-Trials.com ISRCTN 44212338

Bioabsorbable osteofixation for orthognathic surgery

Orthognathic surgery requires stable fixation for uneventful healing of osteotomized bony segments and optimal remodeling. Titanium plates and screws have been accepted as the gold standard for rigid fixation in orthognathic surgery. Although titanium osteofixation is the most widely used approach, the use of bioabsorbable devices has been increasing recently. Biodegradation of bioabsorbable devices eliminates the need for a second operation to remove metal plates and screws. However, long-term stability and relapse frequency in bioabsorbable osteofixation are still insufficiently studied, especially in cases of segmental movements of great magnitude or segmental movements to a position where bony resistance exists. This paper reviews the background, techniques, and complications of bioabsorbable osteofixation and compares bioabsorbable and titanium osteofixation in orthognathic surgery in terms of skeletal stability.

In Vitro Degradation of Poly-L-DL-Lactic Acid (PLDLLA) after Two Processing Methods

This study evaluated thein vitrodegradation of pellet, powder and plates of poly-L-DL-lactic acid (PLDLLA) after two processing methods. Part of the material was reduced to powder by cryogenic milling and part of it molded injected in plate form. The crystallinity was evaluated by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Gel Permeation Chromatography (GPC) before and after immersion in simulated body fluid for 30, 60, and 90 days. The glass transition temperature (Tg) of the pellets and the powder were 61.5°C, 66°C. The Tgs of the plates ranged from 59.55°C to 63.06°C. Their endothermic peaks were observed at 125°C and 120°C, which was not identified to the plates samples. The FTIR spectrum showed bands of amorphous and crystalline content. The XRD results showed a peak related to the crystalline content, and a wide reflection related to the amorphous content. The milling process increased the crystallinity and the molding injection decreased it.

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.

Comparison of biodegradable and titanium fixation systems in maxillofacial surgery: a two-year multi-center randomized controlled trial

Biodegradable osteosynthesis could reduce/delete the problems associated with titanium plate removal. The aim of the present study was to compare the clinical performance in the first 2 post-operative years between a biodegradable and a titanium system in oral and maxillofacial surgery. The multicenter randomized controlled trial (RCT) was performed in the Netherlands from December 2006 to July 2009. Included were 230 patients who underwent a bilateral sagittal split osteotomy (BSSO) and/or a Le Fort-I osteotomy and those treated for fractures of the mandible, maxilla, or zygoma. The patients were randomly assigned to a titanium group (KLS Martin) or to a biodegradable group (Inion CPS). Plate removal was necessary in 16 of the 134 patients (11.9%) treated with titanium and in 21 of the 87 patients (24.1%) treated with the biodegradable system within the first 2 post-operative years [p = .016, HR biodegradable (95% CI) = 2.2 (1.1-4.2), HR titanium = 1]. Occlusion, VAS, and MFIQ scores showed that both groups had good mandibular function and were (almost) free of pain 1 and 2 years post-operatively (http://controlled-trials.com ISRCTN 44212338).

Evaluation of bioresorbable plates in condylar fracture fixation: a case series

The objective of this study was to evaluate the efficacy and stability of bioresorbable plates in condylar fractures in adults. Twelve adult patients who had sustained a condylar fracture, either alone or in combination with other mandibular fractures, were clinically and radiologically assessed for the efficacy and stability of bioresorbable plate and screw fixation. Intraoperatively, a total of seven screw breakages were noted. Six cases showed instability of the fractured fragments after fixation with bioresorbable plates and screws; the other six cases showed adequate stability. A single bioresorbable plate does not provide satisfactory stability for condylar fractures. Also, the screw breakages add additional surgical time and cost to the patient.

Zygomatic complex fracture: A comparative evaluation of stability using titanium and bio-resorbable plates as one point fixation

BACKGROUND

The malar bone represents a strong bone on fragile support and its processes - frontal, orbital, maxillary and zygomatic are frequently the site of fracture. Current study was done to compare the stability of zygomatic complex fracture using Biodegradable plates and titanium miniplates with one point fixation.

MATERIALS AND METHODS

Twenty patients of zygomatic complex fracture were randomly selected and divided in two groups which were further divided into two subgroups (A, B). Group I patients were treated with titanium miniplate at zygomatic buttress and Group II was treated by bio-resorbable plates. One point fixation was done either at zygomatic buttress or at frontozygomatic suture and it was observed that both the site have been the most favored site of rigid internal fixation in terms of stability, aesthetics and prevention of rotation of the fracture segment in either vertical or horizontal axis.

CONCLUSION

There is no significant difference in post operative outcomes between two groups, but still bioresorbable system has some advantage over titanium system as these plates resorbs over a period of time and does not cause any interference with growth and post operative radiotherapy. However application of biodegradable system demands highly précised technique.

Skeletal stability and morbidity with self-reinforced P (L/DL) LA resorbable osteosynthesis in bimaxillary orthognathic surgery

INTRODUCTION

We present a retrospective study of 30 consecutive cases of bimaxillary orthognathic surgery with biodegradable self-reinforced poly-L/DL-lactide plates and tacks, for the same indication of Angle class III malocclusion. We reported the skeletal stability and morbidity at 1 year after surgery.

PATIENTS AND METHODS

All patients underwent bimaxillary procedure. We used self-reinforced poly-L/DL lactic acid copolymer. Stabilization of Lefort I osteotomy was achieved by four plates L-shaped. Sagittal split osteotomies were fixed by two straight-plates. Lateral cephalograms were taken before (T0), soon after (T1) and more than 1 year after surgery (T2). Eight standard landmarks and four angular measurements were taken into account. All differences of the landmarks and angles were measured at T1 and T2. The regular clinical follow-up was scheduled for a minimum period of 1 year.

RESULTS

The mean advanced maxillary was 3.33 mm and the mean mandibular setback was 6.13 mm. The mean mandibular relapse was 2.2 mm (non-significant). Horizontal maxilla mean variation was 0.8 mm at 1 year at A-point. Vertical maxilla stability depends on maxillary movements: impaction stability is better as an isolated advancement or associated with pull-down movement. We found six inflammatory reactions and two of them need the removal of the plates.

CONCLUSION

Bimaxillary orthognathic procedure with bioresorbable osteosynthesis is a reliable and reproducible method. Angle class III malocclusions could be entirely and successfully managed with bioresorbable osteosynthesis. The stability and suites at 1 year are comparable to titanium osteosynthesis.

Operative treatment of chest wall injuries: indications, technique, and outcomes

Most injuries to the chest wall with residual deformity do not result in long-term respiratory dysfunction unless they are associated with pulmonary contusion. Indications for operative fixation include flail chest, reduction of pain and disability, a chest wall deformity or defect, symptomatic nonunion, thoracotomy for other indications, and open fractures. Operative indications for chest wall injuries are rare.

Rib fracture repair: indications, technical issues, and future directions

Rib fracture repair has been performed at selected centers around the world for more than 50 years; however, the operative indications have not been established and are considered controversial. The outcome of a strictly nonoperative approach may not be optimal. Potential indications for rib fracture repair include flail chest, painful, movable rib fractures refractory to conventional pain management, chest wall deformity/defect, rib fracture nonunion, and during thoracotomy for other traumatic indication. Rib fracture repair is technically challenging secondary to the human rib's relatively thin cortex and its tendency to fracture obliquely. Nonetheless, several effective repair systems have been developed. Future directions for progress on this important surgical problem include the development of minimally invasive techniques and the conduct of multicenter, randomized trials.

Autograft containment in posterolateral spine fusion

BACKGROUND CONTEXT

Pseudoarthrosis rates in lumbar intertransverse fusion remain high. Compression and displacement of the developing fusion mass by the paraspinal musculature may be a contributory factor. Biocontainment devices have been clinically used in the skull and mandible to guide bone regeneration. The role of a mechanical device in containing graft material in the developing posterolateral lumbar spine fusion is unclear.

PURPOSE

To determine the benefits of using a bioabsorbable graft-containment device for lumbar intertransverse fusion, and to evaluate the biocompatibility of this implant by histological analysis of the host tissue reaction.

STUDY DESIGN

A rabbit intertransverse spine fusion model was used to evaluate a bioabsorbable graft-containment implant. Study and control groups were compared with regard to the rate, volume, and quality of fusion, as well as host tissue reaction to the graft and implant.

METHODS

Fourteen adult male New Zealand White rabbits underwent bilateral posterolateral intertransverse spine arthrodesis at L3-L4. The control group (n=7) received autograft alone, and the study group received autografts placed in open meshed hemicylinders fashioned from LactoSorb sheets (LactoSorb; Biomet Orthopedics Inc., Warsaw, IN). Spines were harvested at 6 weeks and imaged. Radiographs and computed tomography (CT) images were used to calculate the rate, area, and volume of fusion mass. Sections were fixed and stained with hematoxylin-eosin and Mallory trichrome for histological analysis of fusion and host tissue response. The Mann-Whitney nonparametric statistical test was used for the radiographic and CT qualitative assessments. The CT volume quantitation was analyzed using the Student t test. A p value of <.05 was used to assign statistical significance.

RESULTS

The fusion rates on radiographs and CT imaging did not show a significant difference (p>.05) between the biocontainment and control groups. The volume of fusion revealed a significant increase with biocontainment (mean+/-standard error; total left+right fusion sides=2.88+/-0.30 cc) compared with controls (2.12+/-0.15 cc) (p<.05). Histology revealed no difference in the maturity or the quality of the fusion mass between the two groups. Inflammatory response around the developing fusion mass and muscle necrosis were slightly increased in the study group. The LactoSorb biocontainment material led to variable inflammatory reaction, with some areas showing little or no response and other showing an inflammatory response with fibrous connective tissue, lymphocyte infiltration, and focal foreign body giant cell reaction.

CONCLUSIONS

The incidence of fusion was similar with or without a containment device for onlay bone graft. A significant increase in the volume of the fusion suggests that a biocontainment device does play a role in protecting the developing fusion mass from the mechanical effects of the paraspinal musculature. The clinical use of this device cannot be justified at this time, and further studies will determine whether this increase in fusion volume will translate into a better incidence and volume of fusion in primate and human models.

Resorbable Anterior Cervical Plates for Single-Level Degenerative Disc Disease

Objective:

Resorbable spinal implants have generated increasing interest. There are minimal data in the literature on the use of resorbable anterior cervical plates. The purpose of this study is twofold. First, we present clinical outcomes of anterior cervical decompression and fusion (ACDF) for single-level degenerative disease using the first commercially available resorbable cervical plate. Second, we compare x-ray outcomes, including pseudarthrosis rates and angulation of healing, between patients receiving resorbable plates and a control group of patients receiving titanium plates.

Methods:

Twenty-four consecutive patients treated with single-level ACDF using a resorbable anterior cervical plate were prospectively evaluated with minimum 12-month follow-up (mean, 15 mo). As a control group, 93 consecutive patients treated with single-level ACDF using a titanium plate with minimum 1-year follow-up were assessed.

Results:

Overall outcomes were good in the resorbable plate group at a mean 15 months follow-up. Neck Disability Index scores decreased from a mean of 64.0 to 20.1% at follow-up (P &lt; 0.001). Numerical Rating Scale pain scores decreased from a mean of 8.0 preoperatively to 2.9 at follow-up (P &lt; 0.001). Three cases of pseudarthrosis [three of 24 (12.5%)] were identified in the resorbable plate group compared with two cases in the control group [two of 93 (2.2%)]. This difference was significant (P = 0.047). Angulation was measured on final x-rays using Cobb angles. Patients in the resorbable plate group healed with a mean 4.52-degree kyphosis, whereas patients in the titanium plate group healed with a mean 2.41-degree lordosis (P &lt; 0.001).

Conclusion:

This report describes, to our knowledge, the first series of patients to undergo ACDF with the first commercially available resorbable cervical plate. Healing in kyphosis and pseudarthrosis was significantly more likely with resorbable implants as compared with the use of titanium plating. Although ultimate clinical outcomes were good, x-ray outcomes may be better with the use of titanium plating.

Segment Stability in Bimaxillary Orthognathic Surgery After Resorbable Poly(L-lactide-co-glycolide) versus Titanium Osteosyntheses

This study compared segment stability after bimaxillary orthognathic surgery, comparing poly(L-lactide-co-glycolide) with titanium osteofixation at 12 months follow up. Fifteen patients were osteofixated with poly(L-lactide-co-glycolide) copolymer, 30 with 2.0-mm titanium miniplates. Preoperative, postoperative, and 1-year follow-up lateral cephalograms were analyzed. Maxillary average advancement in resorbable plate osteosyntheses (+/- standard deviation) was (case numbers/titanium controls) 2.5 (+/- 1.0) mm; n = 7/5.4 (+/- 3.5)mm; n = 21, setback 2.2 (+/- 2.4) mm; n = 7/1.9 (+/- 1.8) mm; n = 8, elongation 6.5 (+/- 3.4) mm; n = 9/3.7 (+/- 5.2) mm; n = 14, intrusion 1.0 (+/- 0.7) mm; n = 5/3.3 (+/- 2.7)mm; n = 13, mandibular average advancement was 5.5 (+/- 3.7) mm; n = 4/6.3 (+/- 8.8) mm; n = 18, setback 11.2 (+/- 7.7) mm; n = 7/7.2 (+/- 3.2) mm; n = 12, mandibular angle enlargement 7.9 (+/- 2.4) degrees ; n = 9/7.9 (+/- 6.6) degrees ; n = 21, reduction 6.9 (+/- 2.6) degrees ; n = 4/6.3 (+/- 6.6) degrees ; n = 9. Changes in landmark position within the study and control groups differed significantly in paired t testing (P =.01); operative movements were comparable in between study and control groups (P = 0.5, two-sided t test), only maxillary advancement was significantly smaller (P = 0.04) within study cases. Absolute instability at advanced A-point was (study group/controls) 1.2 (+/- 0.8)/2.4 (+/- 2) mm; setback 1.8 (+/- 1.9) mm/2.5 (+/- 1.7) mm; elongation at anterior nasal spine (ANS) 2.0 (+/- 1.4) mm/3.1 (+/- 3.6) mm, intrusion 1.1 (+/- 1.1) mm/2.2 (+/- 1.5) mm; advancement instability at B-point was 2.6 (+/- 2.7) mm/5.1 (+/- 8.2) mm, setback 2.7 (+/- 2.6) mm/1.7 (+/- 2) mm; mandibular angle enlargement instability 2.4 (+/- 2.7) degrees /8.2 (+/- 9.6) degrees , angle narrowing 7.0 (+/- 5.4) degrees /4.2 (+/- 5.9) degrees . Absolute postoperative instability was not significantly different in between study and control groups (P = 0.3). Tested resorbable poly(L-lactide-co-glycolide) osteofixation proved to be as reliable in segment fixation as titanium; however, study and control groups were not matched; the study group was small and therefore the results (especially advancement) have to be interpreted as preliminary until larger prospective cohorts become evaluated.

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.

Skeletal Stability in Bimaxillary Orthognathic Surgery: P(L/DL)LA-Resorbable versus Titanium Osteofixation

BACKGROUND

One-year skeletal stability following bimaxillary orthognathic surgery was assessed by comparing poly(L-lactide-co-DL-lactide) to titanium osteofixation.

METHODS

Thirty patients underwent osteofixation with poly(L-lactide-co-DL-lactide) copolymer and 30 had 2.0-mm titanium-miniplate osteosyntheses. Lateral cephalograms were analyzed preoperatively, postoperatively, and at 1-year follow-up. Average +/- SD values were as follows in resorbable plate-osteosyntheses (number of cases/titanium controls): for maxillary advancement, 3.5 +/- 4.1 mm (n = 19)/5.4 +/- 3.5 mm (n = 21); setback, 2.8 +/- 3.7 mm (n = 9)/1.9 +/- 1.8 mm (n = 8); elongation, 4.2 +/- 3.6 mm (n = 18)/3.7 +/- 5.2 mm (n = 14); and intrusion, 1.9 +/- 1.7 mm (n = 12)/3.3 +/- 2.7 mm (n = 13); for mandibular advancement, 4.6 +/- 3.6 mm (n = 10)/6.3 +/- 8.8 mm (n = 18); setback, 7.5 +/- 8.3 mm (n = 20)/7.2 +/- 3.2 mm (n = 12); enlargement of the mandibular angle, 11.8 +/- 9.9 degrees (n = 19)/7.9 +/- 6.6 degrees (n = 21); and reduction, 4.5 +/- 3.2 degrees (n = 9)/6.3 +/- 6.6 degrees (n = 9).

RESULTS

Preoperative to postoperative landmark positions within the study and control groups differed highly significantly (p = 0.008, paired t test), yet the amount of operative movement was comparable between the study and control groups (p = 0.5, two-sided t test). Absolute instability at the advanced A-point was (study group/controls) 2.3 +/- 1.8/2.4 +/- 2 mm, setback was 2.3 +/- 1.9 mm/2.5 +/- 1.7 mm, elongation at the anterior nasal spine was 3.8 +/- 3.1 mm/3.1 +/- 3.6 mm, intrusion was 2.1 +/- 1.9 mm/2.2 +/- 1.5 mm, advancement instability at the B-point was 4.9 +/- 4.3 mm/5.1 +/- 8.2 mm, setback was 3.0 +/- 2 mm/1.7 +/- 2 mm, mandibular angle enlargement instability was 6.7 +/- 8.9 degrees/8.2 +/- 9.6 degrees, and angle narrowing was 6.8 +/- 5.2 degrees/4.2 +/- 5.9 degrees. Absolute postoperative instability did not differ significantly between the study and control groups (p = 0.6).

CONCLUSIONS

Resorbable osteofixation as tested proved to be as reliable as titanium, but as the study and control groups were not matched, the results have to be interpreted as preliminary. Resorbable materials permitted clinically faster occlusal and condylar settling than standard titanium osteosyntheses, as bone segments showed slight clinical mobility up to 6 weeks postoperatively.

A histological and immunohistochemical study of tissue reactions to solid poly(ortho ester) in rabbits

In many cases only the temporary presence of a biomaterial is needed in tissue support, augmentation or replacement. In such cases biodegradable materials are better alternatives than biostable ones. At present, biodegradable polymers are widely used in the field of maxillofacial surgery as sutures, fracture fixation devices and as absorbable membranes. The most often used polymers are aliphatic polyesters, such as polyglycolic acid (PGA) and polylactic acid (PLA). Poly(ortho ester) is a surface eroding polymer, which has been under development since 1970, but is used mostly in drug delivery systems in semisolid form. The aim of this study was to evaluate the tissue reactions of solid poly(ortho ester) (POE), histologically and immunohistochemically. Resorption times and the effect of 2 different sterilization methods (gamma radiation and ethylene oxide) upon resorption were also evaluated. Material was implanted into the tibia and subcutaneously into the mandibular ramus area of 24 rabbits. Follow-up times were 1-10, 14 and 24 weeks. Histological studies showed that POE induces a moderate inflammation in soft tissue and in bone. At 24 week follow-up, inflammation was mild in soft tissue and moderate in bone. In immunohistochemical studies, no highly fluorescent layer of tenascin or fibronectin was found adjacent to the implant. Resorption of gamma-sterilized rods was faster than ethylene oxide-sterilized rods. The total resorption time was more than 24 weeks in both groups. Clinically the healing was uneventful and the implants the well tolerated by the living tissue. This encourages these authors to continue studies with this interesting new material to search for the ideal material for bone filling and fracture fixation.

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.

Degradação acelerada de suportes de poli(épsilon-caprolactona) e poli(D,L-ácido láctico-co-ácido glicólico) em meio alcalino

O estudo da degradação in vitro de polímeros bioreabsorvíveis em soluções alcalinas vem sendo proposto nos últimos anos como alternativa aos estudos tradicionais feitos em tampão fosfato. Este trabalho descreve a degradação acelerada de poli(épsilon-caprolactona) (PCL) e poli(D,L-ácido láctico-co-ácido glicólico) (50/50) (PLGA50), polímeros biodegradáveis e bioreabsorvíveis, amplamente estudados em aplicações biomédicas. Amostras foram preparadas pelo método de fusão seguido de injeção em molde cilíndrico (2 mm diâmetro), a 160 ºC, e submetidas à degradação em soluções de NaOH em pH 12, 13 e 13,7 a 37 ºC. Por meio da caracterização da variação da massa, morfologia e propriedades térmicas, por calorimetria exploratória diferencial, os resultados mostraram que as amostras de PCL são mais estáveis quando comparadas às de PLGA50. Pela taxa de variação das propriedades térmicas foi possível extrapolá-las em função do tempo em pH fisiológico, 7,4. Validado, o estudo da degradação acelerada em meio alcalino mostrou-se como uma técnica útil e de baixo custo para avaliar o comportamento em curtos períodos de degradação.

Five-year experience comparing resorbable to titanium miniplate osteosynthesis in cleft lip and palate orthognathic surgery

OBJECTIVE

To evaluate 5-year outcome stability and complications in orthognathic surgery using resorbable versus titanium osteofixation.

PATIENTS, METHODS

Twenty-two cleft lip and palate maxillary retrognathia cases were operated on using either poly (70L-lactide-co-30DL-lactide) or titanium miniplate osteofixation. All had two-piece Le Fort I maxillary advancement osteotomy, 11 had simultaneous mandibular setback, and 13 had alveolar bone grafts.

RESULTS

Average operative movement and postoperative instability recorded for maxillary horizontal movement (A-point-Nasion) were 2.5 mm and 2.1 mm for the study group, compared with 6.3 mm and 1.9 mm for the control group. For maxillary vertical movement (ANS-Nasion), measured values were 4.9 and 1.3 mm for the study group and 2.3 and 0.9 mm for the controls. For mandibular horizontal movement, measured values were 10.7 mm and 2.8 mm for the study group and 1.9 mm and 0.8 mm for the controls. Gonial angle measures were 7.1 degrees and 3.5 degrees for the study group and 6.7 degrees and 3.1 degrees for the controls. Foreign body granuloma and fistulation occurred in 1 (9%) member of the study group, but was treated successfully with debridement; implant palpability subsided after 24 months. Three (27%) controls required plate removal, but the remaining plates were palpable.

CONCLUSION

In the study group, horizontal maxillary stability appeared inferior to vertical stability, but mandibular stability was more reliable. Because groups were not matched for magnitude or direction of movement, the results of this study are preliminary and should be interpreted cautiously.

Characterization of human primary osteoblast response on bioactive glass (BaG 13–93)- coated poly-L,DL-lactide (SR-PLA70) surfacein vitro

Bioabsorbable polylactide-based polymers are commonly used for bone reconstruction. Although these polymers have proven successful in many applications, they do not have the capacity to induce osteoconduction. Therefore, several strategies have been developed to manufacture osteoconductive polylactide-based composites. In this study, we have investigated in vitro response of human primary osteoblasts for self-reinforced poly-L,DL-lactide 70/30 (SR-PLA70) plates coated with spheres of bioactive glass 13-93 (SR-PLA70 + BaG). Osteoblasts were cultured on SR-PLA70 and SR-PLA70 + BaG plates for 2, 7, or 14 days. By day 7, both materials induced a reduction in total cell population. However, by day 14 the proliferative response of osteoblasts on SR-PLA70 + BaG surface was such that the cell population had regained similar levels as that of day 2 controls. Alkaline phosphatase activity was higher on SR-PLA70 at day 7 but declined to control levels by day 14. There were no significant time-dependent variations in alkaline phosphatase activity on SR-PLA70 + BaG. After in vitro hydrolysis for 7 days, the elemental analysis of SR-PLA70 + BaG surface showed the presence of mineral precipitates that were confirmed as crystalline hydroxyapatite. This was accompanied by osteoblast spreading, protrusions of microvilli adhered to BaG 19-39 surface, cuboidal phenotype and cell surface associated formation of hydroxyapatite microspheres. In conclusion, the SR-PLA70 + BaG composite is capable of inducing a proliferative response of human primary osteoblasts, and appears to support the development of mature osteoblast phenotype. Therefore, the SR-PLA70 + BaG composites appear as promising osteoconductive scaffold candidates for reconstruction and regeneration of bone matrix.