Use of bioabsorbable osteofixation devices in the hand

Polylactic acid bioabsorbable implants of the hand: A review

In the treatment of hand fractures, metal implants are often used to allow early range of motion and a stable fixation. Although they provide adequate bone union, metal implants have been known to cause joint stiffness, painful or prominent hardware, and adhesions, often leading to another surgery for hardware removal. Bioabsorbable implants have been shown to offer comparable results for fracture fixation in the hand while removing the complications seen with retained hardware. In this article, we review biomechanical and clinical studies focused on bioabsorbable implants made of polylactic acid used for orthopedic hand injuries in order to promote their continued use and future research.

Are Absorbable Plates More Resistant to Infection Than Titanium Implants? An Experimental Pre-Clinical Trial in Rabbits

Background: Infection of orthopaedic implants after internal fixation of bone fractures remains a major complication with occasionally devastating consequences. Recent studies have reported that the use of absorbable materials, instead of metallic ones, may lead to a lower incidence of postoperative infection. In this experimental pre-clinical animal study, we compared the infection rate between absorbable implants consisting of copolymers composed from trimethylene carbonate, L-polylactic acid, and D, L-polylactic acid monomers, and titanium implants after the inoculation of a pathogenic microorganism. Material and Methods: We used an experimental implant-related infection model in rabbits. Sixty animals were randomly and equally divided into two groups. In all animals, the right femur was exposed via a lateral approach and a 2.5 mm two-hole titanium plate with screws (Group A), or a two-hole absorbable plate and screws (Group B), were applied in the femoral shaft. Afterwards, the implant surface was inoculated with Pseudomonas Aeruginosa at a concentration of 2 × 108 CFU/mL. The primary outcome was the comparison of the incidence of developed infection between the two groups. The wound condition was monitored on a daily basis and radiographies were obtained at 12 weeks postoperatively. Infection-related laboratory markers (white blood cell count, erythrocyte sedimentation rate, and C-reactive protein values) were assessed at 3, 6, and 16 weeks postoperatively. Histologic analysis and cultures of tissue samples were also performed to evaluate the presence of infection. Results: Clinical and laboratory signs of infection were evident in 11 rabbits in Group A (36.7%), and 4 in Group B (13.3%). The difference between the groups was statistically significant (p = 0.04). Five animals in Group B (16.7%) had clinical and histologic signs of a foreign-body reaction with significantly elevated CRP and ESR values but no simultaneous presence of infection was identified (p = 0.04). Bone remodelling with thickening of the periosteum and surrounding sclerosis was demonstrated radiologically in animals developing infection or foreign-body reactions. Conclusions: Absorbable plates and screws show lower susceptibility to infection compared to titanium ones. However, their application is associated with foreign-body reaction and the potential need for a second surgical intervention.

Experimental study on the biocompatibility and osteogenesis induction ability of PLLA/DDM scaffolds

To investigate the characterization and function of a novel porous osteogenic material (PLLA / DDM) containing polylactic acid and demineralized dentin matrix. The surface morphology and composition of the material were observed by SEM and EDS. The physical characteristics of the material were detected by roughness and water contact angle analyses. The rate of weight loss and change in the pH value of the material were observed by scaffold degradation experiments. Four types of material were investigated: polylactic acid (PLLA) scaffold, demineralized dentin matrix (DDM) particles, PLLA/DDM scaffold and a blank control. The osteogenic effect and osteogenic characteristics of the new materials were explored through in vivo and in vitro osteogenic experiments. SEM analysis showed that DDM powder was uniformly distributed in the polylactic acid scaffold, and the water contact angle revealed that the water absorption of the porous scaffold was improved after the addition of DDM powder. The EDS results showed that the peak values of calcium and phosphorus were obviously increased after the addition of DDM powder, and the porosity test showed that the scaffold had higher porosity after the addition of DDM powder. Scaffold degradation experiments revealed that the scaffold gradually degraded with increasing time, and its pH value slightly increased. The results of cell culture and animal model experiments showed that the porous PLLA/DDM scaffold had good bio-compatibility and promoted cell proliferation and differentiation. In histological and micro-CT evaluations, the material showed good bio-compatibility, biodegradability and bone conductivity with host bone tissue in vivo. PLLA / DDM hybrid showed better performance than PLLA or DDM. The biocompatibility and cell growth promoting properties were stronger than those of single material.

Use of biomaterials in scaphoid fracture fixation, a systematic review

BACKGROUND

Scaphoid fractures account for 60-70% carpal injury. Due to limited vascular supply achieving adequate reduction and healing is important to avoid complications including avascular necrosis. Recent technological advances have led to renewed vigour in bioabsorbable material research to develop devices which could be used without the need for removal and complications including stress shielding and suboptimal imaging.

METHODS

A systematic search of databases including PubMed, Ovid Medline, and Google Scholar databases was made to identify studies related to the use of bioabsorbable materials in scaphoid fixation and postoperative patient outcomes. PRISMA guidelines were utilised for this review.

FINDINGS

Initial search results yielded 852 studies. 124 studies were screened, with 79 patients across 7 studies included in this review. Poly-L-Lactic acid derivatives were the most common biomaterial for scaphoid fixation, with magnesium and polyglycolide also used. Levels of evidence for studies ranged between III-IV. Analysis demonstrated mixed findings with generally comparable outcomes to conventional alloy-based screws.

INTERPRETATION

Development in bioabsorbable materials is ongoing, however there remains a dearth in data regarding their use in the scaphoid. Further research is needed to establish the efficacy and applicability of bioabsorbable devices in the scaphoid bone.

Direct incorporation of mesenchymal stem cells into a Nanofiber scaffold - in vitro and in vivo analysis

Bony defects are a common problem in musculoskeletal surgery. Replacement with autologous bone grafts is limited by availability of transplant material. Sterilized cancellous bone, while being osteoconductive, has limited osteoinductivity. Nanofiber scaffolds are currently used for several purposes due to their capability of imitating the extracellular matrix. Furthermore, they allow modification to provide functional properties. Previously we showed that electrospun nanofiber scaffolds can be used for bone tissue regeneration. While aiming to use the osteoinductive capacities of collagen type-I nanofibers we saw reduced scaffold pore sizes that limited cellular migration and thus colonization of the scaffolds. Aim of the present study was the incorporation of mesenchymal stem cells into the electrospinning process of a nanofiber scaffold to produce cell-seeded nanofiber scaffolds for bone replacement. After construction of a suitable spinning apparatus for simultaneous electrospinning and spraying with independently controllable spinning and spraying devices and extensive optimization of the spinning process, in vitro and in vivo evaluation of the resulting scaffolds was conducted. Stem cells isolated from rat femora were incorporated into PLLA (poly-l-lactide acid) and PLLA-collagen type-I nanofiber scaffolds (PLLA Col I Blend) via simultaneous electrospinning and -spraying. Metabolic activity, proliferation and osteoblastic differentiation were assessed in vitro. For in vivo evaluation scaffolds were implanted into critical size defects of the rat scull. After 4 weeks, animals were sacrificed and bone healing was analyzed using CT-scans, histological, immunhistochemical and fluorescence evaluation. Successful integration of mesenchymal stem cells into the scaffolds was achieved by iteration of spinning and spraying conditions regarding polymer solvent, spinning distance, the use of a liquid counter-electrode, electrode voltage and spinning duration. In vivo formation of bone tissue was achieved. Using a PLLA scaffold, comparable results for the cell-free and cell-seeded scaffolds were found, while the cell-seeded PLLA-collagen scaffolds showed significantly better bone formation when compared to the cell-free PLLA-collagen scaffolds. These results provide support for the future use of cell-seeded nanofiber scaffolds for large bony defects.

Immobilized Macrophage Colony-Stimulating Factor (M-CSF) Regulates the Foreign Body Response to Implanted Materials

The functionality and durability of implanted biomaterials are often compromised by an exaggerated foreign body reaction (FBR). M1/M2 polarization of macrophages is a critical regulator of scaffold-induced FBR. Macrophage colony-stimulating factor (M-CSF), a hematopoietic growth factor, induces macrophages into an M2-like polarized state, leading to immunoregulation and promoting tissue repair. In the present study, we explored the immunomodulatory effects of surface bound M-CSF on poly-l-lactic acid (PLLA)-induced FBR. M-CSF was immobilized on the surface of PLLA via plasma immersion ion implantation (PIII). M-CSF functionalized PLLA, PLLA-only, and PLLA+PIII were assessed in an IL-1β luciferase reporter mouse to detect real-time levels of IL-1β expression, reflecting acute inflammation in vivo. Additionally, these different treated scaffolds were implanted subcutaneously into wild-type mice to explore the effect of M-CSF in polarization of M2-like macrophages (CD68⁺/CD206⁺), related cytokines (pro-inflammatory: IL-1β, TNF and MCP-1; anti-inflammatory: IL-10 and TGF-β), and angiogenesis (CD31) by immunofluorescent staining. Our data demonstrated that IL-1β activity in M-CSF functionalized scaffolds was ∼50% reduced compared to PLLA-only at day 1 (p < 0.01) and day 2 (p < 0.05) post-implantation. There were >2.6-fold more CD206+ macrophages in M-CSF functionalized PLLA compared to PLLA-only at day 7 (p < 0.001), along with higher levels of IL-10 at both day 7 (p < 0.05) and day 14 (p < 0.01), and TGF-β at day 3 (p < 0.05), day 7 (p < 0.05), and day 14 (p < 0.001). Lower levels of pro-inflammatory cytokines were also detected in M-CSF functionalized PLLA in the early phase of the immune response compared to PLLA-only: a ∼58% decrease at day 3 in IL-1β; a ∼91% decrease at day 3 and a ∼66% decrease at day 7 in TNF; and a ∼60% decrease at day 7 in MCP-1. Moreover, enhanced angiogenesis inside and on/near the scaffold was observed in M-CSF functionalized PLLA compared to PLLA-only at day 3 (p < 0.05) and day 7 (p < 0.05), respectively. Overall, M-CSF functionalized PLLA enhanced CD206+ macrophage polarization and angiogenesis, consistent with lower levels of pro-inflammatory cytokines and higher levels of anti-inflammatory cytokines in early stages of the host response, indicating potential immunoregulatory functions on the local environment.

Coaxial nanofiber scaffold with super-active platelet lysate to accelerate the repair of bone defects

To develop biocomposite materials with the local sustained-release function of biological factors to promote bone defect repair, coaxial electrospinning technology was performed to prepare a coaxial nanofiber scaffold with super-active platelet lysate (sPL), containing gelatin/PCL/PLLA. The nanofibers exhibited a uniform bead-free round morphology, observed by a scanning electron microscope (SEM), and the core/shell structure was confirmed by a transmission electron microscope (TEM). A mixture of polycaprolactone and sPL encapsulated by hydrophilic gelatin and hydrophobic l-polylactic acid can continuously release bioactive factors for up to 40 days. Encapsulation of sPL resulted in enhanced cell adhesion and proliferation, and sPL loading can increase the osteogenesis of osteoblasts. Besides, in vivo studies demonstrated that sPL-loaded biocomposites promoted the repair of skull defects in rats. Therefore, these results indicate that core–shell nanofibers loaded with sPL can add enormous potential to the clinical application of this scaffold in bone tissue engineering.

Coaxial electrospinning three-dimensional scaffold and its release various biological factors after filling the bone defect to induce adhesion and proliferation of osteoblasts on the nano scaffold.

Clinical courses and degradation patterns of absorbable plates in facial bone fracture patients

Background

Absorbable plates are widely used in open reduction and internal fixation surgeries for facial bone fractures. Absorbable plates are made of polyglycolic acid (PGA), polylactic acid (PLA), polydioxane (PDS), or various combinations of these polymers. The degradation patterns of absorbable plates made from different polymers and clinical courses of patients treated with such plates have not been fully identified. This study aimed to confirm the clinical courses of facial bone fracture patients using absorbable plates and compare the degradation patterns of the plates.

Methods

A retrospective chart review was conducted for 47 cases in 46 patients who underwent open reduction and internal fixation surgery using absorbable plates to repair facial bone fractures. All surgeries used either PLA/PGA composite-based or poly-L-lactic acid (PLLA)/hydroxyapatite (HA) composite-based absorbable plates and screws. Clinical courses were confirmed and comparisons were conducted based on direct observation.

Results

There were no naturally occurring foreign body reactions. Post-traumatic inflammatory responses occurred in eight patients (nine cases), in which six recovered naturally with conservative treatment. The absorbable plates were removed from two patients. PLA/PGA composite-based absorbable plates degraded into fragments with non-uniform, sharp surfaces whereas PLLA/HA composite-based absorbable plates degraded into a soft powder.

Conclusion

PLA/PGA composite-based and PLLA/HA composite-based absorbable plates showed no naturally occurring foreign body reactions and showed different degradation patterns. The absorbable plate used for facial bone fracture surgery needs to be selected in consideration of its degradation patterns.

Surgical Fixation of Metacarpal Shaft Fractures Using Absorbable Implants: A Systematic Review of the Literature

BACKGROUND

Despite the proven efficacy and advantages of absorbable implants, their use for metacarpal shaft fixation has been limited. This is likely due to the high reported complication rates in early studies with polyglycolic acid (PGA) implants, notably high rates of noninfectious inflammatory reaction (5%-25%), occurring up to 30 weeks after fixation. The objective of this study was to assess the clinical outcomes of newer absorbable plates and screws in the treatment of metacarpal shaft fractures.

METHODS

The authors performed a systematic search of the PubMed, Ovid MEDLINE, and EMBASE databases dating from 1946 to 2017. Primary outcome measures were the development of noninfectious inflammatory reaction and implant failure.

RESULTS

A total of 42 metacarpal shaft fractures in 35 patients were included. The average follow-up time was 20.4 months (n = 24; range: 3.6-61 months). Only 1 case (2.4%) of noninfectious inflammatory reaction was reported with polylactic acid (PLA) plates and PLA/PGA compounds. Noninfectious inflammatory reaction was observed in 4 out of the 9 patients (44.4%) with a trimethylene carbonate/PLA compound. Symptoms appeared after an average time of 15.8 months (range: 12-19 months) post-fixation. Painless prolonged inflammation that resolved spontaneously within 6 months was reported in 7.1% of cases (n = 3). Implant failure with loss of fracture reduction was reported in 9.5% of cases (n = 4).

CONCLUSIONS

Newer absorbable materials appear to have significantly lower rates of noninfectious inflammatory reaction than previously reported. When compared with metallic fixation of the metacarpal shaft, absorbable fixation appears to have comparable complication rates and biomechanical properties.

Increased Runx2 expression associated with enhanced Wnt signaling in PDLLA internal fixation for fracture treatment

Poly-D-L lactide (PDLLA) biodegradable implants to heal fractures are widely applied in orthopedic surgeries. However, whether the process of fracture healing is regulated differently when PDLLA is used compared with traditional metal materials remains unclear. Runt-related transcription factor 2 (Runx2) and canonical Wnt signaling are essential and may interact reciprocally in the regulation of osteogenesis during bone repair. In the present study, a rat femoral open osteotomy model was used to compare the curative efficacy of a PDLLA rod and Kirschner wire under intramedullary fixation for fracture treatment. The dynamic expression of Runx2 and key components of the canonical Wnt signaling in callus tissue during fracture healing was also investigated. The results of the current study indicate that at weeks 4 and 6 following fixation, the callus bone structural parameters of microCT were significantly improved by PDLLA rod compared to that of Kirschner wire. In addition, at weeks 4 and 6 after fixation, the protein and mRNA expression of Runx2 and the positive regulators of canonical Wnt signaling, such as Wnts and β-catenin, were significantly increased. However, the protein and mRNA expression levels of the negative regulators of canonical Wnt signaling, such as glycogen synthase kinase-3β, were significantly decreased in callus tissue when treated with PDLLA rod compared with Kirschner wire. Collectively, these data indicate that compared to the traditional metal material, using PDLLA internal fixation for fracture treatment may further improve bone formation, which is associated with the increased expression of Runx2 and the enhancement of canonical Wnt signaling.

Development of microspheres for biomedical applications: a review

An overview of microspheres manufactured for use in biomedical applications based on recent literature is presented in this review. Different types of glasses (i.e. silicate, borate, and phosphates), ceramics and polymer-based microspheres (both natural and synthetic) in the form of porous , non-porous and hollow structures that are either already in use or are currently being investigated within the biomedical area are discussed. The advantages of using microspheres in applications such as drug delivery, bone tissue engineering and regeneration, absorption and desorption of substances, kinetic release of the loaded drug components are also presented. This review also reports on the preparation and characterisation methodologies used for the manufacture of these microspheres. Finally, a brief summary of the existing challenges associated with processing these microspheres which requires further research and development are presented.

Nanomechanical properties of poly(lactic-co-glycolic) acid film during degradation

Despite the potential applications of poly(lactic-co-glycolic) acid (PLGA) coatings in medical devices, the mechanical properties of this material during degradation are poorly understood. In the present work, the nanomechanical properties and degradation of PLGA film were investigated. Hydrolysis of solvent-cast PLGA film was studied in buffer solution at 37 °C. The mass loss, water uptake, molecular weight, crystallinity and surface morphology of the film were tracked during degradation over 20 days. Characterization of the surface hardness and Young's modulus was performed using the nanoindentation technique for different indentation loads. The initially amorphous films were found to remain amorphous during degradation. The molecular weight of the film decreased quickly during the initial days of degradation. Diffusion of water into the film resulted in a reduction in surface hardness during the first few days, followed by an increase that was due to the surface roughness. There was a significant delay between the decrease in the mechanical properties of the film and the decrease in the molecular weight. A sudden decline in mechanical properties indicated that significant bulk degradation had occurred.

Comparison of different in vitro tests for biocompatibility screening of Mg alloys

Standard cell culture tests according to ISO 10993 have only limited value for the biocompatibility screening of degradable biomaterials such as Mg alloys. The correlation between in vitro and in vivo results is poor. Standard cytotoxicity tests mimic the clinical situation to only a limited extent, since in vivo proteins and macromolecules in the blood and interstitial liquid will influence the corrosion behaviour and, hence, biocompatibility of Mg alloys to a significant extent. We therefore developed a modified cytotoxicity test simulating the in vivo conditions by use of bovine serum as the extraction vehicle instead of the cell culture medium routinely used in standard cytotoxicity testing according to ISO 10993-5. The modified extraction test was applied to eight experimental Mg alloys. Cytotoxicity was assayed by inhibition of cell metabolic activity (XTT test). When extraction of the alloy samples was performed in serum instead of cell culture medium the metabolic activity was significantly less inhibited for six of the eight alloys. The reduction in apparent cytotoxicity under serum extraction conditions was most pronounced for MgZn1 (109% relative metabolic activity with serum extracts vs. 26% in Dulbecco's modified Eagle's medium (DMEM)), for MgY4 (103% in serum vs. 32% in DMEM) and for MgAl3Zn1 (84% vs. 17%), resulting in a completely different cytotoxicity ranking of the tested materials when serum extraction was used. We suppose that this test system has the potential to enhance the predictability of in vivo corrosion behaviour and biocompatibility of Mg-based materials for biodegradable medical devices.

Intramedullary fixation in digital replantation using bioabsorbable poly-DL-lactic acid rods

PURPOSE

To evaluate bioabsorbable poly-DL-lactic acid (PDLLA) intramedullary rods for fracture fixation of amputated digits.

METHODS

From October 2005 to October 2007, we used bioabsorbable rods made of PDLLA as intramedullary fixation in osteosynthesis procedures in 9 cases of digital replantation. Four cases involved the middle phalanx and 5 the proximal phalanx. The amputation level was diaphyseal in all cases. All patients were followed up from 6 months to 2 years, with an average of 13 months.

RESULTS

All fractures healed in 6 to 8 weeks. There were no infections. There was no evidence of hardware failure at 4 weeks after surgery. According to the Tamai et al criteria, the results were excellent in 8 cases and good in 1.

CONCLUSIONS

Using bioabsorbable PDLLA rods for intramedullary fixation can be an effective technique for replantation with fractures through the proximal or middle phalanges. Bioabsorbable rods can provide rigid stable fixation, which allows early mobilization.

Hydroxyapatite reinforced poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) based degradable composite bone plate

Poly(3-hydroxybutyrate) (P3HB), its co-polymers with 3-hydroxyvalerate (HV) (PHBV8 and PHBV22), and their hydroxyapatite (HAp) containing composites (5 and 15%, w/w) were prepared by injection molding. PHBV bone plates with low valerate contents and 15% (w/w) HAp appear to have better mechanical properties than the others. Flexural strengths of 15% (w/w) HAp-loaded P3HB, PHBV8 and PHBV22 were 78.28, 63.45 and 39.38 MPa, respectively. Tensile strengths of 15% (w/w) HAp-loaded P3HB, PHBV8 and PHBV22 were 18.99, 15.44 and 11.02 MPa, respectively. For the ageing test, bone plates were incubated in phosphate-buffered saline PBS (0.1 M, pH 7.4) at 37 degrees C and at pre-determined time points they were removed and subjected to a three-point bending test. Incubation in PBS caused a sharp decrease in the mechanical properties within the first 24 h, followed either by a gradual decrease or no change for a period of about 1 month. SEM results showed that there was no significant material erosion in the 4-week incubation period. P3HB loaded with 15% HAp appeared to yield the most suitable bone plate, insofar as mechanical properties are concerned with potential for further testing in vivo.

Electrospun PLLA nanofiber scaffolds and their use in combination with BMP-2 for reconstruction of bone defects

INTRODUCTION

Adequate migration and differentiation of mesenchymal stem cells is essential for regeneration of large bone defects. To achieve this, modern graft materials are becoming increasingly important. Among them, electrospun nanofiber scaffolds are a promising approach, because of their high physical porosity and potential to mimic the extracellular matrix (ECM).

MATERIALS AND METHODS

The objective of the present study was to examine the impact of electrospun PLLA nanofiber scaffolds on bone formation in vivo, using a critical size rat calvarial defect model. In addition we analyzed whether direct incorporation of bone morphogenetic protein 2 (BMP-2) into nanofibers could enhance the osteoinductivity of the scaffolds. Two critical size calvarial defects (5 mm) were created in the parietal bones of adult male Sprague-Dawley rats. Defects were either (1) left unfilled, or treated with (2) bovine spongiosa, (3) PLLA scaffolds alone or (4) PLLA/BMP-2 scaffolds. Cranial CT-scans were taken at fixed intervals in vivo. Specimens obtained after euthanasia were processed for histology, histomorphometry and immunostaining (Osteocalcin, BMP-2 and Smad5).

RESULTS

PLLA scaffolds were well colonized with cells after implantation, but only showed marginal ossification. PLLA/BMP-2 scaffolds showed much better bone regeneration and several ossification foci were observed throughout the defect. PLLA/BMP-2 scaffolds also stimulated significantly faster bone regeneration during the first eight weeks compared to bovine spongiosa. However, no significant differences between these two scaffolds could be observed after twelve weeks. Expression of osteogenic marker proteins in PLLA/BMP-2 scaffolds continuously increased throughout the observation period. After twelve weeks osteocalcin, BMP-2 and Smad5 were all significantly higher in the PLLA/BMP-2 group than in all other groups.

CONCLUSION

Electrospun PLLA nanofibers facilitate colonization of bone defects, while their use in combination with BMP-2 also increases bone regeneration in vivo and thus combines osteoconductivity of the scaffold with the ability to maintain an adequate osteogenic stimulus.

Free-hand versus novel specialised jig guidance for the passing of intramedullary wires in olecranon fracture fixation: a comparative study

The treatment of olecranon fractures frequently involves the use of tension-band fixation. Although associated with high union rates, this method has a high incidence of morbidity associated with soft tissue compromise and limitation of range of movement requiring frequent re-operation for removal of metal. We describe the use of a simple jig to ensure intramedullary placement of longitudinal K-wires and compare the accuracy of placement of Kirschner (K)-wires using this device with the traditional free-hand method. We found the distance from the centre of the medullary canal, the range and standard deviations of K-wire positions to be significantly more precise when the jig was used. This has applications for the use of the device, both with standard metallic radio-opaque wires and potentially with bio-absorbable pins.

Inflammatory response with osteolysis related to a bioabsorbable anchor in the finger: a case report

Soft tissue fixation of ligaments and tendons in the hand can be achieved by the use of metal or bioabsorbable suture anchors. Advantages of bioabsorbable suture anchors include lack of interference in magnetic resonance imaging, resorption of anchor, replacement by bone, and no need for hardware removal. However, complications of these bioabsorbable implants include inflammatory response to the material use. We present what we believe to be the first case in the hand of a poly(l-lactide-co-d,l-lacitide) suture anchor causing an inflammatory response leading to significant osteolysis 4 months postoperatively after repair of a ring finger flexor digitorum profundus avulsion. Exploration of the distal phalanx revealed an intact implant and repair, no signs of infection, and an extensive bone defect. Pathology showed chronically inflamed tissue. This case has led us to reconsider the use of bioabsorbable anchor sutures in the hand. Further research is necessary to better define the contraindications to bioabsorbable suture anchor use in the hand.

Influence of nanofibers on growth and gene expression of human tendon derived fibroblast

Background

Rotator cuff tears are a common and frequent lesion especially in older patients. The mechanisms of tendon repair are not fully understood. Common therapy options for tendon repair include mini-open or arthroscopic surgery. The use of growth factors in experimental studies is mentioned in the literature. Nanofiber scaffolds, which provide several criteria for the healing process, might be a suitable therapy option for operative treatment. The aim of this study was to explore the effects of nanofiber scaffolds on human tendon derived fibroblasts (TDF's), as well as the gene expression and matrix deposition of these fibroblasts.

Methods

Nanofibers composed of PLLA and PLLA/Col-I were seeded with human tendon derived fibroblasts and cultivated over a period of 22 days under growth-inductive conditions, and analyzed during the course of culture, with respect to gene expression of different extra cellular matrix components such as collagens, bigylcan and decorin. Furthermore, we measured cell densities and proliferation by using fluorescene microscopy.

Results

PLLA nanofibers possessed a growth inhibitory effect on TDF's. Furthermore, no meaningful influence on the gene expression of collagen I, collagen III and decorin could be observed, while the expression of collagen X increased during the course of cultivation. On the other hand, PLLA/Col-I blend nanofibers had no negative influence on the growth of TDF's. Furthermore, blending PLLA nanofibers with collagen had a positive effect on the gene expression of collagen I, III, X and decorin. Here, gene expression indicated that focal adherence kinases might be involved.

Conclusion

This study indicates that the use of nanofibers influence expression of genes associated with the extra cellular matrix formation. The composition of the nanofibers plays a critical role. While PLLA/Col-I blend nanofibers enhance the collagen I and III formation, their expression on PLLA nanofibers was more comparable to controls. However, irrespective of the chemical composition of the fibres, the collagen deposition was altered, an effect which might be associated with a decreased expression of biglycanes.

Potency of double-layered poly L-lactic acid scaffold in tissue engineering of tendon tissue

A successful scaffold for use in tendon tissue engineering requires a high affinity for living organisms and the ability to maintain its mechanical strength until maturation of the regenerated tissue. We compared two types of poly(L-lactic acid) (PLLA) scaffolds for use in tendon regeneration, a plain-woven PLLA fabric (fabric P) with a smooth surface only and a double layered PLLA fabric (fabric D) with a smooth surface on one side and a rough (pile-finished) surface on the other side. These two types of fabric were implanted into the back muscles of rabbits and evaluated at three and six weeks after implantation. Histological examination showed collagen tissues were highly regenerated on the rough surface of fabric D. On the other hand, liner cell attachment was seen in the smooth surface of fabric P and fabric D. The total DNA amount was significantly higher in fabric D. Additionally, mechanical examination showed fabric P had lost its mechanical strength by six weeks after implantation, while the strength of fabric D was maintained. Fabric D had more cell migration on one side and less cell adhesion on the other side and maintained its initial strength. Thus, a novel form of double-layered PLLA fabric has the potential to be used as a scaffold in tendon regeneration.

Bioabsorbable fixation for Mitchell's bunionectomy osteotomy

Although bioabsorbable pins have been used to successfully stabilize a wide range of osteotomies, to date there have been not published studies describing the results of their use for fixation of first metatarsal osteotomies in Mitchell's bunionectomy. The purpose of this retrospective investigation of 78 first metatarsal osteotomies was to evaluate the effectiveness of polydioxanone bioabsorbable pin fixation of the first metatarsal osteotomy in Mitchell's bunionectomy. The mean length of the first metatarsal preoperatively was 6.65 +/- 0.42 cm, and postoperatively it was 6.31 +/- 0.57 cm (P < .0001). The mean first IMA preoperatively was 17.59 degrees +/- 3.51 degrees , and postoperatively it was 9.91 degrees +/- 2.58 degrees (P < .0001). The mean HVA preoperatively was 29.74 degrees +/- 4.70 degrees , and postoperatively it was 12.89 degrees +/- 4.26 degrees (P < .0001). The average time to bony union was 6.01 +/- 0.61 weeks. There were 5 (6.41%) superficial wound infections that resolved with oral antibiotics, 1 (1.28%) deep-seated infection requiring surgical debridement, and 2 (2.56%) patients complained of transfer metatarsalgia. Five (6.41%) patients displayed persistent localized translucency at some portion of the osteotomy site on postoperative radiographs, and there were no cases of progressive osteolysis. In this series there were no complications related to pin fracture or failure of osteotomy fixation. Based on the results observed in this study, it appears that the use of polydioxanone bioabsorbable pins provides satisfactory stabilization of the first metatarsal osteotomy in Mitchell's bunionectomy, and was not associated with any serious complications.

LEVEL OF CLINICAL EVIDENCE

2.

Late results of absorbable pin fixation in the treatment of radial head fractures

The use of bioabsorbable pins with prolonged degradation periods for fracture fixation has raised concerns about adverse soft tissue reactions, including seromas, discharging sinuses, or osteolytic changes. We asked whether bioabsorbable pins of self-reinforced polylactic acid polymer used in radial head fractures resulted in such reactions. We retrospectively reviewed 21 patients followed a minimum of 36 months (mean, 81 months; range, 36-136 months). There were nine Mason II, 10 Mason III, and two Mason IV fractures, which were evaluated clinically and radiographically. All fractures healed well with no radiographic signs of osteolysis. The mean Mayo Elbow Performance score was 93.8 (range, 20-100), which is comparable to the outcome of historical groups with radial head arthroplasty. The mean range of flexion of the elbow was 9 degrees to 132 degrees , with 79 degrees pronation and 77 degrees supination. The grip strength of the operated arm was not affected in comparison to the contralateral arm (mean range, 38.6 versus 40.9 kg). No material-related adverse effects were observed during and beyond the degradation period. Our data suggest concerns about soft tissue or bony reactions from these materials in radial head fractures are not justified.

Effect of acidic degradation products of poly(lactic-co-glycolic)acid on the apatite-forming ability of poly(lactic-co-glycolic)acid-siloxane nanohybrid material

The effect of poly(lactic-co-glycolic) acid (PLGA) degradation products on the apatite-forming ability of a PLGA-siloxane nanohybrid material were investigated. Two PLGA copolymer compositions with low and high degradability were used in the experiment. The PLGA-siloxane nanohybrid materials were synthesized by end-capping PLGA with acid end-groups using 3-isocyanatopropyl triethoxysilane following the sol-gel reaction with calcium nitrate tetrahydrate. Two nanohybrid materials that had different degradability were exposed to simulated body fluid (SBF) for 1-28 days at 36.5 degrees C. The low degradable PLGA hybrid showed apatite-forming ability within 3 days of incubation while the high degradable one did not within 28 days testing period. The results were explained in terms of the acidity of the PLGA degradation products, which could directly influence on the apatite dissolution.

Poly-L/D-lactide (PLDLA) 96/4 fibrous implants: histological evaluation in the subcutis of experimental design

Poly-L/D-lactide (PLDLA) 96/4 fibrous implants have been introduced to engineer functional fibrous constructions in situ. The current study was undertaken to evaluate the guidance of the fibrous tissue formation and the tissue reaction of porous PLDLA 96/4 scaffolds implanted in subcutaneous tissue. Three various PLDLA 96/4 knitted-mesh scaffolds (Loose, Ordinary, and Dense) were implanted subcutaneously in 32 rats, and followed-up from 3 days until 48 weeks postsurgery. Histological examination showed that PLDLA 96/4 scaffolds provided a structurally supporting element for 48 weeks. They were filled with fibrous tissue by 3 weeks. During the follow-up, loose connective tissue was organized into dense connective tissue with thick collagen bundles. At 48 weeks, no statistically significant difference was found in the amount of loose or dense connective tissue between the scaffold groups of various porosities, although the tendency for higher amounts of loose connective tissue was seen in the Loose type scaffolds. PLDLA filament diameters were 121 mum at 2 weeks, 119 mum at 24 weeks and 116 mum at 48 weeks (P = 0.03 between 2 and 48 weeks). Porous PLDLA scaffold induced fibrous tissue formation in situ. This can be exploited in engineering fibrous tissue constructs in vivo for tissue support or replacement purposes.

Clinical results of absorbable plates for displaced metacarpal fractures

PURPOSE

To present the clinical results of a study of unstable metacarpal fractures treated with absorbable plates.

METHODS

Between July 2004 and June 2006, 12 patients (14 fractures) who presented with displaced, unstable, metacarpal fractures had open reduction and internal fixation. The overall clinical follow-up results and radiographic controls at 6, 12, and 26 weeks after surgery are reported. The clinical outcome was assessed by the Disabilities of the Arm, Shoulder, and Hand score and the visual analogue pain scale.

RESULTS

The involved fingers showed an average final total active motion of 234 degrees (range, 220 degrees-265 degrees). No deformity of rotation>5 degrees was observed in any patient in the clinical follow-up evaluation. One patient had a loss of reduction with a palmar angle of the metacarpal axis of 20 degrees in the sagittal plane. A second patient with secondary loss of reduction required surgical revision, at which time internal fixation was performed by using a titanium plate. Complications included keloid formation and prolonged soft-tissue swelling for more than 6 weeks in 3 patients. No wound margin necrosis, infection, pseudarthrosis, sinus formation, or osteolysis was observed. Bone consolidation was achieved reliably within 6 weeks both clinically and radiologically. The Disabilities of the Arm, Shoulder, and Hand score results 6 weeks after surgery were an average of 30 points compared with 13 after 12 weeks and 3 points after 26 weeks. The visual pain scale showed mean values of 18 after 6 weeks, 2 after 12 weeks, and 0.2 after 26 weeks.

CONCLUSIONS

Absorbable plates are suitable for use in hand surgery and allow early range of motion in combination with an additional orthosis of the hand (as described) for 3 weeks. In the early and medium-term postoperative course, no osteolysis or sterile sinus formation was observed. Metal plates are still the gold standard; however, surgical implants made of amorphous copolymer of L-lactide and glycolic acid in combination with an orthosis constitute a useful and reliable means of metacarpal fracture treatment.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

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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.

Tissue engineering: current and future approaches to ocular surface reconstruction

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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.