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Results for “Absorbable Implants”

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PubMed1999

Antibiotic loaded chitosan bar. An in vitro, in vivo study of a possible treatment for osteomyelitis.

A biodegradable drug delivery system of a gentamicin loaded chitosan bar with sustained antibiotic effect is described. Chitosan has proven to be a biocompatible aminopolysaccharide and a matrix for controlled release of pharmaceuticals. Combined crosslinking, solvent evaporation, and a cylinder model cutting technique was used to prepare the chitosan bar. Sustained diffusion of gentamicin into the surrounding medium was seen using a release test in vitro. Approximately 11% gentamicin was released from the bar in the first 24 hours. The gentamicin released from the bar showed significant antibacterial activity. The bar implanted in the proximal portion of the rabbit tibia produced a low blood concentration of gentamicin, but a much higher concentration was produced in local bone and in the hematoma. In all bone tissue around the bar, the gentamicin concentration exceeded the minimum inhibitory concentration for the common causative organisms of osteomyelitis for approximately 8 weeks. The implant caused no systemic side effects. Based on these test results together with the chitosan characteristics of biodegradable, antibiotic, and immunologic activity, the gentamicin loaded chitosan bar seems to be a clinically useful method for the treatment of bone infection. This system has an advantage over other systems in that it avoids a second operation for removal of the carrier.

Absorbable Implants↗

PubMedDate not supplied

The first clinical study using a new biodegradable implant for the treatment of lips, wrinkles, and folds.

A new tissue augmentation product, made from hyaluronic acid, was clinically evaluated at three clinics in accordance with the new directive, EN 540, for medical implants. One hundred patients were fully assessed following treatments in 285 locations. The treatment was completed when the skin was levelled following one to two injections. At 6 months follow-up of all patients and at 12 months follow-up of a randomized group of the patients all showed that close to 60% of the effect was still there. No serious or permanent adverse events were noted.

Absorbable Implants↗

PubMed2002

A hydrogel material for plastic and reconstructive applications injected into the subcutaneous space of a sheep.

Soft tissue reconstruction using tissue-engineered constructs requires the development of materials that are biocompatible and support cell adhesion and growth. The objective of this study was to evaluate the use of macroporous hydrogel fragments that were formed using either unmodified alginate or alginate covalently linked with the fibronectin cell adhesion peptide RGD (alginate-RGD). These materials were injected into the subcutaneous space of adult, domesticated female sheep and harvested for histological comparisons at 1 and 3 months. In addition, the alginate-RGD porous fragments were seeded with autologous sheep preadipocytes isolated from the omentum, and these cell-based constructs were also implanted. The results from this study indicate that both the alginate and alginate-RGD subcutaneous implants supported tissue and vascular ingrowth. Furthermore, at all time points of the experiment, a minimal inflammatory response and capsule formation surrounding the implant were observed. The implanted materials also maintained their sizes over the 3-month study period. In addition, the alginate-RGD fragments supported the adhesion and proliferation of sheep preadipocytes, and adipose tissue was present within the transplant site of these cellular constructs, which was not present within the biomaterial control sites.

Absorbable Implants↗

PubMed2000

Functional living trileaflet heart valves grown in vitro.

BACKGROUND: Previous tissue engineering approaches to create heart valves have been limited by the structural immaturity and mechanical properties of the valve constructs. This study used an in vitro pulse duplicator system to provide a biomimetic environment during tissue formation to yield more mature implantable heart valves derived from autologous tissue. METHODS AND RESULTS: Trileaflet heart valves were fabricated from novel bioabsorbable polymers and sequentially seeded with autologous ovine myofibroblasts and endothelial cells. The constructs were grown for 14 days in a pulse duplicator in vitro system under gradually increasing flow and pressure conditions. By use of cardiopulmonary bypass, the native pulmonary leaflets were resected, and the valve constructs were implanted into 6 lambs (weight 19+/-2.8 kg). All animals had uneventful postoperative courses, and the valves were explanted at 1 day and at 4, 6, 8, 16, and 20 weeks. Echocardiography demonstrated mobile functioning leaflets without stenosis, thrombus, or aneurysm up to 20 weeks. Histology (16 and 20 weeks) showed uniform layered cuspal tissue with endothelium. Environmental scanning electron microscopy revealed a confluent smooth valvular surface. Mechanical properties were comparable to those of native tissue at 20 weeks. Complete degradation of the polymers occurred by 8 weeks. Extracellular matrix content (collagen, glycosaminoglycans, and elastin) and DNA content increased to levels of native tissue and higher at 20 weeks. CONCLUSIONS: This study demonstrates in vitro generation of implantable complete living heart valves based on a biomimetic flow culture system. These autologous tissue-engineered valves functioned up to 5 months and resembled normal heart valves in microstructure, mechanical properties, and extracellular matrix formation.

Absorbable Implants↗

PubMed2004

Tissue response to a membrane of demineralized bovine cortical bone implanted in the subcutaneous tissue of rats.

The treatment of persistent bone defects has encouraged the search for proper techniques or bone substitutes. In Dentistry, a common problem in the treatment of periodontal bone defects is the growth of tissues within the lesion, such as the junctional epithelium, which impair regeneration of these tissues. Guided tissue regeneration (GTR), based on the separation of the tissues by means of membranes or barriers, was developed in an attempt to improve periodontal regeneration. The aim of this study was to histologically evaluate the tissue response to a membrane of demineralized bovine cortical bone implanted in the subcutaneous tissue of rats. The study periods were 1, 3, 7, 15, 30 and 60 days after implantation. Analysis of the histological sections demonstrated a moderate to intense inflammatory response at 1 and 3 days, moderate at 7 and 15 days, and almost absent at 30 and 60 days. Resorption of the membrane began 15 days after implantation, and at 60 days only remnants could be detected in some animals. We concluded that the demineralized bovine cortical bone membrane was well tolerated by the tissues and is completely resorbed after 30-60 days by mononuclear cells and multinucleated giant cells, which disappear upon completion of the process.

Absorbable Implants↗

PubMed2026

Bioabsorbable vs. titanium screws in first metatarsophalangeal joint arthrodesis: a pilot randomized controlled trial with 2-year follow-up.

INTRODUCTION: To assess the feasibility and preliminary clinical outcomes of bioabsorbable screw fixation in first metatarsophalangeal joint arthrodesis compared to conventional titanium screw fixation. METHODS: In this prospective pilot randomized controlled trial, 30 patients were allocated 1:1 to bioabsorbable or titanium cannulated lag screw fixation. Arthrodesis was performed using a cup-and-cone technique at two Finnish hospitals. Full weight-bearing in an orthopaedic shoe was allowed after six weeks. Outcomes included AOFAS and VA-FAS FA-VAS scores, union rates, and complications assessed at 3, 6, 12, and 24 months. RESULTS: Both groups showed significant functional improvement with no between-group differences. At 24 months, mean AOFAS scores were 89.1 (SD 2.7) in the titanium group and 90.0 (SD 0.0) in the bioabsorbable group (p = 0.23). Mean FA-VAS total scores (sum of pain, function, and complaints subscales) were 1948 (SE 59.4) in the titanium group and 1914 (SE 61.4) in the bioabsorbable group (p = 0.655). Union rate was 90% overall; nonunion occurred in one titanium and two bioabsorbable patients, all requiring revision. No implant-related complications or hardware removal surgeries were recorded. Degradation of bioabsorbable screws caused no adverse clinical or radiographic reactions. CONCLUSIONS: Bioabsorbable screws appear safe and feasible in first metatarsophalangeal joint arthrodesis, with preliminary outcomes comparable to titanium fixation. These findings support the conduct of a larger confirmatory trial. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03133039, registered 28 April 2017. https://clinicaltrials.gov/ct2/show/NCT03133039.

Humans↗

PubMedDate not supplied

The effect of implanting gentamicin-impregnated polymethylmethacrylate beads in the tarsocrural joint of the horse.

OBJECTIVE: To determine the effect of intra-articular gentamicin-impregnated polymethylmethacrylate (PMMA) beads inserted in the equine tarsocrural joint on the synovial fluid, synovial lining, and cartilage, and to determine the peak and sustainable gentamicin concentrations in synovial fluid and plasma. STUDY DESIGN: Pharmacokinetic, cytologic, and histologic study of the effect of gentamicin-impregnated PMMA on normal equine tarsocrural joints. ANIMALS: Five healthy adult horses. METHODS: Gentamicin-impregnated PMMA bead strands (3 strands each of 40 beads, with each strand containing 100 mg gentamicin) were surgically inserted into one radiographically normal tarsocrural joint in 5 horses. Each horse had both joints flushed with 1 L of lactated Ringer's solution before bead administration. Synovial fluid total protein concentration, white blood cell (WBC) count, gentamicin concentration, synovial histology, cartilage integrity, and cartilage glycosaminoglycan (GAG) concentrations were determined. RESULTS: Gentamicin concentration (mean +/- SEM peak concentration, 27.9 +/- 2.27 microg/mL) occurred in the first 24 hours and remained above 2 microg/mL for 9 days. Gentamicin concentrations in control joints and the plasma remained below detectable levels. The synovial fluid WBC count for treated joints was increased compared with control joints for 72 hours, but was similar at day 6. The synovial protein concentration in gentamicin-treated joints remained increased for 21 days. Synovium in treated joints had diffuse synovitis, whereas control joints had less fibrovascular proliferation. Superficial cartilage erosion was present in all treated joints. There was no difference in the GAG content of treated and control joint cartilage. CONCLUSIONS: Short-term implantation of gentamicin (300 mg)-impregnated PMMA beads can provide therapeutic levels of gentamicin (>2 microg/mL) in the normal tarsocrural joint for 9 days; however, gentamicin-impregnated PMMA beads induce synovitis and superficial cartilage erosion. CLINICAL RELEVANCE: Temporary intra-articular administration of antibiotic-impregnated PMMA may be an effective way to treat septic joints that require constant high concentrations of antibiotics.

Absorbable Implants↗

PubMed2003

Regeneration of the alveolar crest using titanium micromesh with autologous bone and a resorbable membrane.

Guided bone regeneration (GBR) has been used for the regeneration of bone in conjunction with the placement of oral implants. The aim of the present study was to clinically and histologically evaluate the use of a titanium micromesh and a resorbable membrane in the GBR technique in patients with alveolar crest defects due to periodontitis, trauma, and extractions. Eighteen patients participated in this study, and 50 implants were inserted. The postoperative healing was uneventful, no dehiscences were observed, and all implants were functioning successfully at 7-year follow-up. At reentry, in all cases, the space under the titanium mesh was completely filled by bone. From a clinical point of view, in all patients, no residual bone defects were observed and a significant increase of the alveolar width or height was found. In all cases, a good esthetic result of the restorative procedures was present.

Absorbable Implants↗

PubMed2003

Angiogenesis around new AB-polymer networks after one week of implantation in mice.

Biomaterials research is expected to forward new materials to be used as, e.g., implant materials or as scaffolds for tissue engineering. It is central for such a scaffold material to create the track on which those cells can inhabit the scaffold needed to rebuild functional tissue substitutes. The tissue engineering concept expects a gradual gain in functionality of the newly created tissues while the scaffold materials are degraded and subsequently eliminated. Not only for the elimination of the degradation products the angiogenesis of new blood vessels is thought to play an important role. In the present study, a new biomaterial, a non-porous polymeric AB-network based on oligo (epsilon-hydroxycaproate) and oligobutylacrylate, was implanted in animals. Male NMRI mice were implanted subcutaneously for one week. Immediately after the explantation, the probes were examined histologically. Already one week after implantation, there was a strong tissue-integration of the polymer. Importantly, blood vessels occurred at the polymer surface. There were also clusters of cells around the vessels, which were phenotypically similar to fat cells. The mechanism of the early integration of the polymer is not clear. The relationship between the new periimplant vessels and the integration of the polymer has to be studied.

Absorbable Implants↗

PubMed1997

A comparative study of gut suture, human amnion collagen, bovine skin collagen and Vicryl suture implants in rats.

This study compares the persistence and histological characteristics of gut suture with those of human amnion collagen, bovine collagen, and Vicryl suture implants in rats. Gut suture and human amnion collagen more resembled living tissue than did bovine collagen and were characterized by their cellularity and the presence of numerous capillaries. The Vicryl suture implants were quickly absorbed. Picrosirius polarization revealed the synthesis of host collagen by rat fibroblasts which immigrated into the gut suture and human amnion collagen implants. The authors suggest the potential of gut suture as a soft tissue substitute to improve linear skin contour deficits.

Absorbable Implants↗

PubMed2004

Peripherally administered growth hormone increases brain dopaminergic activity and swimming in rainbow trout.

There is increasing evidence that growth hormone (GH) has important behavioral effects in fish, but the underlying mechanisms are not well understood. To investigate if peripherally administered GH influences the monoaminergic activity of the brain, and how this is correlated to behavior, juvenile rainbow trout were implanted intraperitoneally with ovine GH. Fish were either kept isolated or in groups of five. The physical activity and food intake of the isolated fish were observed after 1 and 7 days, when brains were also sampled. The content of serotonin, dopamine, and noradrenaline and their metabolites in hypothalamus, telencephalon, optic tectum, and brain stem was then analyzed. For fish kept isolated for 7 days following implant, GH increased swimming activity and the levels of the dopamine metabolite 3, 4-hydroxy-phenylacetic acid (DOPAC) were higher in all brain parts examined. In the optic tectum, the levels of the dopamine metabolite homovanillic acid (HVA) were lowered by the GH treatment. One-day GH implant did not affect behavior or monoamine levels of isolated fish. In the fish kept in groups, a 7-day GH implant increased the hypothalamic levels of DOPAC, but not in the other brain parts examined, which may indicate an effect on the brain dopaminergic system from social interactions. It can be concluded that peripherally administered GH may function as a neuromodulator, affecting the dopaminergic activity of the rainbow trout brain, and this is associated with increased swimming activity.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1998

Stimulation of fracture healing by local application of humoral factors integrated in biodegradable implants.

Growth stimulation by growth hormones or by IGF-1 is well known whereas publications about stimulation of fracture healing with these substances are rare. One of the main effects of IGF-1 is angiopoiesis which consequently may be expected to induce and accelerate the soft tissue callus formation. BMP-2 is a stimulator for osteoclasts and osteoblasts and prepares the osseous reparation. RhBMPs, mostly BMP-2, are already used in the reconstruction of the cranial vault. The main disadvantage of these proteins is the quick inactivation after about 20-30 minutes. Local stimulation without systemic effects might be avoided by releasing a low but constant dose of IGF-1 or BMP. We speculate that the combination of a reasonable implant with an integrated drug release system may enlarge the field of application of biodegradable implants in the treatment of fractures. Such an implant might remarkably reduce the time for fracture healing and also lower the costs of postoperative treatment. In this paper we report our animal models in which we have tested constructive principles of biodegradable implants, we present the first clinical experiences with polyactates (PLLA) in the osteosynthesis of children, and we describe our inventions concerning drug releasing implants. 1) PLLA-implants a) The animal models We performed on oblique osteotomy of the right metacarpal bone in 48 juvenile calves and osteoplastic reconstructions of the cranial vault in 28 juvenile Göttinger minipigs. Biodegradable osteosynthesis with PLLA implants led to results as good as with conventional materials in both animal models, so that we proceeded to clinical evaluation in children. b) The clinical application in children 35 children, aged 6 weeks to 17 years, had resorbable osteosynthesis of their cranioplasties for correction of congenital malformations and posttraumatic reconstructions. The follow-up ranged from 5-15 years. 2) Invention of a drug-releasing system IGF-1 or BMP-2 is planned to be incapsulated by evaporation technique into nanospheres of low PDLLA (Poly-DL-Lactite) with a molecular weight of about 20,000 and an expected resorption time of 2-3 weeks (patent pending). 3) Concept of our drug-releasing resorbable implants Plates could be built up in multilayers of PDLLA sheets, separated by a spongiform matrix containing the IGF-1- or BMP-2-loaded nanospheres. The screws are hollow due to an internal driving system. The specially designed thread could also contain nanospheres, which would be brought into the cortical bone and the medullary space. The cavity of the screw is filled up with nanospheres after tightening.

Absorbable Implants↗

PubMed2006

Dynamics of subcutaneous tissue response to the implantation of tetracycline-treated or untreated membrane of demineralized bovine cortical bone in rats.

This study aims to conduct a histological evaluation of tissue response to a membrane obtained from demineralized bovine cortical bone, associated or not, to tetracycline (TTC). TTC treated and untreated bovine membranes were implanted in the subcutaneous tissue of rats (n = 120). The animals were killed 1, 3, 7, 15, 30, and 60 days after surgery. The tissue around the material was fixed in 10% buffered formalin for 24 h. Sections of 6 mm were stained with hematoxylin and eosin. In general, moderate to intense inflammatory response was observed in the initial periods (1 and 3 days), moderate response in the 7- and 15-day periods, and that was remarkably reduced at 30 and 60 days. Resorptions of the membranes by mononuclear cells (fibroblasts and macrophages) and multinucleated giant cells were observed 15 days after implantation. Only the remnants of the material could be detected in some animals in 60 days. Both membranes were tolerated by the tissue and were completely resorbed after 30-60 days. While the association of TTC apparently accelerated the biodegradability of the membrane substrate, no significant differences were found in the tissue response behavior between the two groups tested.

Absorbable Implants↗

PubMed2000

Inductive activity of recombinant human growth and differentiation factor-5.

Growth and differentiation factor-5 (GDF-5) is a divergent member of the transforming growth factor-beta/bone morphogenetic protein (BMP) superfamily that is required for proper skeletal patterning and development in the vertebrate limb. Based on the homology of GDF-5 with other bone-inducing BMP family members, the inductive activity of a recombinant form of human GDF-5 (rhGDF-5) was evaluated in a series of in vitro assays and in vivo bone-formation models. The in vitro response to rhGDF-5 resulted in the formation of chondrogenic nodules in fetal rat calvarial cells cultured in the context of collagen or collagen/hyaluronate extracellular matrices. Matrices loaded with rhGDF-5 induced ectopic cartilaginous and osseous tissue when implanted in subcutaneous or intramuscular sites. In non-human primate long-bone-defect and spinal-fusion models, rhGDF-5 combined with a mineralized collagen matrix induced bone formation in a manner equivalent to autogenous bone. These results highlight the unique potential of rhGDF-5 in a wide variety of orthopaedic applications.

Absorbable Implants↗

PubMed2004

Minimally invasive sinus floor elevation procedures for simultaneous and staged implant placement.

Osteotome techniques are used as a less invasive alternative to the lateral window osteotomy to increase the volume of bone in the posterior maxilla. Implants may be placed simultaneously for four to six months after performing osteotome-mediated sinus floor elevation, depending upon the residual crestal bone remaining beneath the sinus floor. This article describes the clinical indications and techniques for localized internal sinus elevation using osteotomes. The incorporation of this minimally invasive crestal approach to sinus augmentation into the clinical practice results in increased case acceptance with reduced treatment duration, trauma and cost.

Absorbable Implants↗

PubMed2004

Optimal degradation rate for collagen chambers used for regeneration of peripheral nerves over long gaps.

The experimental study of peripheral nerve regeneration has depended heavily on the use of a nerve chamber in which the stumps of the transected nerve are inserted. A large variety of chamber fillings and chamber types have been used in an effort to induce a higher quality of regeneration across the gap initially separating the two stumps. In this study we studied the morphology of nerves regenerated across a 15 mm gap following implantation of a series of five chambers. The chambers were fabricated from type I collagen and possessed identical pore volume fractions as well as average pore diameters, but differed in cross-link density continuously along the series. The residual mass of the implanted chambers at 9 weeks was observed to increase continuously with increasing cross-link density along the series, indicating a continuous decrease in degradation rate. The quality of regenerated nerves, determined by the number of large diameter fibers (A-fibers) per nerve, the average diameter of all axons and the ratio of area occupied by axons (N-Ratio), was superior at an intermediate level of chamber degradation rate. The maximal quality of peripheral nerve regeneration corresponded to an optimal degradation rate with an estimated chamber half-life of approximately 2-3 weeks following implantation. A speculative mechanistic explanation of the observed optimum focuses on the hypothetical role of cell and cytokine traffic that may take place through holes in the chamber generated by the degradation process. The data show the presence of a hitherto unreported optimal chamber degradation rate that leads to regenerated nerves of maximum quality.

Absorbable Implants↗

PubMed2007

Passivating protein coatings for implantable glucose sensors: evaluation of protein retention.

The long-term function of implantable biosensors is limited by the foreign-body reaction (FBR). Since the acute phase of the FBR involves macrophage attachment mediated by adsorbed fibrinogen, preadsorption, and retention of other proteins might reduce the FBR. The retention of preadsorbed albumin, hemoglobin, von Willebrand's factor, and high-molecular-weight kininogen was therefore measured after exposure to plasma. The retention of preadsorbed proteins after incubation with monocyte cultures and implantation in rats was also measured. Fibrinogen adsorption from plasma to the preadsorbed surfaces was also measured. Hemoglobin adsorption was higher than that for other proteins, and it also had the greatest retention after exposure to blood plasma. When surfaces preadsorbed with hemoglobin were incubated with monocytes, more of the hemoglobin was displaced than that after incubation in plasma, while still more hemoglobin was displaced when the surfaces were implanted in vivo. Protein preadsorption on polystyrene greatly reduced fibrinogen adsorption. However, polyurethane surfaces used for glucose sensors had low fibrinogen adsorption compared with polystyrene, and this low level was not further reduced by preadsorption with other proteins. Preadsorbed proteins on polymers appear to be removed by passive exchange and/or displacement by plasma proteins and by proteases released by monocytes.

Absorbable Implants↗

PubMed2001

Resorbable mesh in the treatment of orbital floor fractures.

A variety of materials have been used to reconstruct defects of the orbital floor. Autogenous materials such as bone and cartilage have the obvious drawback of the necessary donor site, whereas alloplastic implants carry the potential risk of infection, particularly when in communication with the maxillary sinus. Consequently, there has been interest in the use of resorbable alloplastic material that acts as a barrier until completely degraded. In this series, a total of 12 patients with orbital defects larger than 1 cm2 were treated by the placement of a resorbable mesh plate of polyglycolic and polylactic acid (Lactosorb). Of the total of 12 patients treated, 3 were lost to follow-up. Of the remaining 9 patients, the mean follow-up was 6 months, with the longest follow-up being 15 months and the shortest 1 month. Two patients developed enophthalmos. In each case, this measured 2 mm using Hertel exophthalmometry, and was present in the early postoperative period (less than 1 month). The cause of the enophthalmos in both patients was found to be a technical error in placement of the mesh. One patient developed an inflammatory reaction along the infraorbital rim requiring implant removal. This occurred at 7 months. From the above series, it is concluded that resorbable mesh is an acceptable material for reconstruction of the orbital floor in selected patients. It is believed that larger floor defects are better suited for nonresorbable alloplastic reconstruction, and that placement of the mesh over the infraorbital rim is unnecessary and places the patient at risk for a local inflammatory reaction.

Absorbable Implants↗