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Results for “Absorbable Implants”

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At least 811 records · Page 45Linked to original sources

PubMed2000

The bone regenerative effect of platelet-derived growth factor-BB delivered with a chitosan/tricalcium phosphate sponge carrier.

BACKGROUND: In order to achieve optimal effects, growth factors including platelet-derived growth factor (PDGF) should be delivered with a biodegradable carrier that will release therapeutic concentrations over a sufficient length of time. The purpose of this study was to evaluate the bone regenerative effect of PDGF-BB delivered with a chitosan/tricalcium phosphate (TCP) sponge carrier in a rat calvarial defect model. METHODS: The PDGF-BB-loaded chitosan/TCP sponge carrier was fabricated by freeze-drying a mixture of chitosan solution and TCP powder and soaking in a PDGF-BB solution. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with 125I-labeled PDGF-BB. Chitosan/TCP sponges with and without PDGF-BB were implanted into 8 mm calvarial defects in rats. Rats were sacrificed at 2 and 4 weeks following implantation, and histologic and histomorphometrical examinations were performed. RESULTS: In vitro evaluation demonstrated that an effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. In the histologic examination, the chitosan/TCP sponge carrier promoted osseous healing of the rat calvarial defects as compared to controls. The addition of PDGF-BB to the carrier further enhanced bone regeneration. Evidence of the degraded sponge matrix was observed mingled within the newly formed bone without connective tissue encapsulation. CONCLUSIONS: The results of this study support the use of chitosan/TCP sponges as a delivery system for growth factors and demonstrate that PDGF-BB loaded onto chitosan/TCP sponge carriers has an osteogenic effect on bone regeneration in vivo.

Absorbable Implants↗

PubMed1985

Carbon fiber debris within the synovial joint. A time-dependent mechanical and histologic study.

The consequences of release of carbon debris within the synovial joint are of interest to surgeons contemplating the intra-articular repair of cruciate-deficient knees with a carbon fiber-based material. Coverage of carbon fiber implants with absorbable polymer as well as autogeneic graft material has resulted in surgical procedures that minimize potential fiber release. However, finite risk of release of fiber debris certainly exists. With this in mind, a controlled animal experiment to model debris release in the synovial joint was performed. As a positive control, magnesium tetrasilicate (talc) in suspension was injected into the knees of rabbits. Talc produced a transient synovitis severe enough to alter the mechanical properties of the joint cartilage. Carbon fiber debris, when similarly injected, also produced a synovitis. However, the synovitis induced by carbon particulate was not of sufficient severity or duration to alter the mechanical properties of the cartilage. Neither talc nor carbon fiber debris appeared to physically abrade cartilage.

Animals↗

PubMed2005

Biocompatibility of titanium implants modified by microarc oxidation and hydroxyapatite coating.

A thin hydroxyapatite (HA) layer was coated on a microarc oxidized titanium (MAO-Ti) substrate by means of the sol-gel method. The microarc oxidation (anodizing) enhanced the biocompatibility of the Ti, and the bioactivity was improved further by the sol-gel HA coating on the anodized Ti. The HA sol was aged fully to obtain a stable and phase-pure HA, and the sol concentration was varied to alter the coating thickness. Through the sol-gel HA coating, the Ca and P concentrations in the coating layer increased significantly. However, the porous morphology and roughness of the MAO-Ti was altered very little by the sol-gel treatment. The proliferation and alkaline phosphatase (ALP) activity of the osteoblast-like cells on the MAO/HA sol-gel-treated Ti were significantly higher than those on the MAO-Ti without the HA sol-gel treatment.

Absorbable Implants↗

PubMed2002

Biodegradation of carbonate apatite/collagen composite membrane and its controlled release of carbonate apatite.

The aim of this study was to investigate the biodegradation of carbonate apatite (CO(3)Ap)/collagen composite membrane as a new guided tissue regeneration membrane in vivo and to estimate its controlled release of CO(3)Ap in vitro. To control the biodegradation of the guided tissue regeneration membrane and to promote hard tissue regeneration in the periodontal region, we added CO(3)Ap into the collagen membrane. To investigate the biodegradation of CO(3)Ap/collagen composite membranes, the prepared membranes (CO(3)Ap:0, 10 wt %) were cut into 5 x 5 x 0.1 mm and subcutaneously implanted into the backside of male rats under general anesthesia. The explanted membranes were investigated histologically. To estimate their controlled release of CO(3)Ap in vitro, the membranes (CO(3)Ap 0-10 wt %, 5 x 5 x 0.1 mm) were immersed into collagenase solution and compulsorily dissolved for 48 h. Histological results suggested that the membrane had a good biocompatibility and the biodegradable period was shortened with the presence of CO(3)Ap. In the solubility experiments of the membrane, eluted Ca concentrations gradually increased with total dependence on the dissolution of the collagen membrane. Our study demonstrated that the biodegradation time can be controlled by CO(3)Ap contents in the membrane and CO(3)Ap could be released from the membrane with the biodegradation period.

Absorbable Implants↗

PubMed2003

First evidence that bone marrow cells contribute to the construction of tissue-engineered vascular autografts in vivo.

BACKGROUND: Materials commonly used to repair complex cardiac defects lack growth potential and have other unwanted side effects. We designed and tested a bone marrow cell (BMC)-seeded biodegradable scaffold that avoids these problems. METHODS AND RESULTS: To demonstrate the contribution of the BMCs to histogenesis, we labeled them with green fluorescence, seeded them onto scaffolds, and implanted them in the inferior vena cava of dogs. The implanted grafts were analyzed immunohistochemically at 3 hours and subsequently at 2, 4, and 8 weeks after implantation using antibodies against endothelial cell lineage markers, endothelium, and smooth muscle cells. There was no stenosis or obstruction caused by the tissue-engineered vascular autografts (TEVAs) implanted into the dogs. Immunohistochemically, the seeded BMCs expressing endothelial cell lineage markers, such as CD34, CD31, Flk-1, and Tie-2, adhered to the scaffold. This was followed by proliferation and differentiation, resulting in expression of endothelial cells markers, such as CD146, factor VIII, and CD31, and smooth muscle cell markers, such as alpha-smooth muscle cell actin, SMemb, SM1, and SM2. Vascular endothelial growth factor and angiopoietin-1 were also produced by cells in TEVAs. CONCLUSIONS: These results provide direct evidence that the use of BMCs enables the establishment of TEVAs. These TEVAs are useful for cardiovascular surgery in humans and especially in children, who require biocompatible materials with growth potential, which might reduce the instance of complications caused by incompatible materials and lead to a reduced likelihood of further surgery.

Absorbable Implants↗

PubMed2001

Reduction of abdominal adhesions using composite collagen-GAG implants for ventral hernia repair.

Structural biomaterials can restore abdominal wall integrity but may cause adhesions to the underlying viscera. Collagen-glycosaminoglycan (CG) matrices induce the formation of connective tissue and may reduce adhesion formation to permanent biomaterials such as polypropylene (PP) mesh. Composite implants were created by interposing PP mesh within a porous CG matrix created composite implants. The implants were cross-linked with glutaraldehyde one group (CG-G/PP) or left untreated (CG-nG/PP) and compared to PP mesh. At 4 weeks, the abdominal wall was assessed for the degree of adhesions. The composite implants developed a nascent connective tissue-like structure that reduced adhesions to the bowel. The thickest connective tissue developed in the CG-G/PP group (0.7 +/- 0.1 mm) and thinnest in the PP mesh (0.05 +/- 0.01 mm). The surface area covered with adhesions was greatest in the PP group (72 +/- 17%) compared with the CG-G/PP group (28 +/- 15%) or the CG-nG/PP group (21 +/- 8%). Bowel preferentially adhered to the PP mesh, whereas omentum had some adherence to all constructs. Integrating a biodegradable extracellular matrix analog with a permanent structural biomaterial reduced adhesions in this animal model. Alterations in cross-linking of the CG matrix altered the biological response. This technology may be useful in reconstructive surgery by reducing adhesion formation, while maintaining the strength of permanent structural biomaterials.

Abdominal Muscles↗

PubMed2005

[Bioabsorbable osteofixation devices].

There is continued interest in the development of new biomaterials. The application of new implantable biomaterials requires intense research and thorough evaluation. Much time and effort has been required to overcome the risks and problems associated with the bioabsorbable devices. For surgical bone fixation, these materials were investigated since the 1960's. Different polymer properties were explored to ensure adequate strength and biocompatibility. High-molecular-weight bioabsorbable polymers were initially used, followed by addition of reinforcement materials. The most recent materials are self-reinforced, small yet strong devices. The newer generations contain bioactive substances such as antibiotics and growth factors. Bioabsorbable materials are constantly changing as we try to adopt the principles of tissue engineering. Surgeons are using new techniques to exploit these polymers and their bioabsorbable properties. It is hoped that this multidisciplinary approach of surgery and research will continue to help the further evolution of biomaterial science.

Absorbable Implants↗

PubMed2006

Long-term magnetic resonance imaging evaluation of bioresorbable anterior cervical plate resorption following fusion for degenerative and traumatic disk disruption.

STUDY DESIGN: A retrospective magnetic resonance imaging (MRI) review of a series of patients who underwent a single-level anterior cervical discectomy and fusion followed by anterior plate stabilization using an anterior cervical resorbable mesh plate and screw system. OBJECTIVE: MRI evaluation of the long-term implant resorption properties of a bioresorbable anterior cervical plate and the adjacent peri-implant soft tissue environment. SUMMARY OF BACKGROUND DATA: The use of bioresorbable anterior cervical plates for immediate cervical stabilization following an anterior cervical discectomy and fusion presents several distinct advantages over metallic instrumentation. Bioresorbable polymers may diminish, by their resorbability, implant-related complications such as loosening, migration, and failure of instrumentation, as well as stress shielding of the underlying fusion. Information on the intermediate and long-term bony and soft tissue reaction to the resorption byproducts of these biomaterials is limited. METHODS: There were 9 consecutive patients who underwent single-level anterior cervical decompression and fusion using allograft cortical bone, followed by bioresorbable polylactide anterior mesh plate and screw fixation. Following institutional review board approval, 5 of the 9 patients agreed to postoperative MRI assessment of the peri-implant area. An independent radiologist then characterized implant degradation, and the presence of soft tissue inflammation and swelling during the resorption phase of the bioresorbable plate. RESULTS: At an average follow-up of 32 months, MRI assessment showed no evidence of soft tissue swelling or inflammation related to the resorption of a bioresorbable anterior plate in any of the 5 patients. In addition, none of the patients complained of any dysphagia or phonation difficulties. CONCLUSIONS: Based on MRI assessment, these devices, at more than 2-year follow-up, did not indicate any local chronic inflammation or swelling resulting from their degradation. Clinical symptoms of dysphagia or dysarthria, a common reported problem following anterior cervical spine procedures, were not observed in any patient.

Absorbable Implants↗

PubMed2006

Annuloplasty for valve repair with a new biodegradable ring: an experimental study.

BACKGROUND AND AIM OF THE STUDY: The biodegradable ring was recently developed for mitral and tricuspid annuloplasty. The study aim was to assess the histological biocompatibility of the biodegradable ring and orifice area growth in a porcine model. METHODS: The smallest (size 16) biodegradable ring was implanted into the tricuspid annulus of 16 juvenile pigs. All animals were followed up by transthoracic echocardiography to evaluate tricuspid valve function. Animals were sacrificed at one, three, six, nine and 12 months after implantation. Macroscopic and histological analyses were performed on three sections per ring implantation site. Parameters from the study group were compared to those obtained from control animals that underwent cardiopulmonary bypass without ring implantation. RESULTS: Histological examination showed that the biodegradable ring was gradually replaced by fibrous tissue, with complete hydrolytic degradation within six months. The thickness of the dense fibrous tissue reached that of the initial ring at 12 months. No fibrous tissue development was observed in control animals. Echocardiography showed no signs of tricuspid valve dysfunction, a preserved ventricular contractility, and physiological growth of the tricuspid valve orifice. Macroscopic measurement of the valve orifice area confirmed that the generated fibrous tissue allows for physiological growth of the native annulus. CONCLUSION: The concept of annulus remodeling using a biodegradable ring which preserves the growth potential of the native annulus opens new perspectives for valve repair procedures in the pediatric population. An undoubted contribution is also made to evolving annuloplasty technology.

Absorbable Implants↗

PubMed2007

Stability of alginate-polyornithine microcapsules is profoundly dependent on the site of transplantation.

Alginate encapsulation is a form of cell-based therapy with numerous preclinical successes but recalcitrant complications related to stability and reproducibility. Understanding how alginate stability varies across different transplant sites will help identify indications that might benefit most from this approach. Alginate stability has been quantified in the peritoneum, but there are no systematic studies comparing its relative stability across transplant sites. This study compares the stability of alginate-polycation microcapsules implanted in the peritoneum to those implanted in the brain and subcutaneous space at 14, 28, 60, 90, 120, and 180 days in-life. Using Fourier-Transform Infrared Spectroscopy (FTIR), the surface of explanted capsules was analyzed for the relative proportion of alginate (outer coat) and the polycationic polyornithine (middle coat). Using a mathematic relationship between FTIR peaks related to these two material components, an index was generated to compare the stability of four different alginates. A notable difference was observed with rapid breakdown in the peritoneum. Conversely, identical alginate capsules transplanted into the brain or subcutaneous space were stable for the 6 month study. These data suggest that (1) successful intraperitoneal transplantation requires modifications of the capsule configuration, the host environment, or both and (2) that sites such as the brain and subcutaneous space are inherently less hostile to conventional alginate capsule configurations.

Absorbable Implants↗

PubMed2000

DegraPol-foam: a degradable and highly porous polyesterurethane foam as a new substrate for bone formation.

Bone morphogenetic protein (BMP) is known to require a suitable carrier to induce ectopic bone formation in vivo. To evaluate the suitability of DegraPol-foam, a degradable, elastic, and highly porous polyesterurethane foam as carrier for BMP-induced bone formation, a fraction containing all the active BMPs (BMP cocktail) was combined with DegraPol-foam and implanted subcutaneously into rats. DegraPol-BMP scaffolds were found to induce osteogenesis 2 weeks after implantation as evidenced by morphological and biochemical observations. In addition, the osteoblast-compatibility of DegraPol-foam was examined here. In vitro, primary rat osteoblasts and osteoblasts from the human cell line (HFO1) attached and proliferated preferentially on the surface of the DegraPol-foam. Both cell types exhibited relatively high attachment and low doubling time that resulted in a confluent cell multilayer with spindle-shaped morphology on the surface of the foam. Osteoblasts produced high concentrations of collagen type I and osteocalcin, and expressed increasing levels of alkaline phosphatase (ALP) activity. Taken collectively, both osteoblasts from rat tibia and from the human cell line HFO1 showed high cell attachment and growth, and preserved their phenotype. The geometrical structure of DegraPol is a suitable carrier for BMP for the induction of bone formation.

Absorbable Implants↗

PubMed2002

Use of a bioabsorbable anterior cervical plate in the treatment of cervical degenerative and traumatic disc disruption.

OBJECT: Anterior cervical discectomy and fusion (ACDF) is a widely accepted treatment for anterior degenerative or traumatic instability of the cervical spine. To reduce or eliminate complications such as implant migration and failure, imaging degradation, and fusion stress shielding that are occasionally associated with spinal instrumentation, attention has been given to the use of bioresorbable anterior cervical plate (ACP) devices. This paper is a preliminary report of a retrospective series in which a resorbable mesh and screw system was used for graft containment in single-level ACDF. METHODS: A review of patient charts and imaging studies was conducted to determine functional outcome, fusion success, and potential soft-tissue reaction to implant resorption. Nine patients with a cervical degenerative disc disease or traumatic disc disruption were treated between October 2001 and March 2002. Follow up averaged 206 days. Eight patients were found to have an excellent result, one patient had a good result, and no patients had a satisfactory or poor result. At the time of follow-up examination, 77% of patients were found to have a radiographically solid fusion. The two patients without a solid fusion were examined only an average 8 months postoperatively and manifested no symptoms related to fusion nonhealing. No significant soft-tissue reaction was noted clinically or radiographically in any of the patients. CONCLUSIONS: The results of this preliminary study indicate that bioresorbable ACP systems for single-level ACDF are both safe and effective.

Absorbable Implants↗

PubMed2000

Advances in endosseous implants: the 'sandwich' split cortical graft for dental implant placement.

Endosseous implants have restored normal function and dental health to many patients. When implants were introduced as an effective treatment modality, their efficacy was limited by the amount of available bone. Today, various grafting procedures can surgically create bone width and volume. Implants can be placed in more ideal locations for successful prosthetic reconstruction. Autogenous bone has been considered the "gold standard," and the most predictable graft material. However, harvesting autogenous bone requires a second surgical site, increased surgical and healing time, and increased morbidity. A loss of a single tooth or multiple teeth leads to atrophy of the alveolus and reduction of osseous width and height (volume). "Sandwich" split cortical graft surgery can be used as the surgical procedure of choice to re-establish bone volume and contour. With this procedure, the recipient site is also the site for the donor cortical bone. A bone replacement graft material is placed within the cancellous compartment and is contained by the autogenous cortical block harvested from the recipient bed. Sandwich split cortical graft surgery offers the obvious advantage of autogenous bone without the need for a second surgical site.

Absorbable Implants↗

PubMed2000

Chronic allograft rejection associated vasculopathy and synthetic biodegradable vascular grafts: a lesson to learn?

In chronic allografts, graft vessels eventually develop so-called "transplant vascular sclerosis" or "intimal hyperplasia". A major question is whether the cells in the neointima are donor or recipient derived. The process of transplant vascular sclerosis closely resembles the remodeling of the vascular wall as seen when synthetic biodegradable small caliber vascular grafts are implanted. In this model, the cells in the newly developing neointima as well as neomedia are, by definition, recipient derived. By using cardiac allografts as well as aortic allografts exchanged between a female donor and a male recipient (rats), the origin of the neointimal vascular smooth muscle cells could be traced by looking for the Y-chromosome in isolated (alpha-actin positive) intimal cells using PCR. In both models these intimal cells were found to be of recipient-origin. It is proposed, that, basically, this remodeling process is part of a normal healing process. Whereas in biodegradable grafts this "healing process" appears to be self limiting, in allografts the process goes on beyond the needs of functional repair, eventually, in some cases, leading to total vascular occlusion. Future therapeutic protocols might try and aim at controlling this essentially normal repair process.

Absorbable Implants↗

PubMed1999

Incorporation of three types of bone block implants in the facial skeleton.

The regenerative response on autogenous cancellous and cortical bone grafts, and on a commercial available xenogenous resorbable bone mineral (RBM) (Bio-Oss, Geistlich-Pharma, Wolhusen, Switzerland) was compared in standardized bony defects related to a paranasal sinus. On 15 skeletally mature goats four critical sized full thickness bone defects were trephined in the frontal bone. These defects were filled at random with a cortical bone plug, a cancellous bone plug, a plug of spongious RBM cut into shape or left empty. Fluorochrome bone markers were injected subcutaneously 1 and 5 weeks after transplantation, and one week before the animals were killed. The animals were killed at 3, 6, 12 and 24 weeks after surgery. Histological evaluation showed that autogenous bone grafts were all accepted and incorporated in a similar way as in calvarial defects. RBM was only osteoconductive. New bone was formed at the margins of the defects, and only little of the RBM was incorporated. Most of the RBM was gradually resorbed by multinucleated osteoclast-like cells.

Absorbable Implants↗

PubMed2006

Biomechanical strength of reconstruction plates when used for medial support of MED-El cochlear implants: implications for diagnostic MRI.

PURPOSE: It is hypothesized that a mesh reconstruction plate designed to fit a cochlear implant (CI) internal device will provide immediate structural support to the site of the implant and that this strength far exceeds the forces induced by a 1.5-tesla MRI. PROCEDURES: Human calvarial specimens were drilled and plated with reconstruction mesh. Force was applied until failure was reached. RESULTS: Mean maximum force, mean force to first failure and mean displacement measures for group 1 (resorbable mesh, n = 10) were 302.9 N, 283.0 N and 3.05 mm, respectively. The mean maximum force for group 2 (0.4-mm titanium mesh, n = 10) and group 3 (0.6-mm titanium mesh, n = 8), were 121.3 and 234.0 N, respectively. Mean force of first failure was 92.0 N for group 2 and 164.8 N for group 3. CONCLUSIONS: The force required for failure of the mesh is significantly greater than the 0.17 N exerted on a CI magnet by a 1.5-tesla MRI scan.

Absorbable Implants↗

PubMed2002

The effect of transforming growth factor-beta1, released from a bioabsorbable self-reinforced polylactide pin, on a bone defect.

Transforming growth factor-beta 1 (TGF-beta1)is a polypeptide growth factor which has been shown to increase bone formation in experimental studies. In this study it was combined to a bioabsorbable self-reinforced poly-LD-lactic acid fracture fixation pin. To assess the effect of TGF-beta1 on the healing of a bone defect, the pins were implanted in the rat distal femur next to a bone defect filled with a viscose cellulose sponge. The pins used in the study group (13 rats) contained 50 microg of TGF-beta1, whereas in the control group of nine rats an identical pin without the growth factor was used. In the histologic examination at 1, 3 and 6 weeks no difference was detected in the amount of bone inside the viscose cellulose sponge between the rats treated with TGF-beta1 and those with no added growth factor. At 3 weeks there was more fibroblast-rich mesenchymal tissue inside the viscose cellulose sponge in the rats treated with TGF-beta1. In the radiographic examination at 3 weeks there was an increase in the amount of new periosteal bone on the bone defect in the TGF-beta1-treated rats.

Absorbable Implants↗

PubMedDate not supplied

Effect of co-solvents on the controlled release of calcitonin polypeptide from in situ biodegradable polymer implants.

The objective of this study was to design an in situ biodegradable polymer implant controlled-release drug delivery system, using novel combinations of co-solvents and a model polypeptide, calcitonin (CT), and to assess the release of drug as a function of these co-solvents. Formulations were prepared by dissolving/ suspending CT polypeptide in poly-(lactic acid) (PLA) polymer solutions/suspensions containing combinations of a hydrophobic (benzyl benzoate, BB) and a hydrophilic (benzyl alcohol, BA) solvent. The CT-PLA mixtures were each injected into test tubes containing phosphate buffered saline solution to form the in situ implant and sampling was conducted over a 28-day period. The samples were analyzed for drug content using a modified Lowry protein assay procedure. Cumulative drug release demonstrated a rank-order correlation depending on the amount of the hydrophobic (BB) and hydrophilic (BA) solvents within each system. Increasing the amounts of the hydrophobic solvent, BB, in formulations demonstrated a 1.2-4.4-fold increase in CT release. Stability studies of all formulations over a 4-month period showed progressive increase in degradation of the CT polypeptide, especially at 37 degrees C, but a slower degradation pattern prevailed at 4 degrees and 20 degrees C. Differential scanning calorimetric studies revealed a homogenous mixture of drug in the polymer matrix. Overall, these studies demonstrated the feasibility of designing controlled release systems capable of releasing a polypeptide drug as a function of influence of different co-solvent combinations.

Absorbable Implants↗