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Results for “Absorbable Implants”

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PubMed2005

Novel tissue-engineered biodegradable material for reconstruction of vascular wall.

BACKGROUND: To solve several problems with artificial grafts, we sought to develop a novel bioengineered material that can promote tissue regeneration without ex vivo cell seeding and that has sufficient durability to be used for artery reconstruction. Here, we tested whether this biodegradable material could accelerate the in situ regeneration of autologous cardiovascular tissue, especially of the arterial wall, in various models of cardiovascular surgeries. METHODS: The tissue-engineered patch was fabricated by compounding a collagen-microsponge with a biodegradable polymeric scaffold composed of polyglycolic acid knitted mesh, reinforced on the outside with woven polylactic acid. Tissue-engineered patches without precellularization were grafted into the porcine descending aorta (n = 5), the porcine pulmonary arterial trunk (n = 8), or the canine right ventricular outflow tract (as the large graft model; n = 4). Histologic and biochemical assessments were performed 1, 2, and 6 months after the implantation. RESULTS: There was no thrombus formation in any animal. Two months after grafting, all the grafts showed good in situ cellularization by hematoxylin/eosin and immunostaining. The quantification of the cell population by polymerase chain reaction showed a large number of endothelial and smooth muscle cells 2 months after implantation. In the large graft model, the architecture of the patch was similar to that of native tissue 6 months after implantation. CONCLUSIONS: A tissue-engineered patch made of our biodegradable polymer and collagen-microsponge provided good in situ regeneration at both the venous and arterial wall, suggesting that this patch can be used as a novel surgical material for the repair of the cardiovascular system.

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PubMed2004

Smooth muscle-like tissues engineered with bone marrow stromal cells.

Bone marrow-derived cells have demonstrated the ability to differentiate into multiple mesenchymal cell lineages. Here we tested whether smooth muscle (SM)-like tissues can be created in vivo with bone marrow stromal cells (BMSCs). Cultured canine BMSCs, which expressed SM cell-specific markers including SM alpha-actin and SM myosin heavy chain, were seeded on three-dimensional, biodegradable polymer scaffolds and implanted into peritoneal cavity of athymic mice. The cell-scaffold constructs retrieved 4 weeks after implantation formed three-dimensional tissues. Immunohistochemical analyses showed that the tissue reconstructs expressed SM alpha-actin and SM myosin heavy chain. Masson's trichrome staining showed the presence of significant amounts of collagen in the tissue reconstructs. Cells labeled with a fluorescent tracer prior to implantation were still present in the tissue reconstructs 4 weeks after implantation. Non-seeded scaffolds (control groups) retrieved 4 weeks after implantation did not exhibit extensive tissue formation. This study demonstrates the potential of BMSCs as an alternative cell source for tissue engineering of SM.

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PubMed2004

Bioresorbable composite bone paste using polysaccharide based nano hydroxyapatite.

Aim of this study concerns to the development of bioresorbable composite materials for bone repair and regeneration. Despite nano hydroxyapatite (HA) has wide range of medical applications, particles mobilization and slow resorbable nature limits its use in certain applications particularly, periodontal and alveolar ridge augmentation. To enhance its usage, we have prepared HA composite bone paste with a natural polysaccharide, chitosan, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods and suggesting that the nano HA crystallites are well intact with the chitosan macromolecules. FT-IR results are indicating the existence of hydroxyl and amide groups in addition to the characteristic peaks of nano HA in the composite paste. The physical nature of paste form implies that it would be highly beneficial for the particle immobilization upon implantation. In vitro physiological stability and solubility of the composite was performed in phosphate buffered saline under physiological condition and found that the rate of resorbability of composite was quite higher than nano HA. These findings suggest that the HA/chitosan composites may have a great impact on human health care systems as bioresorbable bone substitute.

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PubMedDate not supplied

Histologic findings with a bioabsorbable anterior cruciate ligament interference screw explant after 2.5 years in vivo.

We retrieved a high-molecular-weight poly-L-lactic) (PLLA) anterior cruciate ligament (ACL) interference screw (Arthrex, Naples, FL) after 30 months in vivo during revision ACL surgery. Gross, histologic, histomorphometric, and molecular weight measurements were carried out on the implant and the surrounding bone. These studies showed a 75% decrease in the molecular weight of the screw, with implant fragmentation and new bone formation adjacent to the screw and graft. Healing of the graft within the bony tunnel with no significant inflammatory reaction had occurred. The clinical implications of these findings are that this implant dissolves slowly, and it was physically present at 30 months in vivo. It is a safe, nonreactive alternative to traditional metal interference screws used for ACL graft fixation. It will eventually be substituted by bone and will eliminate some of the problems associated with metallic devices.

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PubMed2003

Cell attachment and biocompatibility of polytetrafluoroethylene (PTFE) treated with glow-discharge plasma of mixed ammonia and oxygen.

The plasma generated from a gas mixture of NH3 plus O2 (NH3 + O2) has been used to impart unique chemical and biological characteristics to polytetrafluoroethylene (PTFE). PTFE treated with NH3 + O2 plasma was physiochemically distinct from surfaces treated with plasma of either NH3 or O2 alone, as determined by electron spectroscopy for chemical analysis (ESCA). The contact angle analysis revealed that the PTFE surfaces became less hydrophobic after plasma treatments. ESCA results indicate the presence of oxygen-containing groups and nitrogen-containing groups at the plasma-treated surfaces. PTFE treated with NH3 + O2 plasma resisted the attachment of platelets and leukocytes in a manner similar to untreated PTFE; however, the attachment of bovine aorta endothelial cells was substantially increased. Once attached, these cells grew to confluency. The increased endothelial cell attachment was higher than that observed following plasma treatment with each gas used separately, which could be attributed to the considerable amount of CF(OR)2-CF2 formed on the NH3 + O2 plasma-treated PTFE surface. At 14 days after subcutaneous implantation in rats, the PTFE wafers treated with NH3 + O2 plasma demonstrated less encapsulation and lower levels of inflammatory cells compared to controls. Collectively, the results suggest that NH3 + O2 plasma treatment imparts a unique character to PTFE and could be useful in certain in vivo applications.

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PubMed2002

Regeneration of soft and hard tissue periodontal defects.

Periodontitis is characterized by the formation of periodontal pockets and bone loss. Although the basic treatment emphasizes the control of bacterial plaque, the clinician is confronted with the need to correct soft and/or hard tissue defects that develop as a consequence of the disease. This article reviews the current status of regenerative approaches in treating soft and hard tissue defects (based mainly on findings from our own laboratory) and assessed the global applicability of these procedures. Many different techniques have been suggested to treat those defects with, in general, a high degree of success. From the present knowledge it can be concluded that periodontal soft and hard tissue regeneration is possible. Treatment of areas with localized gingival recession or insufficient keratinized gingiva can be achieved with soft tissue grafts or pedicle flaps, as well as with the use of dermal allografts. The treatment of hard tissue defects around teeth and implants can be approached using different types of bone grafts, guided tissue or bone regeneration, or a combination of these. The predictability of many of these therapies, however, still needs to be improved. Since most of these techniques are sensitive, specific, and expensive, their present universal application is limited.

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PubMed2004

Bioabsorbable self-reinforced plates and screws in craniomaxillofacial surgery.

Bioabsorbable fixation devices have been used in craniomaxillofacial (CMF) surgery since the early 70's. In our departments the experimental use started in the 80's with self-reinforced (SR) polylactide devices. The first clinical operations were carried out in 1991. Since that time, we have used different types of self-reinforced bioabsorbable devices in the fixation of several hundreds of osteotomies and fractures. Patients' acceptance has been generally excellent and very few complications occurred during this follow-up of over 10 years. The complications have been minor and have not affected the end results of the operations. In only one oncologic patient, the devices needed to be removed and replaced with a rigid reconstruction plate. The minor complications consisted mainly of a few infections, dehiscence of the wound and plate exposure together with granulation tissue in the operation field. No implant-specific complications were recorded. However, there is a learning curve for the surgeon, as there is with all new methods introduced. Based on our experience, self-reinforced bioabsorbable devices are safe to be used in several indications in the craniomaxillofacial skeleton, also in load-shearing situations.

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PubMed2001

Biodegradable implants in neurosurgery.

BACKGROUND: Biodegradable materials have been used for osteosynthesis by orthopedic surgeons and craniomaxillofacial surgeons for many years. However, such materials are not yet widely used by neurosurgeons despite potential applications. This prospective study was undertaken to evaluate potential applications of biodegradable materials in neurosurgical interventions. METHODS: A total of 104 4-hole plates and 228 screws consisting of copolymer of poly-70 L/30 D,L-lactide were inserted for fixation of bone flaps in 8 patients and for reinsertion of laminoplasties at 28 levels in 16. The craniotomies were performed for removal of a brain tumour in 4 cases, for surgical management of an aneurysm or cerebral AVM in 2, and for treatment of craniocerebral trauma in another 2. Laminoplasties were performed at 25 levels for intraspinal hemangioblastomas in 15 patients. One patient with an ependymoma underwent 3-level laminoplasty. FINDINGS: One patient with severe head injury in whom the bone flap was re-implanted several months following the craniectomy, developed an aseptic necrosis of the bone flap, which had to be removed. Implant rejection was not observed. One patient suffered from mild local pain in the area of a biodegradeable screw in the frontal region following removal of a sphenoid wing meningeoma. None of the patients with laminoplasty showed signs of functional instability or spinal cord compression. Implant rejection was not observed. No delayed healing or infection occurred. Healing was not delayed and no infections occurred. INTERPRETATION: The results encourage further use of biodegradable materials for the described applications. Additional studies will be performed to investigate the usefulness of biodegradable devices in neurosurgery and to obtain long-term results.

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PubMed2003

[Osteosynthesis of combined radius head and capitulum humeri fractures with mini-implants].

INTRODUCTION: Combined injuries of the capitellum humeri and the radial head are rare. Most of them show combined osteocartilaginous lesions and collateral ligament lesions. Recommendations for treatment of these fatal injuries of the elbow are missing. TYPE OF STUDY: Five cases were investigated in an retrospective analysis. The same approach was used for the osteocartilaginous lesion of the capitellum as well as the injury of the radial head. Internal fixation was done with mini-titanimplants, three of them combined with resorbable pins. PATIENTS AND METHODS: Between 1996-1999 five patients (four men, one woman) with combined injury of the radial head and the capitellum were stabilized. The average age was 34 years (31-40 years). All fractures were stabilized by a direct radial approach with 1.5 mm or 2.0 mm lag screws partly with resorbable pins. All patients were evaluated radiologically and clinically according to the Mayo-elbow-performance score. RESULTS: All patients were personally examined after an average period of 12.8 month (8-24 month) by an independent investigator. 4/5 patients were assessed for their satisfaction. No radiological signs of avascular necrosis of the capitellum or arthrosis were found. Three patients showed periarticular calcifications. The range of motion was averagely 124 degrees (extension 5-30 degrees, flexion 110-145 degrees), in three of five cases a secondary intervention for improvement of joint mobility was necessary. The Mayo-elbow-performance score rated for 85 points in average (range 70-100 points). CONCLUSION: Direct screw fixation with mini-implants, eventually combined with resorbable pins allows to use the same approach for anatomic reconstruction and fixation of the capitellum humeri and radial head. Transarticular fragment fixation of the capitellum allows for safe compression. Therefore early functional rehabilitation is possible postoperatively. Secondary interventions for improve joint motion were necessary in three of five cases.

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PubMed2006

In vivo performance of biodegradable calcium phosphate glass ceramics using the rabbit model: histological and SEM observation.

Two MK5 (45CaO-45P(2)O(5)-5MgO-5K(2)O, in mol%) and MT13 (45CaO-37P(2)O(5)-5MgO-13TiO(2), in mol%) glasses are prepared in the meta- and pyrophosphate regions and crystallized to obtain MK5B and MT13B, respectively. MK5B was obtained by controlled crystallization, and MT13B by powder sintering. As a result of these heat treatment processes, the crystalline phases precipitated in the glassy matrix are KCa(PO(3))(3), beta-Ca(PO(3))(2), beta-Ca(2)P(2)O(7) and Ca(4)P(6)O(19) phases for MK5B and CaTi(4)(PO(4))(6), TiP(2)O(7), alpha- and beta-Ca(2)P(2)O(7) phases for MT13B. To assess the in vivo biological behavior of these glass ceramics, a mixed granulometry in the range 250-355 mum and 355-425 mum with a ratio of 1/1 was implanted for 2, 4, and 12 weeks in the tibiae of Japanese white rabbits. The results showed that the in vivo behavior was strongly affected by their solubility. All implanted materials, MK5B and MT13B, and beta-tricalcium phosphate (beta-TCP) as control material, showed signs of degradation in vivo. However, the levels of degradation were quite different throughout the implantation periods. The highest degradation was observed for MK5B glass ceramic and the lowest for MT13B with beta-TCP in-between. All implanted materials allow for new bone formation in the bone defect area. At the longest implantation period (12 weeks), the MT13B and beta-TCP materials were almost completely surrounded by new bone tissue, whereas MK5B showed some unfilled spaces. This behavior is discussed in terms of the high degradation observed in previous studies.

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PubMed2002

The use of bioabsorbable osteofixation devices in craniomaxillofacial surgery.

Because of problems associated with the conventional osteofixation devices used in craniomaxillofacial surgery, bioabsorbable devices have presented an appealing alternative. Devices made of the polymers polyglycolide (PGA) and polylactide (PLA) and their copolymers (PLGA and PLDLA) are currently the most commonly used. Strong implants can be manufactured from these polymers with a self-reinforcing technique and used in the treatment of fractures and osteotomies. Self-reinforced devices have been studied for nearly 2 decades by our multidisciplinary research group for internal fixation of the bone in both experimental and clinical settings. In craniomaxillofacial fractures and osteotomies they have been used for as long as 10 years with no significant clinical problems. Because of more favored degradation characteristics, currently the copolymer devices (PLDLA and PLGA) represent the advancing front in the application of absorbable devices in craniomaxillofacial surgery. By using bioabsorbable devices, several problems associated with conventional biostable devices can be avoided, especially in children. New techniques that are not possible with biostable devices can be developed by using bioabsorbable devices, too. Our experience with and research on self-reinforced devices are shared here.

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PubMed2006

Biocompatible properties of surgical mesh using an animal model.

AIM: To study the biocompatibility of surgical meshes for use in pelvic reconstructive surgery using an animal model. METHODS: Eight different types of mesh: Atrium, Dexon, Gynemesh, IVS tape, Prolene, SPARC tape, TVT tape and Vypro II, were implanted into the abdominal walls of rats for 3 months' duration. Explanted meshes were assessed, using light microscopy, for parameters of rejection and incorporation. RESULTS: Type 1 (Atrium, Gynemesh, Prolene, SPARC and TVT) and type 3 (Vypro II, Dexon and IVS) meshes demonstrated different biocompatible properties. Inflammatory cellular response and fibrosis at the interface of mesh and host tissue was most marked with Vypro II and IVS. All type 1 meshes displayed similar cellular responses despite markedly different mesh architecture. CONCLUSIONS: The inflammatory response and fibrous reaction in the non-absorbable type 3 meshes tested (IVS and Vypro II) was more marked than the type 1 meshes. The increased inflammatory and fibrotic response may be because of the multifilamentous polypropylene components of these meshes. Material and filament composition of mesh is the main factor in determining cellular response.

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PubMed2003

Fracture of Bilok interference screws on insertion during anterior cruciate ligament reconstruction.

New femoral and tibial interference screws for use during anterior cruciate ligament (ACL) reconstruction have been developed using a composite of poly-L-lactic acid (PLLA) and tricalcium phosphate (TCP). The combination is described as having better incorporation than standard bioabsorbable screws with no loss of mass during incorporation and without the brittle nature associated with conventional TCP implants. However, the screw can fracture during insertion, leaving the distal third inside the femoral or tibial tunnel, making extraction and revision difficult. This is a report of 2 cases of PLLA-TCP screw breakage, 1 occurring in the femoral tunnel and 1 occurring in the tibial tunnel.

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PubMed2006

Bioabsorbable implants in the treatment of hand fractures: an update.

UNLABELLED: Bioabsorbable implants have been used extensively in medicine. Many have suggested interest in these materials for hand fractures since they may lead to less implant morbidity and subsequent stiffness, and they have additional advantages: they are radiolucent, they eliminate hardware removal procedures, they limit stress shielding, and they incrementally transfer load to healing fractures. Disadvantages include weakness relative to metal implants, rapid loss of initial implant strength, higher refracture rates, and foreign body reactions. Newer polymers have led to a reduction in these complications and more stable fixation. While not yet incorporated into the armamentarium of most surgeons, there is promise that in the near future they may assist in the management of some hand fractures. LEVEL OF EVIDENCE: Level V (expert opinion).

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PubMed2005

Polyglycolic acid/poly-L-lactic acid copolymer use in laryngotracheal reconstruction: a rabbit model.

OBJECTIVE: To evaluate the tissue response and resorption of the polyglycolic acid/poly-L-lactic acid (PGA/PLLA) implant in laryngotracheal reconstruction and compare its dynamic stability with autologous cartilage grafts. STUDY DESIGN: An interventional, before-after trial. METHODS: Twenty-one white, female, New Zealand rabbits were divided into four groups. Groups A and B underwent laryngotracheoplasty using the PGA/PLLA implants of 3 and 4 mm widths. Group C received autologous ear cartilage grafts. Group D was the control group and did not undergo surgery. The subjects were sedated at 12 months, and the larynges were evaluated in vivo for stability and area measurements by way of endoscopy during spontaneous respiration. The subjects were then killed, the larynges harvested, and the negative intraluminal pressures applied to the laryngotracheal unit were measured in a closed-system apparatus. The larynges were then evaluated for inflammatory reaction and implant resorption by way of histologic analysis. RESULTS: All implanted subjects survived without complications and grew normally. There was no appreciable subglottic collapse during spontaneous respiration under anesthesia. Ex vivo examination of maximum negative intraluminal pressures (-50 cm H2O) in a closed system demonstrated subglottic collapse of 78%, 72%, 61%, and 3% for groups A, B, C, and D, respectively, revealing the inherent weakness in the surgically manipulated airways regardless of grafting material. Histologically, the PGA/PLLA implants were essentially completely resorbed. CONCLUSIONS: PGA/PLLA appears to be a safe and effective synthetic material for use in laryngotracheal reconstruction in the rabbit model while avoiding donor site morbidity and additional operative time. Reconstructed airways maintained adequate strength and patency under physiologic conditions and are comparable with autologous cartilage grafts.

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PubMed2004

Skeletal volume enhancement: implants and osteotomies.

PURPOSE OF REVIEW: Facial plastic surgeons are concerned with improving or restoring function and form. Most surgeons perform primarily soft tissue procedures, which alone are often sufficient. However, deficiencies in the underlying craniomaxillofacial skeleton must also be addressed. Facial skeletal augmentation remains an essential aspect of cosmetic and reconstructive surgery. This article reviews the basic alloplastic biomaterials available for facial volume enhancement, discusses the zygomatic sandwich osteotomy for malar augmentation, and describes recent applications of distraction osteogenesis in the craniomaxillofacial region. An update in tissue engineering and computer modeling is also provided. RECENT FINDINGS: High-porosity expanded polytetrafluoroethylene has been developed to provide a softer feel with less shrinkage and migration because of better biointegration and cellular ingrowth. Long-term results with porous polyethylene have demonstrated superior biocompatibility and minimal complications. Hydroxyapatite cement has been associated with an immunoguided delayed inflammatory reaction that leads to thinning of the overlying skin and exposure of the implant.Applications of distraction osteogenesis are rapidly expanding and include deformities of the mandible, midface, and cranium. There has been a trend toward the use of internal hardware, and internal devices are being developed to deliver a greater degree of vector control. Biodegradable devices have been developed to eliminate the second surgical procedure necessary for hardware removal. In the future, successful tissue engineering could eliminate many of the drawbacks associated with implants and osteotomies. The ability to stimulate stem cells to generate autogenous bone has been demonstrated in the laboratory. A novel application of computer technology that integrates laser surface scanning and digitizing with computer-aided design and manufacturing to produce facial prostheses has been described. SUMMARY: An abundance of alternatives exist for skeletal volume enhancement including alloplastic implants, standard osteotomies, and distraction osteogenesis. The surgeon must evaluate the pros and cons of each technique in the context of each individual patient to determine the most appropriate option. Technologic advances in biomaterials, distraction hardware, computer modeling, and tissue engineering will continue to supply the surgeon's repertoire with improved methods to augment and restore the craniomaxillofacial skeleton.

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PubMed2000

Treatment of traumatically induced synovial sepsis in horses with gentamicin-impregnated collagen sponges.

Eight horses with synovial sepsis induced by trauma were treated by arthroscopic/tenoscopic debridement and lavage followed by the implantation of a gentamicin-impregnated collagen sponge. Seven of them responded favourably and were sound six months after treatment. The other underwent a further surgical procedure and recovered. Gentamicin-impregnated collagen sponges appear to be a safe and useful adjunct in the treatment of septic joints and tendon sheaths, and have the advantage of being bioabsorbable.

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PubMed2006

Influence of copolymer composition of polylactide implants on cranial bone regeneration.

Biodegradable polymers have become useful auxiliary materials for the functional and structural restoration of bone deficiencies. Commercial implants from poly(L/DL-lactide) 70:30 are used clinically for fracture fixation in regions of low load. Implants manufactured from poly(L/DL-lactide) 80:20 are currently being investigated experimentally. The higher degree of crystallinity results in a higher chemical strength and loading capacity which promises advantages for long-term implantation. In this study implants from these two copolymers were applied to promote bone regeneration of bilateral, full thickness, circular cranial defects in 16 adult New Zealand white rabbits. The defects were covered with melt extruded and laser cut polylactide burr hole covers epicranially and endocranially in direct contact to the dura. The defect spaces were kept open with a spacer which created a hollow chamber. Both materials were implanted in each animal. Bone seeking fluorochromes were used to assess the pattern of bone growth. After eight weeks bone regeneration in the defects was assessed radiologically, histologically and by fluorescence microscopy. During the eight weeks observation period the application of a hollow chamber design resulted in almost complete cranial defect healing, whereby the copolymer composition had no effect on the amount or the morphology of the regenerate. The dura mater showed no adverse tissue reactions during these early stages of implantation. Eight weeks is only a short period in the lifetime of the tested polymers and complete bone regeneration can only be expected after complete polymer degradation. Long-term studies or accelerated degradation studies are required to confirm the expected advantages of poly(L/DL-lactide) 80:20.

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