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Results for “Absorbable Implants”

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PubMed2002

Collagen as an implantable material in medicine and dentistry.

Collagen is a highly versatile material, extensively used in the medical, dental, and pharmacological fields. Collagen is capable of being prepared into cross-linked compacted solids or into lattice-like gels. Resorbable forms of collagen have been used to dress oral wounds, for closure of graft and extraction sites, and to promote healing. Collagen-based membranes also have been used in periodontal and implant therapy as barriers to prevent epithelial migration and allow cells with regenerative capacity to repopulate the defect area. It has been hypothesized that membrane regenerative techniques facilitate the natural biological potential by creating a favorable environment for periodontal and peri-implant regeneration. Due to the enormous potential of collagen-based regenerative barriers, clinicians may benefit from a review of potential applications of implantable collagen and knowledge of collagen preparation and membrane types as well as from as awareness of the functional and degradation properties of those materials.

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PubMed2005

Development of a resorbable macroporous cellulosic material used as hemostatic in an osseous environment.

The control of bleeding is a frequently encountered therapeutic problem, particularly during dental surgery. The most efficient substances used to resolve this problem are not risk-free because of their animal or human origins, so cellulosic materials are potentially of interest. The aim of this study was to develop a resorbable macroporous cellulosic material for use as a resorbable hemostatic agent in bone sites. The degradation and the cytocompatibility of the cellulosic material versus controls were evaluated and its behaviour in vivo was studied. An original process using calcium carbonate powder as inverse matrix was used to develop a macroporous material. In order to predegrade the cellulosic material for hemostatic use, oxidation was performed with periodate. A dialdehyde component unstable at physiological pH was thus obtained. The material was found to have cytotoxicity, biocompatibility, and resorption properties similar to control but its hemostatic power was higher.

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PubMed2004

Chondral injury due to migration of a Mitek RapidLoc meniscal repair implant after successful meniscal repair: a case report.

A case of chondral lesion of the medial femoral condyle caused by a bioabsorbable Mitek RapidLoc meniscal repair implant is presented. Meniscal repair was quite successful, but migration of one of the implanted fixation devices resulted in chondral damage, 12 months postoperatively. All orthopaedic surgeons using these new devices should be aware of the possibility of chondral damage of the adjacent femoral condyles.

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PubMed2001

Bone regeneration using recombinant human bone morphogenetic protein-2 (rhBMP-2) in alveolar defects of primate mandibles.

The efficacy of bone morphogenetic protein (BMP) for bone reconstruction has been widely studied in numerous animal experiments, but insufficient information exists about its ability to regenerate bone in primates. The purpose of this study was to evaluate the effects of recombinant human BMP-2 (rhBMP-2) on bone formation in alveolar bone defects in the mandibles of young primates. Marginal bone defects were created in the mandibles of nine 5-year-old rhesus monkeys and rhBMP-2 permeated in a polylactic-co-glycolic acid-coated gelatin sponge (PGS) was implanted into the bone defects. The resected bone treated with rhBMP-2 regenerated completely at 12 weeks postoperatively, and remodelling and consolidation of new bone were seen histologically. This study provides evidence of considerable bone regeneration in alveolar defects after surgical implantation of rhBMP-2 in non-human primates. This technique may be an effective alternative to autogenous bone grafts for reconstructive surgery in clinical practice.

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PubMed2004

Gross, radiology and ultrasonographic evaluation of coral post-implantation in sheep femur.

The study was carried out to evaluate macroscopically the ability of coral to repair a large size bone defect. A total 12 adult, male sheep were used in the study. The large bone defect (2.5cm x 0.5cm x 0.5cm) was created surgically on the left proximal femur and replaced by a block of coral (Porites sp.). Radiographs were obtained immediately after surgery and at 2, 4, 8 and 12 weeks post-implantation. Ultrasonographic examinations were carried out every 2 weeks after implantation up to 12 weeks using ultrasound machine (TOSHIBA Capasee II) connected with 7MHz frequency transducer. The sheep were euthanased at 2, 4, 8, and 12 weeks post-implantation and the bone examined grossly. Both ultrasonographs and radiographs taken at 8 and 12 weeks showed that the implants had been resorbed and left the space that much reduced in size. There was no sign of implant rejection observed in all animals. The results showed that processed coral has potential to become bone substitute for reconstructive bone surgery.

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PubMed2006

Heparin-immobilized biodegradable scaffolds for local and sustained release of angiogenic growth factor.

Heparin-immobilized porous biodegradable scaffolds were fabricated to release basic fibroblast growth factor (bFGF) in a sustained manner. Heparin was covalently conjugated onto the surface of macroporous PLGA scaffolds fabricated by a gas-foaming/salt-leaching method. Sustained release of bFGF was successfully achieved for over 20 days due to high affinity of bFGF onto the immobilized heparin. It appears that bFGF release rate was regulated by the specific interaction between bFGF and heparin. The bFGF fraction released from the scaffolds maintained its bioactivity, as judged from determining the proliferation extent of human umbilical vein endothelial cells (HUVECs) in vitro. When heparin-immobilized scaffolds loaded with bFGF were implanted subcutaneously in vivo, they effectively induced the formation of blood vessels in the vicinity of the implant site. This study demonstrated that local and sustained delivery of angiogenic growth factor for tissue regeneration could be achieved by surface modification of porous scaffolds with heparin.

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PubMed2006

Tissue response to polyglycolide, polydioxanone, polylevolactide, and metallic pins in cancellous bone: An experimental study on rabbits.

The purpose of this study was to investigate, qualitatively and histoquantitatively, the tissue response of rabbit femur cancellous bone to polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins under identical conditions. Eighty knees in 50 rabbits were operated on by inserting bioabsorbable pins (PGA, PDS, or PLLA) together with metallic Kirschner wire in 60, and two metallic Kirschner wires alone in 20 knees, while 20 knees served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. Cancellous bone tissue response to implants was studied using histological, histomorphometrical, microradiographical, and oxytetracycline fluorescence methods. Residual fragments of PGA and PDS were seen at 24 weeks. Complete degradation of these polymers had taken place before 52 weeks. No signs of degradation of the PLLA pins were observed within the entire follow-up period. The osteoid formation surfaces at tissue implant-interface were statistically larger in all test groups as compared to intact controls. The number of macrophages at tissue implant-interfaces increased in all bioabsorbable implant specimens until 6 weeks, and with PGA until 12 weeks. No differences in the osseous response emerged when comparing groups of bioabsorbable implants with each other or with stainless steel group. Bioabsorbable pins and metallic Kirschner wires evoked an osteoconductive response in the cancellous bone surrounding implant, but the response intensity between implants displayed no differences. This suggests a simple, nonspecific walling-off new-bone front type of response. Consequently, the polymers possessed no specific osteostimulatory or osteoinhibitory properties. Within the follow-up, no significant differences in biocompatibility between the implants appeared, and no frank inflammatory foreign-body reactions occurred. The small-volume pins obviously did not exceed the local tissue tolerance and clearing capacity of the bone.

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PubMed2004

Results of meniscal repair using a bioabsorbable screw.

PURPOSE: With most all-inside arthroscopic meniscal repair devices, the surgeon has no need for additional incisions or arthroscopic knot tying, and surgical time is decreased compared with traditional suture repair. Although previous studies have examined the pullout strength of various all-inside devices, clinical data is lacking and has been presented for only a few implants. This study evaluates the clinical results of meniscal repair using a bioabsorbable screw. TYPE OF STUDY: Retrospective case series. METHODS: Twenty-five patients underwent 26 all-inside meniscal repairs using this device. Patient interviews were performed as was retrospective evaluation of patient records. Complications and repeat surgeries were noted. RESULTS: The average age of the patients was 28.8 years (range, 15 to 44). The surgeries included 19 medial meniscus repairs and 7 lateral meniscus repairs; 12 patients underwent concomitant anterior cruciate ligament (ACL) reconstruction. We found 11 isolated meniscal repairs in stable knees and 2 isolated meniscal repairs in ACL-deficient knees. An average of 3.6 screws (range, 1 to 6) were used during the meniscal repairs. Eighteen of 25 patients were contacted at an average of 106 weeks (range, 70 to 189) postoperatively. The mean Tegner score was 5, and the mean modified Lysholm score was 84. Three repeat surgeries were performed for failure of meniscal healing, and one repeat surgery was performed for migration of an implant. An additional patient who underwent medial meniscal repair noted a painless mild prominence on the medial aspect of the knee approximately 8 weeks after surgery. This prominence resolved completely over 6 months and did not require a second surgery. CONCLUSIONS: The bioabsorbable screw appears to be a safe and effective device for meniscal repair. Rare complications occurred that involved implant migration and transient inflammatory responses. Clinical success appears comparable to reported results with other methods of meniscal repair. LEVEL OF EVIDENCE: Level IV, case series.

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PubMed1999

Stability studies of a somatostatin analogue in biodegradable implants.

In recent years, peptides and proteins have received much attention as drug candidates. For many polypeptides, particularly hormones, it is desirable to release the drug continuously at a controlled rate over a period of weeks or even months, and thus a controlled release system is needed. Polylactic acid (PLA) is a biocompatible and biodegradable material with wide utility for many applications, including the design of controlled release systems for pharmaceutical agents. Pharmaceutical development of these delivery systems presents new problems in the area of stability assessment, especially for peptide drugs. In this study, we aimed to investigate the influence of different steps, during the manufacturing of an implant, on peptide stability in the polymeric matrix. Polylactic acid implants containing vapreotide, a somatostatin analogue, were prepared by extrusion. The effects of time, extrusion and temperature on the peptide stability were studied. The influence of various gamma sterilization doses, as well as the conditions under which the implants were irradiated, were also investigated. Peptide stability in the polymeric matrix was evaluated at various temperatures and at various time intervals up to 9 months.

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PubMed1999

Serial magnetic resonance imaging evaluation of operative site after fixation of patellar tendon graft with bioabsorbable interference screws in anterior cruciate ligament reconstruction.

Magnetic resonance imaging (MRI) is accepted as the imaging procedure of choice for showing internal derangement of the knee. In contrast to metal implants, bioabsorbable interference screws do not produce an artifact and provide an opportunity to expand the evaluation of the postoperative anterior cruciate ligament (ACL) ligament repair. There is the potential to evaluate the implant, the graft, the adjacent tissue, and the surgically created bone tunnels. The purpose of this study was to evaluate with MRI the postoperative site of ACL patellar tendon autografts in which bioabsorbable screws were used for fixation. It was hypothesized that a time line of bone tissue changes resulting from this type of surgery could be developed based on the expanded evaluation of MRI. From January 1993 through October 1997, 270 patients underwent surgical repair of a disrupted native ACL. There were 173 men 97 women; the average age was 25.1 years, (range, 17 to 50 years). There were 155 right knees and 115 left knees. In addition to the conventional postoperative clinical assessment and plain film radiographs, opportunistic MRIs were obtained with the patient's permission. The examinations were performed at different postoperative intervals from the third postoperative day to 4 years postoperatively. A total 206 MRIs from various time intervals were available for study. The study protocol was designed to look for loss of integrity of the screws, adjacent fluid collection, tunnel widening, and tunnel healing or narrowing. The hypothesis was substantiated in this study. The use of MRI provided observations not available by other imaging methods. The absence of metal implants for fixation provided an opportunity to examine the adjacent tissue in detail and to form a time line of the tissue response in this type of surgery.

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PubMed2006

Collective review: bioactive implants coated with poly(D,L-lactide) and growth factors IGF-I, TGF-beta1, or BMP-2 for stimulation of fracture healing.

Demographic data reveal that due to the increasing aging of the population, complications with the musculoskeletal system will increase in the next years. One major problem in orthopedic and trauma surgery are the delayed healing or non-unions of long bone fractures. The exogenous application of growth factors can stimulate the bone healing to reduce these complications. Beside the choice of the optimal growth factor the application system is important. Therefore, we developed a new bioactive coating method for implants, which is based on a biodegradable poly(D,L-lactide) (coating thickness: 10 mum). This coating allows the incorporation of growth factors and the controlled release of these factors during the healing process without the need for further devices. The effect of different growth factors (IGF-I, TGF-beta1, and BMP-2) locally released from coated intramedullary implants on fracture healing was investigated with biomechanical and histological analysis in rats. All investigated growth factors stimulated the fracture healing as assessed with biomechanical tests and histological analysis. The local application of combined IGF-I and TGF-beta1 had the most stimulating effect on fracture healing, followed by the effect of BMP-2, IGF-I, and TGF-beta1 alone. Bioactive coating of biomechanical well-established implants can on the one hand stabilize the fracture and on the other hand stimulate healing processes to increase healing and to reduce the rate of complications.

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PubMed1999

Bone morphogenetic protein but not transforming growth factor-beta enhances bone formation in canine diaphyseal nonunions implanted with a biodegradable composite polymer.

BACKGROUND: The purpose of the present study was to create an effective bone-graft substitute for the treatment of a diaphyseal nonunion. METHODS: A standardized nonunion was established in the midportion of the radial diaphysis in thirty mongrel dogs by creating a three-millimeter segmental bone defect (at least 2 percent of the total length of the bone). The nonunion was treated with implantation of a carrier comprised of poly(DL-lactic acid) and polyglycolic acid copolymer (50:50 polylactic acid-polyglycolic acid [PLG50]) containing canine purified bone morphogenetic protein (BMP) or recombinant human transforming growth factor-beta (TGF-beta1), or both, or the carrier without BMP or TGF-beta1. Five groups, consisting of six dogs each, were treated with implantation of the carrier alone, implantation of the carrier with fifteen milligrams of BMP, implantation of the carrier with 1.5 milligrams of BMP, implantation of the carrier with fifteen milligrams of BMP and ten nanograms of TGF-beta1, or implantation of the carrier with ten nanograms of TGF-beta1. At twelve weeks after implantation, the radii were examined radiographically and the sites of nonunion were examined histomorphometrically. RESULTS: We found that implantation of the polylactic acid-polyglycolic acid carrier alone or in combination with ten nanograms of TGF-beta1 failed to induce significant radiographic or histomorphometric evidence of healing at the site of the nonunion. The radii treated with the carrier enriched with either 1.5 or fifteen milligrams of BMP showed significantly increased periosteal and endosteal bone formation on histomorphometric (p < 0.05) and radiographic (p < 0.02) analysis. CONCLUSIONS: Bone formation in a persistent osseous defect that is similar to an ununited diaphyseal fracture is increased when species-specific BMP incorporated into a polylactic acid-polyglycolic acid carrier is implanted at the site of the nonunion. TGF-beta1 at a dose of ten nanograms per implant did not induce a similar degree of bone formation or potentiate the effect of BMP in this model. CLINICAL RELEVANCE: The biodegradable implant containing BMP that was used in the present study to treat diaphyseal nonunion is an effective bone-graft substitute.

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PubMed2006

Reduction of face and neck laxity with anchored, barbed polypropylene sutures (Contour Threads).

The use of nonabsorbable sutures for lifting lax, aging skin is an increasingly popular option for cosmetic surgeons. Contour Thread (Surgical Specialties Corp.) are novel modified polypropylene sutures recently approved for this purpose by the US FDA. Design and technical modifications incorporated into this implant may reduce complications and limitations seen with previous, similar products. Early experience has been positive, although the durability of cosmetic effect and the potential for long-term complications remain to be seen.

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PubMedDate not supplied

The effects of resorbable plates on rabbit ear cartilage.

BACKGROUND: When performing septorhinoplasty, deviated segments of septal cartilage can be straightened using cartilage or bone as splinting grafts. In some cases, autologous material is not available without an additional surgical procedure to harvest cartilage or bone. It is possible that resorbable plates can be used to splint and straighten deviated cartilage. Experience using bioresorbable rigid fixation devices on cartilage has been limited. OBJECTIVE: To examine early histopathologic changes of rabbit ear cartilage and adjacent soft tissue following implantation with bioresorbable plates. DESIGN: Nonrandomized, placebo-controlled trial. SUBJECTS: Twelve adult New Zealand white rabbits. MATERIALS AND METHODS: Ten adult New Zealand white rabbits (20 ears) underwent stenting of intact ear cartilage with LactoSorb plates (Lorenz, Jacksonville, Fla). Rabbits were killed 28 days after implantation, and the soft tissue, plates, and cartilage were harvested and prepared for histological examination. As controls, 2 rabbits (4 ears) underwent dissection and closure without stenting. RESULTS: Six rabbits experienced superficial skin breakdown on the ventral surface of the ear caused by excessive wound tension of the implant. The cartilage-plate interface and the surrounding soft tissues stenting the dorsal side of the ear remained free of inflammation or necrosis for all animals. Simple elevation of the perichondrium revealed no differences in the appearance of the cartilage between the control and test rabbits. CONCLUSIONS: Resorbable plates have no deleterious effects on cartilage during the first month of implantation. While short-term studies have documented the safety and efficacy of using bioresorbable plates, further studies are recommended.

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PubMed2005

Use of resorbable plates and screws in pediatric facial fractures.

PURPOSE: The use of resorbable plates and screws for fixation of pediatric facial fractures is both well tolerated and effective. It enables realignment and stable positioning of rapidly healing fracture segments while obviating any future issues secondary to long-term metal retention. PATIENTS AND METHODS: Forty-four pediatric facial fractures were treated over a 10-year period at our institution using differing techniques of polymeric bone fixation. Twenty-nine mandible fractures in patients under the age of 10 (age range, 6 months to 8 years) were treated. Displaced fractures of the symphysis, parasymphysis, body, and ramus underwent open reduction and either 1.5-mm or 2.0-mm plate and screw fixation in 14 patients. Subcondylar fractures were treated by a short period of maxillomandibular fixation (3 weeks) achieved with suture ligation between resorbable screws placed at the zygoma and symphysis or a circummandibular suture attached to a zygomatic screw. Fifteen patients (age range, 4 to 11 years) with isolated frontal, supraorbital, intraorbital, or orbitozygomatic fractures were treated by open reduction and internal fixation with 1.5-mm resorbable plates, mesh, and screws. RESULTS: No long-term implant-related complications were seen in any of the treated patients. CONCLUSIONS: Resorbable polylactic and polyglycolic acid plates and screws can be an effective fixation method for facial fractures in children in the primary and secondary dentition periods.

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PubMed1998

Internal fixation of maxillofacial fractures: indications and current implant technologies and materials.

Rigid fixation techniques are frequently utilized for the repair of maxillofacial skeletal injuries. This paper reviews the commonly available implants and materials along with their typical indications. The focus is primarily on the most recent trends and developments. Latticework plates and meshes provide greater fixation strength with smaller amounts of metal; modern reconstruction plates allow for fixation of the screws directly to the plates; self-drilling screws make application faster and easier. Resorbable implants made of various polyester polymers are now available, though their indications remain limited thus far. Future developments are discussed as well, including the advent of endoscopic plate placement and image-guided skeletal repositioning.

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PubMed2001

Effects of guided bone regeneration with non-resorbable and bioabsorbable barrier membranes on osseointegration around hydroxyapatite-coated and uncoated threaded titanium dental implants placed into a surgically-created dehiscence type defect in rabbit tibia: a pilot study.

The purpose of this study was to evaluate the effects of guided bone regeneration (GBR) with either a non-resorbable (ePTFE) or bioabsorbable barrier membrane (RSLT) on osseointegration and extent of bone formation around hydroxyapatite-coated (HA) and uncoated threaded titanium (Ti) dental implants placed into surgically-created dehiscence type defects in rabbit tibia. A dehiscence type bone defect, approximately 3 mm in width and height was surgically created on the outer surface of the bone in each tibia of 9 rabbits. For the conventional group, either a HA or a Ti implant was then placed at this site. After the same procedure was performed as in the conventional group, the implant site of the GBR group was covered with either an ePTFE or a RSLT. After 4 months, the rabbits were sacrificed. Specimens were prepared and examined histometrically. It was found that the mean percentage of osseointegration tended to increase in HA compared to Ti implants, both with and without membranes. There was a tendency that the extent of newly regenerated bone was higher in the GBR group than that in the conventional group.

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PubMed2004

Collagen containing neonatal astrocytes stimulates regrowth of injured fibers and promotes modest locomotor recovery after spinal cord injury.

The use of collagen as a vehicle to transplant neonatal astroglial cells into the lesioned spinal cord of the adult rat allows a precise application of these cells into the lesion gap and minimizes the migration of the transplanted cells. This approach might lead to anatomical and functional recovery. In the present study, 20 adult female Wistar rats were subjected to a dorsal hemisection at thoracic spinal cord levels. Cultured cortical neonatal rat astrocytes were transplanted into the lesion with collagen as a vehicle (N = 10). Prior to transplantation, the cultured astroglial cells were labelled with fast blue. Control rats received collagen implants only (N = 10). During 1 month of survival time, functional recovery of all rats was continuously monitored. Histological data showed that the prelabelled astroglial cells survived transplantation and were localized predominantly in the collagen implant. Virtually no fast blue-labelled GFAP-positive astroglial cells migrated out of the implant into the adjacent host spinal cord. The presence of transplanted neonatal astroglial cells resulted in a significant increase in the number of ingrowing neurofilament-positive fibers (including anterogradely labeled corticospinal axons) into the implant. Ingrowing fibers were closely associated with the transplanted astroglial cells. The implantation of neonatal astroglial cells did result in modest temporary improvements of locomotor recovery as observed during open-field locomotion analysis (BBB subscore) or during crossing of a walkway (catwalk).

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