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Results for “Absorbable Implants”

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PubMed2001

Long-term results of ankle and triple arthrodeses fixed with self-reinforced polylevolactic acid implants in patients with rheumatoid arthritis.

Self-reinforcing polylevolactic acid (SR-PLLA) implants have been used in arthrodeses of patients with rheumatoid arthritis. No long-term evaluation has been published so far. Two patients (three ankles) with destruction of the ankle joint and seven with destruction of the subtalar joint received ten arthrodeses. One out of three ankle arthrodeses healed and nonunion developed in two. Five out of seven triple arthrodeses attained bony union. Two patients with malunion of the subtalar and talonavicular joints are free of symptoms and need no reoperation. One superficial wound infection healed by oral antibiotics. In one patient, an ankle arthrodesis was performed 6 years after the triple arthrodesis of the left foot. SR-PLLA implants can be used in triple arthrodesis in rheumatoid arthritic patients with good results comparable to those of other studies. The problems with nonunion of ankle arthrodeses noticed in former studies are also attributable to this fixation method.

Absorbable Implants↗

PubMed2005

The in vivo degradation, absorption and excretion of PCL-based implant.

The in vivo degradation of poly (epsilon-caprolactone)(PCL) was observed for 3 years in rats. The distribution, absorption and excretion of PCL were traced in rats by radioactive labeling. The results showed that PCL capsules with initial molecular weight (Mw) of 66000 remained intact in shape during 2-year implantation. It broke into low molecular weight (Mw=8000) pieces at the end of 30 months. The Mw of PCL deceased with time and followed a linear relationship between logMw and time. Tritium-labeled PCL (Mw 3000) was subcutaneous implanted in rats to investigate its absorption and excretion. The radioactive tracer was first detected in plasma 15 days after implantation. At the same time radioactive excreta was recovered from feces and urine. An accumulative 92% of the implanted radioactive tracer was excreted from feces and urine by 135 days after implantation. In the mean while, the plasma radioactivity dropped to the background level. Radioactivity in the organs was all close to the background level confirming that the material did not cumulate in body tissue and could be completely excreted.

Absorbable Implants↗

PubMed2006

Influence of the structure of new generation prostheses on shrinkage after implant in the abdominal wall.

When a biomaterial is used to repair an abdominal wall defect, wound contraction can cause the prosthesis to shrink, and the tension generated can provoke recurrence of the defect. This study was designed to determine whether the structure of a prosthesis can directly influence prosthetic shrinkage. Abdominal wall defects (7 x 5 cm) in rabbits were repaired using the laminar prosthesis DualMesh (DM), the composites Sepramesh (Se) and Vypro II (Vy), and the reticular prosthesis Surgipro (PP). The animals were sacrificed 14 and 90 days after surgery, at which time implant specimens were morphologically and immunohistochemically examined to establish the presence of myofibroblasts and macrophages. The size of each prosthesis was measured at the end of the study through image analysis. Morphometric measurements revealed greatest prosthesis shrinkage for Se, PP, and Vy (16.05% +/- 5.08%; 13.75% +/- 4.22%; 16.16% +/- 6.34%), while the DM prostheses only showed a 7.57% +/- 0.62% decrease in size (p < 0.05). In the DM implants, the macrophage response and myofibroblast labeling were reduced. Both biomaterial structure and the macrophage reaction induced at the implant site modulate prosthetic shrinkage, laminar prostheses of the ePTFE type undergoing less shrinkage than reticular meshes. Reduced DM shrinkage was linked to decreased myofibroblast numbers 2 weeks postimplant.

Abdominal Injuries↗

PubMed2000

Biodegradable implants in sports medicine: the biological base.

Biodegradable implants are increasingly used in the field of operative sports medicine. Today, a tremendous variety of implants such as interference screws, staples, sutures, tacks, suture anchors, and devices for meniscal repair are available. These implants consist of different biodegradable polymers that have substantially different raw material characteristics such as in vivo degradation, host-tissue response, and osseous replacement. Because these devices have become the standard implant for several operative procedures, it is essential to understand their biological base. The purpose of this report is to provide a comprehensive insight into biodegradable implant biology for a better understanding of the advantages and risks associated with using these implants in the field of operative sports medicine. In particular, in vivo degradation, biocompatibility, and the osseous replacement of the implants are discussed. A standardized classification system to document and treat possible adverse tissue reactions is given, with special regard to extra-articular and intra-articular soft-tissue response and to osteolytic lesions.

Absorbable Implants↗

PubMed2006

Reconstruction of extensive long bone defects in sheep using resorbable bioceramics based on silicon stabilized tricalcium phosphate.

In this study we evaluated the performance of Skelite, a resorbable bioceramic based on silicon stabilized tricalcium phosphate (Si-TCP), in promoting the repair of a large-sized, experimentally induced defect in a weight-bearing long bone sheep model. Eighteen 2-year-old ewes were used in this study. Animals were sacrificed at 3, 6, and 12 months. One animal entered a very prolonged followup and was sacrificed 2 years after surgery. Bone formation and scaffold resorption were evaluated by sequential x-ray studies, CT scans, histology, immunohistology, microradiography, and quantitative analysis of x-ray studies (optical density) and microradiographs (percentage of bone and scaffold area). Our data show an excellent implant integration and significant bone regeneration within the bone substitute over the course of the experiment. Progressive osteoclastic resorption of the biomaterial was also evident. At 1 year from surgery, the remaining scaffold was approximately 10-20% of the scaffold initially implanted, while after 2 years it was essentially completely resorbed. At the end of the observation period, the segmental defect was filled with newly formed, highly mineralized, lamellar bone.

Absorbable Implants↗

PubMed2003

Operative treatment of flatfoot with talocalcaneal coalition.

Rigid flatfoot or peroneal spastic flatfoot often is associated with a congenital fibrous, cartilaginous, or osseous union of two tarsal bones or more, potentially causing great difficulties in its treatment. Since 1996, 12 patients (14 feet) with painful flatfoot and restricted motion of the hindfoot attributable to talocalcaneal coalition, were treated by resection of the coalition and subtalar arthroereisis by a bioreabsorbable implant. The results were evaluated by the ankle hindfoot clinical rating system of the American Orthopaedic Foot and Ankle Society. These clinical results also were evaluated statistically. Radiographs and computed tomography scans were taken preoperatively and postoperatively. Eight (57.1% of patients) had excellent results, three (21.4% of patients) had good results, and three (21.4% of patients) had fair results. No poor results, or subjective or objective complications were reported. On the basis of these early results, arthroereisis by implanting a bioreabsorbable device after removal of the tarsal coalition, seems to be an effective procedure for the treatment of symptomatic flatfoot associated with talocalcaneal coalitions: correcting the relationship between talus and calcaneus, restoring the alignment of the hindfoot, and reducing pain.

Absorbable Implants↗

PubMed2006

Bioactive and bioresorbable cellular cubic-composite scaffolds for use in bone reconstruction.

We used a novel composite fibre-precipitation method to create bioactive and bioresorbable cellular cubic composites containing calcium phosphate (CaP) particles (unsintered and uncalcined hydroxyapatite (u-HA), alpha-tricalcium phosphate, beta-tricalcium phosphate, tetracalcium phosphate, dicalcium phosphate dihydrate, dicalcium phosphate anhydrate or octacalcium phosphate) in a poly-D/L-lactide matrix. The CaP particles occupied greater than or equal to 70 wt% (greater than or equal to 50 vol%) fractions within the composites. The porosities of the cellular cubic composites were greater than or equal to 70% and interconnective pores accounted for greater than or equal to 70% of these values. In vitro changes in the cellular geometries and physical properties of the composites were evaluated over time. The Alamar Blue assay was used to measure osteoblast proliferation, while the alkaline phosphatase assay was used to measure osteoblast differentiation. Cellular cubic C-u-HA70, which contained 70 wt% u-HA particles in a 30 wt% poly-D/L-lactide matrix, showed the greatest three-dimensional cell affinity among the materials tested. This composite had similar compressive strength and cellular geometry to cancellous bone, could be modified intraoperatively (by trimming or heating) and was able to form cortico-cancellous bone-like hybrids. The osteoinductivity of C-u-HA70, independent of biological growth factors, was confirmed by implantation into the back muscles of beagles. Our results demonstrated that C-u-HA70 has the potential as a cell scaffold or temporary hard-tissue substitute for clinical use in bone reconstruction.

Absorbable Implants↗

PubMed2006

Control of filtering bleb structure through tissue bioengineering: An animal model.

PURPOSE: To devise a means of providing controlled resistance between the anterior chamber and the subconjunctival space after trabeculectomy by implantation of a biodegradable, porous collagen matrix. METHODS: Matrices were implanted in the right eyes of 17 rabbits after trabeculectomy, while left eyes served as surgical controls. The scleral flap was sutured loosely, and the implant provided pressure on the scleral flap to reduce overfiltration. Trabeculectomy in the control eyes was performed with tight sutures using standard methodology. Intraocular pressure (IOP) was measured before surgery and on days 3, 7, 14, 21, and 28 after surgery. Masson trichrome and alpha-smooth muscle actin stains were used for histologic study of the filtering blebs. RESULTS: The initial postoperative IOP reduction was approximately equal, at 14% to 16%, for both groups. In the implanted group, the IOP continued to decrease to 55% below baseline at day 28 as the implant gradually degraded. In the control group, IOP had returned to the preoperative level by day 21. Histologic examination with Masson trichrome and alpha-smooth muscle actin stains showed a prominent bleb in the implanted group compared with scar formation and limited bleb formation in the control group. CONCLUSIONS: Implantation of a biodegradable, porous collagen matrix in the subconjunctival space offers the potential for a new means of avoiding early scar formation and maintaining long-term IOP control by creating a loosely structured filtering bleb.

Absorbable Implants↗

PubMed2001

Extraction site reconstruction for alveolar ridge preservation. Part 1: rationale and materials selection.

Alveolar ridge resorption has long been considered an unavoidable consequence of tooth extraction. While the extent and pattern of resorption is variable among individuals, there is a progressive loss of ridge contour as a result of physiologic bone remodeling. Over the long term, prosthodontic complications, loss of function, and inadequate bone for the placement of dental implants may result. Guided bone regeneration techniques and the use of bone replacement materials have both been shown to enhance socket healing and modify the resorption process. This review describes the process of alveolar bone loss, materials for extraction site grafting, and proposed mechanisms for ridge preservation.

Absorbable Implants↗

PubMed2002

Healing of subcapital femoral osteotomies fixed with self-reinforced poly-L-lactide screws: an experimental long-term study in sheep.

Subcapital femoral osteotomies of ten young adult sheep were fixed with two bioabsorbable, self-reinforced, poly- L-lactide (SR-PLLA) lag screws of 4.5 mm in diameter. At 3 weeks radiographs were taken to check the reduction and fixation achieved. After follow-up periods of 12 weeks, 1 year and 3 years with three sheep in each group, and of 7 years and 4 months with one sheep, the sheep were killed, and the healing of the osteotomies, degradation and tissue response of the implants were examined radiographically, histologically and microradiographically. All osteotomies healed with a firm bony union. There was no dislocation or wound infection. Histologically, there was no marked tissue response in the bone tissue. At 12 weeks the implants were grossly intact, at 1 year granulation tissue and new bone formation had started to penetrate into the implant, and at 3 years the implant area was mostly replaced by connective tissue and new bone, but implant material was still seen as little islands surrounded by some lymphocytes. At 7 years and 4 months, the implant material had been degraded and replaced by tight bone. Self-reinforced poly- L-lactide lag screws seem to possess adequate mechanical properties and good biocompatibility for this demanding fixation.

Absorbable Implants↗

PubMed2005

Short term in vivo biocompatibility testing of biodegradable poly(D,L-lactide)--growth factor coating for orthopaedic implants.

Fracture healing can be stimulated by exogenous application of growth factors. Using porcine and rat models the efficacy of locally delivered IGF-I and TGF-beta1 from an implant coating has been demonstrated. A thin and biomechanical stable biodegradable poly(D,L-lactide) was used to coat implants and serve as a drug carrier. Due to reports of possible foreign body reactions caused by polymer materials in orthopedic surgery, this study investigated the biocompatibility of the polylactide implant coating and the locally released growth factors during the time course of rat tibial fracture healing (days 5, 10, 15, and 28 after fracture). Monocytes/macrophages and osteoclast were detected using an monoclonal antibody against ED1 (comparable to CD68 in mice and human). The antibody ED1 stains monocytes, macrophages and osteoclast in the bone marrow and in the newly formed fracture callus. A moderate density of the monocytes/macrophages was seen in the proximal part of the medullary canal, but almost no cells were detectable in the region distal to the fracture. The amount of stained cells increased during the observation time with a maximum at days 10 and 15 followed by a decrease at day 28. No differences were detectable between the investigated groups from day 5 to 15 post fracture indicating, that the used poly(D,L-lactide) or the incorporated growth factors do not evoke an elevated immunological response compared to the uncoated titanium implant at the investigated time points. A significantly higher amount of ED1 positive cells was measured 28 days after fracture in the control group compared to the groups with the coated implants. In conclusion, no indication of a foreign body reaction due to the use of the polylactide or the growth factors was found indicating a good short-term biocompatibility of this bioactive coating.

Absorbable Implants↗

PubMed2006

Preliminary experience with tissue engineering of a venous vascular patch by using bone marrow-derived cells and a hybrid biodegradable polymer scaffold.

OBJECTIVE: Currently available synthetic polymer vascular patches used in cardiovascular surgery have shown serious shortcomings, including thrombosis, calcification, infection, and lack of growth potential. These problems may be avoided by vascular patches tissue-engineered with autologous stem cells and biodegradable polymeric materials. The objective of this study was to develop a tissue-engineered vascular patch by using autologous bone marrow-derived cells (BMCs) and a hybrid biodegradable polymer scaffold. METHODS: Hybrid biodegradable polymer scaffolds were fabricated from poly(lactide-co-epsilon-caprolactone) (PLCL) copolymer reinforced with poly(glycolic acid) (PGA) fibers. Canine bone marrow mononuclear cells were induced in vitro to differentiate into vascular smooth muscle cells and endothelial cells. Tissue-engineered vascular patches (15 mm wide x 30 mm long) were fabricated by seeding vascular cells onto PGA/PLCL scaffolds and implanted into the inferior vena cava of bone marrow donor dogs. RESULTS: Compared with PLCL scaffolds, PGA/PLCL scaffolds exhibited tensile mechanical properties more similar to those of dog inferior vena cava. Eight weeks after implantation of vascular patches tissue-engineered with BMCs and PGA/PLCL scaffolds, the vascular patches remained patent with no sign of thrombosis, stenosis, or dilatation. Histological, immunohistochemical, and scanning electron microscopic analyses of the retrieved vascular patches revealed regeneration of endothelium and smooth muscle, as well as the presence of collagen. Calcium deposition on tissue-engineered vascular patches was not significantly different from that on native blood vessels. Immunofluorescent double staining confirmed that implanted BMCs survived after implantation and contributed to regeneration of endothelium and vascular smooth muscle in the implanted vascular patches. CONCLUSIONS: This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and hybrid biodegradable polymer scaffolds.

Absorbable Implants↗

PubMed1999

Incorporation of particulated bone implants in the facial skeleton.

The purpose of this study was to compare the regenerative response of autogenous cortical and cancellous bone chips and a natural particulate resorbable bone mineral (RBM) (Bio-Oss, Geistlich-Pharma, Wolhusen, Switzerland) in standardized bony defects relating paranasal sinuses to one another and to bone blocks. On 13 skeletally mature female goats four standardized critical-sized full thickness bone defects were made in the frontal bone overlying the frontal sinus. These defects were filled at random with cortical bone chips, cancellous bone chips, spongiosa granules of a RBM 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. Autogenous cancellous bone chips is the material of choice for bridging a bony defect in the maxillofacial area where there is no need for mechanical strength. They heal in the same way as cancellous bone blocks do. Cortical bone chips are not reliable enough to be used as a solitary bone-grafting material under these conditions. A cortical block as a solitary implant gives better results. RBM granules as solitary implant in a critical-sized defect do not stimulate osteoconduction but give rise to an extensive osteoclastic activity stimulated by the mutual loose relation. A solid block of RBM is in a similar case more reliable.

Absorbable Implants↗

PubMed2006

Biocompatibility of natural latex implanted into dental alveolus of rats.

The present study investigated the biocompatibility of a biopolymer based on vegetable latex extracted from the Hevea brasiliensis rubber tree, implanted into the bony alveolar cavity after dental extraction in rats. A granule of latex (area = 0.25 +/- 0.04 mm(2)) was implanted inside the alveolus immediately after extraction of the upper right incisor, and the animals were sacrificed 7, 21 and 42 days after the procedure. The hemi-maxillas were decalcified and processed for embedding in paraffin to obtain semi-serial longitudinal sections 5 mum thick, and then stained with hematoxylin-eosin. The latex granule was observed in the cervical third of the alveolus without any foreign body reaction, or persistence of the initial acute inflammatory reaction. Bone repair in the areas adjacent to the material was quantified, and a decrease was noted in the thickness of the fibrous capsule surrounding the implants from 92.8 +/- 9.3 microm on day 7 to 9.4 +/- 1.8 microm on day 42 (ANOVA, P = 0.01). The quantitative data confirmed acceleration of bone formation (statistically significant at 5%) in parallel with a decrease of connective tissue in the areas around the implants. These results show that the tested material is biologically compatible, and progressively integrated into the alveolar bone, simultaneously accelerating bone formation and playing an important role in the healing process.

Absorbable Implants↗

PubMed2000

Adverse tissue reactions to bioabsorbable fixation devices.

Among 2528 patients operated on using pins, rods, bolts, and screws made of polyglycolic acid or polylactic acid, 108 (4.3%) were affected by a clinically significant local inflammatory, sterile tissue reaction. The three most common indications for the use of these fixation devices were a displaced malleolar fracture, a chevron osteotomy for hallux valgus, and a displaced fracture of the radial head. In 107 patients, the reaction was elicited by a polyglycolic acid implant, and in one patient by a polylactic acid implant. The incidences were 5.3% (107 of 2037) and 0.2% (one of 491), respectively. The adverse tissue responses to polyglycolic acid were seen 11 weeks after the operation, on average, whereas the reaction to polylactic acid occurred 4.3 years after fixation of an ankle fracture. The mild reactions consisted of a painful erythematous papule of a few weeks' duration. Those of medium severity had a sinus that discharged remnants of the implant for up to 6 months. In the patients affected by severe reactions, extensive osteolytic lesions developed at the implant tracks. The histopathologic picture was that of a nonspecific foreign body reaction. In four patients with vigorous reactions, an arthrodesis of the wrist or ankle later was necessary because of severe osteoarthritis. Several markers of increased risk of the occurrence of a foreign body reaction were found. These included a poorly vascularized bone section such as scaphoid, use of a quinone dye as an additive in the polymer, and an implant geometry with large surface area (screw versus pin or rod). For polyglycolic acid implants, the risk of an adverse tissue response in a given clinical situation can be estimated from the findings of this study. For slow degrading polymers like polylactic acid, however, the ultimate biocompatibility still is unsettled, and additional clinical research with long followup is required.

Absorbable Implants↗

PubMed1998

[Resorbable interference screws. Histologic study 4.5 years postoperative].

The use of degradable implants in recent years has brought not only good results. Foreign body reactions to implantation of degradable polymers clearly curtailed the initial expectations. Bioabsorbable polymers have been used for sutures, vascular clips, and fixation implants for both intra-articular fractures and malleolar fractures. In the literature these implants are controversial. Potential benefits remain for the use of this material for interference screws if the problems of inflammation are minimal and the fixation properties are sufficient. There is no need for a second operation for removal. In one patient, 4,5 years after to implantation of an degradable interference screw (Copolymer 85/15 D,L lactide glycolide; Biologically Quiet, Instrument Makar, Inc. Mount Hope, MI 48864, USA) we took an biopsy and made histological examinations. No foreign body reaction or inflammation signs could be detected.

Absorbable Implants↗

PubMed2004

Absence of an effect of injectable and implantable progestin-only contraceptives on subsequent risk of breast cancer.

Animal data indicate that both estrogens and progestins could be carcinogenic and that progestins could serve as tumor promoters. Human studies have not confirmed an increased risk of breast cancer from long-term use of oral contraceptives, but have shown an increased risk from hormone replacement therapy including progestins. The present study analyzed the relationship between breast cancer and use of injectable and implantable progestin-only contraceptives. Analyses were performed on data collected in a population-based, multicenter, case-control study, the Women's Contraceptive and Reproductive Experiences Study of the National Institute of Child Health and Human Development. The study involved 4575 randomly sampled cases with invasive breast cancer diagnosed between 1994 and 1998, and 4682 controls, identified using random digit dialing. We assessed the association between exposure to injectable contraceptives and risk of breast cancer. The use of injectable contraceptives was not associated with an increased risk of breast cancer [odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7, 1.2]. Risk was not increased among current users, defined as women who used injectable contraceptives within 1 year of the reference date (OR = 0.7, 95% CI: 0.4, 1.3) or those who initiated use in the 5 years immediately preceding the reference date (OR = 0.9, 95% CI: 0.5, 1.4), or with use beginning before age 35 (OR = 0.9, 95% CI: 0.6, 1.3). Among users, risk increased with increasing duration of use (p = 0.03). However, short-term users (<6 months duration) were at decreased risk relative to never users (OR = 0.6, 95% CI: 0.4, 1.0). When the short-term users were then excluded from the duration-response analysis, the slope of the duration-response became slightly (and nonsignificantly) negative. Risk was not increased among women with 24 or more months of use relative to never users (OR = 1.4, 95% CI: 0.8, 2.5). No increased risk was seen from implantable contraceptives either, although the sample sizes were small. This study does not support an increased risk of breast cancer associated with the use of injectable or implantable progestin-only contraceptives in women aged 35 to 64.

Absorbable Implants↗

PubMed2003

Rat Schwann cells in bioresorbable nerve guides to promote and accelerate axonal regeneration.

A micro-structured, biodegradable, semipermeable hollow nerve guide implant was developed to bridge nerve lesions. Quantitative comparison of cell migration and axonal growth using time lapse video recording in vitro revealed that axons grow eight times faster than neuritotrophic Schwann cells migrate. To accelerate regeneration, purified Schwann cells are best injected into nerve guides before implantation. Nerve guides made from resorbable poly-lactide-co-glycolide support Schwann cell attachment, cell survival, and axonal outgrowth in vitro. The therapeutic concept aims at the development of an 'intelligent neuroprosthesis' that first mediates regeneration and then disappears.

Absorbable Implants↗