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Biomedical subjects

S Gilberg

Publications and source records attributed to S Gilberg.

13 recordsLinked to original sources
PubMed2004

Fibrovascularization of porous polyethylene (Medpor) orbital implant in a rabbit model.

PURPOSE: To evaluate the porous polyethylene (Medpor) orbital implant in a rabbit model and compare it with three other currently available porous implants: Bio-Eye coralline hydroxyapatite (HA), FCI(3) synthetic HA, and aluminum oxide (Bioceramic). METHODS: The porous polyethylene implant was examined macroscopically and microscopically (with scanning electron microscopy). Implantation was performed in 10 adult male New Zealand albino rabbits. Each animal underwent enucleation of the right globe under general halothane gas anesthesia, followed by placement of a 12-mm porous polyethylene implant. In 5 animals, the implant was encased in polyglactin 910 (Vicryl mesh); in the other 5, it was left unwrapped. The implants were moistened in saline before placement. Implant vascularization was evaluated by histopathology at 4, 8, 12, 16, and 24 weeks. RESULTS: The porous polyethylene implant was found to have a smoother exterior surface than the Bio-Eye, FCI(3) synthetic HA, and aluminum oxide implants. Rather than a uniform interconnected porous architecture, there was an extensive system of interconnected channels through the implant, ranging in size from 125 to 1000 microm. On high-power examination there was a more solid, woven appearance without any sign of the microcrystals seen in the other porous implants. One rabbit had a retrobulbar hemorrhage after surgery and was euthanized. All the other rabbits tolerated the implant well, and there were no complications. On histopathologic examination, fibrovascularization gradually increased over time. One implant was completely vascularized at 12 weeks, and both implants harvested at 16 weeks were completely vascularized. The implant harvested at 24 weeks showed only partial vascularization (14%). CONCLUSIONS: The porous polyethylene orbital implant represents an alternative implant for use after enucleation or evisceration or for secondary implantation. In our rabbit model, the porous polyethylene implant was well tolerated without complication. Complete fibrovascularization was first seen at 12 weeks. Porous polyethylene orbital implants appear to vascularize more slowly than Bio-Eye coralline HA, FCI(3) synthetic HA, and aluminum oxide implants.

Animals↗
PubMed2001

Proliferation of human fibroblasts in vitro after exposure to orbital implants.

BACKGROUND: Porous orbital implants allow fibrovascular ingrowth and integration with the extraocular muscles. The available implants have different structural characteristics, which may influence orbital response. We studied the proliferation of orbital fibroblasts in vitro after exposure to four different orbital implants. METHODS: Four orbital implant biomaterials were studied: hydroxyapatite (Bio-Eye), synthetic hydroxyapatite, porous polyethylene (Medpor) (pore sizes 150 microm and 400 microm) and aluminium oxide (Bioceramic implant). Human fibroblasts obtained from orbital fat at the time of elective blepharoplasty were cultured and then exposed to the individual implants. Cell growth was assessed with immunocytochemical analysis using bromodeoxyuridine, a thymidine analogue. After DNA denaturation, the cells were washed, incubated with secondary antibody and visualized. RESULTS: The fibroblasts growing on the Bio-Eye, synthetic hydroxyapatite, and 150-microm and 400-microm Medpor implants all had debris associated with them. The Bioceramic implant was free of this debris. The Bioceramic implant and the 150-microm Medpor implant had the greatest number of fibroblasts on the coverslips. INTERPRETATION: The proliferation of fibroblasts, as determined by visualization of actively dividing cells with bromodeoxyuridine, differed on the various implants studied. The lack of debris associated with the Bioceramic implant may be related to the crystalline structure of the implant.

Aluminum Oxide↗
PubMed2000

The Molteno M-Sphere.

PURPOSE: To analyze a mammalian hydroxyapatite (HA) implant known as the Molteno M-Sphere, recently approved by the Food and Drug Administration of the United States. METHODS: The authors examined the implant macroscopically, with chemical analysis (x-ray powder diffraction, x-ray fluorescence spectrophotometry), and microscopically with scanning electron microscopy. Animal implantation of six Molteno M-Spheres was carried out in six adult male New Zealand albino rabbits. Implant vascularization was evaluated by means of magnetic resonance imaging and histopathologic sectioning. RESULTS: The M-Sphere was found to have multiple interconnected pores throughout with an average pore size of 300 microm to 600 microm. This implant was very light-weight (0.31 g) and fragile. It was made up of pure HA. Magnetic resonance imaging studies showed implant enhancement to its center by 4 weeks after implantation. Histopathologically, fibrovascularization occurred uniformly throughout the 4, 8, and 12-week rabbit implants. CONCLUSIONS: The M-Sphere is an alternative type of HA implant that recently has been reintroduced into the United States for use after enucleation, evisceration, or as a secondary implant. It has multiple interconnected pores allowing central fibrovascularization as early as 4 weeks in a rabbit model. Its light weight and fine trabecular framework, however, are associated with increased implant fragility when compared with other available HA implants (BioEye and FCI3 synthetic HA). The implant requires careful handling because routine handling may damage the implant. The implant is currently approved by the United States Food and Drug Administration.

Animals↗
PubMed2000

Brazilian hydroxyapatite implant.

PURPOSE: To evaluate a synthetic hydroxyapatite (HA) (manufactured in Brazil) in a rabbit model. METHODS: Nine New Zealand white rabbits underwent enucleation of one eye followed by implantation of either a 12-mm Brazilian synthetic HA implant or a 12-mm BioEye, wrapped in polyglactin 910 mesh. Magnetic resonance imaging was performed to assess fibrovascular ingrowth 4, 8, and 12 weeks after implantation. Three animals were killed at each of the times for histopathologic examination. The Brazilian implant was also examined chemically and by scanning electron microscopy. RESULTS: The Brazilian HA was found to be heavier than either the BioEye or synthetic FCI3 HA implants. It did not have a visible, regularly arranged interconnected porous architecture. Rather, it had randomly appearing channels apparent on its external and internal surface in addition to large cystic areas within the body of the implant. Scanning electron microscopy revealed the implant to have a microporous architecture in addition to the large channels and cystic cavities. Histopathologically, central vascularization occurred by 4 weeks and was also present at 8 and 12 weeks. In three Brazilian implants an unrecognizable, nonbirefringent material was identified. The cause of it was unclear. Chemical analysis confirmed the implant to consist of pure HA. CONCLUSION: The Brazilian implant is pure HA that appears solid but has randomly arranged channels as well as a microporous architecture that allows vascularization to its center. It is heavier than other available HA implants and has the presence of an unidentified foreign material within it. Although this implant is less expensive and does not require a costly manufacturing process, the structural characteristics of the material do not offer any theoretical or clinical advantages. The implant is only available in Brazil at this time.

Animals↗
PubMed1999

Complications associated with pegging hydroxyapatite orbital implants.

OBJECTIVE: Prior studies of hydroxyapatite orbital implant complications have primarily focused on complications of the implant itself with only occasional mention of the complications associated with the peg system. This in part may be because of a low rate of pegging and, thus, a small sample size to evaluate. Therefore, a full range of complications that can occur with pegging has not been presented. The objective of this study was to determine the complications associated with pegging and to discuss ways to manage them. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS/INTERVENTION: The authors analyzed all of the complications associated with pegging 165 of a possible 275 hydroxyapatite implants implanted by 2 surgeons over 7 years. MAIN OUTCOME MEASURES: The following data were recorded: type of surgery performed, size of implant used, type of hydroxyapatite used, peg system used, time of pegging, follow-up duration, problems encountered, and treatment. RESULTS: Sixty-two (37.5%) of the 165 patients who had pegged implants were found to have problems with their pegs. Twenty-one (33.8%) of the 62 patients with peg problems had more than 1 peg-related problem. Complications associated with pegging included discharge (37%; 23 of 62), pyogenic granulomas (30.6%; 19 of 62), peg falling out (29%; 18 of 62), poor transfer of movement (11.2%; 7 of 62), clicking (11.2%; 7 of 62), conjunctiva overgrowing peg (4.8%; 3 of 62), poor-fitting sleeve (4.8%; 3 of 62), part of sleeve shaft visible (4.8%; 3 of 62), peg drilled on an angle (4.8%; 3 of 62), hydroxyapatite visible around peg hole (3.2%; 2 of 62), peg drilled off-center (3.2%; 2 of 62), popping peg (3.2%; 2 of 62), and excess movement of peg (3.2%; 2 of 62). The most serious complication occurring in two individuals (3.2%) was implant infection requiring implant removal. CONCLUSION: There are several potential complications that can occur after pegging the hydroxyapatite implant. These problems are generally of a minor nature but often require additional patient visits that would not ordinarily have been required if the peg was not in place. The most serious peg problem is implant infection, which may necessitate implant removal. These potential peg problems should be reviewed with the patient before the procedure is performed.

Adolescent↗
PubMed1998

The synthetic hydroxyapatite implant: a report on 65 patients.

Sixty-five patients receiving the FCI synthetic hydroxyapatite implant (FCI3, FCI, Issy-Les-Moulineaux, France) after enucleation, evisceration, or as a secondary implant were studied under human trial guidelines established by Health and Welfare Canada. The implant is chemically identical to the original coralline Bio Eye (Integrated Orbital Implants Inc., San Diego, CA, U.S.A.), is easy to work with, and was implanted without difficulty using a wrap of polygalactin 910 (Vicryl mesh, Ethicon, Inc.) in the majority of patients. Postoperative drilling was carried out at approximately 6 months and found to be much easier than drilling of the Bio Eye. The implant could be hand drilled using drill bits rolled between the thumb and index finger. Postoperatively, patients were followed-up from 7 to 24 months and did not have any problems different from those associated with the original hydroxyapatite implant derived from sea coral (Bio Eye). One case of conjunctival dehiscence occurred at 4 weeks and required a temporalis fascia patch graft to repair. One implant became infected after drilling and had to be removed. The motility obtained with the third-generation FCI implant (FCI3) was similar to that seen with the Bio Eye, in comparable patients. That is, those receiving implants after an evisceration, on the whole, had better motility than those receiving an implant after primary enucleation or secondary implantation. The FCI3 hydroxyapatite implant is a viable alternative to the original Bio Eye hydroxyapatite implant. It's advantages are: 1) reduced cost, and 2) ease of drilling (a motorized drill is not required). The implant was given Health and Welfare approval in Canada on February 26, 1997.

Biocompatible Materials↗
PubMed1998

Scanning electron microscopic examination of porous orbital implants.

OBJECTIVE: To compare the structural makeup of five porous orbital implants: two made of coralline hydroxyapatite (Bio-Eye and Chinese implant), one of synthetic hydroxyapatite (FCI), one of porous polyethylene (Medpor) and one of alumina. The Bio-Eye, Medpor and alumina implants are currently available in Canada. OUTCOME MEASURES: Pore size, pore interconnectivity and microcrystalline architecture. RESULTS: The Bio-Eye had multiple interconnected pores ranging from 300 microns to 700 microns in width; higher-power views showed coarse-appearing crystals approximately 2 microns wide. The FCI implant showed similar interconnectivity of the pores but fewer pores, which were about 300 microns to 500 microns in size. Higher-power views showed hexagonal crystals about 1 micron to 5 microns in size. The Chinese hydroxyapatite implant had multiple interconnected pores ranging from 200 microns to 700 microns in size. The crystals were similar in appearance to those of the Bio-Eye but were smaller and more granular. The 150-micron pore size Medpor implant had irregularly shaped pores ranging from 100 microns to 500 microns in size. The 400-micron pore size implant had pores that looked more like channels that coalesced; the pores and channels ranged in size from 125 microns to 1000 microns. In both cases higher-power views showed a woven texture. In the alumina implant the pores were well connected and evenly distributed and were approximately 500 microns in size. On high-power studies the implant showed a cobblestone-like pattern of crystals approximately 4 microns to 5 microns wide. CONCLUSIONS: There are notable differences in pore size, pore interconnectivity and microcrystalline architecture between the implants studied. These features may be important in the overall biocompatibility of the implant.

Aluminum Oxide↗
PubMed1998

Topical versus intravenous administration of tranexamic acid: a comparison of intraocular and serum concentrations in the rabbit.

BACKGROUND: Tranexamic acid has been shown to greatly reduce the incidence of secondary hemorrhage when administered orally or intravenously. Topical administration of the drug should result in much lower serum concentrations, with fewer adverse effects. We performed a study to determine whether topical application of tranexamic acid would yield higher intraocular concentrations and lower serum concentrations of drug than intravenous administration. METHODS: Ten New Zealand white rabbits received 25 mg/kg of tranexamic acid intravenously every 8 hours for 3 days. Another group of 10 rabbits received one drop (0.05 mL) of commercially available tranexamic acid solution (100 mg/mL) every 8 hours for 3 days to one eye. Tranexamic acid levels in the aqueous humour, vitreous humour and serum 1 hour after administration of the last dose of drug were determined. RESULTS: Analysis of variance showed that aqueous concentrations of tranexamic acid were significantly higher with topical delivery than with intravenous administration (15 vs. 9 micrograms/mL)(p < 0.05). Serum concentrations were significantly lower following topical administration (9 vs. 19 micrograms/mL)(p < 0.01). The drug was not detected in the vitreous humour in either group. INTERPRETATION: Topical delivery of tranexamic acid may prove to be valuable in yielding therapeutic intraocular concentrations of drug in patients with hyphema while minimizing systemic toxicity.

Administration, Topical↗
PubMed1997

Use of galeal or pericranial flaps for reconstruction or orbital and eyelid defects.

The use of galeal or pericranial flaps for craniofacial reconstruction is well recognized. The excellent blood supply of the flap permits vascularized support for skin, bone, or cartilage grafts in otherwise unsatisfactory recipient sites. The pericranial flap was used in 1 patient with a large orbital bony defect and the galeopericranial flap was used in 3 patients with various periocular defects produced by trauma or following tumor extirpation. In the case of an orbital defect induced by chronic cocaine abuse, the pericranial flap successfully sequestered the orbit from the nasal cavity while providing support for the globe. In 3 of the 4 cases involving eyelid reconstruction, the galeopericranial flap served a dual function in providing vascular supply to the underlying free tarsal graft and to the overlying free skin graft. This tissue flap is analogous to a median forehead flap, except skin is not transposed and a second-stage inset revision is not required.

Adult↗
PubMed1995

The use of Vicryl mesh (polyglactin 910) for implantation of hydroxyapatite orbital implants.

Hydroxyapatite (HA) implants currently are most commonly wrapped in donor sclera before implantation to facilitate placement within the orbit and allow attachment of the extraocular muscles. Although the risk of acquiring a transmittable disease through donor sclera is extremely low, some individuals remain concerned about receiving nonautologous material. As an alternative to sclera, autologous temporalis fascia, or autologous fascia lata, we have been wrapping HA in "Vicryl mesh" before insertion into the orbit. The Vicryl mesh-wrapped implant goes into the socket readily, allows one to easily attach the extraocular muscles, and has no risk of transmittable disease. In addition, the Vicryl mesh is readily available at most hospitals and is dissolvable.

Durapatite↗