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Alloplastic materials in rhinoplasty.

PURPOSE OF REVIEW: This review examines implant materials currently used in rhinoplasty. In revision cases, the most desirable autogenous grafts from the septum are often unavailable in adequate quantities. The 'ideal' implant has strict requirements concerning biocompatibility, plasticity, stability of form, resistance to infection, and removability. RECENT FINDINGS: Silicone implants continue to be used in spite of frequent reports of rejection. In spite of its described absorption, conserved cartilage can help in preserving profiles. Increasingly, good results are being reported with porous polyethylene, although Proplast is sometimes used in its place. Despite the fact that AlloDerm is partially absorbed, it can still be useful. GoreTex is effective for smaller defects. Mersilene mesh is not absorbed and retains its stability of shape. 'Turkish Delight' (diced cartilage with a wrapping) seems to be absorbed when the wrapping is made of Surgicel, but a wrapping of autogenous fascia provides lasting results. SUMMARY: Several alloplastic materials do have a place in nasal surgery. Provided that the correct techniques are employed, side effects from their use are no greater than the complications resulting from the use of autogenous costal cartilage, with the intervention necessary for its harvesting.

Biocompatible Materials↗

Porous prostheses: an electron microscopic study.

Proplast and Plastipore prostheses, removed at revision surgery, have been examined under the electron microscope. Foreign material in the multinucleated foreign body giant cells, previously reported under the light microscope, has been confirmed. The appearances were consistent with the conclusion that the giant cells were breaking down the prostheses by two different modes of action. X-ray elemental analysis is of limited value in this investigation because of the low atomic number of the elements involved. However, such analysis of this foreign material was consistent with the conclusion that it arose from the prosthesis.

Biocompatible Materials↗

Comparison of ossicular replacement materials in a mouse ear model.

Four biomaterials, UF45S5 Bioglass, Silastic, Plasti-Pore, and Proplast, were used to replace the incus in a mouse ear model. Bioglass, a bioactive glass ceramic, compared favorably with the other test materials in maintaining surgical positioning between malleus and stapes and remaining stable to a blast of nitrogen gas and to pick manipulation. In a short-term animal study, Bioglass showed histocompatibility comparable to that of these other implant materials now used in ossicular replacement surgery in humans.

Animals↗

Airway repair with pedicled composite grafts--clinical experience.

In particular surgical situations, part of the airway wall may have to be excised for different reasons, perhaps because of a large tumor or extensive scar tissue. The repair of large laryngotracheal defects, impossible to reconstruct with segmental resection and end-to-end anastomosis or to repair with existing adjacent tissue, is a challenge. A prerequisite for reconstruction of such defects is a graft composed of well-vascularized mucosal lining and a supportive framework to keep the airway patent. A three-stage procedure, based on the creation of an autogenous mucosal cyst, has been developed and used clinically in a series of patients. The three most recent patients who have undergone reconstruction with pedicled muscle Proplast mucosa grafts are presented. In two of the patients, large unilateral laryngeal tumors were removed and the third had a large patent tracheostoma.

Adult↗

The use of synthetic implant material in osteoplastic frontal sinusotomy.

The use of homologous fat in obliterating frontal sinus operations has proved to be a satisfactory technique. It does entail, however, a separate procedure to obtain the graft. Furthermore, the implanted fat has a tendency to shrink or absorb in varying degrees. Proplast has been used in a series of osteoplastic frontal sinus operations. The implant block is a highly porous preparation of Teflon fluorocarbon polymer and vitrous carbon fibers. It can be easily carved into desired shapes or it may be implanted in peices. The porosity of the substance permits in-growth of connective tissue. Eight obliterating frontal sinus procedures using the osteoplastic flap technique and implanting the synthetic material are reported. There have been no failures to date after 1 to 5 years follow-up.

Adult↗

Total hip arthroplasty with a low-modulus porous-coated femoral component.

Fifty-seven patients had sixty-three total hip replacements, performed using a femoral stem with a soft, low-modulus porous coating of Proplast and a conventional acrylic-cemented acetabular component. Forty-seven of the hips were followed for an average of thirty-seven months. Seventeen (36 per cent) of the forty-seven hips were judged to be clinical failures, and five of the failures were revised by inserting a new femoral component and fixing it with acrylic cement. The prostheses were thought to have failed because they had inadequate support, due to deficiencies in the design of the stem and in the fit of the implant in the femur. The five retrieved prostheses were found to have fibrous-tissue ingrowth into the coating, which had failed by shear within its substance. Therefore, we concluded that the coating had insufficient strength to withstand normal weight-bearing loads. To improve performance, a more stable prosthesis with a stronger porous coating is needed. In addition, a posterior surgical approach through a transtrochanteric osteotomy may give better exposure of the femoral canal and facilitate the use of longer-stem (140 to 153-millimeter) designs, which are less likely to be inserted in a varus position.

Biocompatible Materials↗

Temporal and malar-zygomatic reduction and augmentation.

The temporal fossa, zygomatic arch, and malar-midface should be considered jointly when augmentation of the temporal area or reduction of the zygomatic arch are to be carried out. These anatomic areas relate so closely to one another that altering one affects the other. In addition, augmentation of the malar-midface area may be done if one of the other two procedures is to be considered, or if a brow lift, subperiosteal face lift, or other reason for using a coronal incision exists. Use of the coronal incision for malar augmentation is probably not justified because of the large amount of surgery required in spite of the lesser morbidity associated with this approach in terms of amount of infections, lip stiffness, and hypesthesia. Planning a surgical procedure must be done in the office, by examining the patient at eye level to determine the amount of zygomatic arch reduction and the amount of temporal fossa augmentation necessary. Similarly, the three zones of the malar-midface complex must be assessed, with the amount of augmentation of each zone determined prior to the day of surgery. The surgical procedure is then executed through a coronal incision, with the dissection extending down to the zygomatic arch. If the temporal muscle is to be elevated out of its fossa, it is cut on its anterior, superior, and posterior edges, elevating it out of its fossa so that a Proplast implant, typically 3 to 4 mm thick and finely tapered on its superior and posterior edges, with suturing done anteriorly, may be inserted. The muscle is then resutured to its aponeurosis on all three edges. If the zygomatic arch and malar-midface area are to be approached, the dissection is carried to the deep and superior edge of the zygomatic arch, and the periosteal elevator is used to elevate the soft tissue off the lateral and inferior edge. The arch and malar-midface are cleared of soft tissue, extending the tunnel to the upper buccal sulcus. The arch is then reduced with a contouring burr to the thinness desired. Alternatively, the malar-midface area may be augmented with synthetic material precisely positioned, with a suture around the zygomatic arch, holding it in position as measured from the lateral orbital rim. The incision in the temporal fascia is then resutured, and the coronal incision is closed.(ABSTRACT TRUNCATED AT 400 WORDS)

Aluminum Oxide↗

[Porous synthetic materials in external ear reconstruction].

An investigation was done on the suitability of four porous synthetic materials--Dacron, porous polyethylene, Proplast II and Teflon--for use as a framework in external ear reconstruction. For this purpose, folded implants up to 1,8 mm thick were implanted under the abdominal skin of rats to create a standing skin fold. The fibrin glue proved useful. After 10 months the most convincing of the synthetic materials was porous polyethylene, which offered advantages over the other materials in handling, and retained a lasting form. This synthetic was also used in clinical reconstruction of the external ear.

Animals↗

Superior sulcus deformity.

Two cases of late reconstruction of the orbit in which there had been moderate disruption of orbital anatomy are presented. Emphasis is given to correction of superior sulcus deformity by implantation of a light, porous biocompatible alloplastic material--Proplast. Surgical technique is described and considerations are offered for selecting patients for this procedure.

Adult↗

Biocompatible ossicular implants.

Proplast and Plastipore, two new biocompatible implant materials that encourage tissue ingrowth, were used in 225 tympanoplasties. A 12 to 28-month follow-up shows that in 133 tympanoplasties using a drum-to-footplate or total ossicular replacement prosthesis (TORP), there was an average air conduction gain of 19 dB and 65% closure of the air-bone gap to within 20 dB. In 17 tympanoplasties using a drum-to-stapes or partial ossicular replacement prosthesis (PORP), there was an average air conduction gain of 20 dB and 100% closure of the air-bone gap. In 53 tympanoplasties/mastoidectomies using a TORP, there was an average air conduction gain of 19 dB and 87% closure of the air-bone gap. In 22 tympanoplasties mastoidectomies using a PORP, there was an average air conduction gain of 25 dB and 100% closure of the air-bone gap. Five (2.2%) of the 225 Plastipore prostheses have extruded.

Animals↗

Ossicular replacement prostheses.

To find a way of improving the results of ossicular reconstruction in ears that were rendered hard of hearing by chronic otitis media, the suitability of two biocompatible materials has been investigated. After three years' experience with Proplast and two years with Plastipore, it is concluded that for ears which lack an incus and stapes arch, these materials provide results at least as good as those previously reported with homologous materials and have the advantage of easy manipulation, timesaving, and ready availability. As with all foreign material in the chronically infected middle ear, the risks of extrusion cannot be ignored. The results so far indicate that this problem can be overcome with the use of cartilage film to separate the prosthesis from the tympanic membrane.

Auditory Threshold↗

Mandibular reconstruction using implantable stabilization plates.

The consequences of substantial mandibular loss usually are disturbances in mastication and often in cosmesis. In an attempt to arrive at an easy and reliable technique of reconstructing mandibular defects, a selected group of patients were treated using rigid, implantable reconstruction plates. These were used to provide continuity and stability for the residual mandible with or without the use of graft materials. These have included autogenous fresh, irradiated, or frozen bone, and polytetrafluoroethylene carbon fiber sponge (Proplast). A discussion of the principles and technique of using reconstruction plates is outlined.

Aged↗

Compatibility of autologous fibrin adhesive with implant materials.

A safe, effective method for securing autologous and alloplastic implants would benefit modern surgery substantially. We studied the effects of a new autologous fibrin tissue adhesive with various alloplastic implants and ear cartilage. Twelve rabbits had Proplast (a woven combination of Teflon and organic fibers), Silastic, Supramid polyfilament surgical sheeting, and ear cartilage implanted. One side of each animal had implants secured with tissue adhesive. The other, control side had identical implants placed in "subcutaneous tunnels." The tissue adhesive was biodegradable and produced no apparent toxic reaction, infection, or foreign-body reaction. It did not adhere to Silastic, but bound to the other implants. Glued implants had no more clinical or histologic evidence of inflammation than controls. Autologous fibrin tissue adhesive seems to be promising as a safe, biologic bonding material for securing certain alloplastic and autologous implants.

Animals↗

Significant premaxillary augmentation.

Substantial premaxillary augmentation is necessary as an adjunctive treatment in most cleft rhinoplasties and in those patients exhibiting an acute nasolabial angle due to retrusion of the premaxila. We describe our technique of evaluation and treatment of this condition using a custom-carved piece of material made from a woven combination of Teflon and organic fibers (Proplast). Detailed technical illustrations as well as patient results are demonstrated. We have found this technique in our hands to be a simple, safe, and effective means of correction of significant premaxillary retrusion.

Adult↗

Administration of beta-aminopropionitrile to human beings with urethral strictures: A prelimary report.

(1) No toxic signs or symptoms and no unusual laboratory determinations were observed in five patients with posterior urethral strictures treated by dilatation of the urethra and administration of 1 gm per day of beta-aminopropionitrile (BAPN) for twenty-one days. (2) Patients treated with 1 gm daily of BAPN for twenty-one days showed an increase in cold saline-extractable and acid-extractable collagen in proplast sponge-collected and dermal scar tissue comparable with that reported previously after doses of 3 to 5 gm of BAPN daily. (3) Significant reduction in the breaking strength of newly synthesized connective tissue was observed in patients treated with BAPN. (4) None of the patients in this study showed abnormalities in net collagen synthesis or in synthesis of noncollagenous protein. (5) The difference in the results of this study and two previous trials of BAPN in human beings which were discontinued because of toxic and or hypersensitivity signs and symptoms is hypothesized to be the result of development of highly purified BAPN fumarate.

Aminopropionitrile↗

Tissue reaction to intraperitoneally implanted catheter materials.

The limiting factor that introduces long-term complications of intraperitoneal (i.p.) catheters used, for example, with the Programable Implantable Medication System (PIMS) is the encapsulation of the catheter tip with tissues due to tissue reaction. The objective is the development of new catheters for PIMS or other systems for i.p. insulin delivery that allow continued insulin flow. The study is based on two hypotheses: (1) vascularized tissue will grow into a porous end plug mounted at the catheter tip (100-300 microns pore diameter), with sufficient blood supply to carry the insulin to the circulation; (2) use of a narrow pore diameter (25 microns or less) end plug will prevent tissue ingrowth yet allow insulin flow. The biological response to the following materials, all designed for use in catheters, were studied: polyurethane, segmented polyether-urethane, alumina coated on Teflon (proplast regular and micro-pore), pyrolytic carbon, high density polyethylene, ultra high molecular weight polyethylene, hydroxyapatite, bioglass, and expanded Teflon. Some of these materials also are used for several other applications: vascular grafts, in the cardiovascular system, and for dental, orthopaedic, and other purposes. The shape and size of the end plugs made from each of the materials were as similar as possible to minimize size effects. The test materials were implanted i.p. in 12 dogs for a period of 12 weeks. The cylindrical plugs were typically 1.5-2.5 cm long, with an inside diameter of 0.3 cm, and an outside diameter of 0.6 cm. When the explants were retrieved, thin capsules were observed, of varying thickness and blood supply, surrounding the end of the catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Kinetics of colonization of a porous vitreous carbon percutaneous implant.

Implants of porous vitreous carbon with pore diameters 200-500 microns were surgically placed in rabbits and pigs. Skin colonization experiments were carried out by topically inoculating concentrations of Staphylococcus aureus and Escherichia coli in a test area adjacent to the implant and to a remote control area. Subsequent swab cultures were taken at 6, 24, 48 and 72 h and one or more weeks. In vitro attachment studies were also performed using bacteria stained with FITC on 1 mm slices of the porous carbon. Proplast was used as a control. Results showed that despite a temporary high rate of colonization and obvious binding of the bacteria to the carbon, the skin-implant interface resists infection by both normal and pathogenic flora.

Animals↗