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Results for “soft-tissue implants”

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At least 91 records · Page 5Linked to original sources
PubMed1989

Establishment of a neovascular bed in a collagen-impregnated polyurethane sponge.

A technique for promoting vascularization of a polyurethane sponge is demonstrated in the present study. Collagen-impregnated polyurethane sponges (Hypol, 2002) Foamable Hydrophilic Prepolymer (FHP) were implanted in the femoral fossa of rats for 1 day to 6 weeks. The ligated femoral artery/vein was pulled through the sponges to facilitate more complete neovascularization. Light-microscopic evaluation of the implanted sponges revealed that significant vascularization had occurred by the seventh day of implantation, and was maximal by the fourth to sixth week. Sponges containing collagen had a more thorough vascularization process than sponges without collagen, perhaps due to a more uniform pore size as demonstrated by scanning EM. Time course studies suggested that the artery/vein pull-through enhanced the development of the neovascularization process in the center of the sponges. We conclude that significant vascular tissue in-growth can be developed in polyurethane sponges and that both collagen and centrally placed blood vessels help promote the vascularization process. Potential applications could extend to a variety of bioartificial systems including endocrine or hepatic transplantation, soft-tissue prosthetic materials, bone grafts, or drug delivery systems. Further studies would be useful in providing additional information on the factors promoting neovascularization, and on the potential applications of this methodology using the present or similar biomaterials.

Animals↗
PubMed1991

Orthopedic fixation devices.

Orthopedic fixation devices are used in the treatment of fractures, soft-tissue injuries, and reconstructive surgery. After fracture reduction, internal, external, or intramedullary fixation devices may be used to provide stability and maintain the alignment of bone fragments during the healing process. They must be strong and secure enough to allow early mobilization of the injured part, as well as the entire patient. Compression is used whenever possible to increase the contact area and the stability between fragments and to decrease the stress on the implant. Screws are used primarily to provide interfragmental compression or to attach plates, which can then provide compression, prevent displacement, and support the fragments during healing. Pins and wires can be used for fixation of small fragments or fractures in small bones and for attachment of external fixation devices and traction. A basic understanding of the devices and principles of use is needed to interpret radiographs obtained after the treatment of musculoskeletal injuries.

Fracture Fixation↗
PubMed1992

Biocompatibility of surgical-grade dense polycrystalline alumina.

This article reviews the knowledge about biocompatibility of alumina since its introduction as a material for use in joint replacements. Alumina is a hydrophilic material with high wettability allowing very low friction with negligible wear. Macrophages loaded with alumina particles show no morphologic alteration and do not lose their chemotactic ability. The host response has been studied for bulk and particulate alumina in soft tissues, as well as in human and animal bone under loaded and nonloaded conditions. The soft-tissue response to bulk alumina exhibits minimal fibrosis, and direct bone contact is achieved at compression-loaded interfaces. Examination of human biopsies from failed total hip prostheses reveals a foreign-body reaction containing predominantly macrophages loaded with alumina particles. No lymphocyte or plasma-cell infiltration is observed because of the absence of soluble component release. The amount of necrosis and fibrosis was lower than that associated with metal or polyethylene debris. In summary, alumina exhibits greater bioinertness than all other implant materials currently available for joint replacement.

Aluminum Oxide↗
PubMed1992

Experimental applications of porous (coralline) hydroxylapatite in middle ear and mastoid reconstruction.

Hydroxylapatite is a ceramic implant material which has been extensively investigated in the orthopedic and oral surgical literature. A set of animal experiments was carried out to determine the feasibility of the use of porous (coralline) hydroxylapatite for middle ear and mastoid reconstruction. Coralline hydroxylapatite was placed in the mastoid bulla of dogs and was carved into struts which were placed into the middle ear and against the tympanic membrane. Coralline hydroxylapatite is a highly biocompatible material which showed abundant ingrowth when in contact with host bone. There was also good soft-tissue ingrowth and fibrous tissue fixation within the middle ear and against the tympanic membrane. Hydroxylapatite is generally accepted to be osteoconductive, but not osteogenic. However, one of the specimens described with chronic inflammatory mucosal changes, shows de novo new bone formation within the pores of the graft. While normally the bone formed in coralline hydroxylapatite is secondary (lamellar), in this specimen primary (woven) bone was found. Porous (coralline) hydroxylapatite appears to be an excellent otologic graft material. It biointegrates with the host, is osteoconductive, and under certain circumstances may be osteogenic.

Animals↗
PubMed1991

Osteopromotion for cranioplasty. An experimental study in rats using a membrane technique.

Various techniques for treatment of large cranial defects have been reported, but the use of alloplastic materials still seems to predominate. The authors have applied and explored a new approach for bone repair which appears promising, even for use in less osteogenic environments such as the adult calvaria. Seventy-two adult Sprague-Dawley rats each received bilateral 8-mm trephine defects in the temporoparietal area; this defect size precludes spontaneous osseous healing during the lifetime of the animal. Five surgical procedures, employing various alternatives of biologically inert expanded polytetrafluoroethylene membrane positioning and intramembranous bone-chip implantation, were performed and compared to control defects. Slight improvement of bone regeneration was demonstrated with subperiosteal ectocranial and endocranial membranes, alone or in combination, and with bone chips alone or in combination with an outer or inner membrane. Virtually complete bone healing was observed in animals receiving both an outer and an inner membrane with interpositioned bone chips. The latter appeared to function primarily as space-holders by keeping the membranes separated throughout the defect. Consequently, this technique seems to significantly promote bone repair by excluding soft-tissue components from the bone-healing site.

Animals↗
PubMed1989

The mentalis muscle: an essential component of chin and lower lip position.

The soft-tissue chin may become ptotic following surgery in this area. The mentalis muscles which are responsible for proper central lip motion and chin point position may be affected. The mentalis muscle origin may require resuspension at a proper level. This reattachment may be performed by means of an intraoral approach. Non-absorbable sutures are used to hold the soft-tissue chin upward. The exact method involves placing drill holes through the alveolar bone, into which sutures are passed. These sutures are then placed through the lower mentalis muscles and tightened. Chin and lip position may be corrected in certain cases. Ancillary procedures are required to correct vestibular scarring and submental scars.

Adult↗
PubMed1992

The use of Gore-Tex implants in aesthetic surgery of the face.

Deep wrinkles and folds usually are not completely or permanently corrected with face lifting, fat or collagen injections, chemical peels, and other known procedures. It is suggested that a permanent implant, well tolerated by human tissues, could be helpful as an isolated or associated procedure. An expanded synthetic polymer known as Gore-Tex expanded polytetrafluoroethylene soft-tissue patch is available and is easy to use to approximate and correct defects; it also can be used as a filling material or to replace other kinds of prostheses to get better projection of frontal, orbital, malar, and chin areas. I have used this material in my clinic for 5 years. Indications and results of the first cosmetic cases are reported herein.

Adolescent↗
PubMed1989

Interaction between Pasteurella haemolytica, sulfadiazine/trimethoprim, and bovine viral diarrhea virus.

A study was designed to develop and define a sc tissue chamber as a suitable device for establishing a soft-tissue infection model in cattle and to use this model to study the interaction between Pasteurella haemolytica, sulfadiazine/trimethoprim, and bovine viral diarrhea virus (BVDV). Thermoplastic tissue chambers were implanted in the paralumbar fossae of 20 calves. At 35 days after implantation, calves were allotted to 4 groups of equal size and the calves in 2 groups were inoculated intratracheally with a New York-1 strain of BVDV. At 45 days after implantation, all chambers were inoculated with a 6-hour culture of P haemolytica serotype 1. Starting 36 hours after bacterial inoculation, sulfadiazine/trimethoprim was administered IV once a day to half of the virus-inoculated calves and to half of those calves that had not been exposed to virus. Inoculation of P haemolytica into tissue chambers resulted in the establishment of a localized soft-tissue infection, characteristic of pneumonic pasteurellosis. Despite the maintenance of chamber antimicrobial concentrations that exceeded minimal bactericidal concentrations established in vitro, the infections were not sterilized. This lack of efficacy was associated with decreased pH and increased protein concentrations in chamber fluids after inoculation. Infection with BVDV, which is thought to depress host defenses, had no effect on the response of P haemolytica to sulfadiazine/trimethoprim administration. Observation of responsive antibody titers, bacterial phagocytosis, and high leukocyte viability within P haemolytica-infected chambers documented functional host defenses within tissue chambers.

Animals↗
PubMed1992

[Epitheses of the face].

Despite progress in maxillofacial cancer surgery, most patients present disfiguration of their faces. External prostheses are a pleasing alternative to camouflaging maxillofacial mutilations after tumor ablation. Established indications for external prosthesis are: 1. the patient refusing soft-tissue reconstruction, 2. patient's multimorbidity, and, 3. the impossibility of fully reconstructing a specific maxillofacial defect. Consequently, the benefits of applying external prosthesis include the simple camouflage of an unsightly tumor defect, the ease in supervising any possible local tumor growth beneath the external prosthesis as well as helping to prevent patient's isolation. Thus, external prostheses are a good option in the rehabilitation of maxillofacial surgery patients.

Adult↗
PubMed1989

Volume augmentation of the anophthalmic orbit with cross-linked collagen (Zyplast).

Injectable glutaraldehyde cross-linked collagen (Zyplast) has been used to augment the soft-tissue volume of the anophthalmic sockets of five patients. Follow-up of more than 1 year has demonstrated that this material can be used safely with long-lasting results. Enophthalmos and pseudoptosis were treated by injecting Zyplast transconjunctivally into the muscle cone. Superior sulcus deepening was treated by injecting Zyplast transcutaneously into the superior extraconal fat posterior to the orbital septum ("preaponeurotic fat pad"). In some cases the size of the ocular prosthesis required can be decreased. Surgical volume augmentation of the socket and superior sulcus was averted in all five patients.

Collagen↗
PubMed1990

A method for reconstruction of large full-thickness defects of the bony thorax.

Wide resection in 12 cases of malignant or potentially malignant lesions of the chest wall resulted in full-thickness loss of skeleton and frequently of overlying soft tissues (defect greater than or equal to 15 cm in its smallest diameter or at least 90% of the sternum resected). In reconstruction of the defect, steel bars were used to replace lost ribs and a double layer of Marlex mesh for intercostal spaces. Soft-tissue coverage and primary closure were accomplished with current plastic surgical procedures and good stability of the chest wall was achieved. Protracted respiratory support was required in only one case. Postoperative pain was managed with epidural anesthesia and routine analgesics. Functionally and cosmetically satisfactory long-term results were obtained, with no infection and no need for removal of prosthetic material. The overall 5-year and 10-year actuarial survival rates were 60% and 37.5%. If lesions are radically resectable, the extent of thoracic wall resection need not be restricted because of inability to close the defects.

Adult↗
PubMed1992

[Favorable results of the surgical treatment of intra-articular crush fractures of the distal femur].

Severely comminuted intra-articular femoral fractures are usually associated with major soft-tissue damage as a part of serious multiple injuries. Surgical treatment should aim at exact anatomical restoration of the articular surface. Internal fixation should be stable so that functional after-treatment is possible, a condition of achieving an optimal result. In a period of over 7 years, 24 patients with 26 intra-articular comminuted fractures were operated on. Twenty patients had multiple injuries (ISS > 18), 11 fractures were complicated. Postoperatively, impaired wound healing occurred in three elderly patients; in two of these amputation was necessary. Considering the severity of the injury, the long-term results were good: ten of the 16 patients examined with 18 fractures recovered completely, in the other cases the functional result wa adequate to good. Surgical treatment of comminuted intra-articular fractures of the distal femur is to be adapted to the individual case; depending on the fracture type and the associated damage a selection is to be made from various implants and techniques. With consistent, individually adapted application of the current AO techniques good results can be obtained.

Adult↗
PubMed1992

Quantitative analysis of lidocaine hydrochloride delivery by diffusion across tissue expander membranes.

Permeability of Silastic tissue expander shells to lidocaine was studied to investigate the feasibility of intraluminal lidocaine injection for pain relief during soft-tissue expansion. Both intact expanders and an apparatus using isolated Silastic membrane segments were used to partition solutions of various lidocaine concentrations, and the rate of diffusion was quantitatively measured using a fluorescence polarization immunoassay. Lidocaine flux was found to follow Fick's law of passive diffusion with respect to time, surface area, and concentration gradient for the first 9 hours, with a permeability coefficient of 10.3 +/- 2.6 micrograms (h.cm2.percent)-1 (mean +/- SD) and diffusion coefficient of 7.5 x 10(-7) cm2/min for an average membrane thickness of 473 +/- 23 microns. After 9 hours, the lidocaine flux decreased exponentially, although the concentration gradient across the membrane remained essentially the same order of magnitude. Plasma proteins in the outer bathing solution and methylparaben used as a preservative in the standard lidocaine formulation had no influence on the change in transport flux with time. At the end of the linear portion of the diffusion curve, less than 2 percent of the total intraluminal lidocaine had crossed the membrane. Potential toxicity in the event of implant rupture limits the maximum total lidocaine dose to approximately 500 mg within an expander at any one time. Within these limits, the capacity for lidocaine delivery of 500 mg lidocaine by a 640-cc tissue expander would be only 6 mg during the first 9 hours after administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffusion↗
PubMed1990

A clinical evaluation of resorbable hydroxylapatite for the repair of human intra-osseous defects.

One of the goals of periodontal therapy is actual hard- and soft-tissue regeneration or at least the functional repair of periodontal defects. Alloplastic materials used in the past included dense hydroxylapatite grafts which were non-resorbable and often exfoliated. A new resorbable hydroxylapatite biomaterial [OsteoGen (HA RESORB)] was used during flap surgery. After the usual initial therapy, full-thickness flaps were elevated. A through debridement of the roots and osseous defects was accomplished. The defects were measured and then filled with OsteoGen. The mean initial bone defect depth was 4.47 mm. These defects were re-evaluated by the probing of bone levels after a 4-6-month healing period. A mean of 2.26 mm of new bone fill was obtained. This represents an average fill of 51%. Seventeen of the 22 defects had 42% or more actual new bone fill. No foreign body reaction or exfoliation occurred.

Alveolar Bone Loss↗
PubMed1989

The internal oblique-iliac crest osseomyocutaneous free flap in oromandibular reconstruction. Report of 20 cases.

Microvascular free tissue transfer techniques using composite flaps are the most reliable method for the combined bone and soft-tissue reconstitution of oromandibular defects. Functional oromandibular reconstruction requires that maximum tongue mobility be achieved along with dental prosthetic rehabilitation. The internal oblique-iliac crest osseomyocutaneous microvascular free flap was used in 20 patients for oromandibular reconstruction. The internal oblique muscle, based on the ascending branches of the deep circumflex iliac artery and vein, was used to resurface mucosal defects of the oral cavity and pharynx. The iliac bone, because of its length, width, and natural contour, is the best source of vascularized bone for mandibular reconstruction. The improved soft-tissue component of this composite flap markedly improved the functional results. Reconstruction failed in one patient. Eleven patients underwent dental rehabilitation with either a tissue-borne or osseointegrated implant-borne denture. Follow-up of longer than one year showed minimal donor site morbidity.

Adult↗
PubMed1991

Analysis of silicon in human breast and capsular tissue surrounding prostheses and expanders.

Diffusion of polydimethylsiloxane from silicone breast prostheses and soft-tissue expanders has been associated with capsular contraction. We used electron dispersive x-ray analysis and scanning electron microscopy to assess the presence of silicon in capsular tissue surrounding three categories of breast prostheses and expanders. Breast and subcutaneous tissues external to the capsules were used as control specimens. Semiquantitative results allowed capsules to be ranked according to implant type. Silicon was localized within the inner 2.0 mm of capsular tissue. The analyses of tissues from 2 patients exhibiting unilateral, Baker grade IV contraction after bilateral placement of prostheses showed less silicon present in the severely contracted capsule than in the less-contracted capsule. Results from this study diminish the importance of silicon as the initiator of capsular contraction.

Breast Diseases↗
PubMed1992

Use of a calf prosthesis and tissue expansion in aesthetic reconstruction of the leg.

We present a technique for reconstruction of the legs in patients with soft-tissue loss and formation of large scars with retraction of this tissue in the pretibial region. In such patients, a subcutaneous tissue expander is placed in the region adjacent to the scar tissue. With expansion, we obtained sufficient skin for use in the reconstruction, and the resulting asymmetry in leg diameter was compensated for by means of one or two calf prostheses, depending on the patient.

Adult↗
PubMed1991

Ultrasonographic measurement of the soft-tissue of the upper jaw.

For preimplantation diagnoses, various mechanical methods for measuring the width of the soft tissue and thus measuring indirectly the osseous bed of the implant can be used. The ability to determine soft tissue thickness above the jaw by ultrasound was evaluated in 8 autopsy specimens. The data obtained were compared with findings from the needle measurement method which is usually employed in clinical practice. The ultrasound measurement method produced realistic data in all sectional planes chosen.

Anthropometry↗