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PubMed1989

Fabrication of facial prostheses by applying the osseointegration concept for retention.

Initial clinical studies applying the osseointegration concept for retention of facial prostheses have been encouraging. The results of these preliminary investigations indicate new treatment possibilities with facial prostheses anchored to the cranial skeleton by osseointegrated implants. Osseointegrated rehabilitation of the maxillofacial prosthetic patient presents the potential for overcoming many of the disadvantages associated with conventional retentive methods. Fabrication and support for facial prostheses by using osseointegrated implants for retention are described.

Facial Bones↗

PubMed1998

Vacuum-formed matrix as a guide for the fabrication of craniofacial implant tissue bar-retained auricular prostheses.

Craniofacial implant-retained auricular prostheses usually require a tissue bar and/or retentive elements in addition to the prosthetic ear. Complete coverage of the tissue bar and retentive elements in a given bulk of prosthetic material is sometimes difficult to achieve, but it is crucial to ensure that all the prosthetic components are kept within the contour of the auricular prosthesis to maintain esthetics and form. This article describes a method for fabrication of auricular prostheses with all the elements predictably confined within the anatomic contour of the prostheses.

Ear, External↗

PubMed1999

Long-term study of quality and safety of osseointegration for the retention of auricular prostheses.

The aim of this article is to describe the safety and quality of the osseointegrated implant technique for the retention of craniofacial prostheses, to present a protocol for collection of clinical data, and to discuss the impact of the procedure on the patient quality of life. A protocol was designed and used to study patients who had received auricular prostheses consecutively since 1979 at our department. The patients were asked to answer a questionnaire designed to describe symptoms and problems specific for someone wearing an auricular prosthesis. In total, 99 patients received 107 prosthetic ears (8 patients had bilateral defects) retained on 309 implants (2 to 4 implants/ear). Patients of all ages were represented, and only 9 discontinuities were reported. Most patients (95%) wear their prosthesis every day, in most cases more than 10 hours/day. The follow-up period ranged from 1 to 12 years, giving a total of 2624 postoperative observations of implants, with a 3% incidence of significant skin reaction. We conclude that the surgical technique for auricular prostheses retained on osseointegrated implants is simple and associated with a low rate of peroperative and long-term complications. It offers a high degree of stability and aesthetic satisfaction.

Adolescent↗

PubMedDate not supplied

Biomechanical and computer analysis of radial head prostheses.

Radial head fractures can lead to significant upper extremity disability. A comminuted radial head fracture with a medial collateral ligament tear presents a clinical conundrum. The radiocapitellar (RC) joint should be maintained, yet the head frequently cannot be reduced and stabilized. The silicone rubber implant currently available is not biomechanically or clinically satisfactory, and thus there is a need for a more suitable prosthetic replacement for the radial head. We have attempted to design such a prosthesis and have examined prosthetic design with various materials that would best transmit force of the RC joint. Design configurations based on our cadaveric and radiographic measurements were tested with structural finite element method computer analyses. Materials examined included titanium alloy, cobalt-chrome alloy, alumina ceramic, and ultrahigh molecular weight polyethylene (UHMWPE). Metals and ceramic transmitted force at the distal bone and implant interface and strain shielded the proximal radial cortex while UHMWPE distributed load uniformly through the cortex and along the entire bone and implant interface. In addition, load transmission comparisons were made with the intact radial head, with a silicone prosthesis, and with 6 and 10 mm thick UHMWPE prostheses in cadaveric specimens. UHMWPE prostheses transmit more force to the RC joint than the silicone prosthesis and with leads closer to physiologic levels at all flexion angles. UHMWPE prostheses not only transmit much more force than silicone, but because of substantially less deformation under load, also provide more stability to the joint.

Biomechanical Phenomena↗

PubMed2003

Control of neural prostheses for grasping and reaching.

In recent years several neural prostheses have been developed and tested as orthoses or as therapeutic systems for hemiplegic and tetraplegic subjects aiming to improve the upper extremities function. The use of neural prostheses demonstrated that the targeted group of subjects could significantly benefit from functional electrical stimulation that is integrated in goal directed movements. In this paper the control for neural prostheses is explained using available systems that apply either surface or implantable interfaces to sensory-motor systems. Further more, a new strategy that has been tested for control of reaching and grasping within a neural prosthesis especially designed for neurorehabilitation is described. This, so-called, coordination strategy was based on mimicking the output space model of natural control determined in reach/grasp/release movements of healthy humans.

Central Nervous System Diseases↗

PubMed1986

Penile prostheses in spinal cord injured patients: combined psychosexual counselling and surgical regimen.

Since 1981, forty spinal cord-injured patients have received penile prostheses using a combined approach of early sexual counselling during the acute rehabilitative phase of injury, followed by implantation in suitable candidates no less than nine to twelve months following injury. Early counselling is begun in private and group sessions, and stresses reassessment of body image, sexuality and sexual alternatives. The penile prosthesis is mentioned briefly during the acute phase of rehabilitation. Further counselling at the patient's request following discharge from the unit identifies those patients with continued interest in a penile prosthesis. Suitable surgical candidates must have a stable bladder program, have had a recent urologic X-ray evaluation, have sterile urine at the time of implantation, and be free of decubiti. All preoperative patients undergo MMPI testing and are seen by a sexual counsellor. Both the semi-rigid and inflatable penile prostheses are offered to the patient with a thorough discussion along with printed material on the advantages and disadvantages of each prosthesis, as well as surgical and postoperative complications. Patients are given a preoperative parenteral antibiotic regimen along with supervised antibiotic cleansing of the genitalia. Surgical techniques for each prosthesis is discussed. Following surgery, the patients are continued on antibiotics and are instructed not to engage in intercourse for six weeks. They are also seen by a sexual counsellor postoperatively. There have been a total of forty implantations; thirty-four patients having had semi-rigid implants and six inflatable prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1977

[The value of xero-radiography of the breast following mammoplasty with silicone prostheses (author's transl)].

The well known advantages of xero-radiography make this particularly suitable for the evaluation of silicone prostheses which were implanted either after a subcutaneous mastectomy or during plastic surgery. Xero-radiography is valuable for demonstrating the soft tissues behind NaCl and Makrodex prostheses and is therefore particularly suitable when searching for tumours in these patients. In addition, it allows one to judge the cosmetic results, such as thickness and shape of the soft tissues, contours and wrinkling of the prostheses.

Breast↗

PubMed2004

Early experiences with cervical disc prostheses.

UNLABELLED: The standard cervical disc surgery includes removal of the disc and fusion using an anterior approach. The loss of motion associated with fusion has prompted a search for other options. Early experiences and results after implantation of disc prostheses allowing for biomechanical motion of healthy discs are evaluated in this study. PATIENTS AND METHODS: 51 prostheses were implanted in 50 patients using an anterior approach. Follow-up ranged from one month to 14 months. RESULTS: The only significant complications were haemorrhages in two cases requiring surgical removal but otherwise all patients had an uneventful recovery. No infection or dislocation of the implants or formation of new spondylophytes have been noted yet. Resolution of pain and neurological disorders were excellent with a back-to-work rate of 80 % at three months after surgery. CONCLUSION: As the implantation of cervical disc prostheses carries no obvious risk higher than the risk of conventional anterior fusion, further analysis of its practicability and long-term outcome is recommended.

Adult↗

PubMed2001

Ungual prostheses.

Whatever the origin and the nature of the trauma, behind every request for ungual prostheses there is always the question of how realistic the effect on others will be. Our publications in 1978, 1988 and 1999 and 30 years of experience in this field have consequently led to a comparative study on the evolution of the quality, fixation and indications of our prostheses. The replacement nail is still a difficult issue as sometimes it is simply a matter for the 'nail boutiques', but can even involve surgery in the more complex cases. Prostheses replicate the volume and shape of the finger. Treating a nail is an intricate task but an essential one for the aesthetic and functional comfort of the patient.

Esthetics↗

PubMed1981

The mechanical properties of breast prostheses.

The mechanical properties of inflatable and gel-filled breast prostheses were evaluated using the Instron Universal Testing Machine. Prosthesis strength characteristics were evaluated in terms of compression strength (rather than tensile strength) because of the relationship to closed capsulotomy. The compression breaking strength of prostheses ranged from 0.62 to 10.8 pounds per square inch. There was considerable variation among prostheses. Pressures exceeding these values have been recorded during closed compression capsulotomy. The clinical relevance of these results is discussed.

Breast↗

PubMed1989

Adherence of microorganisms to breast prostheses: an in vitro study.

The quantitative and morphological characteristics of microbial adherence of four organisms--Staphylococcus epidermidis, S. aureus, Escherichia coli and Candida albicans--to the surfaces of different breast prostheses were observed. Semiquantitative adherence studies based on a modification of Maki's roll culture technique even after short contact times showed (1) increased microbial adherence at higher concentrations of the organisms and (2) differences in adherence properties between gram-positive bacteria and other organisms tested, noted also at lower organism concentrations. Scanning electron microscopy (SEM) to identify microorganisms on foam-covered prostheses, however, revealed organisms in the interstitial spaces that were not recovered by the plating technique. Other features on SEM were extracellular "slime" produced by S. epidermidis, which appears to act as a cement by which bacteria are held against prosthetic surfaces. These in-vitro findings suggest that brief exposure of the prostheses to a few organisms, particularly gram-positive bacteria, at the time of implantation would be sufficient inoculum for bacterial adherence to prosthetic surfaces.

Bacterial Adhesion↗

PubMed1990

The fate of soluble steroids within breast prostheses in humans.

The long-term fate of 6-alpha-methyl-methylprednisolone hemisuccinate (MPHS) placed into breast prostheses prior to implantation in humans was determined. MPHS hydrolyzes to the active form 6-alpha-methylprednisolone (MP) in water, which then diffuses out of the implant. Twenty prostheses were recovered 5.3 to 34.7 months after placement, and the solution inside was analyzed for MPHS and MP. Half-lives were calculated for the hydrolysis of MPHS to MP (3.4 +/- 0.58 months [mean +/- SEM]) and for the diffusion of MP out of the prostheses (20.63 +/- 6.10 months). The large half-lives found imply that MPHS slowly hydrolyzes to MP, and that active steroid is released for a longer time than was previously thought. This long release could be the cause of the long-term effects seen with steroids used in this manner.

Breast↗

PubMed1991

In vitro adhesion of endogenous skin microorganisms to breast prostheses.

Bacterial proliferation on polymeric biomaterials varies with the material and microorganism. Subclinical infection is implicated frequently as the initiative factor in capsular contracture around breast prostheses. The ability of endogenous skin microorganisms to produce an exopolysaccharide "slime" is emerging as an important factor in biomaterial colonization. This study was designed to demonstrate the ability of microorganisms of varying slime productivity to colonize, in vitro, different kinds of breast prostheses. Six-millimeter disks from seven kinds of silicone prostheses and polyurethane foam were exposed to three radioactivity labeled strains of bacteria, one slime producer, and two non-slime producers, for 1 hour. Data were expressed as colony-forming units bound per disk. There was no significant difference in adherence between the bacterial strains used, suggesting that initial adherence was nonspecific. The adherence did not appear to be related to surface type, whether smooth or textured, nor to the polymeric composition of the implant material, whether silicone or polyurethane, nor to the presence or absence of slime. Also, adherence was consistent with expected nonspecific bacterial adherence to biomaterials.

Bacterial Adhesion↗

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↗

PubMed2002

The role of synthetic and biological prostheses in reconstructive pelvic floor surgery.

PURPOSE OF REVIEW: Uterovaginal prolapse and urinary incontinence are common problems whose pathogenesis remains unclear. As life expectancy increases, significantly greater numbers of women will present with pelvic floor prolapse and incontinence requiring surgical intervention. Currently, the lifetime risk of undergoing prolapse or continence surgery in the USA is one in 11, and up to 30% of patients will require repeat prolapse and 10% repeat continence surgery. In an attempt to improve surgical outcomes and to preserve vaginal capacity and coital function, a number of synthetic and biological prostheses have been developed. This review aims to look at the controversies that exist as the 'ideal' prosthetic material is developed. RECENT FINDINGS: The recent literature has reflected the increasing interest in the use of biological prostheses (Allograft/Xenograft) and synthetic absorbable meshes. There has been a focus on the risk factors for erosion seen with the use of synthetic non-absorbable material and a review of techniques for the reduction and management of this complication. The advent of mesh placement in minimally invasive continence surgery (tension-free vaginal tape, intravaginal sling, and Supra Public ARC) is now seeing surgical success to 5 years, but the reporting of complications remains inconsistent. SUMMARY: The use of prosthetics in pelvic floor and continence surgery is an evolving field. Further randomized controlled trials are required to evaluate the role of both biological and synthetic prostheses in reconstructive surgery, to determine which type of prosthesis is most suitable for specific procedures. Prosthetic reinforcement should not be used to replace good surgical techniques.

Bioprosthesis↗

PubMed1996

Cold spots on bone scans in patients wearing weighted breast prostheses.

A bone scan is frequently obtained in patients with breast cancer for evaluation of possible metastatic bone disease or for evaluation of response of known metastases to treatment. These patients commonly wear breast prostheses after unilateral or bilateral mastectomies. On some bone scans, the authors have observed artifacts resulting from certain breast prostheses. In particular, in the patient described, a weighted breast prosthesis was not removed during Tc-99m HMDP bone scanning and was interpreted as being permanent pacemaker or defibrillation unit. The scintigraphic appearance of several commonly used, commercially available weighted breast prostheses is discussed.

Bone and Bones↗

PubMed1996

Long term bone remodeling around the Charnley femoral prostheses.

Femoral bone remodeling after total hip replacement was studied by following patients who received 326 Charnley femoral prostheses for 10 to 20 years (mean, 13.3 years). The radiographic state of the bone remodeling was visually assessed and measured with a digitizer. Demineralization that started proximally and then progressed distally caused cortical thinning, which correlated with widening of the intramedullary canal, not with changes that developed in the periosteal width, and occurred in the medial femoral neck, around the proximal half of the stem, and around the distal half in 87%, 33%, and 10%, respectively. Cortical thinning around the distal half of the stem was always accompanied by proximal thinning, and extensive cortical thinning (both proximal and distal) correlated with both lower clinical scores and radiologic loosening of the femoral prosthesis. A low canal flare index of Noble, a large canal width, and a patient age of 60 years or more were risk factors for extensive cortical thinning. Accelerated polyethylene wear was related to resorption of the medial femoral neck but not to cortical thinning or radiological loosening. Cortical thickening occurred only around the distal half of the stem in 29%. These findings establish a basis for the performance of cemented femoral prostheses, and allow comparison of bone remodeling when evaluating other femoral prostheses.

Adolescent↗

PubMed1983

Analysis of the surface morphology of recovered silicone mammary prostheses.

The surfaces of 11 silicone mammary prostheses were examined by scanning electron microscopy (SEM) and energy dispersive x-ray spectrography (XES). Three of the prostheses were recovered from clinical cases and eight from guinea pig models. The surfaces of the prostheses were covered with an investing film and by 2- to 5-microns spheres aggregated in 40- to 200-microns-wide patches. The embeddedded spheres were blebbed and surrounded by pits. X-ray energy spectrography showed high levels of sodium, chlorine, and potassium. It is concluded from this evidence that phagocytic cells embed themselves within the envelope, perhaps by an immune-mediated phagocytic process.

Animals↗