Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prosthesis Fitting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
PubMed2006

A survey of public health policy on bilateral fittings and comparison with market trends: the evidence-base required to frame policy.

This report presents a review of the situation in a number of countries with respect to public health policy for funding of hearing aid services in general and support to bilateral fittings in particular. The data show considerable variations among the countries studied in number of hearing aids fitted per 1000 inhabitants, differing by a factor of 6 between the extremes. Also the percentage of bilateral fittings differs with an average estimated to be of the order of 50%. For hearing-impaired children, bilateral fittings are given full financial support in most countries studied. The data presented indicate the need for a reliable, scientifically valid evidence-base regarding bilateral hearing aid fitting.

Australia↗
PubMed1995

On the feasibility of using neural nets to derive hearing-aid prescriptive procedures.

A neural net is a "black box" information processing system that can be used for pattern matching, optimal prediction, or functional approximation. A neural net requires a minimal amount of a priori knowledge about the problem to be solved, but can require large amounts of data to converge to a solution. For a hearing-aid fitting procedure, a multilayer perceptron net was trained to generate an optimum match between a set of input pure-tone audiograms and the corresponding best frequency response and gain for each subject. The feasibility of using neural nets to select hearing-aid response characteristics was tested using both simulated and real audiometric data. The simulation results indicate that a neural net can be successfully trained to reproduce a fitting rule such as the NAL-R procedure, and that a minimum of about 50 sets of audiometric response data are needed for the net to converge to a generalized solution. When used to predict, from the pure-tone audiograms, the best frequency response characteristics determined for subjects having severe-to-profound hearing losses, the neural net was more accurate than the NAL-R fitting procedure derived from the same data.

Audiometry, Pure-Tone↗
PubMed2003

Interactions of hearing aid compression release time and fitting formula: effects on speech acoustics.

The effects of the interaction of compression release time and prescribed gain on running speech processed through a hearing aid on KEMAR was investigated. A digital instrument was programmed to fit a mild to moderate sloping hearing loss using probe microphone measures to reach targets prescribed by NAL-NL1, DSL I/O, FIG.6 or ASA2p with release times of 40 and 640 ms for each condition. Recordings were made through KEMAR and analyzed to determine the long-term-average-speech spectra, consonant-to-vowel ratios and the RMS amplitude of 32 phonemic units. Aided and unaided results were compared. Within each prescriptive formula, changes in release time affected all of the speech measures subsequent to programming the instrument to a static-composite signal. The short release-time condition produced the greatest alteration to the speech signal. Release time may need consideration when fitting hearing aids to target gain prescriptions.

Acoustics↗
PubMed2000

Factors influencing success of monovision contact lens fitting: survey of contact lens diplomates.

BACKGROUND: Contact lenses are frequently fitted so that one eye is focused for distance and the other for near (monovision) in order to reduce the dependence of presbyopic patients on bifocal spectacle correction. METHODS: We surveyed Diplomates in the Cornea and Contact Lens section of the American Academy of Optometry (N = 179) regarding their estimates of success with monovision fitting and factors influencing their perception of success. Results were statistically analyzed to determine the fitting philosophies of responders estimating that they achieve high success rates (HSRs) and low success rates (LSRs), respectively. RESULTS: Completed surveys were returned by 98 Diplomates (54.8%), who estimated an overall success rate of approximately 71.7% with monovision; 50.5% "totally successful" (wear monovision correction full-time without problems or need for additional correction) and 21.2% "successful" (wear monovision full-time, but experience some symptoms of blur or other discomfort, may wear over-correction at times for driving or detailed near work). Sighting dominance was the most frequently used method to determine the distant eye, followed by the plus-lens test. The HSR group tended to be more likely to take occupational factors into account when deciding which eye to use for the distance lens, and they used more flexibility in determining the near-add power. The LSR group discontinued monovision sooner than the HSR group, who continued treatment for longer than 4 weeks during the adaptation period much more often for all add ranges. CONCLUSIONS: Practitioners who regard monovision treatment as very successful have somewhat different fitting philosophies than those who regard monovision as unsuccessful. Implementation of highly successful practitioners' fitting techniques may increase success with monovision contact lens fitting.

Adaptation, Ocular↗
PubMed1996

[H mesh prosthesis in the treatment of ventral hernia].

The Authors report their experience in the treatment of ventral hernias using a Marlex mesh moulded in an original way with a technique partially derived from plastic surgery. The complete mobilization of the umbilicus through a circular incision allows to fit this prosthesis symmetrically below the rectus abdominis muscles for the entire extension of the hernia.

Female↗
PubMed2002

Quantitative descriptors of corneal topography that influence soft toric contact lens fitting.

PURPOSE: Empirical soft toric contact lens fitting based on manifest refraction and keratometry often presents unanticipated fitting and power errors upon initial lens dispensing. However, corneal topography may provide features that influence soft toric lens performance, flexure, and back vertex power in situ, which may assist in improved fitting guidelines. In this study, quantitative topographic descriptors were generated and analyzed as potential variables in predicting soft toric fitting success. METHODS: One hundred five eyes of 54 patients were empirically fit with back surface toric, prism ballasted, soft contact lenses after videokeratography was performed with the EyeSys 2000 (v. 4.0) or Humphrey Atlas (v. A6) instrument. Custom software was written to generate 54 separate quantitative descriptors of shape and astigmatism from the raw data files. A logistic regression was used to determine which variables significantly contributed to a successful or failed fit. RESULTS: Two types of empirical fitting failures were identified: loose fit (n = 15) and power errors (n = 17). The following variables were associated with a fitting failure: flat simulated keratometry (SimKf2b) within the central 3 mm zone, steep simulated keratometry (SimKs2b) within the central 3 mm zone, a difference between central and peripheral flat meridian axis (DIFFAXIS), and a difference between central and peripheral astigmatism (DIFFASTIG). For fitting failures caused by power errors, a larger steep SimKs2b (p< 0.01) and smaller DIFFAXIS (p< 0.05) were associated with a failed fit. For failures caused by physical fit of a selected base curve, a smaller DIFFAXIS (p< 0.05), larger steep SimKs2b (p< 0.05), and larger DIFFASTIG (p< 0.01) were associated with a failed fit. CONCLUSIONS: Novel quantitative descriptors of corneal shape and toricity derived from topography are associated with empirical soft toric contact lens fitting failures. Future algorithms or recommendations for improved soft toric lens selection may be derived from such indices to develop a predictive model for successful soft toric lens fitting using corneal topography data.

Contact Lenses, Hydrophilic↗
PubMed2005

Effects of minimum stimulation settings for the Med El Tempo+ speech processor on speech understanding.

OBJECTIVE: The aim of this study was to assess the effects of variations in the settings for minimum stimulation levels on speech understanding for adult cochlear implant recipients using the Med El Tempo+ speech processor. DESIGN: Fifteen patients served as listeners. The test material included sentences presented at a conversational level in noise (74 dB SPL at +10 dB signal-to-noise ratio), sentences presented at a soft level in a quiet background (54 dB SPL), consonants in "vCv" environment (74 dB SPL re: vowel peaks), and synthetic vowels in "bVt" environment (54 dB SPL re: vowel peaks). The patients' speech processors were programmed with minimum stimulation levels set to behavioral threshold, set to 10% of most comfortable loudness, and set to 0 muA. RESULTS: The level of speech understanding achieved in the behavioral threshold condition was not significantly different from that achieved in either the 10% of most comfortable loudness or 0 muA conditions for any test material. Only 2 of the 15 patients demonstrated performance differences of greater than 10 percentage points between the 0 muA condition and the behavioral threshold condition on more than a single test. CONCLUSIONS: Our results demonstrate that there are no grievous consequences, in terms of speech understanding, for setting minimum stimulation levels below behavioral thresholds. The time savings from setting thresholds to 10% of MCL or 0 muA may be especially useful during the initial device fitting.

Acoustic Stimulation↗
PubMed1998

Clinical evaluation of a new, above-elbow, body-powered prosthetic arm: a final report.

The AdVAntage Arm is an above-elbow (AE) body-powered arm designed to improve upon, and overcome, some of the major limitations of conventional prostheses. It is the result of research and development (R&D) accomplished at the Center for Engineering Design (CED), University of Utah and Sarcos Research Corporation (SRC), Salt Lake City, UT. The AdVAntage Arm was developed to provide the following main features: lightweight, independent elbow and terminal device (TD) control, and a cable recovery system for full TD actuation at any elbow position. The Department of Veterans Affairs (VA) Rehab R&D Service's Technology Transfer Section (TTS), with collaboration from the VA National Prosthetic and Sensory Aids Service (PSAS), managed a multi-center clinical evaluation of the precommercial AdVAntage Arm (the Arm). The purpose was to objectively assess and affirm the Arm's functional advantages, reliability, clinical application, and commercial readiness. Eleven VA prosthetic services served as evaluation sites with a total of 16 subjects with amputation (14 unilateral and 2 bilateral). Fifteen prosthetists provided their comments. Overall, the results demonstrated that the Arm could be fit for use by persons with transhumeral, and even with forequarter, amputation. Once the learning curve was overcome, the majority of subjects reported that the Arm offered several functional advantages over their conventional prosthesis. Its overall light weight, separation of elbow and TD function, and cable recovery system allowed opening and closure of the TD at any elbow position; resulting in a more fluid manner of use and allowing subjects to perform more activities from waist level and above (especially in the outstretched and overhead positions). At the conclusion of clinical trials, 10 subjects elected to keep the Arm for continued use. The manufacturer is committed to the commercial marketing and technical support of the arm. Based upon the clinical findings, the AdVAntage Arm was recommended for commercial production and availability, upon prescription, to appropriate veteran beneficiaries.

Activities of Daily Living↗
PubMed1999

Diagnostic bitoric rigid gas permeable contact lenses.

PURPOSE: To simplify the fitting of bitoric rigid gas permeable (RGP) contact lenses. METHODS: We prescribed bitoric RGP lenses using two kinds of diagnostic lenses at random. One type of lens was a diagnostic polymethylmethacrylate (PMMA) spherical lens and the other was a diagnostic RGP bitoric lens. RESULTS: The bitoric RGP lenses that were prescribed using a diagnostic bitoric lens required fewer parameter changes compared with the bitoric RGP lens prescribed using a diagnostic PMMA spherical lens. CONCLUSIONS: The diagnostic RGP bitoric lens simplifies the prescription of bitoric RGP lenses and is very useful in fitting astigmatic corneas.

Adolescent↗
PubMed1977

Design of total hip prosthesis: the femoral stem.

This report is a summary of the research carried out in an effort to improve the reliability of total hip replacement procedures. The current state of knowledge of hip mechanics was examined and found adequate in its description of the normal hip, but totally lacking in any but qualitative terms in its description of the diseased hip, or the load transfer between prosthesis and bone in reconstructed hips. The mechanics of the hip joint and femur indicate that the positioning of the femoral head is crucial in achieving a correct balance between muscle force and joint load. Consequently, it is recommended that a great deal more attention be devoted to the positioning of the prosthesis at hip surgery. Experimental and theoretical studies were directed to one aspect of total hip replacement - the design of the femoral stem. Results indicate that all current designs should be adequate if set in acrylic, and provided subsequent bone resorption is small. Further results indicated satisfactory load transfer from a long thick prosthesis stem, fitted without acrylic cement.

Acetabulum↗
PubMed2005

Fit of metal ceramic crowns cast in Au-1.6 wt% Ti alloy for different abutment finish line curvature.

OBJECTIVES: The purpose of this study was to evaluate the fit of metal ceramic crowns cast in Au-1.6 wt% Ti alloy and investigate the effect of abutment finish line curvature on the fit of crowns. METHODS: Three types of finish line curvature abutments were prepared (1, 3 and 5mm-curvature). For each type of abutment, five metal ceramic crowns of the facial veneered type were fabricated, which were cast in Au-1.6 wt% Ti alloy. Used as controls, another fifteen specimens were made from a commercially available gold alloy. The fit was measured in the as-cast and after porcelain application. RESULTS: In the as-cast specimens, the greater the finish line curvature was, the larger the gaps exhibited at the mesial and distal margins of copings, compared with labial and lingual margins. The distal margin of copings for 5mm-curvature abutments showed the largest gap (35 (7) microm). After porcelain application, the greater was the finish line curvature, the larger the labial marginal gap became (mean 44, 34, 25 microm, respectively, for 5, 3, 1mm-curvature). However, there was no significant difference on marginal gaps between specimens of Au-1.6 wt% Ti alloy and control gold alloy. SIGNIFICANCE: This study indicated that the metal ceramic crowns cast in Au-1.6 wt% Ti alloy had equivalent accuracy to those that cast in control gold alloy, and the abutment finish line curvature had a significant effect on the marginal fit of metal ceramic crowns.

Crowns↗
PubMed1998

Development of a wide field height eye topographer: validation on models of the anterior eye surface.

PURPOSE: The aim of this research was to develop a corneal topographer that determines the shape of the entire anterior surface of an eye without assumptions, and with uniformly high accuracy in the center and periphery. METHODS: Based upon a double projection of two sine wave gratings and analysis of the distortion of the sine wave gratings due to the corneal-scleral shape, point-by-point measurements of surface elevation were obtained with a sample density equal to the pixel density of the CCD-detector. Using this principle, a prototype topographer, called the Maastricht Shape Topographer (MST), was developed. The accuracy and reproducibility of the instrument were evaluated using bispheric models of the anterior surface of the eye. RESULTS: The average accuracy of height measurements was +/- 0.55 micron in the 10-mm central area and +/- 22.50 microns in the periphery (14 to 19 mm). Reconstruction accuracy of the radius of curvature was +/- 0.0155 mm (+/- 0.88 D) in the center and +/- 0.0313 mm in the periphery (sclera). Average height reproducibility standard error was 0.0282 micron in the center and 2.6156 microns in the periphery. CONCLUSIONS: With the MST, unambiguous shape measurements of the entire anterior surface of the eye are possible, with accuracy up to clinically accepted standards. MST is able to measure height over a wide area of 20 mm, with a 6-mm depth of field. The tested prototype of the device can be further improved by the use of custom-made optics in order to increase signal to noise ratio in the periphery of the image. This height topographer could offer a reliable method in cases where shape is of paramount importance, e.g., in (scleral) contact lens fitting and refractive surgery.

Contact Lenses↗
PubMed2005

The DSL method for pediatric hearing instrument fitting: historical perspective and current issues.

The Desired Sensation Level (DSL) Method was originally developed in the early 1980s to provide clinicians with a systematic, science-based approach to pediatric hearing instrument fitting that ensures audibility of amplified speech by accounting for factors that are uniquely associated with the provision of amplification to infants and young children who have hearing loss. This review identifies and describes several of the primary factors that have been considered in the development of the DSL Method. Specifically, the issues discussed relate to: (1) the definition and measurement of relevant acoustic, electroacoustic and audiometric variables; (2) how the external ear acoustics of infants and young children are accounted for in the DSL Method for both audiometric assessment and in the fitting of amplification; and (3) how the DSL Method has evolved concurrently with developments in hearing instrument and electroacoustic measurement technologies. Finally, current issues in the field are identified that have motivated the development of version 5.0 of the DSL Method for hearing instrument fitting.

Algorithms↗
PubMedDate not supplied

Photogrammetry--an alternative to conventional impressions in implant dentistry? A clinical pilot study.

PURPOSE: The purpose of this clinical pilot study was to describe a photogrammetric technique to determine implant positions in the oral cavity, and to test and compare this technique to conventional impression/master cast procedures for fabrication of titanium frameworks with a computer numeric-controlled (CNC) milling technique. MATERIALS AND METHODS: Implant positions were recorded by means of conventional impressions/master casts as well as intraoral 3-dimensional photogrammetric measurements in 2 patients who were provided with 5 Brånemark implants each in the edentulous mandible. For each patient 2 titanium frameworks were made by means of a CNC milling technique (All-in-One). Both frameworks had an identical design, but the orientations of the framework cylinder fit surfaces were machined either from measurements from the master casts or from the intraoral photogrammetric measurements. The frameworks were tried for fit in the oral cavity and on the master casts. RESULTS: Both cases showed different precision of fit when comparing the 2 frameworks on the master casts. One of the 2 photogrammetric frameworks was not considered acceptable when tried on the models. In the oral cavity, however, all 4 frameworks presented comparable fit, and all were accepted for clinical use. CONCLUSION: The clinical experiences with try-in of the 4 different frameworks indicated that the photogrammetric technique could be a valid option for conventional impressions when using CNC milling fabrication in implant dentistry. The different results from the model and oral examinations also imply the difficulties of assessing clinical fit when testing fit at the master cast level only.

Computer-Aided Design↗
PubMed1999

Computer assisted implantation of the femoral stem in THA - an experimental study.

Fourteen femoral stems were implanted either manually by an experienced surgeon or by a robot in fresh human cadaveric femora. The neck-shaft angle, the anteversion, the length of the femoral neck and the gap between stem and bone was measured in each specimen. Implantation by robot showed higher precision in reconstructing the true anatomic situation as well as providing a better press fit.

Arthroplasty, Replacement, Hip↗