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 415 records · Page 23Linked to original sources
PubMed1996

Fitting hearing aids to individual loudness-perception measures.

OBJECTIVE: The purpose of this study was to compare the prescribed gain, compression ratios, compression thresholds, and the relative predicted speech intelligibility (Speech Intelligibility Index [SII], American National Standards Institute 3.79, proposed) provided by four strategies proposed for selecting hearing aid parameters for low-threshold compression hearing instruments and by a traditional threshold-based hearing aid fitting procedure. The strategies used were Desired Sensation Level Input/Output (DSLTM[i/o]; Cornelisse, Seewald, & Jamieson, 1994), Visual Input-Output Locator Algorithm (VIOLA; Cox, 1994), FIG6 strategy (Killion, Reference Note 2), Ricketts and Bentler strategy (RAB), and a threshold-based hearing aid fitting procedure (National Acoustics Laboratories-Revised [NAL-R]; Byrne & Dillion, 1986). These new strategies have been suggested as alternatives to threshold-based strategies, which do not provide the varying amounts of target gain, as a function of input level, necessary to fit low-threshold compression hearing aids. DESIGN: The electroacoustic prescriptions and the predicted speech intelligibility were calculated across all five fitting strategies for 20 subjects. The threshold and loudness growth information used for each fitting was reported previously (Ricketts & Bentler, in press). RESULTS: Comparison across prescriptions revealed that the NAL-R strategy (due to the linear gain provided) prescribed the least gain for low-level inputs and the greatest gain for high-level inputs. Gain comparisons across fitting by loudness (FBL) strategies revealed a more shallow frequency response slope for strategies that require individual measures of loudness growth (RAB, VIOLA) in comparison with strategies that assumed average data (FIG6, DSLTM[i/o]). SII results revealed greater predicted speech intelligibility for the FIG6 and the DSLTM[i/o] compared with the NAL-R, RAB, and VIOLA. These differences were most apparent in noise backgrounds and least evident when loudness differences were minimized. CONCLUSIONS: It appears that differences in SII scores across the FBL fitting strategies are due, in part, to differences in the loudness of the output signal. It is assumed that differences in high-frequency shaping may also be a factor. These data do not appear to support the use of additional clinical time to obtain individual loudness growth measures. However, due to the fact that SII results are based on average performance, it is difficult to predict whether differences across these fitting strategies would be realized in actual measures of speech intelligibility or sound quality on an individual basis.

Correction of Hearing Impairment↗
PubMed2003

Corneal desiccation in rigid contact lens wear: 3- and 9-o'clock staining.

The current knowledge of treatment options together with signs and symptoms, classification, prevalence, and etiology of 3- and 9-o'clock staining in rigid contact lens wear are described in this review article. In total, 11 treatment options for the management of 3- and 9-o'clock staining were found in the literature. Five of these treatment options are related to lens parameters, namely edge lift, edge thickness and shape, back surface geometry, total diameter, and back optic zone radius. Three other options are related to lens performance: movement, centration, and surface wettability. Three more variables can be identified: blinking habits, tear supplements, and, finally, switching to a hydrogel material. There is controversy on how to adjust the most important individual variables for management of 3- and 9-o'clock staining. The advocated treatment options are often related to the fitting techniques used: lid attachment or interpalpebral fit. Implications for practice and for further research are discussed.

Contact Lenses↗
PubMedDate not supplied

Marginal fit of titanium metal-ceramic crowns.

PURPOSE: This study aimed to compare the marginal fit of 2 kinds of metal-ceramic crowns-crowns cast from commercially pure titanium and Procera titanium crowns. MATERIALS AND METHODS: Ten copings of each type were prepared, veneered with low-fusing porcelain, and bonded with glass-ionomer cement. Marginal fit was assessed before and after cementation, and the data were analyzed statistically. RESULTS: There were significant differences among mean values of marginal fit between the groups. Cementation increases discrepancies in both groups. CONCLUSION: Casting titanium has resulted in the highest discrepancies in marginal fit of both groups.

Analysis of Variance↗
PubMedDate not supplied

[Revision total hip arthroplasty: how do metaphyseal onset, diaphyseal fill and a three-point-stem-fixation influence the postoperative subsidence of a revision straight-stem?].

AIM: It was the purpose of this study to determine the postoperative subsidence of a cementless hip revision stem in regard to the degree of metaphyseal onset, diaphyseal fit and a three-point contact of the stem in the femur. METHODS: Data of 50 revision total hip replacements using a cementless revision straight stem (PFM-R) could be investigated. The degree of subsidence was measured on pelvic X-rays 6 and 12 months postoperatively. The degree of metaphyseal onset, diaphyseal fit and a three-point contact of the stem in the femur was determined on the immediate postoperative X-rays. RESULTS: The amount of subsidence was strongly related to the degree of metaphyseal onset. With minor onset (up to 25 % of the possible) stems subsided 9.4 (6 months), respectively, 13.2 millimeters (12 months) in average within the investigation periods. If there was a large degree of metaphyseal onset (more than 75 % of the possible) the average subsidence was only 1.6 (6 months) or 0.9 millimeters, respectively (12 months). Neither the amount of diaphyseal fit nor the presence of three-point contact of the stem in the femur influenced the subsidence significantly. Conclusion The amount of the postoperative subsidence of stems in cementless revision total hip arthroplasty is predominantly influenced by the degree of the metaphyseal onset of the prosthesis.

Adult↗
PubMed2002

Periprosthetic modelling of femoral component fit using computed tomography data for total hip arthroplasty: a feasibility study.

The aim of the work was to create a new three-dimensional periprosthetic multi-criteria optimisation technique to identify the best six degrees of freedom transform to position a porous-coated anatomic cementless femoral component for three factors, including: first, maximisation of the degree of contact achieved between designated bone ingrowth surfaces and the periprosthetic bone; secondly, minimisation of the bone mass to be removed to accommodate the component and thirdly, the extreme constraint of the component to be positioned so that it does not project beyond the periosteum. Discrete integrals were computed over regions of interest derived from the polyhedral component mesh in transaxial CT scan planes, using a polygon scan-conversion algorithm. A new biomedical imaging volume rendering technique utilising dynamic virtual textures was developed to visualise the design trade-offs. Pareto-optima were identified for four femora that matched an average-sized component. The non-linear, multi-modal fit metric was quadratic near minima, with a narrow trough of equivalent fit values within 3mm of translation and 3 degrees of rotation with respect to the canal axis, and possessed a dependence most pronounced for distal-directed insertion against varus/valgus rotation. The study gives previously unavailable data on the three-dimensional femoral component fit and is the first report that demonstrates that fitting the implant using several design criteria in a multi-criteria optimisation scheme is feasible.

Arthroplasty, Replacement, Hip↗
PubMed2001

Contact lens fitting in a patient with keratectasia after laser in situ keratomileusis.

We present a case of unilateral iatrogenic keratectasia developing 15 months after bilateral laser in situ keratomileusis using a broad-beam excimer laser (Bausch & Lomb Keracor 116) to treat -3.5 -1.5 x 85 diopters of myopia. Preoperative pachymetry in the eye measured 450 microm without topographical changes suggesting keratoconus or forme fruste keratoconus. Contact lens fitting to provide 20/25 visual acuity is described.

Adult↗
PubMed2002

A model of a nucleus 24 cochlear implant fitting protocol based on the electrically evoked whole nerve action potential.

OBJECTIVE: The goal of this study was to model a cochlear implant fitting protocol based on the electrically evoked whole nerve action potential (EAP) measured using the Neural Response Telemetry capabilities of the Nucleus C124M cochlear implant. The model and data were based on the significant correlations found between the EAP threshold and growth function slope and psychophysical threshold and, dynamic range, respectively, in 12 subjects (Franck, Reference Note 3; Franck & Norton, 2001). DESIGN: Using a retrospective split-half study design, these correlations found between psychophysical mapping levels and EAP data from six of the subjects were used in a model to predict psychophysical mapping levels from EAP data of the other six subjects. RESULTS: Predicted psychophysical mapping levels from the model of the EAP-based fitting protocol closely approximated measured cochlear implant fitting psychophysics. CONCLUSIONS: The close approximation of the measured data to the model data indicates the feasibility of the clinical use of an EAP-based cochlear implant fitting protocol. The realization of this model would only require two loudness judgments from the patient, whereas traditional fitting requires 44, and would be fit in a live-voice mode, accounting for across-electrode loudness summation.

Auditory Threshold↗
PubMed2000

Assessment of ophthalmology residents' contact lens training.

PURPOSE: To characterize the nature and duration of contact lens training in ophthalmology residency training programs and to ascertain the comfort level of residents in fitting various types of contact lenses and in dealing with common contact lens-related complications. METHODS: Surveys were mailed to 126 ophthalmology residency program directors/coordinators and requested to be distributed to 1,381 ophthalmology residents. The questionnaire addressed issues related to contact lens training, hours of clinical and didactic training, comfort with fitting a variety of different types of contact lenses and dealing with common contact lens-related complications, and plans for incorporation of contact lens dispensing into future practice. RESULTS: Two hundred and forty-nine residents (18%) responded from 84 programs (67%). Most programs (87%) have some form of supervised contact lens training, frequently conducted by an optometrist (61% of programs), that consists of 20 hours or less of clinical experience and 20 hours or less of didactic training. A majority of the responding graduating residents (66%) feel comfortable fitting spherical soft contact lenses, while less than half of all residents feel comfortable fitting any other type of contact lens. In addition, most residents (65%) feel comfortable diagnosing and treating common contact lens-related complications. CONCLUSIONS: Most ophthalmology residency programs offer some form of supervised contact lens training which allows a majority of residents to feel comfortable fitting only spherical soft contact lenses, while also dealing comfortably with most contact lens-related problems. A comparison with previous data suggests increasing comfort with fitting most types of contact lenses over the last decade.

Contact Lenses↗
PubMedDate not supplied

Transtibial energy-storage-and-return prosthetic devices: a review of energy concepts and a proposed nomenclature.

Prosthetic devices that can store and return energy during gait enhance the mobility and functionality of lower-limb amputees. The process of selecting and fitting such devices is complicated, partly because of confusing literature on the topic. Gait analysis methods for measuring energy characteristics are often incomplete, leading to inconsistencies in the energy classifications of different products. These inconsistencies are part of the reason for the lack of universally accurate terminology in the field. Inaccurate terminology perpetuates misunderstanding. In this paper, important prosthetic energy concepts and methods for measuring energy characteristics are reviewed. Then a technically accurate nomenclature and a method of functional classification are proposed. This review and proposed classification scheme should help to alleviate confusion and should facilitate enhancement of the design, selection, and fitting of prosthetic limbs for amputee patients.

Amputees↗
PubMedDate not supplied

Medical rapid prototyping and 3D CT in the manufacture of custom made cranial titanium plates.

This report describes a new method of custom making cranial titanium plates for the repair of skull defects. We have combined 3D CT imaging and surface modelling with rapid prototyping (RP) technology to produce physical models of our patients' skulls from which custom titanium plates were made. We have expanded the use of image processing tools applied to the CT image data to fabricate a representation of the skull defect. Medical RP models are relatively expensive and particular attention has been paid to developing image processing methods to reduce costs. Our technique used the patient as their own model and generated data from the contralateral side of the head where appropriate. We present the results of 10 patients who have had a custom made cranial titanium plate fitted and discuss the models for these cases. The benefits of our custom made titanium plates are reduced patient attendances to hospital and a more accurate titanium plate which has improved fitting and cosmesis.

Bone Plates↗
PubMed2001

Estimation of psychophysical levels using the electrically evoked compound action potential measured with the neural response telemetry capabilities of Cochlear Corporation's CI24M device.

OBJECTIVE: The goal of this study was to estimate psychophysical levels using the electrically evoked compound action potential (EAP), measured with the Neural Response Telemetry capabilities of Cochlear Corporation's Nucleus CI24M cochlear implant system. DESIGN: Twelve postlingually deafened adults with at least 3 mo of implant experience with the CI24M were subjects in this study. EAP growth functions were successfully quantified on each active electrode of every subject. Correlation and regression analyses were performed between EAP measures and cochlear implant fitting psychophysics. Other information including performance, etiology and duration of hearing loss, and individual electrode impedance was considered. RESULTS: EAP thresholds were found to be highly correlated with psychophysical thresholds. The rate of EAP growth with increasing stimulation levels was also found to be correlated with the dynamic range of loudness limits and psychophysical thresholds in some subjects. No relationship was evident between EAP measures and speech perception tests. CONCLUSIONS: Information from EAP growth function measurements may be used to estimate psychophysical information used in cochlear implant fitting but not to predict performance with the device.

Adult↗
PubMed2005

Genetic algorithms for adaptive psychophysical procedures: recipient-directed design of speech-processor MAPs.

OBJECTIVES: The goal of the research is to evaluate the application of genetic algorithms (GAs) in listener-directed optimization of audio-processing designs. We hypothesize that cochlear-implant recipients can use a GA-guided adaptive psychophysical search procedure to select useful designs from among a large number of speech processor MAPS. DESIGN: An adaptive psychophysical procedure was developed in which a listener's preferred four out of eight speech processor MAPs were updated according to a genetic algorithm. Experiments involving cochlear-implant recipients were conducted to characterize both the convergence behavior of the adaptive procedure as well as properties of the MAPs optimized by the recipient. RESULTS: Results from five cochlear-implant recipients indicate that the adaptive procedure converges to useful speech processor MAPs within twenty iterations. CONCLUSION: The results suggest a means whereby a potentially large number of audio-processing designs can be searched efficiently by a human listener without requiring excessive amounts of feedback or prior knowledge about the listener's preferences. In the case of cochlear-implant recipients, it may be possible to use this procedure as an aid to the clinician in the fitting of a speech processor MAP.

Adaptation, Physiological↗
PubMed2004

Keratoconus fittings: apical clearance or apical support?

PURPOSE: To examine the relative merits of apical support and apical clearance fitting of rigid gas-permeable contact lenses for keratoconus. METHODS: After an historic review of fitting approaches for keratoconus, a case report is described in which an adventitious apical clearance fitting for early keratoconus might have been associated with accelerated progress of the ectasia. DISCUSSION: The hypothesis that apical clearance fittings increase the risk of accelerating ectasia progression in early keratoconus is examined in counterpoint to the hypothesis that apical support fittings increase the risk of apical scarring. Reference is made to the responses of normal corneas to apical clearance fitting and to apical contact fittings used in orthokeratology fittings. The tendency for corneas to mold to contact lens curvature is reviewed. The possibility that reduced corneal thickness or tissue softening and associated changes to the biomechanical properties of the cornea in keratoconus may facilitate molding with apical clearance fitting is examined. CONCLUSIONS: Known and putative risk factors for fitting complications that are associated with apical clearance and apical touch contact lens fitting are given as a basis for the reader to draw conclusions about the management of contact lens fitting for keratoconus. The possibility of symptomless adverse responses is a strong indication for frequent routine aftercare reviews.

Child↗
PubMed1998

Insertion gain versus median ear corrected coupler gain: a comparison of two fitting methods in new NHS hearing aid users.

Although hearing aid fitting by insertion gain measurement is known to be an accurate and reliable technique, it is rarely used routinely in the UK National Health Service (NHS) because of high demands on staff and time. This study investigated whether an alternative, more practical procedure of fitting by median ear corrected coupler measurements would be as beneficial to NHS patients. Forty patients took part in a double-blind cross-over study comparing the two fitting methods. Results show that the insertion gain fittings were significantly better than the coupler fittings in terms of both patient preference and speech discrimination in noise. It is concluded that, even with the limited response adjustments available, individual deviations from the median ear make routine hearing aid fitting by insertion gain measurement indeed desirable in the NHS.

Adult↗
PubMed2001

Use of teleoptometry to evaluate acceptability of rigid gas-permeable contact lens fits.

BACKGROUND: Teleoptometry involves the transmission of digitized optometric information from a remote site for analysis by an expert. This project assessed computer compression of video data showing contact lens fitting relationships and the transmission of these data to a specialist for evaluation METHODS: Fifty-five sets of video clips showing dynamic fluorescein patterns of rigid gas-permeable lens fits, topographic corneal maps, and basic information on lens parameters were evaluated-live and again after digitization and electronic compression-by a contact lens specialist. The evaluator was asked to determine whether lens fit was acceptable and, if not, how the lens parameters should be changed. RESULTS: Comparison of lens evaluations made live versus compressed showed agreement on fit acceptability for approximately 80% of the subject/lens combinations. When the evaluator concluded for both presentations that the lens was unacceptable, the same change in lens parameters was recommended 67% of the time. DISCUSSION: Agreement for the majority of live and compressed video observations suggests that teleoptometric consultation on contact lens fitting is feasible. When technology advances to the point at which large files can be sent quickly via the Internet, it is likely the practice of transmitting video clips and other information to obtain fitting assistance will become commonplace.

Adult↗
PubMed1995

The effect of sprue design and alloy type on the fit of three-unit metal/ceramic bridges.

This study was designed to compare the effect of three sprue designs and three types of metal alloy/ceramic on the accuracy of fit of three unit bridges. A sprue design which has straight sprues attached directly to the pattern but does not have a button of excess metal connecting the sprues together after casting, produced the best marginal accuracy, irrespective of the alloy type used. Of the three alloys used (gold, palladium and nickel/chromium based alloys) the gold alloy produced better fitting bridges with each sprue design used.

Analysis of Variance↗
PubMed1998

Rigid gas permeable contact lens fitting after radial keratotomy.

PURPOSE: The purpose of our study was to determine whether radial keratotomy (RK) patients could be fit with rigid gas permeable (RGP) contact lenses based on postoperative keratometry measurements. METHODS: Thirteen eyes from eight post-RK patients were fit with RGP lenses for residual refractive errors. Since these patients were self-referred and were operated on elsewhere, preoperative keratometry readings were not available. We used postoperative keratometry readings for base curve selection; and spherical polymethylmethacrylate diagnostic lenses were used for fitting. RESULTS: Visual improvements averaged 3.85 Snellen lines (range: 1-8 lines). Prefitting visual acuities were: 20/30 (5 eyes); 20/40 (1 eye); 20/ 50 (1 eye); 20/60 (1 eye); 20/70 (3 eyes); 20/150 (1 eye); and 20/200 (1 eye). Final visual acuities were 20/20 (7 eyes), 20/25 (4 eyes), 20/30 (1 eye), and 20/40 (1 eye). CONCLUSION: We found that when fitting post-RK eyes with RGP contact lenses preoperative keratometry was unnecessary, and an empirical fitting method based on postoperative keratometry was successful.

Adult↗