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PubMed1998

A new technique for morphologic measurement of the femur. Its application for Japanese patients with osteoarthrosis of the hip.

The cementless femoral prostheses developed in Western countries have commonly been used for Japanese patients, but it has been noted that it is difficult to achieve a good fit between the cementless femoral prostheses and some femora. In Japan, there are many patients with secondary osteoarthrosis (OA) of the hip, but Western designed femoral prostheses seem to be mainly for use with primary OA of the hip. To design femoral prostheses better suited to Japanese patients, a new method to study the morphometry of the femur is required--one which can determine the particular features of the femur in Japanese patients. In this study, a new morphologic measurement technique of the femur is proposed and applied to a number of Japanese OA patients in order to demonstrate its efficacy. In this technique, a three-dimensional solid model based on the outer and inner borders of the femoral cortex is constructed from 3-D CT images and computer-aided design (CAD) software. The bone axis is defined as the line of best fit to the centers of gravity of the femur cross sections in each CT plane by using the least square method. A new femur coordinate system is considered based on this bone axis. The corrected outer borders of the cortex are reconstructed in sections perpendicular to the bone axis. The angle between the principal axis of inertia of the sections and a plane defined by the femur coordinate system is selected as providing a good measurement of the torsion value to characterize the femur morphology. The angles of principal axis were measured in 110 OA and 36 normal hips, and then compared with each other. A significant difference between the OA and normal group was observed especially in the proximal region above the section 6 mm below the level of the lesser trochanter. It is suggested that the anteversion of the femoral neck influences the torsion of the parts below the lesser trochanter. From the results, it is demonstrated that the proposed measurement technique is a reliable and efficient means of determining femur morphology.

Adult↗
PubMed2003

Hearing aid rehabilitation: what do older people want, and what does the audiogram tell?

The demands/needs for audiological/otological services under optimal conditions were investigated within the framework of three epidemiological investigations. The study population consisted of 559 people, 318 women and 241 men, 70-91 years old. The participants were offered audiological and otological services, including hearing aid fitting. Fifteen per cent of the participants asked for audiological/otological services. Six per cent of the participants were equipped with hearing aids as a result of the study. Almost all of those with severe hearing loss either had been equipped with hearing aids prior to the study, or took advantage of the offer to get such devices. This figure represented about half of those with moderate hearing loss and about 20% of those with mild hearing loss. After the study, 19% were equipped with hearing aids, but in all 25% had hearing aids or had expressed a wish to get one. The percentages of elderly people with mild-to-moderate hearing loss, who contemplated purchasing an aid, but did not do so, were large, between 10%, and 22%. More than 11% consulted a doctor when the opportunity was offered to them. Most of them wanted the consultation because of progressive hearing loss. Middle ear disease was another important reason for a consultation.

Age Factors↗
PubMed2006

Clinical field testing of vulcanized rubber feet for trans-tibial amputees in tropical low-income countries.

In a prospective, controlled study, 186 prosthetic rubber feet of different designs were fitted to amputees with trans-tibial prostheses. There were 158 amputees available for follow-up. The amputee compliance was good and 89% were satisfied with their device. After 18 months of use one VI-Solid rubber foot from VVAF in Cambodia had failed, as compared to 11% failures with the same foot with a heel cavity, 3% with the EB-1 sandwich construction from POF in Vietnam, all performing significantly better than the 62% encountered with the vulcanized rubber foot from ICRC in Cambodia; the latter representing half of the feet failing in amputees walking bare-footed. Nearly all failures were located at the foot-sole or the keel. The failure rate was 20% for the HI-Cambodia foot after 12 months. After 24 months of use, still only one VI-Solid rubber foot had failed and this foot design was found superior to the others in regard of durability.

Adolescent↗
PubMedDate not supplied

Fitting hearing aids to adults using prescriptive methods: an evidence-based review of effectiveness.

The use of a prescriptive fitting approach for hearing aid selection has been a common practice for the past 60-70 years. While there are prescriptive approaches that have been validated, in recent years it has become popular to deviate from these validated methods and use manufacturers' proprietary algorithms, which in many cases are significantly different. This research review was designed to examine if there was evidence supporting the use of specific gain requirements for hearing aid fitting. Specifically, the question that was asked was "Are there real-world outcome measures from adult patients that show a preference for the gain prescribed by a specific prescriptive fitting procedure?" Inclusion criteria were as follows: adult subjects, consistent technology (e.g., different prescriptive methods compared using same hearing aids), real-ear verification of gain, and real-world outcome measures. For this review, in addition to subjective responses, preferred use gain was considered a real-world outcome measure. The National Acoustic Laboratories' revised (NAL-R), revised for severe/profound (NAL-RP), and the National Acoustic Laboratories-Non-Linear 1 (NAL-NL1) prescriptive methods were used as a common reference, as they have been the most commonly studied methods with adults. Eleven studies were identified that met the inclusion criteria. Eight of the studies supported gain similar to that prescribed by the NAL-R or NAL-RP methods; three studies supported prescribed gain less than the NAL-R or NAL-RP. There was no evidence that gain greater than that prescribed by the NAL methods should be used. The level of evidence was moderate, as the supporting studies were either Level 2 or Level 4, and the statistical power of the studies was low.

Adult↗
PubMed2000

[Clinical comparison of a digital with an analog hearing aid].

The benefit of innovative hearing aid technology can be evaluated in clinical trials. The present study describes the comparison of a new digital hearing aid with an analogue device serving as a reference. The tests were carried out with 15 experienced hearing aid wearers. To prevent the influence of different fitting algorithms such as prescriptive or loudness-based the digital devices were not renewed fitted but their level- and frequency-depending gain was adjusted to that of the reference. Different tests concerning loudness perception (category loudness scaling) speech discrimination in noise (the Göttingen sentence test) and self-assessment of the benefit by questionnaires were performed. All tests yielded slightly better results for the digital hearing aid. The speech audiometric evaluation showed somewhat better discrimination for the test-device. The questionnaires yielded a marked preference for the digital device. Because the study was not blinded influences due to the knowledge of the subjects of testing a new technology generally can occur. On the other hand, the question arises whether present audiometric tests sufficiently consider signal processing of modern hearing systems. Furthermore, one has to take into account that only a few of the features of digital technology such as noise-reduction and feedback-cancellation were considered in this study to allow for a sensible comparison. Because of the large number of possibilities offered by digital technology additional benefit by the hearing aid can be expected.

Analog-Digital Conversion↗
PubMed2003

The hearing aid revolution: fact or fiction?

OBJECTIVE: To present the experiences of consumers with traditional hearing aids (T-HAs) and digital signal processing hearing aids (DSP-HAs) during the period 1999-2001, based on data obtained from an ongoing quality assurance programme. MATERIAL AND METHODS: A questionnaire is mailed to subjects fitted with HAs 3-4 months after the fitting, and includes questions concerning satisfaction with the HA, frequency of use of the HA, ability to manipulate the HA, satisfaction with the overall services of the department and need (if any) for additional appointments. RESULTS: The response rate was 69.5%, and thus information was obtained from 14 325 subjects (44.9% male, 55.1% female; median age 72 years; range 18-97 years). Of the respondents, 7,983 (55.7%) had been provided with T-HAs and 6,342 (44.3%) with DSP-HAs. The results of the questionnaire were as follows: 71.4% of those fitted with a T-HA were very satisfied/satisfied with it, compared to 68.1% with a DSP-HA (p < 0.05); 91.6% and 89.1%, respectively used their HA daily/weekly (p < 0.05); 80.5% and 82.2%, respectively, were able to manipulate their HA; 96.2% and 97.3%, respectively were satisfied with the overall services of the department; and 32.5% and 48.5%, respectively, indicated a need for an additional appointment (p < 0.05). A comparison between high- and low-cost DSP-HAs showed that 68.4% and 68.2%, respectively were very satisfied/satisfied with their HA (p = NS). CONCLUSIONS: According to consumers the "HA revolution" has failed to materialize; the significantly higher proportion of subjects with DSP-HAs who need an additional appointment represents a heavy burden on the hearing health services. The lack of a difference between the benefits obtained with low- and high-cost DSP-HAs emphasizes the need for appropriately designed and performed trials before new HA technology is launched.

Adolescent↗
PubMed1997

Hearing instruments and health technology--an evaluation.

This contribution compares a currently worn hearing instrument (i.e. R-HI) with a programmable multiband full-dynamic range compression behind-the-ear HI (i.e. T-HI), based on subject preference for HI, and, in addition, compares the preference for a linear/ non-linear amplification-mode (i.e. L-mode/C-mode). Finally, it evaluates some health technology aspects related to the devices. N = 34 experienced HI-users at a median age of 72 years (range 22-84) completed the trial, n = 5 being monaurally, and n = 29 being binaurally fitted. The trial comprises an unblinded comparative study of the R-HI and T-HI, in either C-mode or L-mode amplification, and a double-blind crossover study evaluating the C-mode versus the L-mode amplification. The results of the unblinded study showed that 94% (n = 32/34) preferred the T-HI, whereas two subjects preferred their current HI. The double-blind crossover study concerning the preference for the C-mode and L-mode, respectively, in the T-HI, showed that 72% (n = 23/32) had a significant preference for the non-linear amplification, whereas 28% (n = 9/32) preferred the linear amplification. Provided that the price of the T-HI is kept unchanged, a health technology evaluation may imply an estimate of 30 mill. DKR added costs on a national basis, which should be taken into account within the national hearing services.

Adult↗
PubMed1998

Marginal fit and surface roughness of crowns made with an accelerated casting technique.

STATEMENT OF PROBLEM: Conventional investing and casting techniques following the manufactures' recommendations are time-consuming. Accelerated casting techniques have been reported, but their accuracy has not been adequately studied for complete crown castings. PURPOSE: This study evaluated the marginal fit and surface roughness of complete crowns made with a conventional and an accelerated casting technique. MATERIALS AND METHODS: Part I of the study determined the mean time interval required for each investment to reach its maximum exothermic setting reaction temperature. Part II determined the marginal discrepancy of standardized complete crowns cast in a high noble metal ceramic alloy, with the use of four phosphate-bonded investments. A conventional technique (as recommended by the manufacturer) was compared with an accelerated technique that used 13- to 17-minute bench set time (as determined in part 1 for each investment)_ and 15-minute wax elimination cycle in a 815 degrees C (1500 degrees F) preheated furnace. Part III evaluated the surface roughness of castings made with the same techniques as in part II. RESULTS: For the marginal discrepancy and surface roughness, crowns fabricated with the accelerated casting technique were not significantly (P > 0.05) different from those fabricated with the conventional technique. CONCLUSION: The accelerated casting technique described in this study could be a vital alternative to the time-consuming conventional techniques.

Crowns↗
PubMed2003

An examination of changes in hearing-aid performance and benefit in the elderly over a 3-year period of hearing-aid use.

This brief report describes the changes in hearing-aid performance and benefit in 9 elderly hearing-aid wearers over a 3-year period following the hearing-aid fitting. Objective measures of hearing-aid performance included three measures of speech recognition: (a) the Nonsense Syllable Test (NST) presented at 65 dB SPL and a +8 dB signal-to-noise ratio (SNR), (b) the Connected Speech Test (CST) presented at 50 dB SPL in quiet, and (c) the CST presented at 65 dB SPL and a +8 dB SNR. Subjective, self-report measures of hearing-aid benefit included the Hearing Aid Performance Inventory (HAPI; B. E. Walden, M. E. Demorest, & E. L. Helper, 1984) and the Hearing Handicap Inventory for the Elderly (HHIE; I. Ventry & B. Weinstein, 1982). Performance and benefit measures were obtained at postfit intervals of 1 month, 6 months, 1 year, 2 years, and 3 years using a standardized measurement protocol. Individual data were evaluated using 95% critical differences established previously for each benefit measure and applied around the scores observed at the 1-month postfit interval. Little evidence was seen for systematic improvement in aided performance or benefit, consistent with that expected from acclimatization, in any participant or for any measure of benefit.

Aged↗
PubMed2005

The Desired Sensation Level multistage input/output algorithm.

The Desired Sensation Level (DSL) Method was revised to support hearing instrument fitting for infants, young children, and adults who use modern hearing instrument technologies, including multichannel compression, expansion, and multimemory capability. The aims of this revision are to maintain aspects of the previous versions of the DSL Method that have been supported by research, while extending the method to account for adult-child differences in preference and listening requirements. The goals of this version (5.0) include avoiding loudness discomfort, selecting a frequency response that meets audibility requirements, choosing compression characteristics that appropriately match technology to the user's needs, and accommodating the overall prescription to meet individual needs for use in various listening environments. This review summarizes the status of research on the use of the DSL Method with pediatric and adult populations and presents a series of revisions that have been made during the generation of DSL v5.0. This article concludes with case examples that illustrate key differences between the DSL v4.1 and DSL v5.0 prescriptions.

Adolescent↗
PubMed2004

Evaluation of an adaptive directional system in a DSP hearing aid.

The effectiveness of an adaptive directional microphone design, as implemented in the Phonak Claro behind-the-ear hearing aid, is evaluated. Participants were fit bilaterally and tested in 2 environments, an anechoic chamber and a moderately reverberant classroom, with the microphones in the fixed (cardioid) setting and the adaptive setting. Five speakers were placed between 110 degrees and 250 degrees azimuth around the listener. Speech-weighted noise was presented from those speakers at an overall level (OAL) of 65 dB (A). Noise was increased by 8 dB from 1 speaker at a time, using 2-s modulation and random assignment, while the output from the other speakers was reduced to maintain the constant OAL. Results of 2 speech perception tasks used as outcome measures indicated that the adaptive system was not able to follow the dominant noise source in the presence of lower level noise sources. Self-report measures obtained after blinded home trials were consistent with laboratory findings that the participants did not perceive this adaptive microphone design to be more effective than the default fixed-microphone option.

Adult↗
PubMedDate not supplied

Quantifying and responding to patient needs and expectations.

Comprehensive audiometric testing serves as the cornerstone of adult hearing aid fittings for many clinicians. The data will serve to define the degree, configuration, and site of lesion of the hearing loss. The data will be used in prescriptive formula to preset the hearing aid and may be entered into probe microphone or hearing aid test box equipment to provide verification targets. Clinicians are comfortable obtaining audiometric data, have an accepted way of obtaining these data, and are comfortable discussing these data with patients and other professionals. The patient, however, is not a walking audiogram and may bring all sorts of interesting nuances to the process. Just as part of the clinician's comfort with using audiometric data comes from the standard process of obtaining and reporting these data, the clinician who chooses to go beyond the audiogram in terms of data collection with a patient must have a means for gathering and quantifying additional information. The following case describes a method of obtaining and quantifying the patient's listening and communication needs. The case illustrates the use of these measures in recommending appropriate communication and safety solutions.

Aged, 80 and over↗
PubMed2000

Experimental and computational approach for the evaluation of the biomechanical effects of dental bridge misfit.

Dental bridges supported by osseointegrated implants are commonly used to treat the partially or completely edentulous jaw. The bridges are manufactured in metal alloy using a sequence of technological steps which well match the requirement to get custom overstructures but does not guarantee geometrical and dimensional tolerances. Dentists often experience that a perfect fit of the bridge with the abutments is almost impossible to achieve. When a misfitting bridge is forced on the abutments, deformations may occur inducing a permanent preload at the fixture-bone interface and the greater the misfit the greater is the preload and the risk of implant failure. This work gives an evaluation of the biomechanical effects induced by a misfitting bridge when forced on two supporting dental implants. The strains induced in the bridge have been measured using two purposely designed and fabricated experimental devices allowing different types of misfit. FEM 3D models of the bridge and of the bridge anchored to the bone by implants have been developed. The former has been validated by simulating the same loading conditions as in the experimental tests and comparing the bridge strains. Both models have been used for the evaluation of the stress induced in the bridge and at the fixture-bone interface by bridge length errors. The results show that the method may help to estimate the stress distribution in the bridge and bone as a consequence of different dental bridge misfits.

Biomechanical Phenomena↗
PubMedDate not supplied

Oedematous corneal response of the fellow control eye to lotrafilcon a and vifilcon a hydrogel contact lenses in the rabbit.

PURPOSE: To compare central corneal swelling after 24 h in eyes wearing Lotrafilcon A (high Dk silicone hydrogel) and Vifilcon A (low Dk hydrogel) lenses and the fellow control eyes of rabbits. METHODS: 24 New Zealand albino rabbits, free of corneal and conjunctival disease, were anaesthetised with ketamine and xylazin. In 12 rabbits, the right eye was fit with the high Dk Lotrafilcon A silicone hydrogel lens. In the other 12 rabbits, the right eye was fit with the low Dk Vifilcon A hydrogel lens, whereas the left eyes were kept as control eyes. Thereafter, the lens-fitted eyes had partial tarsorrhaphy that left a central gap of approximately 4 mm in length. After 24 h the eyelids were opened and the lenses removed. Central corneal thickness was measured using an ultrasonic pachymeter (Mentor O&O-Advent). RESULTS: Central corneal oedema induced by Vifilcon A lens was significantly higher than that with the Lotrafilcon A lens (p < 0.0001). The oedema of the fellow eyes paired with the Vifilcon A lens-wearing eyes was also higher than that of the fellow eyes paired with the Lotrafilcon A lens-wearing eyes (p < 0.01). CONCLUSIONS: The Lotrafilcon A lens induced significantly less corneal oedema than the Vifilcon A lens. Corneal oedema of the fellow eyes appears to be influenced by the swelling of the contralateral lens-wearing eyes. The oedema of the fellow control eye was significantly lower when there was less oedema in the contralateral eye wearing a high Dk silicone hydrogel lens. This may be a sympathetic physiological response. The presence of silicone in the high Dk hydrogel lens may suppress corneal oedema in the lens-wearing eye, thus affecting the fellow eye.

Animals↗
PubMed2000

Improving audibility with nonlinear amplification for listeners with high-frequency loss.

In contrast to fitting strategies for linear amplification that have been frequently refined for listeners with different degrees of hearing loss, we know relatively little about the effects of nonlinear amplification for differing audiometric configurations. The purpose of the current study was to determine whether increases in audibility with nonlinear amplification improved speech recognition to a comparable degree for listeners with sloping sensorineural loss as for a comparison group of listeners with flat sensorineural loss. Consonant recognition was examined as a function of audibility with wide dynamic range compression amplification and with linear amplification. For linearly amplified speech, listeners with flat and sloping loss showed similar improvements in recognition given the same increases in audibility. Results for nonlinearly amplified speech indicated that the listeners with flat loss showed a greater rate of improvement as audibility increases than the listeners with sloping loss. This difference is largely due to superior performance by the listeners with sloping loss for low-audibility speech in comparison to equivalent group performance for high-audibility speech.

Adult↗
PubMed1998

Optimization of speech processor fitting strategies for Chinese-speaking cochlear implantees.

OBJECTIVES: To compare speech recognition performance in Chinese-speaking cochlear implant patients with a speech processor program selected by the clinical audiologist in Taiwan and with a new speech processor program based on the Washington University clinical procedure developed by Skinner et al. STUDY DESIGN: Six adult Chinese-speaking patients implanted with the Nucleus cochlear implant system participated in this study. METHODS: A fitting procedure developed in 1995 by Skinner et al. at Washington University School of Medicine was used to create a new speech processor program to optimize each patient's hearing in everyday life. Speech tests (vowels, consonants, tones, and words), sound-field thresholds, and a self-report questionnaire were used to evaluate each patient's performance with his or her previous speech processor program and a new one. RESULTS: Four of the six patients had significant changes from the previous to the new speech processor program. These changes were associated with improvement in score on at least one speech test, more sensitive sound field thresholds, and reported improvement in some everyday listening situations on the questionnaire. CONCLUSIONS: These results suggest that use of this procedure with adult cochlear implantees may improve benefit in everyday life. Analysis of the speech test stimuli and patients' responses provides a basis for modification or creation of new Mandarin Chinese speech tests for preoperative and postoperative evaluation of adult cochlear implant patients.

Adolescent↗
PubMed2005

Change of proliferation rate of corneal epithelium in the rabbit with orthokeratology lens.

OBJECTIVE: To investigate the cell proliferation rate of normal corneal epithelium with extended orthokeratology lens (OKL) wear in comparison with extended rigid gas-permeable (RGP) lens wear. METHODS: Twenty-four rabbits were fitted unilaterally with either an OKL or an RGP lens, and the other eye was used as a control. They were injected with 5-bromo-2-deoxyuridine (BrdU) 24 h prior to being sacrificed. The rabbits were sacrificed at 1, 3, 7 and 14 days after lens fitting. The cornea from the superior limbus to the center was taken at 1.0-mm intervals. The BrdU-labeled cells were counted in medium power fields (x200) in each sample using light microscopy. RESULTS: The number of BrdU-labeled cells in the RGP lens group initially increased, but the number decreased in the corneal center and superior limbus by 32 and 8%, respectively, after 14 days. There was no statistically significant change. However, the number of BrdU-labeled cells in the OKL group decreased after 3 days, and the number of BrdU-labeled cells was reduced in the center and superior limbus by 63 and 8%, respectively, after 14 days. The change in proliferation in the corneal center in the OKL-wearing rabbits was statistically significant compared to the control (p < 0.05). CONCLUSIONS: Wearing an OKL had a greater effect on the change of the proliferation pattern in the epithelium than wearing an RGP lens, which suggests that the OKL might be less physiologic than the RGP lens is.

Animals↗
PubMedDate not supplied

The effect of tooth preparation form on the fit of Procera copings.

PURPOSE: This study evaluated the marginal and internal adaptation of Procera copings using different tooth preparations. The variations comprised 4 finish line forms, 3 occlusal forms, 3 occlusocervical undulation forms to the proximal finish line, and 3 proximal auxiliary retention forms. MATERIALS AND METHODS: One hundred twenty preparations were made and copings were fabricated, cemented, embedded in an epoxy resin, sectioned, and measured at 14 sites. RESULTS: The feather-edge finish line had the highest mean external marginal opening (135 +/- 79 microns), compared with the chamfer finish line (64 +/- 38 microns), the 0.8-mm rounded shoulder (51 +/- 34 microns), and the 0.5-mm rounded shoulder (68 +/- 56 microns). All 3 forms of occlusal reduction produced comparable internal adaptation at the axial wall. Specimens with normal occlusal reduction had the best occlusal adaptation at the cusp tip but not to a statistically different degree from the exaggerated form. Variations in the vertical height of interproximal finish lines did not significantly affect marginal opening. However, proximal retentive features less than 2.5 mm wide and more than 0.5 mm deep cannot be accurately reproduced with the present Procera scanner tip. CONCLUSION: Feather-edge finish-line forms, deep retentive grooves, and deep occlusal morphology are not well reproduced using this system, but all other finish-line forms and design variations are accurately and clinically acceptably reproduced using this system.

Analysis of Variance↗