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Developments in the trans-tibial prosthetic socket fitting process: a review of past and present research.

A revolution in trans-tibial prosthetic design began at the end of World War II with the development of new materials and a dramatic improvement in the understanding of biomechanics. Early research was based mainly on the improvement of existing prosthetic design practice. Today, research has been focused on providing a better understanding of stump/socket interface biomechanics and improving socket fit by attempting to quantify the normal/direct stresses at the interface. The purpose of this review paper is to question whether research and prosthetic education/training to date has significantly improved our understanding of what makes a good socket. Although there is no doubt that advances in socket fitting techniques have been made what is not clear is the actual extent to which these advances have improved the quality of sockets fitted. It is suggested that a new approach is needed which can overcome some of the inherent problems of designing and manufacturing a comfortable high quality socket. It is also suggested that current research and education/training in the fields of pressure/interfacial interaction measurement and Finite Element Analysis techniques have limited potential to address many of these problems. There is also little evidence that current computer aided design systems offer any significant advantages over more conventional techniques.

Amputation, Surgical↗

Marginal fit of restorations before and after cementation in vivo.

Triturated luting cements provide convenient clinical handling. This study clinically evaluated the influence of two trituration capsule cement systems on the marginal fit of inner copings for telescoping crowns. Using a randomized parallel design, one coping was cemented using zinc phosphate cement (Phosphacap) and one using a glass-ionomer cement (Ketac-Cem Maxicap) for each of 12 patients. A blind examination of the marginal fit of the restorations was made before and after cementation using the replica technique and a scanning electron microscope. The mean marginal discrepancies for all cast copings were approximately 30 microns (median 23 microns) before cementation. They increased significantly after cementation to 86 microns (median 63 microns) in the zinc phosphate cement copings but to only to 47 microns (median 44 microns) in the glass-ionomer cement copings.

Crowns↗

Contact lens fitting following unsuccessful refractive surgery.

A retrospective review of case notes of consecutive patients referred to a contact lens clinic after unsuccessful refractive surgery was carried out to determine the success of contact lens fitting. The main outcome variables in determining success were visual improvement, contact lens tolerance, fitting characteristics and wearing time. Thirteen eyes were fitted with conventional rigid gas permeable (CRGP), 10 with soft and 19 with reverse geometry rigid gas permeable contact lenses (RVG). The mean spectacle visual acuity (VA) was 6/9 (20/30) [range: 6/24 (20/80) to 6/5 (20/15)] and the mean VA after contact lens fitting was 6/6 (20/20) [range: 6/18 (20/60) to 6/5 (20/15)]. Of the 42 eyes, the contact lens VA was better than spectacle acuity in 25 (59.5%) eyes, equal in 14 (33.3%) and worse in three (7.1%). A total of 33 (78.6%) eyes were still wearing their lenses at the last visit. Contact lenses can be a valuable method of managing poor VA after refractive surgery.

Contact Lenses↗

Sound quality judgements of new hearing instrument users over a 24-week post-fitting period.

The time course of changes in perceived sound quality after hearing instrument fitting has not been studied systematically It is possible, for example, that patients may object to additional high frequency gain when fitted, but not after a period of auditory acclimatisation. The aim of this study was to utilise sound quality judgements to compare two frequency responses in new users at 4-week intervals over a 24-week post-fitting period. The null hypothesis was that there would be no change in sound quality judgements over time. A total of 16 elderly subjects were fitted monaurally with the same model of linear, programmable hearing instrument. This was set to a standard response that provided 26-29 dB of real-ear insertion gain at 2000 4000 Hz. This program was worn by the subjects for the duration of the study. All subjects reported greater than four hours of daily use. The alternative response which was used in a paired comparison paradigm, provided a mean gain reduction of 3, 8, 13, and 16 dB at 2000, 3000, 4000 and 6000 Hz, respectively. Subjects compared the standard and the alternative responses for sound quality along dimensions of comfort, clarity, and overall preference while listening to running speech presented in quiet, steady noise, and speech babble. At the time of fitting there was a small preference for the standard response when judging clarity, but the alternative response was preferred for comfort and preferred overall. Repeated-measures analysis of variance (ANOVA) for each quality dimension did not reveal any statistically significant change over time. It is concluded that this pattern of preference is unaffected by acclimatisation to amplification, at least over the initial 24 weeks of instrument use.

Acoustics↗

Using electrically evoked auditory reflex thresholds to fit the CLARION cochlear implant.

This paper describes a method for measuring electrically elicited auditory reflex thresholds (EARTs) in young children who use the CLARION Multi-Strategy Cochlear Implant. The EART is an objective measure that can guide the fitting of a cochlear implant in individuals who are unable to perform behavioral tasks required to program the device. Reflexes were obtained in 11 of 17 pediatric Clarion users. The EART current level indicated a point at which an auditory percept was present and the sound was loud, but not uncomfortable. The EART then was used as a basis for conditioning behavioral responses, and as a guideline for setting most comfortable loudness levels.

Cochlear Implantation↗

Self-reported need of information, counselling and education: needs and interests of re-applicants.

An interview study was performed to establish and evaluate the need for education and counselling of hearing aid users (HA users) in order to review present procedures of information and potential referral to the educational sector. The study comprises 102 consecutively selected hearing-impaired adults (>18 years), the only inclusion criterion being experienced HA user. The interview took place immediately after the patient's latest HA fitting appointment and consisted of 24 structured and closed questions. The findings indicate that a significant proportion of HA users, especially the elderly, do not experience a need for or show an interest in further education and counselling concerning their hearing handicap. It is concluded that the present organization of services meets the demands of a majority of re-applicants.

Adult↗

Contact lenses for children.

Contact lenses for children are used to correct a variety of conditions. This paper reviews fitting of soft, silicone elastimer, and rigid gas-permeable contact lenses for therapeutic treatment of aphakia, anisometropia, myopia, hyperopia, esotropia, irregular astigmatism, and nystagmus. Cosmetic custom designs are described for the treatment of aniridia, albinism, amblyopia, and corneal disfigurement. Working with children and gaining their trust requires inventiveness and patience. Prescribing contact lenses for them requires developing good cooperation between the child, the parents, and the practitioner. The rewards of contact lenses wear for the appropriate pediatric patients include improving not only their vision but also their quality of life.

Child↗

Rehabilitation considerations of prosthetic fittings for Kaposi's sarcoma amputees.

PURPOSE: We report on cutaneous limb manifestations of Kaposi's sarcoma and the secondary infection of these lesions that necessitated five lower-limb amputations. METHOD: The cases are briefly described and prosthetic adaptations in respect to pressure, traction and sweating on the skin are considered. RESULTS: All four patients ambulated initially; one lady died, the double amputee stopped walking owing to the excessive physical demand, and two patients ambulate freely. CONCLUSION: Special considerations to the cutaneous/prosthesis interface are necessary in order to provide these patients with optimal ambulatory ability.

Aged↗

[Treatment of coxarthrosis with fitted total hip prostheses replacement].

The treatment of hip osteoarthritis with total hip arthroplasty has continuously evolved since it was first introduced in the sixties. The problem of aseptic loosening of the cemented prostheses, mainly in young active patients, has stimulated two different types of research: on one side the improvement of cementing techniques and on the other side the development of cementless osteoinegrable implants. We discuss the problems of these cementless hip prostheses. Recently published anatomic and biomechanic studies have led to the development of personalized custom femoral stems for each patient. The conception technique and first clinical results are described.

Adult↗

A practical approach to and long-term results of fitting silicone contact lenses in aphakic children after congenital cataract.

PURPOSE: This prospective study investigated characteristics of fit and performance of silicone contact lenses under conditions of permanent wear in cases of aphakia after congenital cataract. METHODS: Seventeen aphakic children (8 eyes unilateral, 18 eyes bilateral) were fitted with silicone contact lenses on an empirical basis without the use of keratometry. The lenses were worn on a permanent basis, with a routine replacement every 3 months. The follow up was 6 years, with evaluation lens parameters, fitting characteristics, lens condition, replacement rate, wearing time, complications, and visual acuity. RESULTS: The back optical zone radius (BOZR) remained stable at 7.50 mm, up to the age of 1.5 years old. At the age of 4 years, almost all eyes needed a BOZR of 7.90 mm. Mean +/- SD contact lens power was +25.47 diopter (D) +/- 4.0 (range +32.00 D - +20.00 D) at 3 months of age, and +17.94 D +/- 3.8 (range +29.00 D - +15.00 D) at 3 years of age. This represents an average decrease of 0.23 D per month. The power decrease in unilateral cases was significantly lower (P < 0.01) than in bilateral aphakia. Snellen visual acuity at 4 years of age was 0.1 to 0.3 (20/200-20/60) in 15 eyes, 0.3 to 0.5 (20/60-20/40) in 10 eyes and greater than 0.5 (>20/40) in 1 eye. Lens usage over a total period of 90 wearing years was 5.6 lenses/eye/year, including the regular exchange every 3 months. No serious complications occurred. A positive correlation (r = 0.89) was found between age and deposit buildup. With the need for permanent wear reduced, therefore, 73% of the eyes were refitted with high-water content soft lenses or high gas-permeable (HGP) lenses, when the patients ranged in age from 4 to 6 years old. CONCLUSIONS: The procedure for fitting silicone lenses in aphakic children is feasible in an easy and logical way without keratometry. Permanent wear with a low complication rate is possible up to the age of 3. with a lens usage (including a 3-month regular exchange) of 5.6 lenses/eye/year. From the age of 3, deposit formation is the determining factor for refitting with high-water content soft or HGP lenses.

Aphakia, Postcataract↗

Acetabular strains produced by oversized press fit cups.

The purpose of this study was to determine the amount of acetabular deformation that occurs when acetabular components of different sizes are press fit. The change in acetabular volume was calculated for 1- to 3-mm oversized cup diameters with acetabuli ranging from 40 to 80 mm. An axisymmetric finite element model was used to determine the maximum acetabular strain that occurs when oversized cups are inserted in different acetabuli. The highest acetabular strains occur at the cup periphery, indicating that the resultant compressive force between the lateral pelvis and cup enhances press fit stability. In addition, higher maximum strains occur when the same millimeter amount of oversizing is used in a small compared with a large acetabulum. When a constant millimeter increment in cup oversizing is used, there may be a greater risk of pelvic fracture in a small acetabulum and a greater risk of inadequate press fit stability in a large acetabulum. To achieve the same amount of acetabular deformation and magnitude of strain, more oversizing is needed in a large acetabulum and less oversizing is needed in a small acetabulum. These results suggest that 1 mm of oversizing should be used for cups that are less than 52 mm in diameter, 2 mm of oversizing should be used for cups from 52 to 76 mm in diameter, and 3 mm of oversizing should be used for cups that are more than 76 mm in diameter.

Acetabulum↗

[Periprosthetic mineral density in cement-free hip replacement arthroplasty].

SUBJECT: We analysed the periprosthetic bone mineral density (BMD) in a prospective longitudinal study over two years after operation and in a separate cross-sectional study more than five years after implantation of cementless total hip arthroplasty (CLS-stem, Mecron threaded acetabular cup) by using dual-energy X-ray absorptiometry (DEXA). MATERIALS AND METHODS: In n = 53 patients (29 women, 24 men) we analysed the periprosthetic BMD prospectively in certain periods. All patients had an uncomplicated postoperative course and good clinical outcome (Merle d'Aubigne score > 12). In the cross-sectional study we analysed 23 patients (13 women, 10 men). Regions of Interest (ROI) were defined according to Gruen et al. for the periprosthetic femur and to De Lee and Charnley for the periprosthetic acetabulum. RESULTS: BMD significantly decreases in the periprosthetic femur as well as in the periprosthetic acetabulum during the first three months. In men BMD reaches its lowest values between six months (femur) and one year (acetabulum) after operation and then increases to 96.2% at the femur and 93.8% at the acetabulum. In women BMD decreases during the entire follow-up to 89.4% at the periprosthetic femur and 80.0% at the periprosthetic acetabulum. In the proximal zones 1 and 7 of the femur and the cranial-medial zone II of the acetabulum we observed the highest decrease of mineralisation. More than five years after implantation of the prosthesis BMD in the femur showed only little changes. On the other side BMD around the threaded acetabular cup significantly decreased to 67.4% in women and 79.1% in men. CONCLUSION: The results reflect the different stress on the periprosthetic bone after implantation of the prosthesis and fit to earlier reported good clinical results of the CLS-stem and to increased loosening rate of threaded acetabular cups after five years. Analysing changes of mineralisation in cementless total hip arthroplasty DEXA together with the analization scheme according to Gruen at the femur and to De Lee and Charnley at the acetabulum is a useful method and has been reliable in clinical practise.

Absorptiometry, Photon↗

Evaluation of feedback-reduction algorithms for hearing aids.

Three adaptive feedback-reduction algorithms were implemented in a laboratory-based digital hearing aid system and evaluated with dynamic feedback paths and hearing-impaired subjects. The evaluation included measurements of maximum stable gain and subjective quality ratings. The continuously adapting CNN algorithm (Closed-loop processing with No probe Noise) provided the best performance: 8.5 dB of added stable gain (ASG) relative to a reference algorithm averaged over all subjects, ears, and vent conditions. Two intermittently adapting algorithms, ONO (Open-loop with Noise when Oscillation detected) and ONQ (Open-loop with Noise when Quiet detected), provided an average of 5 dB of ASG. Subjects with more severe hearing losses received greater benefits: 13 dB average ASG for the CNN algorithm and 7-8 dB average ASG for the ONO and ONQ algorithms. These values are conservative estimates of ASG because the fitting procedure produced a frequency-gain characteristic that already included precautions against feedback. Speech quality ratings showed no substantial algorithm effect on pleasantness or intelligibility, although subjects informally expressed strong objections to the probe noise used by the ONO and ONQ algorithms. This objection was not reflected in the speech quality ratings because of limitations of the experimental procedure. The results clearly indicate that the CNN algorithm is the most promising choice for adaptive feedback reduction in hearing aids.

Aged↗

Report of the Eriksholm Workshop on auditory deprivation and acclimatization.

The terminology used in studies documenting changes in auditory performance following fitting of hearing aids has been diverse. Definitions for the auditory deprivation effect and auditory acclimatization are offered as a first step in rationalization. Two statements summarize current knowledge concerning auditory deprivation effects and auditory acclimatization, as well as considering the potential implications for research, field trial and clinical practice applications. Potential areas for future research are identified.

Auditory Perception↗

Adaptive dynamic range optimization (ADRO): a digital amplification strategy for hearing aids and cochlear implants.

Adaptive dynamic range optimization (ADRO) is an amplification strategy that uses digital signal processing techniques to improve the audibility, comfort, and intelligibility of sounds for people who use cochlear implants and/or hearing aids. The strategy uses statistical analysis to select the most information-rich section of the input dynamic range in multiple-frequency channels. Fuzzy logic rules control the gain in each frequency channel so that the selected section of the dynamic range is presented at an audible and comfortable level. The ADRO processing thus adaptively optimizes the dynamic range of the signal in multiple-frequency channels. Clinical studies show that ADRO can be fitted easily to all degrees of hearing loss for hearing aids and cochlear implants in a direct and intuitive manner, taking the preferences of the listener into account. The result is high acceptance by new and experienced hearing aid users and strong preferences for ADRO compared with alternative amplification strategies. The ADRO processing is particularly well suited to bimodal and hybrid stimulation which combine electric and acoustic stimulation in opposite ears or in the same ear, respectively.

Algorithms↗

Factors that allow a high level of speech understanding by patients fit with cochlear implants.

Three factors account for the high level of speech understanding in quiet enjoyed by many patients fit with cochlear implants. First, some information about speech exists in the time/amplitude envelope of speech. This information is sufficient to narrow the number of word candidates for a given signal. Second, if information from the envelope of speech is available to listeners, then only minimal information from the frequency domain is necessary for high levels of speech recognition in quiet. Third, perceiving strategies for speech are inherently flexible in terms of the mapping between signal frequencies (i.e., the locations of the formants) and phonetic identity.

Cochlear Implantation↗

Problems and solutions for fitting amplification to patients with Ménière's disease.

Fitting amplification to a patient with Ménière's disease (MD) can present several challenges to the dispensing audiologist. These challenges include the presence of fluctuating hearing loss, a rising audiometric configuration, unilateral or asymmetrical hearing loss, reduced dynamic range, and reduced word-recognition scores. The presence of any one of these characteristics could create obstacles for a successful hearing aid fit. The presence of most if not all of these characteristics in a single patient can readily challenge the skills of even the most experienced dispensing audiologist. In addition to the audiometric challenges, this patient population has the added psychological problems associated with feeling ill due to the nausea secondary to vertiginous attacks and the anxiety associated with the unpredictable nature of the course of these attacks. This paper summarizes numerous strategies and technologies that could be implemented by the audiologist to address these unique challenges and provide a greater opportunity for a successful hearing aid fit. These suggestions include (1) advantages offered by digital signal processing; (2) using directional microphones and assistive listening devices to improve speech recognition in noise; (3) using wireless hearing aids as well as the bone anchored hearing aid; (4) counseling patients on the realistic expectations from amplification in noisy listening situations and for those with poor speech recognition; (5) using multiple programs for patients with fluctuating hearing loss; and (6) offering suggestions on programming the frequency-gain/output response for a rising configuration.

Equipment Design↗

[40% of hearing aids are not worn. Making sure the device doesn't wind up in the drawer!].

Early diagnosis of a hearing impairment, follow-up and timely effective intervention are the aims of optimal management of the hard-of-hearing patient. Today, every fifth adult has a hearing problem. This means that the general practitioner not only faces a diagnostic challenge, but also needs to concern himself with the prevention of a hearing loss or its further progression. In the event of a hearing aid being required, the individual needs of the patient must be taken into account. Currently available are behind-the-ear and in-the-ear, both as digital and analog devices. The most expensive, smallest and most modern device is not necessarily the best option for the individual patient, and fitting should be a cooperative effort on the part of the ENT physician and the hearing aid specialist. Required is a specific history, comprehensive counseling of the patient, a phase of testing at home and, where necessary, concomitant acoustic training. The German Society for the Hard-of-Hearing has advice centres in many towns and cities that provide information and counseling on rehabilitation and the legal rights of the deaf.

Adult↗