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At least 1,441 records · Page 80Linked to original sources
PubMed1997

Calibration problems encountered while monitoring stump/socket interface pressures with force sensing resistors: techniques adopted to minimise inaccuracies.

Force sensing resistors (FSR) have been used to measure dynamic pressures at the interface between appliance and patient. Inaccuracies using FSRs have been reported. This paper summarises both the calibration problems encountered and the techniques adopted to minimise inaccuracies. It is considered that, by calibrating the transducers attached to the socket, and by adopting a strict test protocol, FSRs may provide a guide to the dynamic pressure distribution applied to the trans-tibial stump during gait.

Amputation Stumps↗
PubMed1997

Weight bearing and velocity in trans-tibial and trans-femoral amputees.

The purpose of this study was to review the clinical utility of static weight bearing (SWB) and maximal self-selected ambulatory velocity as objective quantifiable measures in an outpatient lower limb prosthetic clinic. Seventy-three (n = 73) consecutive trans-tibial (TTA) and trans-femoral amputees (TFA) attending an outpatient prosthetic clinic were studied. Prosthetic weight bearing was measured on a bathroom scale (mass in kg), normalised to body mass then expressed as a percentage and labelled static weight bearing (SWB). Maximum safe self-selected ambulatory velocity over a 10 metre level walkway (m/s) was measured with a stopwatch. The SWB mean for the TTA group was 94.93% range 77-100%) and 88.36% for the TFA group (range 43-100%). The mean ambulatory velocity was 1.70 m/s (range 0.07-5.75) for the TTA group and 0.78 m/s (range 0.10-1.54) for the TFA group. A statistically significant relationship (p < 0.05) was found between SWB and ambulatory velocity in trans-tibial and trans-femoral amputees in this study. A ceiling effect was noted in the trans-tibial group with 42% achieving 100% SWB through their prosthetic limb so it was concluded that ambulatory velocity was the more sensitive measure in established trans-tibial prosthetic limb users. SWB may be the more appropriate quantifiable measure for use in established trans-femoral prosthesis users. Prosthetic training programmes would benefit from the objective measurement of SWB. Once optimal SWB was achieved, ambulatory velocity would be the more sensitive measure of prosthetic use.

Adolescent↗
PubMed1999

Analyses of prosthetic episodes in trans-tibial amputees.

The prosthetic episodes, i.e. actual processes of provision, identifying number of prostheses, their maintenance, repairs and replacements were analysed for 104 trans-tibial amputees aged 16 and over, over a 10 year period. The purpose of this investigation was to identify how frequently a new prosthesis is actually required for this group of amputees and what are their maintenance requirements. Variations of requirement between the amputee groups of aged 16-60 and over 60 years are also addressed. In the 10 years period of the study the amputees needed an average of 5.04 new prostheses, 6.25 refits, 2.28 major repairs and 17.04 day repairs. The younger amputees, i.e. below the age of 60 years, required significantly more new prostheses (p=0.003), more refit of sockets (p=0.0012) and more day repairs (p=0.01). Traumatic amputees below the age of 60 years needed significantly more day repairs compared to the non-traumatic amputees in the older age group (p=0.003).

Adolescent↗
PubMed1999

Interface pressures and shear stresses: sagittal plane angular alignment effects in three trans-tibial amputee case studies.

Interface pressures and shear stresses at different sagittal plane angular alignment settings were measured on 3 trans-tibial amputee subjects ambulating with patellar-tendon-bearing total contact prostheses. Substantial socket-shank angular alignment modifications in the sagittal plane had minimal effect on stance phase peak interface pressures, though more substantial effects on stance phase peak resultant shear stresses. No consistent trend of a greater stress at misaligned vs nominally aligned settings was identified. Changes in interface stresses from session to session tended to be greater than those for different alignment settings, suggesting that subjects compensated well for misalignments but less well for session differences.

Adult↗
PubMed2003

Preserving the abductor mechanism in robotic THR: the influence of stem design and cutterpath.

OBJECTIVE: The tip of the greater trochanter is the attachment site for the abductor muscles of the hip joint. Its preservation in robotic and conventional THR is important for normal gait. The effect of different stem designs and robotic cutterpaths on the preservation of the trochanter tip is examined. MATERIALS AND METHODS: One anatomical stem, one straight stem, and one stem specifically designed for robotic THR were implanted virtually in CT scans of osteoarthrotic hip joints using the Torch preoperative planning unit (URS-ortho). In transverse sections of the trochanter tip, dimensions of the trochanter area removed by the milling tool were recorded for each stem design and different cutterpaths (3-axis versus 5-axis milling). RESULTS: Five-axis milling showed significantly better results than 3-axis milling. For straight stems, more bone was removed than for anatomic stems. The most favorable results were achieved with 5-axis milling and a curved stem specifically designed for robotic THR. CONCLUSIONS: The introduction of 5-axis milling in robotic THR is an improvement of the technique and makes preservation of the abductor mechanism at the tip of the greater trochanter easier for the surgeon.

Arthroplasty, Replacement, Hip↗
PubMed2002

Comparison of an 'intuitive' NHS hearing aid prescription method with DSL 4.1 targets for amplification.

This study aimed to evaluate current practice in a National Health Service Trust in setting hearing aid output to meet amplification targets prescribed by desired sensation level (DSL) using a range of NHS hearing aids. A consecutive sample of 33 patients was drawn from the hearing aid waiting list of the Royal Devon & Exeter Hospital (RD&E). The age range was 33-83 years. Patients not giving written consent and those with complex hearing losses were excluded. At review, pure-tone audiogram, uncomfortable loudness levels, real-ear coupler difference, user gain and maximum output were recorded. Data were entered into DSL 4.1 prescription software. Wilcoxon tests were used to compare the measured user gain and maximum output with DSL 4.1-generated targets. The results demonstrate significant differences (p<0.05) at 0.25, 0.5, 0.75, 1.5, 2, 3, 4 and 6 kHz between target and measured values for user gain. This study reveals that the routine intuitive method for prescribing hearing aids at the RD&E is not effective in meeting targets for amplified speech as prescribed by DSL.

Adult↗
PubMed2003

Benefits from hearing aids in relation to the interaction between the user and the environment.

It is becoming increasingly recognized that, in addition to the influence of audiometric variables and associated psychoacoustic abilities, the benefits from and candidature for various signal-processing schemes in hearing aids are strongly influenced by listeners' characteristics (such as motivations, expectations, and personality), and also the auditory environments in which those listeners are required to function (i.e. their auditory ecology). We will report elsewhere an experiment on a group of 50 listeners in a within-subject, randomized, blind, crossover design of five different hearing aid rationales, of which two contained linear amplification and three contained non-linear amplification which differed only in release-time constant. This article reports the interaction between the audiometric and cognitive characteristics of listeners, and the test conditions under which speech identification procedures are conducted (presentation level, signal-to-noise ratio, and temporal characteristics of interfering noise). The analyses show significant interactions between hearing impairment and cognitive ability, and the extent to which, when tested unaided, listeners can derive advantage from temporal structure in a background noise. The analysis then addresses the benefits of amplification (defined as the difference between performance in the amplified and unaided conditions) and shows significant interactions between cognitive ability, the temporal characteristics of interfering noise, and the time constants of non-linear amplification rationales. The direction of the interaction is that listeners with greater cognitive ability derive greater benefit from temporal structure in background noise when listening via fast time constants, one of whose effects is to facilitate 'listening in the gaps'.

Amplifiers, Electronic↗
PubMedDate not supplied

Rehabilitation and orthotic management of congenital and acquired meromelia in the lower limbs of children.

Children with limb deficiencies or amputations of the lower extremities should be enabled to stand or walk according to their state of development, because standing and walking are among the most important preconditions for the best possible integration. Supplying them with a prosthesis, orthosis and orthoprosthesis is therefore indispensable for rehabilitation. While a prosthesis replaces parts of the extremities, an orthosis stabilizes the existing extremity. Orthoprostheses compensate longitudinal malformations, have a supporting effect, allow growth to be controlled and compensate for shortening. Just as important as the remedy is early medical treatment. The medical team taking care of the patient works out a treatment plan where responsible cooperation with the parents is of utmost importance. The focus of all efforts is, of course, the handicapped child. Examples are used to demonstrate the course of successful rehabilitation of children and adolescents with damaged limbs. Equally the psychological situation of the parents and child is taken into consideration.

Activities of Daily Living↗
PubMed2005

A multicenter prospective cohort study of the Strata valve for the management of hydrocephalus in pediatric patients.

OBJECT: Previous reports suggest that adjustable valves may improve the survival of cerebrospinal fluid shunts or relieve shunt-related symptoms. To evaluate these claims, the authors conducted a prospective multicenter cohort study of children who underwent placement of Strata valves. METHODS: Patients undergoing initial shunt placement (Group 1) or shunt revision (Group 2) were treated using Strata valve shunt systems. Valves were adjustable to five performance level settings by using an externally applied magnet. The performance levels were checked using an externally applied hand tool and radiography. Patients were followed for 1 year or until they underwent shunt revision surgery. Between March 2000 and February 2002, 315 patients were enrolled in the study. In Group 1 (201 patients) the common causes of hydrocephalus were myelomeningocele (16%), aqueductal stenosis (14%), and hemorrhage (14%). The overall 1-year shunt survival was 67%. Causes of shunt failure were obstruction (17%), overdrainage (1.5%), loculated ventricles (2%), and infection (10.6%). Patients in Group 2 (114 patients) were older and the causes of hydrocephalus were similar. Among patients in Group 2 the 1-year shunt survival was 71%. There were 256 valve adjustments. Symptoms completely resolved (26%) or improved (37%) after 63% of adjustments. When symptoms improved or resolved, they did so within 24 hours in 89% of adjustments. Hand-tool and radiographic readings of valve settings were the same in 234 (98%) of 238 assessments. CONCLUSIONS: The 1-year shunt survival for the Strata valve shunt system when used in initial shunt insertion procedures or shunt revisions was similar to those demonstrated for other valves. Symptom relief or improvement following adjustment was observed in 63% of patients. Hand-tool assessment of performance level settings reliably predicted radiographic assessments.

Brain Diseases↗
PubMed2006

Intraorbital implantation of a stimulating electrode for an optic nerve visual prosthesis. Case report.

Research into visual prosthetics is expected to revolutionize the treatment of blind patients with incurable outer retinal degenerative disease. Substantial evidence shows that useful visual sensations can be produced by controlled electrical stimulation of the optic nerve. To make the optic nerve visual prosthesis more acceptable, implantation techniques safer and less invasive than those previously used have been developed. A medial transconjunctival approach is now used to implant a stimulating electrode around the intraorbital section of the optic nerve. This new technique allows sufficient exposure of the nerve after detaching only one rectus muscle and performing a lateral canthotomy. Previously, an electrode was implanted in the intracranial part of the optic nerve, which required more invasive surgery. The new technique was first developed in cadavers and in patients undergoing eye enucleations. Finally, a 68-year-old blind man suffering from retinitis pigmentosa underwent long-term implantation. In this case report the authors describe the technique and outline some of the challenges involved.

Aged↗
PubMedDate not supplied

A digital processing strategy to optimize hearing aid outputs directly.

A new amplification strategy (ADRO), based on 64 independently operating channels, was compared with a nine-channel wide dynamic range compression strategy (WDRC). Open-platform in-the-ear hearing instruments were configured either with ADRO or the manufacturer's WDRC strategy. Twenty-two subjects with mild to moderate hearing loss took home the ADRO or WDRC hearing aids. After three weeks' acclimatization, the aids were evaluated using monosyllables in quiet at 50 to 65 dB SPL and sentences in eight-talker babble. The acclimatization and evaluation were repeated in the second phase of the balanced reverse-block blind experimental design. The ADRO program showed a statistically significant mean advantage of 7.85% word score (95% confidence interval 3.19% to 12.51%; p = 0.002) and 6.41% phoneme score for the monosyllables in quiet (95% confidence interval 2.03% to 10.79%; p = 0.006). A statistically significant advantage of 7.25% was also found for the ADRO program in background noise (95% confidence interval 1.95% to 12.55%; p = 0.010). The results are consistent with earlier data for listeners with moderate to severe hearing loss.

Acoustic Stimulation↗
PubMed2004

Gain and maximum output of two electromagnetic middle ear implants: are real ear measurements helpful?

We compared the output of two electronic middle ear implants: the Otologics MET device and the Vibrant Soundbridge device. Both devices were programmed in the linear amplification mode. Aided minus unaided sound pressure levels recorded in the ear canal (objective gain) were compared to unaided minus aided soundfield thresholds (functional gain) in 13 patients with severe sensorineural hearing loss. In addition, input/output characteristics were studied with the help of ear canal measurements. Objective gain was consistently lower than functional gain, with wide variation between patients and frequencies. Using input/output data measured in the ear canal in combination with functional gain data, the mean maximum output of the two devices was estimated, expressed in dB SPL. In comparison to NAL-R target values, (functional) gain was adequate; however, the maximum output was low, especially for the Vibrant Soundbridge device.

Adult↗
PubMed2004

Effect of frequency boundary assignment on vowel recognition with the Nucleus 24 ACE speech coding strategy.

Two speech processor programs (MAPs) differing only in electrode frequency boundary assignments were created for each of eight Nucleus 24 Cochlear Implant recipients. The default MAPs used typical frequency boundaries, and the experimental MAPs reassigned one additional electrode to vowel formant regions. Four objective speech tests and a questionnaire were used to evaluate speech recognition with the two MAPs. Results for the closed-set vowel test and the formant discrimination test showed small but significant improvement in scores with the experimental MAP. Differences for the Consonant-Vowel Nucleus-Consonant word test and closed-set consonant test were nonsignificant. Feature analysis revealed no significant differences in information transmission. Seven of the eight subjects preferred the experimental MAP, reporting louder, crisper, and clearer sound. The results suggest that Nucleus 24 recipients should be given an opportunity to compare a MAP that assigns more electrodes in vowel formant regions with the default MAP to determine which provides the most benefit in everyday life.

Adult↗
PubMed2004

Analysis of prefitting versus postfitting hearing aid orientation using the Glasgow Hearing Aid Benefit Profile (GHABP).

Results of this study demonstrate the advantages of both pre- and postfitting hearing aid orientation (HAO) sessions. This study demonstrated that HAO counseling is helpful in expediting hearing aid benefit and satisfaction through the education of our clients and that this benefit and satisfaction is age dependent as measured by the Glasgow Hearing Aid Benefit Profile (GHABP) (Gatehouse, 1997). Patients with greater initial disability, as identified by item 1 of the GHABP, receive significant benefit from prefitting and/or postfitting counseling as compared to patients receiving no counseling. Implications of these findings are discussed.

Aged↗
PubMed2005

Occlusion effect of earmolds with different venting systems.

In this study the occlusion effect was quantified for five types of earmolds with different venting. Nine normal-hearing listeners and ten experienced hearing aid users were provided with conventional earmolds with 1.6 and 2.4 mm circular venting, shell type earmolds with a novel vent design with equivalent cross-sectional vent areas, and nonoccluding soft silicone eartips of a commercial hearing instrument. For all venting systems, the occlusion effect was measured using a probe microphone system and subjectively rated in test and retest sessions. The results for both normal-hearing subjects and hearing aid users showed that the novel vents caused significantly less occlusion than the traditional vents. Occlusion effect associated with the soft silicone eartip was comparable to the nonoccluded ear. Test-retest reproducibility was higher for the subjective occlusion rating than for the objectively measured occlusion. Perceived occlusion revealed a closer relationship to measured occlusion in the ear in which the measured occlusion effect was higher ("high OE" ear) than in the "low OE" ear. As our results suggest that subjective judgment of occlusion is directly related to the acoustic mass of the air column in the vent, the amount of perceived occlusion may be predicted by the vent dimensions.

Case-Control Studies↗
PubMed2005

Performance of a fully adaptive directional microphone to signals presented from various azimuths.

The signal-to-noise ratio advantage of a directional microphone is achieved by reducing the sensitivity of the microphone to sounds from the sides and back. A fully adaptive directional microphone (one that automatically switches between an omnidirectional mode and various directional polar patterns) may allow the achievement of signal-to-noise (SNR) improvement with minimal loss on audibility to sounds that originate from the sides and back. To demonstrate such possibilities, this study compared the soundfield aided thresholds, speech in quiet at different input levels, and speech in noise performance of 17 hearing-impaired participants under three microphone modes (omnidirectional, fixed hypercardioid, and fully [or automatic] adaptive) as the stimuli were presented from 0 degrees to 180 degrees in 45 degrees intervals. The results showed a significant azimuth effect only with the fixed directional microphone. In quiet, the fully adaptive microphone performed similarly as the omnidirectional microphone at all frequencies, input levels, and azimuths. In noise, the fully adaptive microphone achieved similar SNR improvement as the fixed directional microphone. Clinical implications of the results of this study were discussed.

Acoustic Stimulation↗
PubMed2006

Evaluation of a probe-tube insertion technique for measuring the real-ear-to-coupler difference (RECD) in young infants.

A common strategy for measuring the real-ear response of the real-ear-to-coupler difference (RECD) in the pediatric population is to insert a probe-tube separately from the eartip. This strategy is at times difficult to implement while attempting to obtain the measurement from a young infant. An RECD probe-tube insertion technique that involves connecting the probe-tube to an eartip with plastic film for simultaneous insertion was examined on 30 infants. Repeated measurements were completed on each infant to obtain within-session test-retest reliability data. Probe-tube insertion depth was also examined across participants to provide a guideline for the infant population. Findings indicate that reliable RECD values can be obtained in infants when the probe-tube is extended approximately two to four millimeters (mm) beyond the eartip or 11 mm from the entrance to the ear canal. Clinical implications of this work are discussed.

Equipment Design↗