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PubMed2001

The ex vivo wettability of soft contact lenses.

PURPOSE: To investigate the ex vivo wettability of Etafilcon A contact lenses over an eight hour period of wear and observe the influence of surfactant pre-treatment. METHODS: Etafilcon A hydrogel lenses, comprising poly[2-hydroxyethyl methacrylate-co-methacrylic acid] and 58% water, were soaked for 12 hours in either 0.9% saline (control) or a 1% aqueous solution of poloxamine 1107 (treated). The advancing and receding contact angles were subsequently determined ex vivo after various periods of wear in six adapted contact lens wearers using a single-blind, randomised protocol. Contact angles were measured with a dynamic contact angle tensiometer, using the Wilhelmy plate technique. Patient comfort scores were recorded and the static surface tensions of the probe fluids assessed. RESULTS: Control lenses exhibited no change in wetting angles over time, indicating a lack of surface modification by components within the tear film. Treated lenses exhibited a significantly reduced advancing angle (p < 0.001) and hysteresis angle (p < 0.001) when compared with control lenses. In addition, treated lenses were consistently rated as being more comfortable than control lenses (p = 0.04). CONCLUSIONS: This study has shown clearly that new Etafilcon A lenses do not exhibit significant changes in wettability during the initial four hour wearing period. Pre-treatment of such lenses with a polymeric surfactant results in wetting of the lenses due to the adsorption of surfactant. The surfactant is retained by the lens for at least eight hours of wear, resulting in significant improvements in subjective comfort, especially over the first 30 minutes of wear.

Adolescent↗
PubMed2003

Bone-anchored hearing aids in unilateral inner ear deafness.

In nine patients with unilateral deafness and normal hearing in the contralateral ear, measurements of sound localization and speech perception were obtained before intervention, with a conventional contralateral routing of sound (CROS) hearing aid and later with a bone-anchored hearing aid (BAHA) implanted in the deaf ear. Sound localization did not show any differences between the three conditions. Speech perception using short, everyday sentences showed a reduction in the head-shadow effect of 2 dB for both the conventional CROS hearing aid and the BAHA in comparison to the unaided condition. Patients' real-life experiences of the three conditions were evaluated using the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. The results showed a significant benefit with the BAHA in situations involving background noise and reverberation and a reduced aversion to loud sounds in comparison to the unaided and conventional CROS conditions.

Audiometry, Speech↗
PubMed2001

Bone cement with reduced proportion of monomer in total hip arthroplasty: preclinical evaluation and randomized study of 47 cases with 5 years' follow-up.

Bone cement with reduced amount of monomer and low curing temperature may improve implant fixation due to reduced toxicity. We analyzed the mechanical, chemical and thermal properties of such a cement (Cemex Rx) using Palacos R as control. The in vivo performance of the 2 cements was also evaluated in a prospective randomized study of 47 hips, where either of the cement types was used to fixate Lubinus SP2 prostheses with the stem made of titanium alloy. Cemex Rx had a reduced tensile strength, probably because this cement was manually mixed, as recommended by the manufacturer. A standardized labor tory test showed lower curing temperature for Cemex, but measurements at 37 degrees and with prechilled Palacos R and Cemex Rx, as in clinical work, showed no difference. In the clinical study radiostereometric measurements of cup and stem migration showed similar values in the 2 groups up to 5 years after the operation. The cement mantle was stable in both groups, but the stems migrated similarly inside the cement mantle regardless of the type of cement used. Proximal wear was low (0.04-0.05 mm/year) and tended to be lower in the Cemex group (p = 0.02). Aluminum and vanadium levels in serum increased 5 years after the operation, but no difference was noted between the 2 groups. Collagen markers (PICP, ICTP) showed similar increases in bone turnover 6 weeks and 6 months after operation in both groups.

Aged↗
PubMed2002

No functional impairment after Robodoc total hip arthroplasty: gait analysis in 25 patients.

The Robodoc total hip replacement procedure requires a wider exposure of the proximal femur, especially of the greater trochanter, than the standard procedure. Moreover, the leg must be placed in a rigid leg-holder apparatus to obtain fixation in maximal hip adduction and external rotation. This may impair the hip abductors and reduce hip abduction in the mid- and terminal stance phase of the cycle. In this study we compared patients after Robodoc and conventional total hip arthroplasty with three-dimensional gait analysis (VICON System, Oxford Metrics, Oxford, U.K.) to assess the kinematics of the pelvis and hip. 25 patients underwent total hip replacement by means of the Robodoc total hip arthroplasty system, 25 patients were treated with conventional total hip replacement, and 40 healthy volunteers served as controls. None of the patients undergoing total hip replacement, robotic or conventional, obtained normal kinematic gait patterns 6 months after surgery. However, the reduction in hip abduction did not differ significantly in patients undergoing robotic or conventional total hip arthroplasty, which suggests that the robotic procedure did not impair hip abductor function more than the conventional method.

Aged↗
PubMed2002

Robotically-milled bone cavities: a comparison with hand-broaching in different types of cementless hip stems.

We performed an experimental study to compare the effectiveness of robotic bone milling (Robodoc and CASPAR) with hand-broaching as regards primary rotational stability of 7 different cementless stems. Using 48 synthetic femora and a specially-designed apparatus, we compared the implant stability of proximal and distal rotational stem displacement (slip) in relation to the cortex. We also measured stem deformation (twist) and the location of torque transfer from stem to cortex (i.e., fixation pattern). 5-ROM, Antega, and ABG stems were more stable in hand-broached femora. Osteolock stems showed no difference between CASPAR and hand preparation, but rotational stability was better in the Robodoc group. G2, VerSys ET and Vision 2000 stems gave increased rotational stability in the robotic groups. When placed too laterally, Vision 2000 showed a pattern of more distal fixation. The findings emphasize the current difficulties in creating a perfect match of robotically-milled cavity and stem geometry to achieve enhanced primary rotational stability. The pattern of fixation seems to depend not only on stem design, but also on canal preparation and stem positioning.

Arthroplasty, Replacement, Hip↗
PubMed2005

Comparison of analog and digital preoperative planning in total hip and knee arthroplasties. A prospective study of 173 hips and 65 total knees.

INTRODUCTION: Digital correction of the magnification factor is expected to yield more accurate and reliable preoperative plans. We hypothesized that digital templating would be more accurate than manual templating for total hip and knee arthroplasties. PATIENTS AND METHODS: Firstly, we established the interobserver and intraobserver reliability of the templating procedure. The accuracy and reliability of digital and analog plans were measured in a series of 238 interventions, which were all planned using both techniques. RESULTS: Interobserver reliability was good for the planning of knee arthroplasties (e-values 0.63-0.75), but not more than moderate for the planning of hip arthroplasties (e-values 0.22-0.54). Analog plans of knee arthroplasties systematically underestimated the component sizes (1.1 size on average), while the digital procedure proved to be accurate (0.1-0.4 size too small on average). The following figures show percentage of cases receiving a correct implant, allowing an error of one size. Digital templating of the hip arthroplasty was less frequently correct (cemented cup and stem: 72% and 79%; uncemented cup and stem: 52% and 66%) than analog planning (cemented cup and stem: 73% and 89%; uncemented cup and stem: 64% and 52%). INTERPRETATION: Planning of component sizes for total knee arthroplasties is an accurate procedure when performed digitally. Our digital preoperative plans which were performed by someone other than the surgeon were less accurate than the analog plans prepared by the surgeon.

Arthroplasty, Replacement, Hip↗
PubMed2005

Experimental study of an adjustable-length prosthesis in a temporal bone model.

CONCLUSIONS: This prosthesis has the advantage of rapid adjustment at the time of insertion in order to achieve optimal tension and, as a result, optimal sound transmission. OBJECTIVE: To test the acoustic performance of a new, adjustable incus replacement prosthesis in a human temporal bone model. MATERIAL AND METHODS: Experiments were performed in seven human temporal bones, before and after removal of the incus and insertion of the prosthesis. The input comprised 406 pure tones ranging in frequency between 0.1 and 10 kHz at an intensity of 80 dB SPL at the tympanic membrane. The output measurement was stapes footplate displacement, determined by means of a laser Doppler vibrometer. Three lengths of the prosthesis were investigated: optimal, optimal +0.2 mm and optimal +0.4 mm. RESULTS: The optimal-length prosthesis produced similar results to those of an intact middle ear. The slightly longer prostheses decreased middle ear sound transmission at all test frequencies, except those near 1.5 kHz.

Aged↗
PubMed2005

Difficulties in the fixation of prostheses for voice rehabilitation after laryngectomy.

In most patients with advanced or recurrent laryngeal or hypopharyngeal cancer, total laryngectomy is indicated. This means the loss of three main functions: phonation; respiration; and the prevention of aspiration during deglutition. Laryngectomy patients have various options to restore phonation: an oesophageal voice; an electrolaryngeal voice; or a tracheo-oesophageal voice. In the last case a silicone rubber shunt valve is placed in the tracheo-oesophageal wall and phonation is generated when exhaled air is forced through the oesophagus and neopharynx. This method is widely applied in Western Europe. In this paper we review the literature on fixation problems with shunt valves, tracheostoma valves and heat and moisture exchange (HME) filters. Tracheo-oesophageal speech without a valve is not considered. Despite 22 years of experience with the implantation of tracheo-esophageal shunt valves and many improvements in the design, problems still remain, such as biofilm formation with subsequent leakage through the valve, the need for frequent and inconvenient replacements, fistula enlargement leading to leakage around the device and reduced fixation, and infections. The high cost of shunt valves is a drawback to their use worldwide. To enable hands-free speech, different types of tracheostoma valve have been developed. These valves are fixed to the skin or to the tracheostoma by means of an intra-tracheal device. An HME filter is used to protect the airway and maintain physiological balance. Such devices are only suitable for a selected group of patients as fixation to the skin or trachea can be a major problem. Speaking and coughing cause pressure increases, which often result in mucous leakage and disconnection of the valve and/or HME filter. Recommendations are made for future improvements in fixation techniques.

Humans↗
PubMed2005

Compliance, quality of life and quantitative voice quality aspects of hands-free speech.

CONCLUSIONS: With the use of a new automatic stoma valve (ASV) it appears possible to rehabilitate patients who have previously been unsuccessful in acquiring hands-free speech. As well as making daily ASV use possible for an additional group of patients, this new device was also appreciated by many patients as an additional rehabilitation tool for specific occasions. Despite statistically significant improvements in aspects of voice and breathing using this novel ASV, improvement of peristomal adhesion is probably the main factor needed to further increase success rates. Nevertheless, our results show that it makes sense to keep trying to achieve hands-free speech, even if previous attempts have failed. OBJECTIVE: To make a long-term (6 months) assessment of compliance and aspects of voice, breathing and quality of life using a new ASV: the Provox FreeHands heat and moisture exchanger (HME). MATERIAL AND METHODS: This was a prospective clinical multicentre trial in 79 laryngectomized patients (8 regular ASV users, 58 previously unsuccessful users and 13 new users). Data were collected at baseline and after 1 and 6 months by means of European Organization for Research and Treatment of Cancer Quality of Life questionnaires and specific structured questionnaires concerning compliance, skin adhesion, voicing and pulmonary aspects. An objective assessment of voice parameters (maximum phonation time, maximum phonation time while counting, dynamic loudness range and number of pauses in a standard read-aloud text) was made for comparison of different stoma occlusion methods (digital occlusion via an HME and two different ASVs). A subjective assessment of overall voice quality was made. RESULTS: After 6 months, 19% of patients used the new ASV on a daily basis (mean 5 h/day), while 57% used it on an irregular basis as an additional rehabilitation tool for special occasions. Two-thirds of the study group indicated that they would continue to use the new ASV after the study period. With respect to the objective parameters, statistically significantly better maximum phonation times and dynamic loudness ranges were observed with the new ASV compared to the Blom-Singer ASV. However, the best results for all the objective parameters were obtained with digital occlusion via the Provox HME.

Aged↗
PubMed2006

Development and evaluation of a novel tracheostoma button and fixation system (Provox LaryButton and LaryClip adhesive) to facilitate hands-free tracheoesophageal speech.

CONCLUSION: This newly developed tracheostoma button and fixation system was appreciated by the majority of the patients in this study and led to an increased use of automatic speaking valves (ASVs). OBJECTIVE: Development and prospective clinical evaluation of a new tracheostoma button and fixation system to enhance hands-free speech in laryngectomized patients. PATIENTS AND METHODS: The Provox LaryButton and LaryClip adhesive system were prospectively evaluated in 11 patients: 10 male, 1 female; mean age 60.5 years, range 46-80 years; median follow-up since laryngectomy 4.9 years, range 9 months to 21 years. A study-specific questionnaire was used and the observation period was 3 weeks. RESULTS: Eight patients were compliant, three dropped out of the study. The LaryClip adhesive system was tried by seven of these compliant patients, and ultimately used by six. At the start of the study two patients used an ASV on a daily basis, three alternated between an ASV and regular, manually operated heat and moisture exchangers (HME), three only used a HME. At the end of the study, three used the ASV daily, five alternated between ASV and HME. Seven patients indicated that they would continue using the new system, six with clips and one with the button only.

Adhesives↗
PubMed2001

Use of the 'real-ear to dial difference' to derive real-ear SPL from hearing level obtained with insert earphones.

The electroacoustic characteristics of a hearing instrument are normally selected for individuals using data obtained during audiological assessment. The precise inter-relationship between the electroacoustic and audiometric variables is most readily appreciated when they have been measured at the same reference point, such as the tympanic membrane. However, it is not always possible to obtain the real-ear sound pressure level (SPL) directly if this is below the noise floor of the probe-tube microphone system or if the subject is unco-operative. The real-ear SPL may be derived by adding the subject's real-ear to dial difference (REDD) acoustic transform to the audiometer dial setting. The aim of the present study was to confirm the validity of the Audioscan RM500 to measure the REDD with the ER-3A insert earphone. A probe-tube microphone was used to measure the real-ear SPL and REDD from the right ears of 16 adult subjects ranging in age from 22 to 41 years (mean age 27 years). Measurements were made from 0.25 kHz to 6 kHz at a dial setting of 70 dB with an ER-3A insert earphone and two earmould configurations: the EAR-LINK foam ear-tip and the subjects' customized skeleton earmoulds. Mean REDD varied as a function of frequency but was typically approximately 12 dB with a standard deviation (SD) of +/- 1.7 dB and +/- 2.7 dB for the foam ear-tip and customized earmould, respectively. The mean test-retest difference of the REDD varied with frequency but was typically 0.5 dB (SD 1 dB). Over the frequency range 0.5-4 kHz, the derived values were found to be within 5 dB of the measured values in 95% of subjects when using the EAR-LINK foam ear-tip and within 4 dB when using the skeleton earmould. The individually measured REDD transform can be used in clinical practice to derive a valid estimate of real-ear SPL when it has not been possible to measure this directly.

Acoustic Stimulation↗
PubMed2000

Preferred listening levels: the effect of background noise for moderate-to-profoundly hearing impaired aid users.

The effects of background noise on the choice of preferred listening level for moderately-to-profoundly hearing impaired adults were investigated. During three listening conditions: 'quiet' (isolated monosyllables), 'suppress' (speech with noise attenuated in the gaps between words), and 'steady' (speech with continuous noise), subjects chose a level that maximized intelligibility without being uncomfortable while listening through a hearing aid. The group mean preferred level for 'suppress' was significantly higher than for 'steady', indicating that the level of noise between words influenced these subjects' choice of listening level. Average word recognition scores were higher in 'suppress' than in 'steady', but the difference was not statistically significant. Subjective loudness and quality ratings indicated no reduction in comfort or quality at the higher level for 'suppress'. The results suggest that a hearing aid that attenuated the level of background noise between words, or temporarily increased the gain during each word, would enable some listeners to tolerate higher levels of speech, thereby improving audibility and possibly speech perception while maintaining listening comfort.

Adult↗
PubMed2000

Apparent change of masking functions with compression-type digital hearing aid.

Signal perception ability under conditions of a narrow band masker in subjects with hearing aids was examined using a theoretical model of the auditory nerve fibre (ANF) with a deteriorated tuning curve in addition to measurements of actual masking function in subjects wearing hearing aids. The results obtained indicate that the apparent masking function could be affected by the frequency-gain character as well as by the degree of compression. Usually, the compression-type of amplification with flat and/or high-frequency weighted characteristics improves not only the apparent thresholds but also the apparent masked thresholds under conditions of lower frequency masking. On the other hand, a low-frequency masker amplified by a higher gain with low-frequency weighted amplification could cause larger upward-masking effects on the signal perception of the higher frequency signal in some conditions. The present study may contribute to our understanding of the underlying mechanisms of the effects of different amplification by the aid.

Acoustic Stimulation↗
PubMed2001

Objective assessment of hearing aid use.

Hearing aid use was assessed using both objective (time recorded in the memory of the hearing aid) and subjective methods (interview and patient diary) in a clinical series of consecutive adult female and male Finnish and Norwegian hearing aid candidates (n = 84). The median study time was 34 days (minimum 21, maximum 73). Over a third of the subjects used their hearing aid for less than 4 hours a day according to an objective assessment. Both of the subjective methods tended to overestimate the use. This preliminary study shows that an objective assessment of hearing aid use is needed and the subjective methods must be validated.

Acoustic Stimulation↗
PubMed2001

Bilateral hearing aids--effects and consequences from a user perspective.

The present study assesses the experiences with bilateral amplification in a group of 144 people provided with two hearing aids between May 1994 and July 1997. Two-thirds of the participants preferred to use both prescribed hearing aids. The participants reported that they used their hearing aids frequently. Bilateral amplification was appreciated especially for recognizing speech, for sound localization and for superior sound quality. Situations in which the subjects showed the highest appreciation of two hearing aids were when attending lectures and theatre performances and for communication in noisy background situations. There were statistically significant differences between users of bilateral and unilateral hearing aids regarding judgement of sound quality of hearing aid processed signals and localization ability in favour of bilateral hearing aid amplification. The self-assessed advantages of bilateral amplification demonstrated in this study should motivate a generous prescription strategy of two hearing aids.

Acoustic Stimulation↗
PubMed1998

Equivalent threshold sound pressure levels for Sennheiser HDA 200 earphone and Etymotic Research ER-2 insert earphone in the frequency range 125 Hz to 16 kHz.

Equivalent Threshold Sound Pressure Levels (ETSPLs) have been determined for the Sennheiser HDA 200 earphone and the Etymotic Research ER-2 insert earphone. Thirty-one young normal-hearing test subjects participated and the thresholds were determined for all recommended frequencies in the frequency range 125 Hz to 16 kHz. The results for the HDA 200 earphone are generally in very good agreement with the results from two other investigations which are available at present. Only at 6 kHz is a 9 dB deviation found and at 8 kHz a 6 dB deviation is found between the three investigations. For ER-2 it has not been possible to find other ETSPL determinations in the literature.

Adolescent↗
PubMed1998

Clinical evaluation of a portable digital hearing aid with narrow-band loudness compensation.

A new portable digital hearing aid referred to as CLAIDHA (Compensate for Loudness by Analyzing Input-signal Digital Hearing Aid), which employs frequency-dependent amplitude compression based on narrow-band loudness compensation, was clinically evaluated in 159 subjects with hearing loss. The results of speech tests revealed better intelligibility compared with the subject's own hearing aids; the advantage of using CLAIDHA in daily life was also indicated by the results of a questionnaire completed by the subjects. In about 64% of the subjects with a flat, gradually sloping type of hearing loss, CLAIDHA was satisfactorily adopted for daily use. However, in the subjects with a steeply sloping type of hearing loss and subjects with losses mainly at high and low frequencies, with near-normal mid-frequency hearing. this loudness compensation scheme seems to be slightly less effective.

Aged↗
PubMed1998

Procedure for clinical testing of hearing aids.

In 1996, the Danish audiological clinics and hearing aid manufacturers jointly developed a clinical procedure for testing novel hearing aids in a clinical setting. This endeavour cane about because it was being acknowledged that clinical testing of hearing aids was likely to become more prominent as a result of the more advanced signal processing schemes enabled by digital technology in particular. It was understood that future hearing aids would encompass a large variety of diverse features, and that a rigid and detailed test protocol would therefore be inappropriate. The procedure was therefore devised as a framework within which a test protocol can be developed, and constitutes the framework of good scientific and clinical practice.

Hearing Aids↗