Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prosthesis Fitting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed2005

Stump management after trans-tibial amputation: a systematic review.

In order to achieve stump healing after trans-tibial amputation, various methods are applied, such as soft dressings followed by elastic wrapping of the stump, rigid dressings, semi-rigid dressings, and more recently the application of silicon or gel-liners. A systematic literature search was performed to identify the optimal post-amputation management. The methodological quality of the studies was systematically evaluated by using a predefined list of criteria. Only 11 controlled studies were identified and evaluated for their methodological quality. From these studies, no studies were classified as A-level studies, whereas three were classified as B-level, and 8 were classified as C-level studies. Relevant literature appears heterogeneous with respect to patient selection, intervention and outcome measures. Despite the large variability of included studies, this review reveals a trend in favour of rigid and semi-rigid dressings for achieving stump healing and reduction of stump volume. No conclusions can be drawn with regard to the effect on functional outcome. The literature is not conclusive on the effects of early weight bearing on stump healing, volume reduction, and functional outcome. More research is needed for the development of evidence-based clinical practice guidelines concerning management after transtibial amputation.

Amputation, Surgical↗
PubMed2006

Post-traumatic reconstruction of the enucleated contracted eye socket: a comparative study.

Contracted eye socket is a constant cosmetic embarrassment to the patient. It does not only render patients unable to maintain eye prosthesis, but it becomes a source of chronic discharge and irritation. Traumatic injuries to the orbit and neighboring soft tissue lead to a contracted eye socket. To evaluate the use of full thickness and thick split thickness skin graft in the reconstruction of contracted eye socket with achieving satisfactory cosmetic results we used bilateral fish tail incision in continuity with the transverse incision on the back of the eye socket for rising of two unipedicle hinge flaps for creation of upper and lower fornices. Fixation of full-thickness and thick split-thickness skin graft to the created raw area by stitch and splint (non-adherent tulle and eye prosthesis).Twenty-six patients with contracted eye sockets treated with above method from February, 2004 to March, 2005. Eye sockets with adequate size were created in 22 patients and the results were satisfactory, four patients had unsatisfactory results due to partial loss of the full thickness skin graft. We believe that thick split thickness skin graft can be effectively used well than full thickness skin graft in the reconstruction of the contracted eye socket with uncomplicated problems.

Adolescent↗
PubMed1996

Metal on metal surface replacement of the hip. Technique, fixation, and early results.

High volumetric wear of polyethylene plays a central role in periprosthetic bone resorption and the failure of metal on polyethylene total hip resurfacing prostheses. An assessment of technique, initial fixation, and the early results of 21 hips in 19 patients implanted with a metal on metal bearing total hip resurfacing prosthesis, 4 all cementless Wagner prostheses and 17 all cemented McMinn prostheses, is presented. Pain relief was equal to conventional total hip replacement with a better functional result with an average followup of 16 months (range, 10-25 months). The femoral component position and fixation is satisfactory in all 21 hips and there were no femoral neck notches or fractures. All 4 cementless Wagner acetabular components appear to be osseointegrated with stable interfaces. The cemented McMinn acetabular components, however, have shown progressive cement bone interface radiolucencies in 12 hips. This preliminary experience underscores the importance of obtaining secure initial fixation. There have been no problems directly attributable to the metal on metal bearing but the authors will continue to follow these hips and evaluate their performance. The metal on metal hip surface replacement procedure is in evolution. This ongoing experience will help guide total hip surface replacement component design and implantation techniques.

Adult↗
PubMed2001

Effect of radiographic quality on computer-assisted head penetration measurements.

Even the most sophisticated computer-assisted radiographic techniques of measuring femoral head penetration into the polyethylene liner depend on the quality of the radiograph being evaluated, which varies greatly in clinical settings. The authors of this study sought to determine how the accuracy and reproducibility of three commercially available computer-assisted measurement systems differed when measuring optimal radiographs (with sharply defined component edges) and suboptimal radiographs (with less well defined edges). Using three computer-assisted measurement systems, the authors measured head penetration on simulated and clinical hip radiographs. All systems calculated head penetration as the movement of the head center relative to the cup center. To define the periphery of the prosthetic head and cup, one method (System One) used the human eye and a digitizing tablet, whereas the other two methods (System Two and System Three) used digital edge detection algorithms. For simulated hip radiographs, error was calculated as the absolute value of the difference between the known amount of head penetration, determined by a coordinate measuring machine, and the amount of penetration determined by the software. Three way analysis of variance showed a significant difference in absolute error among the three measurement techniques. System One had a significantly smaller absolute error (0.11 +/- 0.06 mm) than did System Two (0.25 +/- 0.25 mm) and System Three (0.19 +/- 0.13 mm). In addition, three-way analysis of variance showed that optimal radiographs were associated with a significantly lower absolute error (0.14 +/- 0.09 mm) than were suboptimal radiographs (0.23 +/- 0.22 mm). For optimal radiographs, there was no significant difference in error among the three measurement methods; all systems were accurate and reproducible. However, for suboptimal radiographs absolute error increased and varied widely, and a significant difference among the methods existed. These data show the susceptibility of head penetration measurements to radiographic technique and underscore the importance of good quality radiographs for all analyses of head penetration.

Analysis of Variance↗
PubMed2001

Tibiofemoral conformity and kinematics of rotating-bearing knee prostheses.

Increasing tibiofemoral articular conformity theoretically increases articular contact area and reduces contact stresses in total knee arthroplasty. Fixed-bearing knee designs possess relatively low tibiofemoral conformity, in part to allow tibiofemoral rotation without generating excessive stresses at the articulation or the implant-bone interface. This study analyzed knee kinematics of mobile-bearing designs in a closed chain dynamic knee extension model in posterior cruciate-retaining design with high- and low tibiofemoral conformity and posterior cruciate-substituting designs with and without rotational constraint. Overall, for all conditions, the mobile-bearing insert rotated with the femur in the presence of tibiofemoral axial rotation. In addition, the correlation of bearing rotation with femoral rotation was stronger for the high-conformity and rotationally-constrained designs than for the low-conformity designs and strongest for the posterior cruciate-retaining high-conformity condition. Changes in conformity or rotational constraint did not appear to affect femoral roll back, tibiofemoral axial rotation, or varus-valgus angulation. The results suggest that mobile-bearing inserts rotate with the femur and increasing conformity or rotational constraint in mobile-bearing design knee prostheses does not affect knee kinematics adversely, at least under closed chain knee extension conditions in vitro.

Biomechanical Phenomena↗
PubMed2002

Varus and valgus flexion laxity of total knee alignment methods in loaded cadaveric knees.

Both total knee alignment methods, the anatomic and classic, seek to achieve stability in flexion and extension. However, posterior femoral condyle referencing (anatomic alignment) combined with perpendicular tibial resection (classic alignment) results in a 3 degree relative internal rotation of the femoral component with lateral joint opening. The current cadaver study investigated the influence of total knee alignment methods and femoral component malrotation (3 degrees and 6 degrees internal and external malrotation) on femorotibial laxity. Varus and valgus excursion tests were done at 0 degrees, 30 degrees, 60 degrees, and 90 degrees knee flexion under vertical loading conditions of 150 N. None of the alignments produced increased laxity in extension. The largest laxity was found on the varus test at 60 degrees flexion with the femoral component at 6 degrees internal rotation. A 3 degree internal rotation of the femoral component showed increased varus laxity only for the combined alignment method. This finding shows that the femoral component position of the combined alignment method is a 3 degree relative internal malrotation and that an additional internal malrotation may compromise varus stability. Posterior femoral condyle referencing did not provide proper femoral component rotation. A ligament tensor may be helpful in determining femoral component rotation after soft tissue release in extension is performed.

Arthroplasty, Replacement, Knee↗
PubMed1999

Influence of automatic gain control parameter settings on speech understanding of cochlear implant users employing the continuous interleaved sampling strategy.

OBJECTIVE: The purpose of the present study was to gather data on the influence of compression ratio and attack and release times of slow-acting front-end automatic gain control (AGC) systems on speech understanding of cochlear implant users in various listening situations. The data should allow evaluation of the usefulness of front-end AGC in body-worn speech processors. DESIGN: Subjects were 12 experienced postlingually deafened adult users of the Med-El Combi-40 multichannel cochlear implant. Six different front-end configurations, including a linear setting, the standard AGC of the Med-El Combi-40 processor, and four slow-acting dual front-end AGCs (use of two instead of one level detector for improved transient handling), were evaluated in two experiments. In experiment 1, tests were performed at 55, 70 and 85 dB SPL, roughly corresponding to soft, medium and loud speech. Experiment 2 was intended to evaluate the quality of transient handling of the six configurations. In this experiment an intense transient ("chink") at 100 dB SPL was spliced onto the beginning of each sentence (presented at 85 dB SPL). RESULTS: At 55 dB SPL subjects performed significantly more poorly with the linear setting than with the AGC settings, but no differences in performance could be found for the AGC settings. At 70 dB SPL subjects showed the poorest performance with the high compression ratio dual front-end AGCs. No differences in performance of the six front-end configurations were found at 85 dB SPL. In the presence of intense chinks, performance of the standard AGC dropped significantly. CONCLUSIONS: The results indicate that slow-acting front-end AGC can be used effectively in speech processors for cochlear implants to expand the range of input levels that are audible for the cochlear implant user, without any need to adjust a processor control, and that incorporation of an additional fast-acting AGC component can improve performance under conditions where intense transients occur.

Adult↗
PubMed2000

Impact of noise source configuration on directional hearing aid benefit and performance.

OBJECTIVE: To evaluate the impact of the position of noise source(s) and reverberation on the directional benefit and performance of three commercially available directional hearing aids. DESIGN: Directional benefit and performance were measured for four different configurations of competing noise source(s) in two different reverberant rooms. Three pairs of hearing aids representing three commercial models were selected based on electroacoustic evaluation of directivity. Directional benefit and performance of 25 subjects with symmetrical, sloping, sensorineural hearing loss were measured in all test environments using a modified version of the Hearing in Noise Test. RESULTS: Both reverberation and configuration of the competing noise source(s) significantly affected directional benefit and performance. There was no significant correlation between directional benefit and directional performance. The order of benefit and performance across hearing aid brands (from best to worst) varied depending on the noise source configuration. CONCLUSIONS: Data revealed increasing reverberation significantly decreased directional benefit and performance. The absolute and relative (rank ordering) directional benefit and performance varied across hearing aid brand, with noise source configuration. These results suggest that data collected in traditional test environments (e.g., a single competing noise placed at 180 degrees azimuth) cannot be used to accurately predict directional benefit or performance in the majority of other test and real-world environments. The impact of reverberation and noise source configuration on directional benefit/performance can be explained fairly well by the interaction between the spatial properties of the noise source(s) and the polar directivity patterns of the hearing aids.

Aged↗
PubMed2000

Duration, compression, and the aided loudness discomfort level.

OBJECTIVE: The purpose of this investigation is to determine how the unaided and aided loudness discomfort level (LDL) varies with the duration of the input signal and whether the electroacoustic characteristics of compression circuits affect this relationship in a manner that may alter the listener's dynamic range for short duration sounds. DESIGN: Ten hearing-impaired and 20 normal-hearing listeners participated. LDLs were determined for noise bursts of durations ranging in six steps from 32 to 1024 msec, using a two-alternative, forced-choice adaptive tracking procedure in which input level varied until LDL was achieved. LDLs were also obtained for continuous discourse, using a clinical procedure. Subjects were also given the opportunity to self adjust maximum output SPL to their LDL using either output limiting or volume controls in response to fixed 90 dB SPL noise bursts. Testing was conducted unaided and with hearing aids representing two analog (output compression limiting, wide dynamic range compression) and four digital compression circuits. Primary circuit contrasts included compression threshold, compression ratio, attack time and the presence or absence of unity gain at high levels. RESULTS: For the unaided condition, both normal-hearing and hearing-impaired subjects showed increasing LDLs with decreasing signal duration. Under aided conditions, circuits with compression thresholds of 45 to 50 dB SPL and compression ratios of 2:1 produced LDL functions that were similar in slope to the impaired listener's unaided functions. Slopes were steeper when the attack time was slow (128 msec) than when it was fast (2 msec). Circuits with compression ratios of 8:1 produced flat LDL duration functions (i.e., a loss of duration-dependent effects). Similar duration-dependent LDL effects were also observed when subjects adjusted their own hearing aid output characteristics in response to 90 dB noise bursts. CONCLUSION: For the unaided condition, results suggest that normal-hearing and hearing-impaired listeners can tolerate short duration sounds at higher levels than long duration sounds, a finding that has implications for hearing aid design. Circuits that preserve the relationship between duration and LDL should allow brief phonemes to be presented at higher levels without discomfort than circuits that do not, possibly resulting in greater audibility or speech recognition. Current results suggest that circuits with low compression thresholds, low compression ratios, and slow attack times might accomplish this objective better than circuits with high compression thresholds, high compression ratios and fast attack times.

Adult↗
PubMed2001

Comparison of procedures to determine electrical stimulation thresholds in cochlear implant users.

OBJECTIVE: This study was designed to evaluate threshold estimation procedures for cochlear implantees, both for clinical and research purposes. Precision and testing time of eight procedures were evaluated. These procedures included three variations of two adaptive tasks and two variations of an adjustment procedure. DESIGN: Electrical thresholds were obtained with eight different procedures. For each procedure, one of three tasks was combined with one of four decision strategies. With the adjustment task, current level was adjusted from "inaudible" to "just audible" or from "clearly audible" to "just audible." With the two adaptive tasks (i.e., "count the number of pulses" and "choose the interval with the pulse"), current level was adjusted during the sequence of trials by subjects' preceding responses according to three decision criteria (Levitt, 1971). Experimental data were collected on both an apical and a basal channel of six Laura cochlear implantees, and test-retest measures were obtained for each procedure, channel and subject. Moreover, total testing time was recorded in each test, to examine the trade-off with precision, and to investigate the feasibility of the procedures in a clinical setting. RESULTS: In general, the "count the pulses" procedures yield higher threshold values than the "choose the interval with the pulse" and adjustment procedures. Precision was not a statistically significant factor, although the test-retest variation was approximately a factor of 2 larger in the adjustment procedures than in the adaptive procedures. Test duration differences were large. Moreover, analyses of the adaptive procedures showed that a stable estimate requires at least six reversals and that the first four reversals should not be taken into account for threshold estimation. CONCLUSIONS: In a clinical setting, where precision and time are important parameters, precise thresholds can be obtained with the adjustment procedure. However, for research purposes, it is advised to use the "choose the interval with the pulse" task together with one of the transformed up-down decision criteria.

Adolescent↗
PubMed2002

Three-month results with bilateral cochlear implants.

OBJECTIVES: To evaluate possible binaural listening advantages for speech in quiet, speech in noise, and for localization in a group of postlingually deafened adults with two cochlear implants functioning independently after 3 mo experience. DESIGN: Nine postlingually deafened subjects who had received a Cochlear Corporation CI24M implant in each ear were evaluated on a number of tasks. The subjects all had audiometric or biographical (e.g., duration of deafness) differences between the ears. Word and sentence materials were presented to the subjects in quiet and in noise with the signal always in the front and the noise from the front or either side. Results are reported for each ear and for both ears with the noise on either side. This allowed evaluation of head shadow and squelch effects. Additionally, localization ability was assessed for broadband noise presented either to the right or left of center at 45 degrees azimuth. Localization was assessed for each ear and for both ears. RESULTS: Results of speech testing in quiet showed a significant advantage for the binaural condition over the better ear in four subjects. In noise, with both signal and noise in front of the subject, a significant advantage of two ears over the better ear was found for four subjects. For noise to one side of the head, when the ear opposite the noise source was added to the ear ipsilateral to the noise, a significant advantage was demonstrated for seven of seven tested subjects. When the ear ipsilateral to the noise was added to the ear contralateral to the noise, a significant advantage was shown for only one of seven (noise on right) and three of seven (noise on left) tested subjects. The localization task showed that all seven tested subjects could discriminate 45 degrees left from 45 degrees right above chance with bilateral stimulation. Three subjects could perform the discrimination above chance with only one ear. However, performance with both ears was significantly better than performance with one ear for two of these latter subjects. CONCLUSIONS: We conclude that bilateral cochlear implants can provide real advantages, particularly when it is possible to utilize the ear that is away from a noise source, thus taking advantage of the head shadow effect. In addition, localization ability was generally better with two implants than with one.

Acoustic Stimulation↗
PubMed2002

Evaluation of electroacoustic test signals I: comparison with amplified speech.

OBJECTIVE: To evaluate the ability of clinical test signals to match the aided levels of real speech, across a range of hearing aid circuit types and strengths. DESIGN: Hearing aids (N = 41) were set to DSL targets for moderate, severe, and profound hearing losses. These hearing aids were tested with three test signals (Fonix Pure Tones, Fonix Composite Noise, and Audioscan Swept), as well as with running speech. The difference between the aided test signal and the aided speech was calculated. RESULTS: Accuracy of matches between aided test signals and aided speech levels depended on circuit type, signal type, and test level. CONCLUSIONS: Clinical test signals can more accurately match the aided levels of speech for all types of hearing aids if they are 1) speech-weighted and 2) temporally modulated. Matches were more accurate at low to moderate test levels (i.e., 50 to 70 dB SPL), and less accurate at high test levels (i.e., 85 dB SPL).

Electric Stimulation↗
PubMed2005

Two new directions in speech processor design for cochlear implants.

Two new approaches to the design of speech processors for cochlear implants are described. The first aims to represent "fine structure" or "fine frequency" information in a way that it can be perceived and used by patients, and the second aims to provide a closer mimicking than was previously possible of the signal processing that occurs in the normal cochlea.

Acoustic Stimulation↗
PubMedDate not supplied

Wound healing in orthopaedic procedures for Klippel-Trenaunay syndrome.

Klippel-Trenaunay syndrome is a triad of cutaneous hemangiomas, varicose veins, and hypertrophy of soft tissue and bone; when combined with arteriovenous fistulas, the syndrome is known as Klippel-Trenaunay-Weber syndrome. Orthopaedic surgical management of localized limb-length discrepancy or hypertrophy in these conditions is frequently indicated, especially in the lower limb. Forty orthopaedic procedures in 21 patients were retrospectively reviewed. Nine (22.5%) wound complications were identified in this study group. All the complications were associated with transverse amputations. All required significant further treatment and extension of hospital stay. Wound complications should be anticipated in patients with Klippel-Trenaunay syndrome having orthopaedic surgical procedures, especially terminal amputations.

Amputation, Surgical↗
PubMed2000

Clinical and finite element analysis of a modular femoral prosthesis consisting of a head and stem component in the treatment of pertrochanteric fractures.

OBJECTIVE: To determine the biomechanical characteristics and potential clinical efficacy of a cementless modular femoral prosthesis consisting of a variable head (50 to 80 millimeters) and stem (length 120 to 280 millimeters, diameter 10 to 20 millimeters) component in patients with pertrochanteric femoral fracture. DESIGN: Finite element analysis (FEA) of different lengths and diameters of prosthesis components and first clinical prospective study in pertrochanteric femoral fracture. METHOD: Using a 3D-CAD program, a model of femoral cortical bone with a pertrochanteric fracture was created and combined with a model of the prosthesis. This model was transferred into an FEA program. After applying a torsion-bending load of 2,000 N (25 degrees, 45 degrees) on the prosthesis, stress distribution in the cortical bone was determined for different lengths (160 to 240 millimeters) and diameters (10 and 12 millimeters) of stem. PATIENTS: Twenty-eight patients with pertrochanteric fractures (very unstable or osteoarthritis) were treated with a modular hip arthroplasty. Complications, fracture healing, and results at first follow-up (average 13 months) were determined. RESULTS: FEA analysis indicated that reduction in stress was less when a prosthesis with a short stem was used. Shear stress in the interface bone/prosthesis was not affected by stem length. Prostheses with thin stems produced higher sheer stresses than those with thick stems. Results of FEA were used as the basis for clinical application of the device. None of the patients died, and all patients were able to walk, although some needed a cane or walker after surgery. There was no increase in thigh pain compared with reported pretrauma levels. Radiographs showed subsidence of up to 5 millimeters in 20 percent of patients. However, all but one prosthesis was stable at follow-up. Fracture healing was achieved in all patients. CONCLUSIONS: If proximal fixation of a femoral uncemented stem cannot be achieved, stem diameter should provide maximum cortical contact to reduce sheer stress. Longer stems do not necessarily provide additional stability. By using this prosthesis and selection method, a good outcome at first follow-up was observed.

Activities of Daily Living↗