Implant verification cast--a predictable restorative system in implant prosthodontics

An implant verification cast is designed to provide an accurate representation of dental implant positions extraorally. It can be used by the laboratory as a trusted cast to create a passively fitting framework and by the clinician to verify framework fit prior to intraoral trial. This article discusses the treatment philosophy behind this specific cast and reviews applications, fabrication techniques and benefits of the verification cast compared to the conventional technique.

Clinical experience with the active middle ear implant Vibrant Soundbridge in sensorineural hearing loss

BACKGROUND/AIMS

To evaluate gain at threshold level and speech recognition performance of 54 subjects with mild-to-severe symmetrical sensorineural hearing loss (SNHL) that received the active middle ear implant system Vibrant Soundbridge (VSB).

METHODS

Pre- and postoperative assessments of hearing thresholds and monosyllabic word discrimination were performed in a homogeneous group of 54 adults who received a VSB system (VORP 502/AP 404) in an active middle ear implant (AMEI) program in a tertiary referral hospital. All subjects included in this study had mild-to-severe, predominately sloping SNHL. Gain at threshold level and speech recognition results were assessed for unaided and aided conditions using the patient's walk-in hearing aid (HA) and the VSB in a retrospective study design.

RESULTS

A comparison of pre- and postoperative unaided air conduction thresholds revealed a mean decrease in pure tone averages of 3.9 dB (0.25-8 kHz). Gain at threshold level (unaided thresholds minus AMEI-aided thresholds) was, on average, 20.9 dB at 0.5 kHz, 20.5 dB at 1 kHz, 23.8 dB at 2 kHz, 30.2 dB at 3 kHz, 36.1 dB at 4 kHz, 37.6 dB at 6 kHz and 37.9 dB at 8 kHz. Monosyllabic word discrimination at 65 dB SPL improved from a mean of 30% in the unaided condition to 44% for the HA-aided condition (p<0.05), with a further increase to 57% for the VSB-aided condition (p<0.05, compared to the HA).

CONCLUSION

The AMEI system VSB can be considered as an effective rehabilitation alternative in subjects with mild-to-severe SNHL and unsatisfying benefit from conventional hearing aids.

Fabrication of a surgical template for orbital implant placement: a case report

Implant placement in orbital sites is challenging because of limited bone volume and poor bone quality. Preoperative optimal implant planning and intraoperative guides are important to ensure success. This article describes the use of computer simulation for implant insertion and fabrication of a surgical template as a drilling guide for orbital implant placement. A 29-year-old woman with a right orbital defect underwent computerized tomographic scanning, and the data were processed with interactive software to simulate orbital implant placement. A surgical template that served as a drilling guide was designed and fabricated to transfer orbital recipient site information from the three-dimensional computer model into the actual orbital implant sites. Three craniofacial implants were placed in the 7:00, 8:00, and 11:00 positions. No unexpected complications or injuries were encountered during the surgery. Magnetic abutments were attached to the implants 2 weeks later. The definitive facial prosthesis was fitted 6 months later, with excellent esthetic results. The surgical template contributed to the success of this treatment.

The road to recovery and rehabilitation for injured service members with limb loss: a focus on Iraq and Afghanistan

Amputation of an extremity due to traumatic injury or a vascular occlusive disease is a life-altering event that occurs when limb salvage is not possible. While an amputation is viewed as a life saving procedure clinically, limb deficiency may result in an immediate loss in social, physical and financial well-being for the patient. Military personnel returning from Operation Enduring Freedom and Operation Iraqi Freedom face unique challenges due to short residual limbs, unplanned amputations, high incidences of multiple limb loss, and accustomed activity levels prior to an amputation. The primary rehabilitation goal for these individuals is to provide them with an expedited recovery and progressive reintroduction into the civilian or active duty population. It is the purpose of this review to discuss the most frequent rehabilitation hardships service members endure following combat related trauma and future of prosthetic limb technology.

Effect of unilateral misfit on preload of retention screws of implant-supported prostheses submitted to mechanical cycling

PURPOSE

The aim of this study was to evaluate the effect of different levels of unilateral angular misfit on preload maintenance of retention screws of single implant-supported prostheses submitted to mechanical cycling.

MATERIALS AND METHODS

Premachined UCLA abutments were cast with cobalt-chromium alloy to obtain 48 crowns divided into four groups (n=12). The crowns presented no misfit in Group A (control group) and unilateral misfits of 50 μm, 100 μm and 200 μm in the groups B, C and D, respectively. The crowns were attached to external hexagon implants with a titanium retention screw with torque of 30 N/cm. Oblique loading of 130 N at 2 Hz was applied on each replica, totalizing 5×10⁴ and 1×10⁶ cycles. Detorque values were measured initially and after each cycling period. Data were evaluated by analysis of variance and Tukey's HSD test (p<0.05).

RESULTS

All groups presented reduced initial detorque values (p<0.05) in comparison to the insertion torque (30±0.5 N/cm) and Group A (25.18 N/cm) exhibited the lowest reduction. After mechanical cycling, all groups presented detorque values from 19.5 N/cm to 22.38 N/cm and the mechanical cycling did not statistically influence the detorque values regardless the misfit level of the replicas.

CONCLUSION

The unilateral misfit influenced the preload maintenance only before mechanical cycling. The mechanical cycling did not influence the torque reduction.

Developing a quantitative measurement system for assessing heterotopic ossification and monitoring the bioelectric metrics from electrically induced osseointegration in the residual limb of service members

Poor prosthetic fit is often the result of heterotopic ossification (HO), a frequent problem following blast injuries for returning service members. Osseointegration technology offers an advantage for individuals with significant HO and poor socket tolerance by using direct skeletal attachment of a prosthesis to the distal residual limb, but remains limited due to prolonged post-operative rehabilitation regimens. Therefore, electrical stimulation has been proposed as a catalyst for expediting skeletal attachment and the bioelectric effects of HO were evaluated using finite element analysis in 11 servicemen with transfemoral amputations. Retrospective computed tomography (CT) scans provided accurate reconstructions, and volume conductor models demonstrated the variability in residual limb anatomy and necessity for patient-specific modeling to characterize electrical field variance if patients were to undergo a theoretical osseointegration of a prosthesis. In this investigation, the volume of HO was statistically significant when selecting the optimal potential difference for enhanced skeletal fixation, since higher HO volumes required increased voltages at the periprosthetic bone (p = 0.024, r = 0.670). Results from Spearman's rho correlations also indicated that the age of the subject and volume of HO were statistically significant and inversely proportional, in which younger service members had a higher frequency of HO (p = 0.041, r = -0.622). This study demonstrates that the volume of HO and age may affect the voltage threshold necessary to improve current osseointegration procedures.

Clinical trial of chlorinated polyethylene for facial prosthetics

PURPOSE

Extraoral maxillofacial prostheses have been fabricated with silicone elastomer for 50 years with few improvements. The objective of this controlled, randomized, prospective, double-blind, single-crossover, multicenter, phase III clinical trial was to determine the noninferiority of chlorinated polyethylene elastomer (CPE) to silicone elastomer for fabricating prostheses.

MATERIALS AND METHODS

Forty-two patients were randomly assigned to wear a custom-made prosthesis fabricated from both materials for 4 months and asked to rate their satisfaction (0 = not satisfied, 10 = completely satisfied). Many other measures of prosthesis performance were investigated (see online appendices).

RESULTS

Of the 28 patients who completed the study, 68% had used silicone prostheses previously. Overall, patients rated the silicone prosthesis higher than CPE (difference: 2.2, 95% confidence interval [CI]: 0.9 to 3.6, P = .017). Previous users had a stronger preference for silicone (difference: 3.3, 95% CI: 1.7 to 4.9, P = .001), while the 9 new users rated the two materials similarly (difference: 0.0, 95% CI: -2.1 to 2.1, P = 1.00).

CONCLUSIONS

The noninferiority of CPE could not be established because of the early termination of the trial. Previous users of silicone prostheses preferred those made of silicone. However, new users expressed no preference between prostheses fabricated with the low-cost CPE or silicone. The authors have developed original clinical trial methodology for assessing extraoral maxillofacial prostheses.

Assessing the fit of implant fixed prostheses: a critical review

PURPOSE

This review critically compares the available clinical and laboratory methods for assessing the fit of an implant prosthesis.

MATERIALS AND METHODS

MEDLINE and PubMed databases were searched for studies related to the fit of implant prostheses or the effect of misfit. Different combinations of key words were used. The screening procedure was performed in two stages. In the first stage, the relevant articles were selected. In the second stage, from those articles, specific inclusion and exclusion criteria were applied.

RESULTS

Fifty-four articles were selected. Two different techniques were identified: in vitro and in vivo. The advantages, disadvantages, and limitations of each technique are discussed. There are clear limitations for the in vivo techniques. The in vitro techniques provide a more accurate measure of prosthesis misfit.

CONCLUSIONS

Because of the variety of techniques and the different parameters assessed by each, it is useful to combine several techniques to assess the accuracy of fit, quantify the effect of misfit, and subsequently determine an acceptable level of fit.

A new cochlear implant electrode design for preservation of residual hearing: a temporal bone study

CONCLUSIONS

Success in conservation of residual hearing after cochlear implantation has benefited patients with high levels of residual low frequency hearing who were not previously considered for conventional cochlear implantation. Technological developments play a key role in minimizing trauma to the cochlea during placement of electrodes.

OBJECTIVES

The Nucleus Straight Research Array (SRA) has been designed and developed as a collaboration project between our centre and Cochlear Ltd with the objective of minimizing trauma to the cochlea with insertion of the electrode via the round window.

METHODS

We studied 22 fresh or thawed fresh-frozen human temporal bones implanted by one otosurgeon with the SRA electrode with a standard round window technique used for cochlear implantation. An additional four temporal bones were implanted with a 'Standard' straight electrode using the same surgical technique. All insertions were performed in the scala tympani of the cochlea.

RESULTS

Evaluation of insertion depth and position of the electrode array inside the cochlea showed little or no evidence of significant intracochlear trauma in the vast majority of bones implanted with the SRA. Handling of the electrode carrier was reported as very satisfactory, which was evident from low resistance to insertion in the majority of cases.

Initial experience and sizing considerations using the three lobed amplatzer ductal occluder

BACKGROUND

The recently released Amplatzer Ductal Occluder 2 (ADO2) was designed specifically for use in small children with moderate-sized shunts and larger children with small patent ductus arterioses (PDA). We report our initial experience with this device.

METHODS

Patients referred with PDA underwent occlusion using the ADO2. This is a fabric-free nitinol wire 3-lobed device. All cases underwent pre-, intra- and post-procedural echocardiography, with follow up at 1 day and one month. Device sizing for device waist diameter and width was based on aortography.

RESULTS

Seven patients with a median age of 3 years and 4 months (range 7 months-23 years) and a median weight of 12 kg (range 7-56 kg) underwent successful PDA closure. The median ductal diameter was 1.5 mm (range 0.4-4 mm). Both transpulmonary (6/7) and transaortic approaches (1/7) were used. Recurrent patency at 24 hours with complete occlusion at 1 month was noted in a single case. A specific device-based length assessment applied resulted in shorter than recommended device selection.

CONCLUSION

The ADO2 broadens the spectrum of PDAs that can be simply and safely treated with devices. The flexibility of the articulations, coupled with the alternative deployment techniques, allow for increased ease of treatment in a range of small patients and specific ductal anatomies. An alternative device-specific length measurement of the duct length may result in less retaining disc protrusion. Broader experience is required to further delineate device and patient selection as well as to document its long-term efficacy and safety.

Correction of CoreValve position using snare traction from a right brachial artery access

Significant paravalvular aortic regurgitation is among the most important limitations of the interventional revalving techniques for the treatment of severe aortic stenosis. We report on the treatment of a patient with severe paravalvular regurgitation following CoreValve implantation by prolonged snare traction from the right brachial artery. Snare traction resulted in upward motion of the valve with subsequent reduction of aortic regurgitation from grades III/IV to grade I.

Randomized controlled trial investigating the effect of an acrylic-based resilient liner on perceived chewing ability in edentulous patients wearing mandibular complete dentures

PURPOSE

The aim of this study was to investigate the effect of an acrylic-based resilient liner (ARL) on perceived chewing ability in patients using mandibular complete dentures compared with that of patients using mandibular complete dentures with a conventional acrylic resin (CAR).

MATERIALS AND METHODS

This randomized controlled trial was conducted at two centers from April 2004 to July 2006. Seventy-four subjects were randomly allocated to either the ARL or CAR group using a random permuted block method after obtaining written informed consent. A valid questionnaire listing 35 foods was used to evaluate the subjects' perceived chewing ability of each item, assessed according to the following scale: 0=cannot eat, 1=can eat with difficulty, and 2=can eat easily. If subjects did not eat the food because they disliked it or had not eaten it since first wearing dentures, they filled in a triangle or square, respectively. These figures were treated as a 0 during analysis.

RESULTS

No significant differences were observed between the ARL and CAR groups. The perceived chewing ability of subjects with new complete dentures was significantly higher than that of those with their old complete dentures. The duration of edentulism was positively associated with perceived chewing ability.

CONCLUSIONS

An ARL applied to mandibular complete dentures has no significant impact on the perceived chewing ability of edentulous patients in comparison to a CAR.

Relationship between prosthesis-patient mismatch and pro-brain natriuretic peptides after aortic valve replacement

BACKGROUND AND AIM OF THE STUDY

It has been shown previously that elevated plasma levels of B-type natriuretic peptide (BNP) and its N-terminal fragment (NT-pro-BNP) are related to the degree and progression of native aortic valve disease. In addition, NT-pro-BNP levels have been shown to decrease after successful aortic valve replacement (AVR). The presence of a valve prosthesis-patient mismatch (PPM) may affect the beneficial effects of AVR, however. The study aim was to investigate the relationship between PPM and NT-pro-BNP plasma levels late after AVR.

METHODS

A series of consecutive patients (42 males, 31 females; mean age 66 +/- 13 years) who had undergone isolated AVR between May 2004 and July 2007 was enrolled into the study. Patients with preoperative moderate to severe mitral regurgitation, coronary artery disease, left ventricular (LV) dysfunction (ejection fraction <45%) and serum creatinine >150 mmol/l were excluded. PPM was defined severe as an indexed effective orifice area (EOAi) < or = 0.65 cm2/m2, or moderate when the EOAi was 0.66-0.85 cm2/m2. Plasma NT-pro-BNP levels and echocardiographic assessments were performed in all patients during routine follow up after surgery.

RESULTS

The patients received either a biological (n = 42) or mechanical (n = 31) prosthesis. Among the patients, 21 had no PPM, 27 moderate PPM, and 25 severe PPM. At a median follow up of 18 months, the mean NT-pro-BNP plasma level was 532 pg/ml (95% CI: 393.1-671.6), and the mean LV mass index (LVMI) 120 +/- 4 g/m2, the LVEF 60 +/- 1%, the peak aortic prosthesis gradient 28 +/- 2 mmHg, and the EOAi 0.74 +/- 0.02 cm2/m2. Multivariate statistical analysis showed that NT-pro-BNP level correlated with age (beta = 0.57, p<0.0001), LVMI (beta = 0.32, p = 0.02), NYHA class (beta = 0.50, p = 0.003) and EOAi (beta = -0.38, p = 0.02).

CONCLUSION

The study results showed that NT-pro-BNP levels were independently related to PPM late after isolated AVR in patients with preserved LV function. However, further investigations are required to confirm these findings and to identify their clinical implications.

Morphometric analysis of anatomic variables affecting endovascular stent design in patients undergoing elective and emergency repair of endovascular abdominal aortic aneurysm

BACKGROUND

Our objective was to identify morphologic trends in elective and emergency endovascular aneurysm repair (EVAR). This work will inform hospitals with endovascular programs about the diameters and lengths of endostents that should be available to efficiently care for patients with these conditions.

METHODS

We performed a retrospective review of patients undergoing elective (n = 127) and emergency (n = 17) EVAR. Using computed tomography and 3-dimensional reconstructions, we evaluated the following: diameters of the aneurysm (D3), the aorta at the superior mesenteric (D1) and renal (D2a,b,c; 3 levels) levels, the iliac arteries (D5a,b; right and left) and the aortic bifurcation (D4); lengths from the lowest renal artery to the distal aspect of the aortic neck (H1), to the aortic bifurcation (H3), to the right and left iliac bifurcations (H4a,b); and angles of the origin of the common iliac arteries on the transverse plane (A1). We used descriptive statistics of trends within groups and independent sample t tests.

RESULTS

In elective and emergency aneurysm repair, D2max (26, standard deviation [SD] 3, mm v. 30.7 [SD 3] mm), D5a (16 [SD 4.7] mm v. 19.3 [SD 5] mm), D5b (15.3 [SD 4] mm v. 18.1 [SD 3.6] mm), H1 (25.6 [SD 8.6] mm v. 18 [SD 2] mm), H4a (173 [SD 22] mm v. 189.5 [SD 22] mm) and H4b (174 [SD 25] mm v. 190 [SD 14] mm) were significantly different between the 2 groups (p = 0.001, p = 0.006, p = 0.007, p < 0.001, p = 0.05 and p = 0.01, respectively). H3 (118 [SD 17] mm v. 121.5 [SD 13.5] mm) was not significantly different (p = 0.40). In elective patients, A1 identified the right common iliac more frequently anterior relative to the left common iliac (mean 23 degrees , SD 16 degrees).

CONCLUSION

Significant anatomic differences between elective and emergency patients will require hospitals to stock separate endovascular devices to treat abdominal aortic aneurysms in both groups.

[Follow-up radiological analysis of hip arthroplasty]

A total hip arthroplasty may be damaged for multiple reasons. The deteriorations are not always detectable by clinical follow-up. The radiological analysis of prosthetic implants therefore appears to be the best index of the component's behaviour. The computerised methods allow to measure prosthesis migration values that were not detectable in the simple X-rays examination and provide information on the quality of the interfaces. The Software reveals early signs of the component's wear and migration which can have a predictive value relative to the long-term results of arthroplasties. They inform us about the stability of prosthetic components. There effectively seems to be a relation between the early migration of an implant and the risk of aseptic loosening in the long-term period; a precise study of the implant's migration during the first two years after implantation aims at obtaining earlier information which, without these techniques, can only be obtained after long-term clinical and radiological follow-up. These methods allows quicker selection of successful implants after a relatively short-term period. In the long-term, they contribute to improve the implant conception.

Partial hand preservation for large soft tissue sarcomas of the hand

PURPOSE

Hand amputations cause marked functional loss for patients. In patients with large soft tissue sarcomas of the hand, partial hand preservation is extremely challenging for surgeons attempting a complete resection of the tumor with negative resection margins. We conducted this review to examine the oncologic outcome, including local recurrence rate and patient overall survival, and functional outcome after resections for large soft tissue sarcomas with partial hand preservation.

METHODS

We performed a retrospective review of all patients with soft tissue sarcomas of the hand treated at our institution from 1995 to 2007. We identified 8 patients who had tumors at least 5 cm in maximum dimension and had tumor resection with partial hand preservation. The mean age at the time of surgery was 49 years (range, 10-80 years). Two patients had myxofibrosarcoma, 2 patients had synovial sarcoma, 2 patients had malignant fibrous histiocytoma, 1 patient had a malignant peripheral nerve sheath tumor, and 1 patient had a liposarcoma. Two patients had low-grade tumors, and 6 patients had high-grade tumors. Two patients had American Joint Committee on Cancer stage 1b tumors, and 6 patients had American Joint Committee on Cancer stage 3 tumors. No patients had distant metastases at the time of surgery. Hand function was evaluated using Musculoskeletal Tumor Society criteria.

RESULTS

Of the 8 patients, 1 died of distant metastatic disease, 1 developed local tumor recurrence and is alive with locally recurrent disease, and the other 6 patients are completely disease-free. The mean Musculoskeletal Tumor Society score was 26 (range, 19-29), with the 2 patients who had received double-ray amputations having the lower scores (19 and 24).

CONCLUSIONS

Partial hand preservation is possible in selected patients with large soft tissue sarcomas of the hand, obtaining low local recurrence rates, good overall survival, and good functional outcome. However, all effort should be made to achieve negative resection margins.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Fluoroscopic navigation system for hip surface replacement

Metal-on-metal hip resurfacing arthroplasties represent an alternative to total hip arthroplasties for young and active patients, enabling the preservation of intact femoral bone and therefore improving the prognosis for future hip joint replacements. Follow-up studies have shown that the main reasons for early implant failure are mal-orientation of the implant stem in relation to the femoral neck axis, and notching of the femoral neck during femoral head preparation, as well as by exposed cancellous bone after implantation. A computer-assisted planning and navigation system for the implantation of femoral hip resurfacing implants has been developed which supports the surgeon during intraoperative fluoroscopy-based planning and navigation of implant positioning. This paper presents the results of a cadaver study performed to evaluate the system's functionality and accuracy.

Unicompartmental knee arthroplasty: indications, techniques, and results

Unicompartmental knee arthroplasty (UKA) was introduced in the early 1970s but did not receive substantial support because total knee arthroplasty was flourishing. In the early 1990s, interest in UKA increased with the introduction of a minimally invasive surgical approach. It is important that the indications for this demanding but achievable surgical technique be strictly observed. The extension and flexion gaps for UKA can be addressed in a similar fashion to total knee arthroplasty and should be equalized. The femoral and tibial components must be properly sized so that the surfaces are well covered without overhang or impingement. UKA results at 10- to 15-year follow-ups are encouraging and are similar to many reported results of total knee arthroplasty.

Attachments of muscles as landmarks for implantation of shoulder hemiarthoplasty in fractures

BACKGROUND

The attachments of muscles and the position of the humeral head are important for a good functional outcome of shoulder hemiarthroplasties after displaced fractures of the proximal humerus. Deviations in the attachments and changes in their spatial position with respect to the humeral head during surgical reconstruction change the biomechanics and reduce the range of motion of the should joint postoperatively.

METHODS AND RESULTS

We used 198 humerus preparations and using 3-dimensional analysis measured the angular relationships between the humeral head axis and medial margin of the greater tuberosity (11.9 degrees +/- 9.1 degrees ), lateral margin of the lesser tuberosity (48.0 degrees +/- 7.8 degrees ), and the crest of the greater tuberosity (27.1 degrees +/- 9.6 degrees ).

CONCLUSION

This study provides average values of the positions of the greater and lesser tuberosities with respect to the humeral head axis. We show that the greater and lesser tuberosities are more reliable than the transepicondylar line for reconstruction of humeral head retroversion.

LEVEL OF EVIDENCE

Basic Science.

Unexpected durability of a Björk-Shiley first-generation aortic valve after 40 years of implantation

The case is reported of a patient who underwent aortic valve replacement (AVR) in 1969 and received a (first-generation) Björk-Shiley Delrin valve. Forty years later, the patient presented to the authors' hospital in congestive heart failure and with echocardiographic evidence of severe stenosis and mild aortic regurgitation. The patient underwent a redo sternotomy and AVR with a bioprosthesis. On gross examination, the explanted 40-year-old mechanical valve appeared intact.

Clinical benefits of the Boston Ocular Surface Prosthesis

PURPOSE

To evaluate the effects of the Boston Ocular Surface Prosthesis (Boston Foundation for Sight, Needham, Massachusetts, USA) on visual acuity (VA) and visual functioning in patients with severe corneal ectasia, irregular astigmatism, or ocular surface disease.

DESIGN

Prospective, interventional case series.

METHODS

The study examined the effects of this prosthesis on VA and visual functioning in consecutive patients with corneal ectasia, irregular astigmatism, or ocular surface disease who had failed conventional therapies and were seen at the Boston Foundation for Sight between January 1 and June 30, 2006. Outcomes were best-corrected VA using Snellen charts and visual functioning using the National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) at 6 months. Clinical data were abstracted from medical records.

RESULTS

Of the 101 patients, 80 were fitted with a prosthesis in one or both eyes, and follow-up Visual Functioning Questionnaire data were obtained in 69 eyes. Best-corrected VA improved by a change in mean logarithm of the minimal angle of resolution (logMAR) units of -0.39 (converted from Snellen) with a change of -0.54 logMAR units in patients with ectasia or astigmatism and -0.22 logMAR units in patients with ocular surface disease. Mean composite visual functioning scores increased from 57.0 to 77.8 (P < .0001). Improvements in composite Visual Functioning Questionnaire scores were similar in patients with ectasia or ocular surface disease; but vision-related subscores improved more in patients with ectasia, whereas subscores for ocular pain, role difficulties, and dependency improved more in patients with ocular surface disease.

CONCLUSIONS

The Boston Ocular Surface Prosthesis significantly improved VA and visual functioning in patients with corneal ectasia, irregular astigmatism, and ocular surface disease who had failed conventional therapies.

The Freedom SOLO valve for aortic valve replacement: clinical and hemodynamic results from a prospective multicenter trial

BACKGROUND AND AIM OF THE STUDY

The study aim was to investigate the early results, hemodynamics and left ventricular remodeling after aortic valve replacement (AVR) with the Freedom SOLO valve, a bovine pericardial valve bioprosthesis, using a single running suture line in a supra-annular position.

METHODS

Between July 2004 and September 2006, a total of 256 patients (116 males; 140 females; mean age 74.5 +/- 6.4 years; range: 41-89 years) who underwent AVR with the Freedom SOLO valve in nine European institutions were enrolled in the study. The indications for AVR were stenosis in 182 patients, regurgitation in 15, and combined in 57. Preoperatively, 37%, 59% and 4% of the patients were in NYHA classes I-II, III, and IV, respectively. Concomitant procedures were performed in 91 patients (36%). A patient subgroup underwent echocardiography preoperatively (n=192), and at one (n=194) and 12 (n=165) months postoperatively.

RESULTS

The early mortality was 2.3% (n=6). There were 18 late deaths (6.2%/pt-yr). After 12 months, 82% of the patients were in NYHA class I-II. Linearized rates were 0.69%/pt-yr for bleeding, 0.34%/pt-yr for thromboembolism, 0.0%/pt-yr for structural degeneration and thrombosis, 1.37%/pt-yr for paravalvular leak, and 2.06%/pt-yr for endocarditis. Five patients required reoperation. Twelve-month transprosthetic regurgitation was graded as absent in 92% of cases. The mean gradient was 42.3 +/- 20.2 mmHg preoperatively, 6.5 +/- 3.8 mmHg at one month, and 6.7 +/- 4.1 mmHg at 12 months. The effective orifice area was improved from 0.78 +/- 0.35 cm2 preoperatively to 1.90 +/- 0.56 cm2 at one month and 1.89 +/- 0.56 cm2 at 12 months. The left ventricular mass was decreased by 23%, from 217.8 +/- 77.2 g/m2 preoperatively to 167.4 +/- 68.2 g/m2 at one year. The mean left ventricular ejection fraction was 65.5 +/- 14.2% preoperatively, and 64.5 +/- 12.5% and 66.0 +/- 10.6% at one month and at 12 months, respectively.

CONCLUSION

The data obtained suggest that the Freedom SOLO stentless bioprosthesis shows excellent early clinical and hemodynamic results, resulting in a significant regression of left ventricular hypertrophy and improvement in left ventricular systolic function.

The late impact of surgical skills and training on the subcoronary implantation of the Freestyle stentless bioprosthesis

BACKGROUND AND AIM OF THE STUDY

Recent data have demonstrated an impact of higher postoperative mean pressure gradient (MPG) across the subcoronary Freestyle stentless bioprosthesis on the mid-term quality of life, but not on that of survival. Thus, the question remains that, with a prolonged follow up, would an effect on duration of survival also evolve?

METHODS

Between 1996 and 2006, a total of 939 patients underwent aortic valve replacement (AVR) for aortic stenosis with the Freestyle stentless bioprosthesis, using the subcoronary technique. A follow up was conducted by mailed questionnaires, and completed by telephone interviews in September 2008. The follow up was 99% complete and totaled 3,468 patient-years (pt-yr); the mean follow up time was 7.7 years (range: 7.3-8.1 years). The maximum follow up was 11.9 years.

RESULTS

Actuarial survival rates at five and 10 years were 73 +/- 2% and 35 +/- 4%, respectively. The cut-off gradient was identified at a postoperative MPG of 20 mmHg, where a gradient >20 mmHg had a negative impact on survival rate (p = 0.008), as indicated by the greatest fall of deviance in the Akaike information criterion. Risk factors also affecting survival rate included atrial fibrillation, diabetes, higher serum creatinine levels, greater age, left ventricular ejection fraction < or = 40%, liver insufficiency, lower body mass index, chronic obstructive pulmonary disease, and peripheral arterial disease. Risk factors for MPG >20 mmHg were a smaller valve size, a higher preoperative gradient, individual surgeons and lesser cumulative experience, and early adopters (surgeons) of the subcoronary stentless valve implantation technique.

CONCLUSION

A higher MPG impedes long-term survival, with the cut-off being at 20 mmHg. A higher MPG was largely influenced by the individual surgeons and their cumulative experience of using the subcoronary technique. Late adopters of the technique profited from the observations of early adopters. The standardization of a surgical technique and the identification of common pitfalls were key to optimizing the surgical outcome after stentless valve implantation.

Analysis of sex and race and the size and shape of the distal femur using virtual surgery and archived computed tomography images

Anthropometric data and stature profiling are needed for the accurate sizing of prosthetic systems in total knee arthroplasty (TKA). The purpose of this study was to collect and analyze anthropometric knee data using a virtual surgical method. Computed tomography images (107) from patients (66) of three races were converted to virtual models and oriented with an anatomical coordinate system. The models were used to obtain anterior-posterior, medial-lateral, and condylar spacing measurements. Mean values for all measurements were larger for males than females in the overall population and within each race, and differences between races were observed. Comparisons of males to females from different races showed overlapping mean measurements for males of one race and females of another. These overlaps indicate that certain measurements relevant to TKA system sizing are not strictly related to sex.

The proximal femur--a second look at rational of implant design

Twenty five pairs (50 bones) of cadaveric femora were studied morphologically and radio logically using standardized techniques to obtain anthropometric data to evaluate the applicability of internationally designed implant and to generate a database for proximal femur to help in design for future implant if these were found unsuitable.

MEASUREMENTS

femoral head diameter, femoral neck diameter, diameter of proximal femur, canal width at above and below lesser trochanter and 7.5 cm below lower margin of lesser trochanter, endosteal and extracortical width, isthmus position from lesser trochanter, femoral neck anteversion, neck shaft angle and intramedullary axis of femur. The mean +/- SD of these values were calculated. These values were compared with those reported in the literature for Hong Kong Chinese, Caucasians and were found to be different. The implant designed for western population should be used judiciously and facture implant designed should be specific for (ours) bones. We found the pyriformis fossa is usually not in line with the intramedullary axis. Thus antegrade itramedullary nailing portal should be anterior and lateral to pyriformis fossa.

Measurement of acetabular cup anteversion with the circle theorem

OBJECTIVE

Malposition of the acetabular cup is the major risk factor of dislocation after total hip arthroplasty. Postoperatively, measuring of acetabular cup anteversion is very difficult. The new method for measuring acetabular cup anteversion on the plain radiograph of the hip with one of the circle theorems in the basic geometry was created.

MATERIAL AND METHOD

An all-polyethylene acetabular cup with known angle of radiographic anteversion was mouthed to the pelvic bone. Antero-posterior hip and pelvis radiographs were taken with the cup in randomly 15 different angles of anteversion. These were reviewed by 3 orthopedic residents. All data from 3 observers were collected and examined for the accuracy, inter-observers reliability and intra-observer reliability of this method. Two films (AP radiograph of the hip and the pelvis) method was used for distinguish between anteversion and retroversion.

RESULTS

The measurements of radiographic anteversion have the accuracy of plus or minus 2 degrees. The reliability coefficients of inter-observer variation in the first and second measurements for all definitions of anteversion are high. Pair t-test showed no significant different between value of the first and the second measurements for all definitions in all observers. The intra- and inter-observer variations were 3 degrees or less for all definitions.

CONCLUSION

The Acetabular cup anteversion measurement using the circle theorem iseasily to perform with high accuracy and consistency for all definitions of cup anteversion.

Pressure characteristics at the stump/socket interface in transtibial amputees using an adaptive prosthetic foot

BACKGROUND

The technological advances that have been made in developing highly functional prostheses are promising for very active patients but we do not yet know whether they cause an increase in biomechanical load along with possibly negative consequences for pressure conditions in the socket. Therefore, this study monitored the socket pressure at specific locations of the stump when using a microprocessor-controlled adaptive prosthetic ankle under different walking conditions.

METHODS

Twelve unilateral transtibial amputees between 43 and 59 years of age were provided with the Proprio-Foot (Ossur) and underwent an instrumented 3D gait analysis in level, stair, and incline walking, including synchronous data capturing of socket pressure. Peak pressures and pressure time integrals (PTI) at three different locations were compared for five walking conditions with and without using the device's ankle adaptation mode.

FINDINGS

Highest peak pressures of 2.4 k Pa/kg were found for incline ascent at the calf muscle as compared to 2.1 k Pa/kg in level walking with large inter-individual variance. In stair ascent a strong correlation was found between maximum knee moment and socket pressure. The most significant pressure changes relative to level walking were seen in ramp descent anteriorly towards the stump end, with PTI values being almost twice as high as those in level walking. Adapting the angle of the prosthesis on stairs and ramps modified the pressure data such that they were closer to those in level walking.

INTERPRETATION

Pressure at the stump depends on the knee moments involved in each walking condition. Adapting the prosthetic ankle angle is a valuable means of modifying joint kinetics and thereby the pressure distribution at the stump. However, large inter-individual differences in local pressures underline the importance of individual socket fitting.

A resin acrylic and plaster solder index technique for realigning an ill-fitting fixed partial denture framework

A resin acrylic and plaster solder index technique is a simple, accurate, secure, and cost-effective way to intraorally realign an ill-fitting fixed partial denture framework. Once the fixed partial denture framework is sectioned and segments are found to fit, an intraoral index preserves the correct relationship among segments and holds castings together securely enough to avoid separating until they can be embedded in solder investment and soldered in the dental laboratory. This technique is described here, together with a literature review and a discussion of the technique's advantages relative to other indexing techniques and materials.

[Evaluation of quality of life following prosthetic replacement of the auricle]

INTRODUCTION

The assessment of quality of life (QOL) of patients is becoming increasingly important in the evaluation of the quality of care. Therefore, we examined the quality of life of patients treated with prostheses following loss of an auricle using a questionnaire.

PATIENTS AND METHODS

Of 18 patients (14 male, 4 female), 10 had lost an auricle due to a neoplasm, 2 traumatically, while 6 patients showed a congenital lack of an auricle. In order to measure the subjective quality of life we used a questionnaire compiled by the WHO (WHOQOL-BREF); we used a self-designed questionnaire for questions relating to the prostheses.

RESULTS

Analysis of the data of all patients with prostheses in comparison with the age-based general population showed a lower score value for quality of life, indicating a poorer quality of life. However, none of the differences were statistically significant. Patients with neoplasms achieved higher values compared with the age-based standard value; in contrast, the other patients showed lower values in nearly every respect. The gender-related analysis of the results showed a poorer quality of life for females than for males.

CONCLUSION

The reason for an auricle defect as well as patient gender influenced the subjective quality of life following prosthetic surgery. The overall acceptance of auricular prostheses can be considered good, especially among patients suffering from neoplasms. In order to be able to evaluate the results and compare the different working groups more sufficiently it would be desirable to use standardized test procedures and a larger patient collective.

The prevalence of occlusal disharmony and its associated causes in complete dentures

AIM

Occlusal disharmony is frequently observed among edentulous patients. With the side effects of occlusal disharmony in mind, the goal of this research was to investigate the prevalence of occlusal disharmony in inserted complete dentures and its associated causes.

METHODS AND MATERIALS

This cross-sectional study was conducted on 107 selected patients. Factors such as age, gender, ridge relationship on the articulator, occlusal scheme, and the performance of a clinical remount from patients' treatment records were investigated. The presence and/or status of any occlusal disharmony was determined by a calibrated prosthodontist extraorally and qualitatively. Occlusal disharmony is defined as the absence of simultaneous bilateral contacts between the opposing posterior teeth in centric relation. The prevalence of occlusal disharmony was determined and the roles of the aforementioned factors were studied and analyzed using a Chi-square analysis. The results were considered significant at p<0.05.

RESULTS

Out of 107 patients, 31 patients (28.8%) showed occlusal disharmony. No statistically significant relationship was found between occlusal disharmony and age, gender, ridge relationships, or occlusal scheme (p<0.5). Twenty-five (81%) out of 31 complete dentures with occlusal disharmony were not clinically remounted. There was a highly significant relationship between the absence of clinical remounting and occlusal disharmony (p<0.001).

CONCLUSION

Within the limits of this study, the prevalence of occlusal disharmony was noticeable. A randomized clinical trial is strongly recommended to investigate factors related to the incidence of occlusal disharmony.

CLINICAL SIGNIFICANCE

It is important to refine the occlusion of a complete denture after laboratory processing of the denture before it is delivered to the patient.

How reliable is an effective orifice area indexed chart?

BACKGROUND AND AIM OF THE STUDY

Patient-prosthesis mismatch (PPM) occurs when a valvular prosthesis is too small relative to the patient's body surface area (BSA). The presence of PPM results in increased transprosthetic gradients and may portend a worse prognosis. It has been shown that reliable effective orifice area (EOA) data can be used to accurately predict PPM, thus preventing its occurrence. The study aim was to assess the predictive abilities of an effective orifice area indexed (EOAI) chart--the Perimount Magna EOAI chart--in the prevention of PPM.

METHODS

A retrospective comparison of projected versus calculated EOA values and the predicted versus actual incidence of PPM was conducted. Forty patients with a Perimount Magna aortic bioprosthesis implanted between 1st January 2006 and 31st March 2009, were identified. The sensitivity, specificity, positive-predictive value (PPV) and negative predictive value (NPV) were each calculated using the Perimount Magna EOAI chart, to assess how well it could predict the incidence of postoperative PPM.

RESULTS

The Perimount Magna EOAI chart had a sensitivity of 35% for predicting postoperative PPM, and an NPV of 53%. The projected EOA-values were almost invariably larger than those actually measured; this resulted in a higher proportion of patients than in whom PPM was predicted preoperatively. This EOAI chart proved to be very specific, with specificity of 100% and a PPV of 100%.

CONCLUSION

The Perimount Magna EOAI chart, based on mean EOA data from a small echocardiographic cohort, represents a poor method of predicting and preventing PPM. Rather, EOAI charts should be based on reliable EOA data that reproducibly predict the expected EOA for that prosthesis.

Free vascularised osteocutaneous filet flap for covering, that permitted sensitive terminal weight-bearing by a thigh stump after transfemoral amputation

We covered a transfemoral amputation stump with a modified free filet flap including the calcaneus. The flap survived, resulting in lengthening of the femur, improved distal weight-bearing, preserved sensitivity of the stump, and the design of a prosthesis with terminal loading of the femur rather than an ischial contained prosthesis.

Using the theory of planned behaviour to develop an assessment of attitudes and beliefs towards prosthetic use in amputees

PURPOSE

To develop a questionnaire based on the theory of planned behaviour (TPB) to predict prosthetic use.

METHOD

In part one, 31 amputees over 50 years of age with peripheral arterial disease completed attitude items containing 27 bipolar adjectives and open-ended questions on behavioural, normative and control beliefs relating to using the prosthesis. Academic, clinical and patient experts (n = 12) identified bipolar adjectives with best face validity. In part two, 15 amputees completed three behavioural format questions relating to prosthetic use and were asked to indicate the easiest to answer.

RESULTS

Following the completion of the attitude items by the amputees and the expert panel review, 5 items remained (Cronbach's alpha = 0.87) with corrected item-total correlations ranging from 0.43 to 0.83. Modal behavioural beliefs concerned mobility (46.5%), independence (25.6%) and participation restrictions (16.3%), normative beliefs concerned family (33.3%), NHS staff (31.7%), friends (19.1%) and other patients (15.9%) and control beliefs concerned stairs (21.1%), slippery/rough surfaces (28.9%), disabled facilities (54.8%) and people helping (22.6%). In relation to part 2, an exact numerical report of hours and days of prosthetic use was found easiest to answer (73%).

CONCLUSIONS

Based on this qualitative and quantitative development work, the questionnaire contains five attitude items, six behavioural, eight normative, eight control belief items and two self-report questions of the behaviour.

Comparison of psychometric properties of the International Outcome Inventory for Hearing Aids (IOI-HA) in various studies Comparación de las propiedades psicométricas del Cuestionario Internacional de Resultados para Auxiliares Auditivos (IOI-HA) en varios estudios

The German translation of the International Outcome Inventory for Hearing Aids (IOI-HA) was used in a variety of studies including a retrospective mailing campaign and three field tests on recently launched hearing aids. The psychometric properties were compared with each other and with results of previous studies in the U.S.A, Wales, and the Netherlands. Like the English and the Dutch version, the German IOI-HA showed high internal consistency, and factor analyses as well as inter-item correlations indicated the existence of a two-dimensional scale. Furthermore, the IOI turned out to be a valid instrument for distinguishing satisfied and non-satisfied customers during the trial period of a hearing aid.

The subjective evaluation of the expansion time constant in single-channel wide dynamic range compression hearing instruments

The present study investigated the subjective evaluation of expansion time constants in single-channel wide dynamic range compression (WDRC) hearing instruments. Thirty participants utilized binaural WDRC hearing instruments for a two-week trial. Subjective evaluations were conducted by having each participant rate their satisfaction with the expansion time constant on a daily basis and by having each participant indicate their preferred expansion time constant following the completion of the two-week trial. Each change in expansion time constant significantly affected listener satisfaction; however, all time constants resulted in satisfactory performance. Of the users expressing a preference, 75% preferred fast-acting over slow-acting expansion. These findings suggest that dynamic expansion parameters play an important role in determining the effectiveness of the feature for a given listener.

Manufacturer Predicted And Measured REAR Values In Adult Hearing Aid Fitting: Accuracy And Clinical Usefulness

Audiologists may fit hearing aids using real-ear aided response (REAR) values predicted by manufacturer's fitting software, rather than actual measured REARs. This study examined how well one manufacturer's software was able to predict REARs for a DSP behind-the-ear product in 41 adults (N = 79 ears) under four conditions (two hearing loss configurations and two inputs). Results showed that for all ears tested, measured REAR values were significantly different from predicted for most of the audiometric frequencies for all four test conditions. Discrepancies between measured and predicted REAR values were greater in males' ears than females'. Few ears' REAR values (< or = 12%) were judged to be clinically similar to predicted. Results suggest audiologists should consider using individual real-ear measures in adult hearing aid fittings until manufacturer software is shown to accurately predict real-ear hearing aid performance.

A two-year longitudinal study of social support following amputation

PURPOSE

(1) To describe one aspect of social support, social integration, longitudinally for 2 years following lower limb amputation and (2) to explore the impact of social support on depression, pain interference, life satisfaction, mobility, and occupational functioning.

METHOD

Eighty-nine adults recruited from consecutive admissions to an orthopaedic surgery service completed telephone interviews 1, 6, 12 and 24 months following amputation surgery. Dependent variables included the Social Integration (SI) sub-scale of the Craig Handicap Assessment and Reporting Technique (CHART) and the Multidimensional Scale of Perceived Social Support (MSPSS).

RESULTS

There was a high level of SI among most persons following lower limb amputations that was relatively unchanged in the 2 years following surgery. However, mean levels of SI were lower in this group compared to a sample without disabilities. MSPSS scores were highly variable, ranging from almost no support to the maximum amount of support. MSPSS was an important concurrent predictor of pain interference, life satisfaction, and mobility, controlling for demographic and amputation-related factors. Baseline MSPSS predicted mobility and occupational functioning 6 months post-amputation, controlling for demographic and amputation-related factors.

CONCLUSIONS

Findings suggest that interventions aimed at improving the quality of social relationships after amputation may facilitate participation in activities.

Preliminary evidence of asymmetry in uncomfortable loudness levels after unilateral hearing aid experience: Evidence of functional plasticity in the adult auditory system

The aim of the study was to compare uncomfortable loudness levels (ULLs) in a group of adults before and after unilateral hearing aid experience. Twelve participants presented with a symmetrical hearing loss consistent with natural ageing. Pure tones were presented to each ear separately, commencing at 60 dB HL and increased in 5-dB step sizes until ULL was reached. The post-fitting ULLs were typically measured three years after fitting. Hearing thresholds were symmetrical and remained unchanged after fitting. Mean ULL values were symmetrical before fitting. The mean ULL values increased (i.e. greater tolerance) in both ears after fitting; however, the increase was greatest in the fitted ear: 14.5 and 7 dB at 2000-4000 Hz in the fitted and not-fitted ear, respectively. A separate two-factor repeated ANOVA (ear and frequency) was performed on the pre and post-fitting ULL data. There was no statistically significant difference for ear (p > 0.05) when comparing the pre-fitting ULLs. However, there was a statistically significant difference for ear (p < 0.01) when comparing post-fitting ULLs. The underlying mechanism for the asymmetry is unknown but it is consistent with learning induced reorganization within the auditory system.

Amputation rehabilitation and prosthetic restoration. From surgery to community reintegration

PURPOSE

The purpose of this review is to summarize the literature related to the advances that have taken place in the management and rehabilitation care of limb amputation.

RESULTS

Prostheses for the lower and upper limb amputee have changed greatly over the past several years, with advances in components, socket fabrication and fitting techniques, suspension systems and sources of power and electronic controls. Higher levels of limb amputation can now be fitted with functional prostheses, which allow more patients to achieve independent life styles. This is of particular importance for the multi-limb amputee. The rehabilitation of more traditional lower limb levels of amputation have also greatly benefited from the technological advances including energy storing feet, electronic control hydraulic knees, ankle rotators and shock absorbers to mention a few. For the upper limb amputee, myoelectric and proportional controlled terminal devices and elbow joints are now used routinely in some rehabilitation facilities. Experimental prosthetic fitting techniques and devices such as the use of osseo-implantation for suspension of the prosthesis, tension control hands or electromagnetic fluids for knee movement control will also be briefly discussed in this paper.

CONCLUSION

It is possible to conclude from this review that many advances have occurred that have greatly impacted the functional outcomes of patients with limb amputation.

Comparison of two adaptive procedures for fitting a multi-channel compression hearing aid

We compared two adaptive procedures for fitting a multi-channel compression hearing aid. "Camadapt" uses judgements of the loudness of speech stimuli and the tonal quality of music stimuli. "Eartuner" uses judgements of the loudness and clarity of speech stimuli with differing spectral characteristics. Sixteen new users of hearing aids were fitted unilaterally, using each procedure. The fittings were assigned to Programs 1 and 2 in the aid, in a counter-balanced order. Subjects kept a diary of their experiences with each program in everyday life. Following 2-4 weeks of experience, they filled in the APHAB and other questionnaires and were re-fitted using both procedures. Camadapt generally led to higher low-level gains and lower high-level gains than Eartuner. Gains recommended by the procedures did not change following experience. Eight subjects preferred the Camadapt fitting and eight preferred the Eartuner fitting. Most subjects gave high overall satisfaction ratings for both procedures. Test-retest reliability was better for Eartuner than for Camadapt. Preference for the Camadapt fitting was associated with slightly better speech communication with Camadapt, while preference for the Eartuner fitting was associated with fewer problems with aversion for that procedure.

Examination of differences between successful and unsuccessful elderly hearing aid candidates matched for age, hearing loss and gender: Evaluación de las diferencias entre los candidatos exitosos y no exitosos de edad mayor, al uso de auxiliar auditivo por edad, grado de hipoacusia y sexo

This study examined group differences on a variety of measures for three groups of elderly hearing aid candidates matched for gender, age and hearing loss. These three groups were: (1) 26 candidates who declined amplification (non-adherents); (2) 24 individuals who purchased hearing aids, but subsequently returned them (rejected HA); and (3) 26 who purchased hearing aids and continued to use their hearing aids for at least the first 6 months following delivery (accepted HA). Following demonstration of adequate reliability for these measures, using the non-adherents as the test retest study sample, group differences were examined for each pre-fit measure. The group of non-adherents who declined amplification differed from the two groups who purchased hearing aids on their scores for the Hearing Handicap Inventory for the Elderly (HHIE) and for several scales of the Communication Profile for the Hearing Impaired (CPHI) that assessed the individual's personal adjustment to hearing impairment. These findings were generally confirmed for the individual data, with the use of discriminant analysis. For the two groups who tried hearing aids, there were no group differences between those who retained them and those who did not. Discriminant analysis, however, indicated that those in the group who retained their (linear) hearing aids tended to have better finger dexterity and higher loudness discomfort levels than those who did not.

Fitting range of the BAHA Cordelle

The performance of the most powerful Bone-Anchored Hearing Aid (BAHA) currently available, the BAHA Cordelle, was evaluated in 25 patients with severe to profound mixed hearing loss. Patients showed bone conduction thresholds at 500, 1000 and 2000 Hz, ranged between 30 and 70 dB HL, and an additional air-bone gap of about at least 30 dB. With the BAHA Cordelle, free-field thresholds improve relative to bone-conduction thresholds with 1.5, 5.0, 17.8, and 4.3 dB at 500, 1000, 2000, and 4000 Hz, respectively, with substantial inter-individual variability. The differences in unaided air conduction thresholds and aided free-field thresholds amount to 45.3, 45.8, 47.5, and 43.5 dB at 500, 1000, 2000, and 4000 Hz, respectively. Speech perception, measured both with monosyllables of the consonant-vowel-consonant type and with bisyllables, showed highly similar results. The fitting range of a (linear) hearing aid is determined by its gain characteristics. Requiring aided speech reception thresholds at or better than 65 dB SPL results in an upper limit of the fitting range of the BAHA Cordelle for bone-conduction thresholds of 51, 56, 67, and 58 dB HL at 500, 1000, 2000, and 4000 Hz, respectively. The dynamic range provided by the BAHA Cordelle was estimated from loudness growth functions at 500, 1500, and 3000 Hz employing 7-point categorical scaling. On average, aided loudness growth functions exhibit normal slopes but they level off at input levels of about 80, 70, 65 dB SPL for 500, 1500, and 3000 Hz stimuli, respectively. Measurements with a skull simulator demonstrated that the levelling-off reflects saturation of the output of the Cordelle. The relatively low saturation levels of the device suggest that increasing maximum output levels may be a worthwhile consideration for candidates with more profound sensorineural loss.

Clinical benefits and risks of bilateral amplification

Clinicians are in the unique position of continually developing a foundation of evidence-based practice each time they evaluate a patient. This is true not only in the field of audiology, but also in all healthcare professions. Typically, evidence-based practice (EBP) is assimilated from a combination of a systematic review of current practices, practitioner experience, academic training and ongoing continuing education through review of journals, textbooks and attendance at meetings as well as informal discussions with colleagues. Clinicians are inundated with information from these sources, and they need to extract the necessary information and apply it to their specific patient population. Evidence-based practice as it applies to the non-medical treatment of hearing loss (with hearing aids) will be discussed. In addition, several studies based on clinical observations are presented for discussion.

Comparison of three procedures for initial fitting of compression hearing aids. III. Inexperienced versus experienced users

We assessed whether gain requirements differ for experienced users and new users when fitted with multi-band compression hearing aids Three procedures for initial fitting were used: the Cambridge method for loudness equalization (CAMEQ), the Cambridge method for loudness restoration (CAMREST), and the desired sensation level input/output (DSL[i/o]) method. Twenty experienced hearing aid users and 20 new users with mild-to-severe sensorineural loss were fitted with Danalogic 163D digital hearing aids, using each procedure in turn in a counter-balanced order. The new users were given a pre-fitting with slightly reduced gains prior to the 'formal' fitting. Immediately after formal fitting with a given procedure, and 1 week after fitting, the gains were adjusted by the minimum amount necessary to achieve acceptable fittings. The amount of adjustment required provided the main measure of the adequacy of the initial fitting. On average, new users required decreases in gain for all procedures, the decreases being larger for DSL[i/o] than for CAMEQ or CAMREST. For experienced users, gain adjustments were small for CAMEQ and CAMREST, but were larger and mostly negative for DSL[i/o]. After these gain adjustments, users wore the aids for at least 3 weeks before filling out the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire and taking part in laboratory measurements of the speech reception threshold (SRT) for sentences in quiet and in steady and fluctuating background noise at levels of 60 and 75 dBSPL. The scores on the APHAB test and the SRTs did not differ significantly for the three procedures. We conclude that the CAMEQ and CAMREST procedures provide more appropriate initial fittings than DSL[i/o]. For inexperienced users, gains typically need to be reduced by about 3dB relative to those prescribed by CAMEQ or CAMREST, although the amount of reduction may depend on hearing loss. An analysis of gain adjustments as a function of order of testing provided some evidence for increased tolerance to high-frequency amplification with increasing experience during the 4-month course of the trial, but this effect did not differ for the experienced and new users.