Ten years of experience with the Ponto bone-anchored hearing system-A systematic literature review

Provision of bone conduction hearing implants in England in adults and children: a review of Hospital Episode Statistics data 2012-2021

OBJECTIVE

Bone conduction hearing implants are a well-established method of hearing rehabilitation in children and adults. This study aimed to review any changes in provision in England.

METHODS

The total number of bone conduction hearing implantations performed was analysed from 2012 to 2021 utilising Hospital Episode Statistics data for England.

RESULTS

The total number of procedures has increased by 58 per cent. One-stage bone conduction hearing implantations in adults accounts for the largest proportion of this increase (93 per cent of the total). The number performed in children has remained stable and accounts for 73 per cent (n = 433) of all two-stage procedures.

CONCLUSION

The data show that bone conduction hearing implant surgery is becoming increasingly popular, particularly in adults. This has correlated with the increase in availability, national recommendations and choice of devices.

Complications and audiological results of percutaneous bone-anchored hearing devices

OBJECTIVE

To describe the post-operative complications and audiological results related to percutaneous bone-anchored hearing devices.

METHODS

A retrospective review was conducted of 44 patients with bilateral conductive or mixed hearing loss who were implanted with unilateral Baha Connect or Ponto devices. A generalised linear model for repeated measurements was used.

RESULTS

Twenty patients were Baha Connect users, and 24 were implanted with Ponto devices. Twenty-seven patients experienced complications. No fewer complications were found in the group of patients using longer abutments. When we compared the frequency of complications between Ponto and Baha Connect users, there was no statistically significant difference (p = 0.90). Free-field hearing thresholds were statistically significantly improved when we compared pre- and post-operative results (p < 0.001). Average speech perception also improved (p < 0.001).

CONCLUSION

Despite percutaneous bone-anchored hearing devices having a high rate of complications, they provide significant audiological benefits.

Post-implantation clinical cost analysis between transcutaneous and percutaneous bone conduction devices

INTRODUCTION

Bone conduction devices (BCD) are effective for hearing rehabilitation in patients with conductive and mixed hearing loss or single-sided deafness. Transcutaneous bone conduction devices (tBCD) seem to lead to fewer soft tissue complications than percutaneous BCDs (pBCD) but have other drawbacks such as MRI incompatibility and higher costs. Previous cost analyses have shown a cost advantage of tBCDs. The purpose of this study is to compare long-term post-implantations costs between percutaneous and transcutaneous BCDs.

MATERIALS AND METHODS

Retrospective data from 77 patients implanted in a tertiary referral centre with a pBCD (n = 34), tBCD (n = 43; passive (tpasBCD; n = 34) and active (tactBCD; n = 9) and a reference group who underwent cochlear implantation (CI; n = 34), were included in a clinical cost analysis. Post-implantation costs were determined as the sum of consultation (medical and audiological) and additional (all post-operative care) costs. Median (cumulative) costs per device incurred for the different cohorts were compared at 1, 3 and 5 years after implantation.

RESULTS

After 5 years, the total post-implantation costs of the pBCD vs tpasBCD were not significantly different (€1550.7 [IQR 1174.6-2797.4] vs €2266.9 [IQR 1314.1-3535.3], p = 0.185), nor was there a significant difference between pBCD vs tactBCD (€1550.7 [1174.6-2797.4] vs €1428.8 [1277.3-1760.4], p = 0.550). Additional post-implantation costs were significantly highest in the tpasBCD cohort at all moments of follow-up.

CONCLUSION

Total costs related to post-operative rehabilitation and treatments are comparable between percutaneous and transcutaneous BCDs up to 5 years after implantation. Complications related to passive transcutaneous bone conduction devices appeared significantly more expensive after implantation due to more frequent explantations.

Minimally invasive surgery as a new clinical standard for bone anchored hearing implants-real-world data from 10 years of follow-up and 228 surgeries

Purpose

To explore the clinical practice development of different surgical techniques when installing bone-anchored hearing implants and their associated trends in outcomes.

Design

Retrospective study of 228 bone-anchored hearing implants in 200 patients, performed over a 10-year period between 2012 and 2022 in a referral hospital.

Method

Real-world data of demography, etiology, surgical setup, complications, and audiological outcomes were collected. Eligibility criteria from clinical practice were applied.

Results

The minimally invasive technique is associated with shorter surgery duration, 20 vs. 44 min as compared to a linear incision technique. The minimally invasive technique was also associated with a lower occurrence of complications when compared to linear incision techniques (intraoperative; 1.8% vs. 4.9%, postoperative; 49% vs. 66%). Most differences were seen in complications relating to skin and wound healing.

Conclusion

Adoption of a minimally invasive surgical technique for the installations of bone-anchored hearing implants can reduce surgical complexity without compromising safety aspects or clinical benefits.

Comparative analysis between effective gain and functional gain in bone-anchored hearing aid users

BACKGROUND

The cases of ear malformations, conductive, mixed, and single-sided deafness hearing loss are candidates for surgery and use of Bone-Anchored Hearing Aids (BAHA). Commonly, the literature highlights two procedures to assess the benefits and characteristics of amplification in users: functional gain (FG) and effective gain (EG).

OBJECTIVE

Estimate and compare the EG and the FG to evaluate the benefits obtained by users of BAHA and, later, to compare tests of speech perception in silence and in noise.

METHODOLOGY

The sample (n=79) was divided into four groups, implanted from February 2014 to February 2021. The following tests were analyzed: pure-tone audiometry by air and bone; research of audiometric thresholds in free field; speech perception tests in silence and in noise.

RESULTS

EG presented lower values than FG in all frequencies. The positive results of the speech perception tests were correlated with worse FG values. EG is the best method for evaluation, as it allows a proper comparison between devices, as well as a comparison with the prescription of validated rules.

CONCLUSIONS

A better evaluation of results was observed on the EG values, indicating that it is a relevant method to assess auditory performance. In addition, the FG results were incompatible with the benefits obtained in the speech perception tests, showing that it is not a reliable tool for monitoring the results with the use of BAHA.

Task force Guideline of Brazilian Society of Otology - hearing loss in children - Part II - Treatment

OBJECTIVES

To provide an overview of the main evidence-based recommendations for the diagnosis of hearing loss in children and adolescents aged 0-18 years.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on childhood hearing loss were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) treatment of sensorineural hearing loss: individual hearing aids, bilateral cochlear implants, cochlear implants in young children, unilateral hearing loss, and auditory neuropathy spectrum disorder; and (2) treatment of conductive/mixed hearing loss: external/middle ear malformations, ventilation tube insertion, and tympanoplasty in children.

CONCLUSIONS

In children with hearing loss, in addition to speech therapy, Hearing AIDS (HAs) or implantable systems may be indicated. Even in children with profound hearing loss, both the use of HAs and behavioral assessments while using the device are important.

An objective bone conduction verification tool using a piezoelectric thin-film force transducer

All hearing aid fittings should be validated with appropriate outcome measurements, whereas there is a lack of well-designed objective verification methods for bone conduction (BC) hearing aids, compared to the real-ear measurement for air conduction hearing aids. This study aims to develop a new objective verification method for BC hearing aids by placing a piezoelectric thin-film force transducer between the BC transducer and the stimulation position. The newly proposed method was compared with the ear canal method and the artificial mastoid method through audibility estimation. The audibility estimation adopted the responses from the transducers that correspond to the individual BC hearing thresholds and three different input levels of pink noise. Twenty hearing-impaired (HI) subjects without prior experience with hearing aids were recruited for this study. The measurement and analysis results showed that the force transducer and ear canal methods almost yielded consistent results, while the artificial mastoid method exhibited significant differences from these two methods. The proposed force transducer method showed a lower noise level and was less affected by the sound field signal when compared with other methods. This indicates that it is promising to utilize a piezoelectric thin-film force transducer as an in-situ objective measurement method of BC stimulation.

Evaluation of the Benefits of Bilateral Fitting in Bone-Anchored Hearing System Users: Spatial Resolution and Memory for Speech

OBJECTIVES

The purpose of this study was to evaluate the benefits of bilateral implantation for bone-anchored hearing system (BAHS) users in terms of spatial resolution abilities and auditory memory for speech.

DESIGN

This is a prospective, single-center, comparative, single-blinded study where the listeners served as their own control. Twenty-four experienced bone-anchored users with a bilateral conductive or mixed hearing loss participated in the study. After fitting the listeners unilaterally and bilaterally with BAHS sound processor(s) (Ponto 3 SuperPower), spatial resolution was estimated by measuring the minimum audible angle (MAA) to achieve an 80% correct response via a two-alternative-forced choice task (right-left discrimination of noise bursts) in two conditions: both sound processors active (bilateral condition) and only one sound processor active (unilateral condition). In addition, a memory recall test, the Sentence-final Word Identification and Recall (SWIR) test was performed with five lists of seven sentences for each of the two conditions (unilateral and bilateral). Self-reported performance in everyday life with the listener's own sound processors was also evaluated via a questionnaire (the abbreviated version of the Speech, Spatial and Qualities of Hearing scale).

RESULTS

The MAA to discriminate noise bursts improved significantly from 75.04° in the unilateral condition to 3.61° in the bilateral condition ( p < 0.0001). The average improvement in performance was 54.28°. The SWIR test results showed that the listeners could recall, on average, 55.03% of the last words in a list of seven sentences in the unilateral condition and 57.23% in the bilateral condition. While the main effect of condition was not significant, there was a significant interaction between condition and repetition (list), revealing a significantly higher recall performance in the bilateral condition than in the unilateral condition for the second repetition/list out of five (10.2% difference; p = 0.022). Self-reported performance with bilateral BAHS obtained via the Speech, Spatial and Qualities of Hearing scale questionnaire was, on average, 4.4 for speech, 3.7 for spatial, and 5.1 for qualities of hearing. There was no correlation between self-reported performance in everyday life and bilateral performance in the MAA test, while significant correlations were obtained between self-reported performance and recall performance in the SWIR test.

CONCLUSIONS

These results showed a large benefit in spatial resolution for users with symmetric BC thresholds when being fitted with two BAHS, although their self-reported performance with bilateral BAHS in everyday life was rather low. In addition, there was no overall benefit of bilateral fitting on memory for speech, despite observing a benefit in one out of five repetitions of the SWIR test. Performance in the SWIR test was correlated with the users' self-reported performance in everyday life, such that users with higher recall ability reported to achieve better performance in real life. These findings highlight the advantages of bilateral fitting on spatial resolution, although bilaterally fitted BAHS users continue to experience some difficulties in their daily lives, especially when locating sounds, judging distance and movement. More research is needed to support a higher penetration of bilateral BAHS treatment for bilateral conductive and mixed hearing losses.

Non-invasive sampling procedure revealing the molecular events at different abutments of bone-anchored hearing systems–A prospective clinical pilot study

Purpose

To investigate the molecular activities in different compartments around the bone-anchored hearing system (BAHS) with either electropolished or machined abutments and to correlate these activities with clinical and microbiological findings.

Materials and methods

Twelve patients received machined or electropolished abutments after implant installation of BAHS. Peri-abutment fluid and tissue were collected from baseline to 12 months. Gene expression of cytokines and factors related to tissue healing and inflammation, regeneration and remodelling, as well as bacterial recognition were determined using quantitative-polymerase chain reaction (qPCR). The clinical status was evaluated using the Holgers scoring system, and bacterial colonisation was investigated by culturing.

Results

The gene expression of inflammatory cytokines (IL-8, IL-1β, and IL-10) and bacteria-related Toll-like receptors (2 and 4) was higher in the peri-abutment fluid than at baseline and in the peri-abutment tissue at 3 and 12 months. Conversely, the expression of genes related to tissue regeneration (Coll1a1 and FOXO1) was higher in the tissue samples than in the peri-abutment fluid at 3 and 12 months. Electropolished abutments triggered higher expression of inflammatory cytokines (IL-8 and IL-1β) (in peri-abutment fluid) and regeneration factor FOXO1 (in peri-abutment tissue) than machined abutments. Several cytokine genes in the peri-abutment fluid correlated positively with the detection of aerobes, anaerobes and Staphylococcus species, as well as with high Holger scores.

Conclusion

This study provides unprecedented molecular information on the biological processes of BAHS. Despite being apparently healed, the peri-abutment fluid harbours prolonged inflammatory activity in conjunction with the presence of different bacterial species. An electropolished abutment surface appears to be associated with stronger proinflammatory activity than that with a machined surface. The analysis of the peri-abutment fluid deserves further verification as a non-invasive sampling and diagnostic procedure of BAHS.

Comparison of two different bone anchored hearing instruments

PURPOSE

To compare the audiological performances of Turkey's most up-to-date bone conduction implant processors.

METHODS

Twenty-six bone-anchored hearing instrument users, thirteen in each group, were evaluated for speech understanding in quiet and several signal-to-noise ratios.

RESULTS

We noticed the differences at 0.5 and 1 kHz measurements in free field frequency specific test, aided SRT scores, non-adaptive and adaptive matrix test results for a few conditions created a statistically significant difference in favor of Baha-6^®.

CONCLUSIONS

Both processors offer positive gains to their users in noisy and silent conditions. However, the data showed statistically significant differences for some measurements that may be critical for patients in daily practice.

The Oticon Ponto System in Adults With Severe-to-Profound and Mixed Hearing Loss: Audiologic Outcomes and Patient Satisfaction

OBJECTIVE

To measure audiologic outcomes and self-assessed satisfaction with the Ponto system in a group of patients who had severe to profound and mixed hearing loss.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Sixteen patients aged 21 to 74 years with severe-to-profound and mixed hearing loss (bone conduction thresholds, ≥45 dB HL).

INTERVENTIONS

Ponto implant surgery.

MAIN OUTCOME MEASURES

Pure-tone audiometry, free-field hearing thresholds, effective gain, word recognition score in quiet, and speech reception threshold (SRT) in noise were assessed. Patient-reported outcomes were collected using the Clinical Global Impression Scale, Glasgow Benefit Inventory, and Abbreviated Profile of Hearing Aid Benefit. Information concerning any medical complications was also gathered.

RESULTS

Both word recognition score and SRT were significantly better after 12 months compared with before surgery. At normal speech level (65 dB SPL), 12 of 16 users had speech discrimination ≥70%. However, at the 12-month follow-up, the average effective gain was -6.2 dB. In general, the self-report outcomes showed good satisfaction in most patients. Postoperatively, skin complications were noted in six patients, of whom two underwent reoperation. All patients were still using the Ponto after an average observation time of 2.7 years.

CONCLUSION

Although skin complications were not uncommon, the Ponto system seems to be an effective method of improving hearing performance and provides subjective satisfaction in real-life situations in patients with severe-to-profound and mixed hearing loss. However, considering the significantly increased bone conduction thresholds and the risk of their further deterioration, long-term follow-up is still needed.

Hearing outcomes in children with single sided deafness: Our experience at a tertiary paediatric otorhinolaryngology unit

INTRODUCTION

Hearing rehabilitation options for single sided deafness (SSD) include contralateral routing of sound (CROS) aids and bone conduction devices (BCDs). This study aimed to review the management of children with SSD at our tertiary paediatric otolaryngology unit over the last 15 years.

MATERIAL AND METHODS

A retrospective cohort study was performed. Primary hearing outcomes were measured using the Children's Home Inventory for Listening Difficulties (CHILD) questionnaire score and secondary hearing outcomes were measured using hearing thresholds for speech in noise. Outcomes were measured pre and post bone conduction device (BCD) trial.

RESULTS

49 patients with SSD were identified. 20 children had trial of a BCD. 16 patients had pre- and post- BCD trial CHILD scores available for analysis. There was a statistically significant improvement in CHILD scores and speech in noise testing at +5 dB and +0 dB following amplification with a BCD. The mean use of BCD was 1.3 h per day.

DISCUSSION

We have described the management of children with SSD in our unit. This study demonstrated a statistically significant benefit of BCD use on hearing outcomes. However, device compliance is low suggesting hearing advice choice in the population is complex and further research is warranted.

Long-term osseointegration of laser-ablated hearing implants in sheep cranial bone

Osseointegration, the ability for an implant to be anchored in bone tissue with direct bone-implant contact and allowing for continuous adaptive remodelling, is clinically used in different reconstructive fields, such as dentistry, orthopedics and otology. The latter uses a bone conducting sound processor connected to a skin-penetrating abutment that is mounted on a titanium implant placed in the temporal bone, thereby acting as a path for transmission of the vibrations generated by the sound processor. The success of the treatment relies on bone healing and osseointegration, which could be improved by surface modifications. The aim of this study was to evaluate the long-term osseointegration in a sheep skull model and compare a laser-ablated implant surface with a machined implant. Commercially available 4 mm titanium implants, either with a machined (Wide Ponto) or a laser-ablated surface (Ponto BHX, Oticon Medical, Sweden), were used in the current study. The surfaces were evaluated by scanning electron microscopy. The implantation was performed with a full soft tissue flap and the osteotomy was prepared using the MIPS drill kit (Oticon Medical, Sweden) prior to installation of the implants in the frontal bone of eight female sheep. After five months, biopsies including the implant and surrounding bone tissue obtained, processed and analysed using histology, histomorphometry, scanning electron microscopy and Raman spectroscopy. The animals healed well, without signs of adverse events. Histomorphometry showed a large amount of bone tissue around both implant types, with 75% of the threaded area occupied by bone for both implant types. A large amount of bone-implant contact was observed for both implant types, with 67%–71% of the surface covered by bone. Both implant types were surrounded by mature remodelled lamellar bone with high mineral content, corroborating the histological observations. The current results show that the laser-ablated surface induces healing similar to the well-known clinically used machined surface in ovine cranial bone. In conclusion, the present long-term experimental results indicate that a laser-ablated implant performs equally well as a clinically used implant with a machined surface. This, together with previously reported, improved early biomechanical anchorage, suggests future, safe and efficient clinical potential.

Ex vivo Evaluation of a New Drill System for Placement of Percutaneous Bone Conduction Devices

The procedure for installation of a percutaneous bone-conducting device has undergone significant improvements since its introduction 40 years ago. Today, the linear incision technique with tissue preservation (LITT-P) and the minimally invasive procedure (MIPS) are the most commonly used approaches. In both these techniques, a gradual increase of the osteotomy using a three-step drilling sequence is utilized, as this approach can allow a stepwise deepening and widening of the osteotomy in the mastoid and can prevent bone overheating. A new minimally invasive procedure (MONO) has been developed that allows an osteotomy to be performed and enables complete removal of the bone volume in one single drill step for a 4 mm implant using a novel parabolic twist drill. Here, the feasibility of the MONO procedure was qualitatively and quantitatively evaluated in terms of the dura response to drill trauma in comparison with the outcomes achieved with guide drills used for the LITT-P and MIPS techniques. Fresh frozen temporal bone from a human cadaver was subjected to penetration by three drills beyond the base of the mastoid bone to different depths. The sites were evaluated, and the damage to and possible penetration of the dura were determined. The results showed that for a drill depth exceeding mastoid bone thickness by not more than 1 mm, damage to the dura was limited or nonexistent, whereas for a drill depth exceeding bone thickness by 2 mm, damage increased, or the dura was penetrated. There was a trend toward more damage and penetration for both the round burr and MIPS guide drill compared with the MONO drill bit. From this experimental ex vivo study, it can be concluded that if the dura is encountered, the MONO system is not more inclined to penetrate the dura than the conventional LITT-P and MIPS systems.

Power output and hearing performance in osseointegrated auditory devices

BACKGROUND AND OBJECTIVE

Osseointegrated auditory devices are hearing gadgets that use the bone conduction of sound to produce hearing improvement. The mechanisms and factors that contribute to this sound transmission have been widely studied, however, there are other aspects that remain unknown, for instance, the influence of the processor power output. The aim of this study was to know if there is any relationship between the power output created by the devices and the hearing improvement that they achieve.

MATERIALS Y METHODS

44 patients were implanted with a percutaneous Baha® 5 model. Hearing thresholds in pure tone audiometry, free-field audiometry, and speech recognition (in quiet and in noise) were measured pre and postoperatively in each patient. The direct bone conduction thresholds and the power output values from the processors were also obtained.

RESULTS

The pure tone average threshold in free field was 39.29 dB (SD = 9.15), so that the mean gain was 29.18 dB (SD = 10.13) with the device. This involved an air-bone gap closure in 63.64% of patients. The pure tone average threshold in direct bone conduction was 27.6 dB (SD = 10.91), which was 8.4 dB better than the pure tone average threshold via bone conduction. The mean gain in speech recognition was 39.15% (SD = 23.98) at 40 dB and 36.66% (SD = 26.76) at 60 dB. The mean gain in the signal-to-noise ratio was -5.9 dB (SD = 4.32). On the other hand, the mean power output values were 27.95 dB µN (SD = 6.51) in G40 and 26.22 dB µN (SD = 6.49) in G60. When analysing the relationship between bone conduction thresholds and G40 and G60 values, a correlation from the frequency of 1000 Hz was observed. However, no statistically significant association between power output, functional gain or speech recognition gain was found.

CONCLUSIONS

The osseointegrated auditory devices generate hearing improvement in tonal thresholds and speech recognition, even in noise. Most patients closed the air-bone gap with the device. There is a direct relationship between the bone conduction threshold and the power output values from the processor, but only in mid and high frequencies. However, the relationship between power output and gain in speech recognition is weaker. Further investigation of contributing factors is necessary.

Clinical Evaluation of a Novel Laser-Ablated Titanium Implant System for Bone Anchored Hearing Systems in a Pediatric Population and the Relationship of Resonance Frequency Analysis With Implant Survival

OBJECTIVE

To evaluate the clinical outcomes of pediatric patients implanted a novel 4.5 mm wide laser ablated titanium bone anchored implant system and to evaluate the implant stability over the first 12-month period.

STUDY DESIGN

A prospective, single-subject, repeated measure, cohort study. Participants served as their own controls.

SETTING

Community and tertiary referral hospital pediatric assessment center.

PATIENTS

A total of 115 consecutive pediatric patients aged 4 to 15 years were implanted with 176 laser ablated titanium bone anchored implants from January 2016 to January 2019.

MAIN OUTCOME MEASURE

Clinical outcomes, implant failure rates, and post implantation implant stability quotient (ISQ) scores were studied over the first 12-month period. Data were analyzed for statistical significance through mixed effect modeling, with the significance level p = 0.01.

RESULTS

A median 12-month survival of 96.6% was observed. Six implants (3.5%) were lost in total, one of these (0.6%) was lost due to trauma. Adverse skin reactions (Holgers grade 2-4) were observed in 4.4% of all postoperative visits, occurring in 22 individuals (19.1%). Neither the ISQ high (ISQH) nor ISQ low (ISQL) values increased significantly between the stage 1 and 2 surgeries. In contrast, the ISQ results, irrespective of abutment size, demonstrated an increasing trend from 49.1 to 57 over the 12 months review period. A statistically significant change was only demonstrated from the 3 months follow up onwards.

CONCLUSION

The use of 4.5 mm wide laser-ablated titanium bone anchored hearing implants resulted in superior survival rates and excellent clinical outcomes compared with previous implant systems.

Achieving stomal continence with an ileal pouch and a percutaneous implant

In this study, a soft-tissue-anchored, percutaneous port used as a mechanical continence-preserving valve in reservoir ileo- and urostomies was functionally and morphologically evaluated in eight dogs. During follow-up, the skin failed to attach to the implant, but the intestine inside the stoma port appeared to be attached to the mesh. After reaching adequate reservoir volume, the urostomies were rendered continent by attaching a lid to the implant. The experiments were ended at different time intervals due to implant-related adverse events. In only one case did the histological evaluation reveal integration at both the implant-intestine and implant-skin interfaces, with a low degree of inflammation and the absence of bacterial colonisation. In the remaining cases, integration was not obtained and instead mucosal downgrowth and biofilm formation were observed. The skin-implant junction was characterised by the absence of direct contact between the epidermis and the implant. Varying degrees of epidermal downgrowth, granulation tissue formation, inflammatory cell infiltration and bacterial growth and biofilm formation were prominent findings. In contrast, the subcutaneously located anchor part of the titanium port was well integrated and encapsulated by fibrous tissue. These results demonstrate the opportunity to achieve integration between a soft-tissue-anchored titanium port, skin and intestine. However, predictable long-term function could not be achieved in these animal models due to implant- and non-implant-related adverse events. Unless barriers at both the implant-skin and implant-intestine junctions are created, epidermal and mucosal downward migration and biofilm formation will jeopardise implant performance.

Systematic and audiological indication criteria for bone conduction devices and active middle ear implants

Certain patients with conductive or mixed hearing loss can benefit from bone-conduction hearing devices or active middle ear implants. Available devices differ in coupling site, energy transfer from the sound processor to the implant, and the active or passive actuator technology. The audiological benefit of those devices depends on the maximum stable power output and the noise floor of the device, the degree and expected stability of the sensorineural hearing loss and the coupling efficiency with the aim on achieving a minumum of 30-35 dB effective dynamic range. The choice of the device is often a trade-off between the optimal audiological solution with respect to the hearing loss, technical device-related parameters and the expected coupling efficiency, the optimal surgical solution with respect to patho-anatomical aspects, device dimensions and the coupling site, invasiveness or surgical risks, and other patient factors with respect to the patients' wish and expectations, social aspects, device usability and connectivity. This review article lists all currently available implantable and conventional bone-conduction hearing devices and active middle ear implants with respect to technical features like maximum power output, market availability, and the expected effective output dynamic range.

Molecular Response to Nanopatterned Implants in the Human Jaw Bone

Implant surface modification by nanopatterning is an interesting route for enhancing osseointegration in humans. Herein, the molecular response to an intentional, controlled nanotopography pattern superimposed on screw-shaped titanium implants is investigated in human bone. When clinical implants are installed, additional two mini-implants, one with a machined surface (M) and one with a machined surface superimposed with a hemispherical nanopattern (MN), are installed in the posterior maxilla. In the second-stage surgery, after 6-8 weeks, the mini-implants are retrieved by unscrewing, and the implant-adherent cells are subjected to gene expression analysis using quantitative polymerase chain reaction (qPCR). Compared to those adherent to the machined (M) implants, the cells adherent to the nanopatterned (MN) implants demonstrate significant upregulation (1.8- to 2-fold) of bone-related genes (RUNX2, ALP, and OC). No significant differences are observed in the expression of the analyzed inflammatory and remodeling genes. Correlation analysis reveals that older patient age is associated with increased expression of proinflammatory cytokines (TNF-α and MCP-1) on the machined implants and decreased expression of pro-osteogenic factor (BMP-2) on the nanopatterned implants. Controlled nanotopography, in the form of hemispherical 60 nm protrusions, promotes gene expressions related to early osteogenic differentiation and osteoblastic activity in implant-adherent cells in the human jaw bone.

Output performance of the novel active transcutaneous bone conduction implant Sentio at different stimulation sites

OBJECTIVES

The output performance of a novel semi-implantable transcutaneous bone conduction device was compared to an established percutaneous bone-anchored hearing system device using cadaver heads. The influence of actuator position, tissue growth below the actuator and mounting it on the surface or in a flattened bone bed on the performance of the implanted actuator was investigated.

MATERIALS AND METHODS

The percutaneous and the new transcutaneous device were sequentially implanted at two sites in five human cadaver heads: 55 mm superior-posterior to the ear canal opening (position A) and, closer to the cochlea, about 20 mm inferior-posterior to the ear canal opening behind the pinna on the mastoid (position B). The ipsi- and contralateral cochlear promontory (CP) velocity magnitude responses to percutaneous and transcutaneous stimulation were measured using laser Doppler vibrometry. In addition, the CP vibration of the transcutaneous device placed directly on the skull bone surface was compared with the placement in a flattened bone bed at a depth of about 3 mm. Finally, the influence of placing a thin silicone interposition layer under the implanted transducer was also explored.

RESULTS

The percutaneous device provided about an 11 dB higher average CP vibration level than the transcutaneous device at frequencies between 0.5 and 10 kHz. The ipsilateral CP vibration responses with stimulations at position B were on average 13 dB higher compared to stimulation at position A. The placement of the transcutaneous transducer at position B provided similar or higher average vibration magnitudes than the percutaneous transducer at position A. The 3 mm deep flattened bone bed had no significant effects on the output performance. Placing a thin silicone layer under the transcutaneous transducer had no significant influence on the output of the transcutaneous device.

CONCLUSIONS

Our results using the CP vibration responses show that at frequencies above 500 Hz the new transcutaneous device at position B provides similar output levels as the percutaneous device at position A. The results also indicated that neither a bone bed for the placement of the transcutaneous transducer nor a simulated tissue growth between the actuator and the bone affect the output performance of the device.

Habitual caffeine intake affects implant osseointegration: An in vivo study

OBJECTIVES

This study aimed to evaluate the effect of habitual caffeine (CAF) intake on stability, bone regeneration, and expression of bone markers at the bone-implant interface.

BACKGROUND

Studies show that habitual CAF alters bone health and remodeling. Yet, there is no information regarding CAF effects on osseointegration of bone-anchored implants.

METHODS

Wistar rats were divided into two groups: one received tap drinking water alone (control) and the other received tap water with CAF (300 mg/L). After 12 weeks, their tibiae received screw-shaped titanium implants. After another 12 weeks, CAF (n = 5) and control (n = 5) animals were sacrificed and the implant stability was evaluated using a removal torque (RTQ) device. Thereafter, the implants were processed for gene expression analysis, and the implantation sites were harvested for histology. Implants with the surrounding bone were dissected en bloc and subjected to micro-computed tomography (micro-CT).

RESULTS

The results showed that implants in the CAF group had an 87% significant increase in RTQ compared to the control. Further, micro-CT revealed a higher proportion of mineralized bone filling the implant threads in the CAF group. The molecular analysis indicated higher expression of bone formation (ALP), remodeling (CatK), and vascularization (VEGF) genes in implant-adherent cells in the CAF group. Histology suggested increased vascularity in the tissue surrounding the implant in the CAF group.

CONCLUSIONS

Within the limit of this study, it is concluded that habitual CAF intake conveys a positive, promoting effect on long-term osseointegration. Clinical studies are worth pursuing to verify this experimental observation.

Power output and hearing performance in osseointegrated auditory devices

BACKGROUND AND OBJECTIVE

Osseointegrated auditory devices are hearing gadgets that use the bone conduction of sound to produce hearing improvement. The mechanisms and factors that contribute to this sound transmission have been widely studied, however, there are other aspects that remain unknown, for instance, the influence of the processor power output. The aim of this study was to know if there is any relationship between the power output created by the devices and the hearing improvement that they achieve.

MATERIALS AND METHODS

Forty-four patients were implanted with a percutaneous Baha® 5 model. Hearing thresholds in pure tone audiometry, free-field audiometry, and speech recognition (in quiet and in noise) were measured pre and postoperatively in each patient .The direct bone conduction thresholds and the power output values from the processors were also obtained.

RESULTS

The pure tone average threshold in free field was 39.29dB (SD 9.15), so that the mean gain was 29.18dB (SD 10.13) with the device. This involved an air-bone gap closure in 63.64% of patients. The pure tone average threshold in direct bone conduction was 27.6dB (SD 10.91), which was 8.4dB better than the pure tone average threshold via bone conduction. The mean gain in speech recognition was 39.15% (SD 23.98) at 40dB and 36.66% (SD 26.76) at 60dB. The mean gain in the signal-to-noise ratio was -5.9dB (SD 4.32). On the other hand, the mean power output values were 27.95dB μN (SD 6.51) in G40 and 26.22dB μN (SD 6.49) in G60. When analysing the relationship between bone conduction thresholds and G40 and G60 values, a correlation from the frequency of 1,000Hz was observed. However, no statistically significant association between power output, functional gain or speech recognition gain was found.

CONCLUSIONS

The osseointegrated auditory devices generate hearing improvement in tonal thresholds and speech recognition, even in noise. Most patients closed the air-bone gap with the device. There is a direct relationship between the bone conduction threshold and the power output values from the processor, but only in mid and high frequencies. However, the relationship between power output and gain in speech recognition is weaker. Further investigation of contributing factors is necessary.

Multimodal Analysis of the Tissue Response to a Bone-Anchored Hearing Implant: Presentation of a Two-Year Case Report of a Patient With Recurrent Pain, Inflammation, and Infection, Including a Systematic Literature Review

Osseointegration is a well-established concept used in applications including the percutaneous Bone-Anchored Hearing System (BAHS) and auricular rehabilitation. To date, few retrieved implants have been described. A systematic review including cases where percutaneous bone-anchored implants inserted in the temporal bone were retrieved and analyzed was performed. We also present the case of a patient who received a BAHS for mixed hearing loss. After the initial surgery, several episodes of soft tissue inflammation accompanied by pain were observed, leading to elective abutment removal 14 months post-surgery. Two years post-implantation, the implant was removed due to pain and subjected to a multiscale and multimodal analysis: microbial DNA using molecular fingerprinting, gene expression using quantitative real-time polymerase chain reaction (qPCR), X-ray microcomputed tomography (micro-CT), histology, histomorphometry, backscattered scanning electron microscopy (BSE-SEM), Raman spectroscopy, and fluorescence in situ hybridization (FISH). Evidence of osseointegration was provided via micro-CT, histology, BSE-SEM, and Raman spectroscopy. Polymicrobial colonization in the periabutment area and on the implant, including that with Staphylococcus aureus and Staphylococcus epidermidis, was determined using a molecular analysis via a 16S-23S rDNA interspace [IS]-region-based profiling method (IS-Pro). The histology suggested bacterial colonization in the skin and in the peri-implant bone. FISH confirmed the localization of S. aureus and coagulase-negative staphylococci in the skin. Ten articles (54 implants, 47 patients) met the inclusion criteria for the literature search. The analyzed samples were either BAHS (35 implants) or bone-anchored aural epitheses (19 implants) in situ between 2 weeks and 8 years. The main reasons for elective removal were nonuse/changes in treatment, pain, or skin reactions. Most samples were evaluated using histology, demonstrating osseointegration, but with the absence of bone under the implants’ proximal flange. Taken together, the literature and this case report show clear evidence of osseointegration, despite prominent complications. Nevertheless, despite implant osseointegration, chronic pain related to the BAHS may be associated with a chronic bacterial infection and raised inflammatory response in the absence of macroscopic signs of infection. It is suggested that a multimodal analysis of peri-implant health provides possibilities for device improvements and to guide diagnostic and therapeutic strategies to alleviate the impact of complications.

Ten years of experience with the Ponto bone-anchored hearing system-A systematic literature review

Background

Bone‐anchored hearing systems (BAHSs) are widely used for hearing rehabilitation and are indicated in cases of conductive and mixed hearing loss and in single‐sided deafness. The Ponto system, that is one available option, has been on the market since 2009.

Objective of review

The aim of this study is to systematically review the literature reporting on the Ponto system, with regard to audiological and surgical outcomes and patient's quality‐of‐life scores.

Type of review

A systematic literature search was performed in the PubMed database 2009‐July 2019.

Search strategy

Search term: ((osseointegrated hearing aid) OR (bone conduction implant) OR (bone anchored hearing) OR BAHA OR BAHS OR BAHI). Pre‐defined inclusion and exclusion criteria were applied.

Evaluation method

English‐language articles reporting original clinical data (audiological, surgical or quality‐of‐life outcomes) on the Ponto system were included.

Articles reporting on Ponto and another BAHS system where the results on Ponto constituted less than 50% of the patient population or including only results on testband or softband devices were excluded.

Results

Audiological outcomes were discussed in 20 publications. Improvement against the unaided thresholds was demonstrated. The functional improvement was on average 33.9 dB. The effective gain or remaining air‐bone gap was on average 6.7 dB. All evaluated data showed aided speech reception thresholds significantly below normal speech level. Twenty‐seven publications reported surgical and follow‐up data for the Ponto system. Implant survival was 97.7%, adverse skin reactions (Holgers ≥ 2) were 5% across visits and 15% across patients. No complications were life‐threatening, causing permanent disability/damage or requiring a hospitalisation. Five studies reported quality of life using the Glasgow benefit inventory, 98% reported an improvement when analysing the score on an individual level.

Conclusions

The outcomes of this systematic review confirm that percutaneous systems provide consistent audiological benefits and improved quality of life for patients. Further, the review demonstrates that the percutaneous systems are safe, with relatively low complication rates. Skin‐related complications are the most common complication type and are experienced by approximately one patient out of seven, or in less than one of 20 follow‐up visits.