Resonance frequency analysis of osseo-integrated implants for bone conduction in a pediatric population - a novel approach for assessing stability for early loading.

OBJECTIVES: The purpose of our study was to directly measure the stability of a bone anchored hearing device (BAHD) abutment using resonance frequency analysis (RFA) in a pediatric population. RFA was used to guide early loading of the abutment following single stage surgery. METHODS: The principle behind RFA is to obtain a numerical value relating to stability. A Smartpeg (1 cm commercially manufactured attachment) is screwed onto the abutment - its resonance in a magnetic field is measured with an Osstell recording device. The degree of movement (vibration) is inversely proportional to the stability of the abutment and a numerical figure, the Implant Stability Quotient (ISQ), is derived. RFA measurements were obtained at surgery, 4 weeks and 16 weeks post implant surgery. Patients were fitted with the new CochlearTM Baha(®) BI300 series implant using a one-stage procedure and based on RFA stability measures, loading of the sound processor occurred any time from 1 week after implant surgery if the RFA measure was 60 units or over. RESULTS: Twenty two consecutive patients were recruited. Eight patients had bilateral BAHD's fitted giving a total of 30 implants. The age range was 2-16 years with an average age of 9 years at time of fitting. The time interval from surgery to loading the processor ranged from 1 to 16 weeks, with an average time of 6 weeks. The mean ISQ value at time of surgery was 61.29 (95% CI = 2.03), at 4 weeks was 61.92 (95% CI = 2.97) and at 16 weeks was 63.45 (95% CI = 3.18). CONCLUSIONS: Our study shows we have been able to operate a successful program of earlier BAHD loading using single stage surgery in children. This is supported by favorable RFA measures of implant stability with average ISQ values of over 60 units.

Evidence for early loading of osseointegrated implants for bone conduction at 4 weeks.

INTRODUCTION: The purpose of our study was to directly measure the stability of the abutment using resonance frequency analysis (RFA) and to report on the change in stability over time for implants loaded 4 weeks postoperatively. MATERIALS AND METHODS: The principle behind RFA is to obtain a numerical value relating to stability. The Osstell RFA recording device measures the resonance in a magnetic field of a 1 cm commercially manufactured attachment (SmartPeg) that is screwed onto the bone conduction device abutment. RFA measurements were obtained at surgery, 1, 4, and 16 weeks after implant surgery. The degree of movement (vibration) is inversely proportional to the stability of the abutment, and a numerical figure, the implant stability quotient (ISQ), is derived. Patients were fitted with the new Cochlear Bone-Anchored Hearing Aid (BAHA) BI300 series implant using a 1-stage procedure and loaded 4 weeks postoperatively. RESULTS: Prospectively 68 consecutive patients were recruited with a male to female ratio of 23:45. Nineteen patients had bilateral BAHA devices fitted, giving a total of 88 implants. The average ISQ change (delta) for the cohort gives a value of 0 at time of surgery. The change in ISQ at 1 week was -0.10 (95% confidence interval [CI], 0.74), at 4 weeks was 1.21 (95% CI, 0.59), and at 16 weeks was 1.60 (95% CI, 0.77). DISCUSSION: Successful early loading of the BAHA sound processor has been achieved. RFA provides a reliable means of assessing stability for loading and measuring implant stability in the longer term. These data support the evidence for early loading at 4 weeks with good clinical safety.

Adult bone anchored hearing aid services in the United Kingdom: building a consensus for development.

AIMS AND OBJECTIVES: In October 2009, a multi-disciplinary group of UK clinicians met to review issues relating to bone-anchored hearing-aid (BAHA) development. The aim was to help define a model for BAHA services and service development via a process of widespread consultation with UK BAHA professionals. METHODS: A modified Delphi technique was used. Statements were proposed by the lead group and sent out for consultation. Those with ≥90% agreement were approved without further discussion. Statements with 50-89% agreement were discussed by the lead group to determine whether they should be included in the final document. Any statement with <50% agreement was removed without discussion. A second consultation was then made, and the process repeated. This led to a final set of consensus statements. RESULTS: The final consensus comprises 33 statements validated by the modified Delphi process. All of these statements achieved >75% agreement, with only six statements having <90% agreement. When these statements were presented to the UK BAHA Professionals group at their annual conference there was 89% agreement from the group for the consensus statements to be accepted. DISCUSSION: The levels of agreement for the final questionnaire show that the mandate for the consensus statements was exceptionally high. Implementation of the consensus is discussed, as are each of the key areas of the consensus, such as funding and minimum assessment standards.

Bone-anchored hearing aid: comparison of benefit by patient subgroups.

OBJECTIVES/HYPOTHESIS: The osseointegrated bone-anchored hearing aid, using the Branemark system, is well established and has proven benefit. The aim was to study quality of life benefits within patient subgroups using the validated Glasgow Benefit Inventory (GBI). STUDY DESIGN: Retrospective questionnaire study. METHODS: Ninety-four consecutive patients were enrolled into the study. Mean patient age was 49 years, with a female-to-male ratio of 1.1:1. Patient subgroups were discharging mastoid cavities, chronic active otitis media, congenital ear problems, otosclerosis, and acoustic neuroma and other unilateral hearing losses. RESULTS: The response rate was 73%. The score for total benefit of bone-anchored hearing aid fitting for the entire group was +33.3 (95% confidence interval [CI], 25-42). Glasgow Benefit Inventory scores for each subgroup were all greater than +20. The congenital atresia group scored highest with +45 (95% CI, 28-61). Variation in benefit across the subgroups has been demonstrated. Fitting of BAHA following acoustic neuroma surgery was shown to be of benefit with a score of +22.2. General benefits scored highest in all subgroups compared with physical and social benefits. CONCLUSION: The study demonstrated the differences in benefit within patient subgroups. Its results can be used to give patients a predictive value at the time of preoperative counseling. The study identified congenital ear disorders as the group likely to obtain maximal benefit. Notably, for the first time, the study demonstrated the documented benefit of restoring stereo hearing to patients who have acquired unilateral hearing loss following acoustic neuroma surgery using a BAHA.