58 Chapter 3.1 97% together with good soft tissue tolerability (23). The potential advantages or disadvantages of this new generation of BAHIs have not yet been evaluated in children. Resonance frequency analysis (RFA) was introduced as a non-invasive, in situ method to assess the stability of BAHI in patients. The RFA of a small transducer rod (smartpeg) attached to the implant is converted into an implant stability quotient (ISQ) (between 1 and 100), where a higher number indicates higher stability. Two ISQ recordings are taken in perpendicular directions ISQ high (ISQH) and ISQ low (ISQL) which are generated due to the different bone characteristics in each direction (24). The ISQ of attached abutments is measured in an identical manner by placement of the smartpeg into the abutment center. ISQ values for BAHI demonstrate trends in stability in individual patients or cohorts over time, and clinical conclusions cannot be drawn from single ISQ values according to a review of 17 studies using ISQ (25). The role of stability measurement in children is still debated but has been used by some centers to help guide early loading in single-stage procedures (12,25). The objectives of this study were to determine implant stability using ISQ at the fixture and abutment levels and implant survival over the first 12-month period in a cohort of 115 consecutive children fitted with the laser ablated Ponto BHX implant system. 2. Materials and methods 2.1 Study Population and Surgery This was a prospective, single-subject, repeated measure, cohort study in which each participant served as their own control. Ethical approval was granted by the research and development committee (REC ref 11/WM/1054, IRAS project ID 145812). Participants aged between 4 and 15 years with unilateral or bilateral, conductive hearing loss eligible for BAHI were recruited at Birmingham Children’s Hospital (Birmingham, England). Following a formal consent process, 115 consecutive children were offered a place in the study. Patient demographics, underlying etiological indications for implantation and surgical techniques were recorded. This center preferred two stage implantations in younger children. Single stage procedures were performed on seven patients (total nine implants). In all but five cases, two fixtures were placed on the indicated side, one acting as a ‘‘sleeper.’’ Typically, a two-stage procedure consisting of a 3-month healing period between surgeries was used. All surgeries were performed by three consultant surgeons between January 2016 and January 2019. The following three surgical techniques were used: 1) linear incision for implant placement followed
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