81 3.2 Clinical evaluation and resonance frequency analysis in Down Syndrome 3. Results A total of 31 consecutive paediatric patients requiring a BAHI with a comorbidity of DS were implanted with the Ponto BHX Oticon™ implant system. 12 children had bilateral implants and 19 had unilateral implants giving a total of 43 implants (3 mm implants n = 34, 4 mm n = 9). 3 patients had single stage surgery (3 implants); 28 patients had two stage surgery. Mean age at surgery was 8.5 years with a slight female predominance (51%). The mean BMI centile was 19.1 [Table 1]. Acquired conductive hearing loss was the most common hearing loss aetiology 48% n = 15. Over the course of the twelve months follow up, 2 fixtures were lost (4.6%) in two separate patients; the first by the 3-month review point and the second at 6 months. Both cases were spontaneous fixture losses due to failed osseointegration. 3.1 Second stage interval analysis The mean healing period between stage one and stage two was 15.8 weeks (SD 3.57, Range 12–24). The longer healing periods were used for patients with very thin bone <2 mm or due to social factors such as medical or school commitments. 3.2 Implant survival For the entire cohort, there was a median 12-month implant survival of 95.3% (n = 41), 4.6% implant failure (n = 2) and no traumatic loss [Table 1]. Both lost fixtures were 3 mm implants and losses occurred within 6 months of surgery. Lost implant systems were replaced outside this study. All data from the patients up to the point of implant loss were included in the analysis. 3 mm implants were used most frequently (n = 34, 79%) and were placed when the thickness of calvarial bone was ≤2 mm. These fixtures were placed with a low torque of 25–30 Nm2 and where possible, positioned flush with the calvarial bone. Both spontaneous fixture loss occurred in female patients ages 14 and 15 years at the time of implantation. One occurred at the 3-month review and the other by 6 months. One of these patients had undergone a single stage procedure performed utilising a linear approach, the other via a two-staged s’shaped incision. Each procedure was performed by a different operating surgeon.
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