Evaluation of Bone Conduction Implant Stability and Soft Tissue Status in Children in Relation to Age, Bone Thickness, and Sound Processor Loading Time.

Objective: To measure the stability, as determined by implant stability quotient (ISQ) values, of bone conduction implants placed using FAST (one-stage) surgery in children to look for the differences between various ages and indications. To monitor the status of the peri-implant soft tissue using the classification proposed by Holgers et al.

Study Design: It was a prospective, open, multicenter study performed in two investigation centers.

Patients: Twenty-two subjects under 18 years of age implanted with the Cochlear BIA300 and BIA400 types of devices at the ENT Departments of Children's Hospitals in Bydgoszcz and Lodz in Poland.

Intervention(s): Implantation and use of the bone conduction implant system. The implants were placed unilaterally or bilaterally according to a one-stage surgical procedure as per normal practice at the hospitals. Loading time was adjusted to individual patient, and it was based on the assessment of implant stability and status of the soft tissue.

Main Outcome Measure(s): The attention was given to the differences in the ISQ values obtained during the subsequent visits in the various age and indication groups. Resonance frequency analysis was performed as per the routine follow-up schedule at the hospital.

Results: Age at the time of implantation on average was 9.8 years (min. 5.2 yr; max. 16 yr). On average, ISQ value on each of the study observations in this group equaled to 59.17 (median, 58.79). Seventh to tenth day post-surgery seemed to be a sensitive period as the lowest ISQ values (on average: 56.38 ISQ) were recorded for these dates. On average, implant was loaded 7.5 weeks after surgery in the study group (min. 2 wk, max. 14 wk). In none of the subjects the significant decrease of the implant stability values after sound processor loading was observed. Statistically significant correlation rate (p < 0.05) showed that the thicker the bone the higher the obtained ISQ value on each of the visits. It was also confirmed that the younger the implanted child, the higher the skin reactions grade at the 2 to 4 weeks post-sound processor fitting. There was no correlation observed between the time of the sound processor fitting and the skin reactions status.