New insight into Baha® implant stability measurements: observations on resonance frequency analysis results

To analyze the results of multiple measurements of resonance frequency analysis (RFA) repeated in patients implanted with Cochlear Baha® BI300 implants to look for trends, which potentially might serve as indicators of successful osseointegration.

Forty-five patients implanted with the BI300 implants at the Department of Otolaryngology, Poznan University of Medical Sciences; consecutive values were available for 14 of these 45 patients.

Evaluation of the implant stability through resonance frequency analysis; 4 to 10 measurements in each patient were performed during the surgery and after 1 week and 1 month.

Attention was focused on the results of RFA, defined as the differences between recorded marginal values of the implant stability quotient (ISQ): the average-ISQ value [(maximal ISQ value + minimal ISQ value)/2] and delta-ISQ (maximal ISQ value - minimal ISQ value).

The average-ISQ value increased from 58.43 at the time of implant placement to 61.89 at the end of the observation period, with a minimum recorded value of 56 and a maximum of 64.5. Delta-ISQ showed a maximal drop from 3.86 at the time of surgery to 1.93 after 1 month. Significant differences were observed between surgery and a month later but also between 1 week and 1 month after surgery.

Our data demonstrate that differences between recorded stabilities of the implant in different planes based on ISQ values tend to decrease over time, indicating that the implant acquires symmetrical stability, which may reflect the good quality of the bone-implant interface.