Longitudinal Evaluation of Bone-Anchored Hearing Aid Implant Stability Using the Advanced System for Implant Stability Testing (ASIST).

Objective: This study aims to provide a clinical evaluation of the Advanced System for Implant Stability Testing (ASIST) for assessment of implant stability for bone-anchored hearing aid patients. We evaluate the longitudinal changes in implant interface stability during the first year following surgery.

Methods: ASIST measurements were collected for 39 patients selected to receive a bone anchored hearing aid for hearing loss. Measurements were collected at the time of surgery and at 3 days, 2 weeks, 1 month, 3 months, 6 months, and 12 months following surgery. Longitudinal changes in ASIST Stability Coefficient (ASC) were determined for each patient. Correlations were investigated between initial implant stability as measured by the ASC and clinical parameters such as operating surgeon, patient age at surgery, and implant type.

Results: ASC values ranged from 11.9 to 137.0 (31.9 ± 18.0). On average, there was a slight decrease in ASC up to 3 months after surgery followed by an increase up to 1 year. Preliminary results presented in this study suggest that there may be differences in the initial stability between operating surgeons (p = 0.0012; p = 0.0049) and there was a trend toward possible differences between different implant types.

Conclusion: We have shown promising results using the ASIST in a clinical setting for longitudinal evaluation of bone-implant interface integrity. Isolating the interface properties from the implant-abutment system allows for objective comparisons across patients that are not possible with other stability measurement systems.