Letter to the Editor in Response to Faber et al. Bone-Anchored Hearing Implant Loading at 3 Weeks

Abstract

To the Editor With great interest, we read the articles in last issues of Otology and Neurotology concerning new osseointegrated implant for bone conduction devices more specifically the BI300 implants (1,2). We feel that some aspects of the former BA210 implant could have been addressed more explicitly in these studies. Within our institute, we had already studied 24 consecutive patients with the BA210 implant (6-mm length) placed by a linear incision technique. The ISQ values were obtained in an identical manner from perpendicular measurements performed at implantation and each visit after 1, 2, 4, and 6 weeks and 6 months of follow-up. The lowest ISQ value was used for analysis. Parts of this work have been presented before (3). The ISQ values increased from implantation till 6 months, without statistical significant differences between the individual moments of follow-up at 2, 4, or 6 weeks (Fig. 1). The Osstell RFA device shows improvement of abutment stability reaching a peak at 2 weeks after implantation, but it gradually increases even after mounting.FIG. 1: ISQ change compared with baseline (with 95% CI).Although the manufacturer still recommends a loading delay of 12 weeks for BA210, mounting at 6 weeks after implantation is generally considered as safe according to the recommendations of the consensus statement of 2005 (4). To determine the in-house protocol, we executed the above-mentioned study and have successfully been mounting at 4 weeks after implantation with the BA210 implant since 2009. One could argue for mounting at 2 weeks with the BA210 implants based on these results. Newer and often more expensive implants have always been a focus of study. The improvements to the BI300 series include a somewhat broader base, which could be unnecessary for stability improvement or earlier mounting. Moreover, the compatibility of the BA200 series with other bone conduction devices is worthy to mention. We think that the timing of mounting a BAHA abutment should be based on a paradigm that comprises more than implant stability alone. The ISQ measurements could be of use to determine implant-specific threshold values for mounting. However, patient-specific (skin) characteristics and intraoperative findings, for example, bone quality and postoperative healing, are some examples that also play an important role in managing moment of mounting. Diane Smit M.D. Rinze A. Tange M.D., Ph.D. Vedat Topsakal M.D., Ph.D. Department of Otorhinolaryngology Head and Neck Surgery, University Medical Center, Utrecht The Netherlands