How To: Surgical Considerations for Osseointegrated Steady State Implant (OSIA2) in Children

Implant placement. The implant was then placed using a conical guide drill, followed by a widening drill. In all cases, a 4-mm implant was placed. The dura was often encountered in this young cohort, but there were no dural injuries. Of note, a 3-mm implant is available and could have been placed as an alternative. A bone bed indicator was attached to the implant and rotated to ensure that the bone surrounding the implant was level enough for placement of the OSIA2. Bone polishing using a 3-mm diamond burr was performed if bony clearance was not achieved. A subperiosteal pocket was created for the receiver–stimulator in similar fashion to a cochlear implant. The direction of placement of the device, which ultimately dictates the site of the external component, was guided by the preoperative placement of a methylene blue mark on the neck of the silastic model. The actuator was seated and fixed to the implant. The wound was then irrigated and closed in layers. Postoperative skull radiographs were performed only on the initial five patients in this series.

Management of the thick skin flap. The need for surgical flap thinning should be rarely required in the pediatric population. Children under 7 years of age rarely have a skin flap thickness of more than 3 to 4 mm in this portion of the scalp (Int J Pediatr Otorhinolaryngol. 2020;130:109853). In older children, skin thickness increases with age and with body mass index (BMI) (Int J Pediatr Otorhinolaryngol. 2020;130:109853). Six of the 43 patients had skin flap thickness nearing or greater than 9 mm. In these patients, the coil of the receiver was placed lateral to the temporalis muscle and fascia. In addition to this maneuver, one patient (BMI of 35) underwent concurrent soft tissue reduction. For this patient, the incision was designed to facilitate flap thinning by bringing it to within 1 cm of the neck of the device. In addition, the coil of the receiver–stimulator was placed in the plane overlying the temporalis fascia. Experience with a prior cohort receiving the first generation OSIA device outlines the utility of a separate incision above the coil of the receiver–stimulator to better access the area of the flap to be thinned.

Management of prior implants and devices. Children in our cohort had previously received percutaneous abutments ipsilateral to the planned side of OSIA2 placement. When the goal was to transition from a percutaneous abutment to an OSIA2, the abutment was first removed, and the soft tissues were left to heal over a period of six to 12 weeks prior to OSIA2 placement. In some children, the retained implants approximated the OSIA2 receiver–stimulator and were removed to avoid contact with it. These implants were so osseointegrated that they needed to be drilled out by an otologic drill. With appropriate planning, removal of the prior implant(s), when necessary, can be done at the time of the abutment removal or at the time of the OSIA2 placement. In children with prior percutaneous devices or transcutaneous devices, the incision for OSIA2 was carefully planned to avoid having compromised skin sitting over the actuator while also allowing access for removal of prior implants when required.