Multicenter Evaluation of the Digisonic SP Cochlear Implant Fixation System with Titanium Screws in 156 Patients

Objectives: We describe and evaluate the process of fixation of the Digisonic SP cochlear implant with two titanium screws. Methods: The characteristics of this implant allow cochlear implantation using a minimal incision, a subperiosteal pocket, and fixation with two titanium screws, without drilling a custom-fitted seat or creating suture-retaining holes in the skull. The fixation system relies on two tailfins for use of osseo-integratable screws, incorporated into the cochlear implant housing. The first version of this fixation system was modified after a case of device migration: The size of the titanium insert inside the silicone tailfin was increased. Data on 156 patients (8 months to 86 years of age) from a 4-year period in 6 cochlear implantation centers were retrospectively evaluated. Ten patients have undergone bilateral implantation. Results: Of 166 implantations, 4 postoperative infections and 1 device failure after head trauma were reported. No cerebrospinal fluid leaks or epidural hematomas were reported. One device migration was observed in the first series; no device migrations occurred in the second series. Conclusions: The fixation system with screws embedded in the Digisonic SP involves a fast and simple surgical technique that seems to efficiently prevent implant migration.