Phase I and Animal Studies of the TACA Implanted Hearing Aid

Abstract

Problem Hearing aid technologies are lacking in terms of cosmesis and comfort, encumber activities such as showering and swimming, and can distort the user's voice due to occlusion effect. The Transcutaneous Air Conduction Aid (TACA) has been developed as an alternative for patients with mild-to-moderate high-frequency sensorineural hearing loss. This new device is designed to bring amplified sound into an open ear canal in an invisible manner. This study presents our investigation into the additional challenge of a percutaneous device at risk for marsupialization and infection at the device-skin interface. Methods TACA phantoms, coated with a fibrous titanium mesh biomaterial, were tested in long-term preclinical implantation studies. Histomorphometric comparison of mesh coated and uncoated TACA phantoms was performed in 3 rabbits at 90 and 180 days. A follow-up study in 7 rabbits was performed to temporally characterize wound healing around the mesh coated implants from 1–13 weeks. Based on promising animal results, a phase I FDA human trial was conducted lasting 6 months. Results Preliminary histomorphometric studies (N=18 phantoms with mesh, 6 without mesh) in 3 rabbits demonstrated that the titanium mesh biomaterial prevented marsupialization and infection at 90 and 180 days. The follow-up study of 42 mesh-coated phantoms in 7 rabbits demonstrated that the epidermal seal was reestablished around the percutaneous projection at 3 weeks, with supporting vascularized connective tissue ingrowth complete at 6 weeks. The human phase I data demonstrated connective tissue ingrowth and epidermal sealing with no evidence of marsupialization or infection. Conclusion The TACA may offer an alternative for patients with sensorineural mild-to-moderate sloping high frequency hearing loss. Percutaneous implant studies in rabbits and man demonstrated the safety of this novel percutaneous device. Significance Preclinical and clinical demonstration of feasibility and safety. Support This work was supported by Implanted Acoustics, Santa Clarita, California.