Abstract
Background Neurophysiological studies with awake monkeys typically require chronic cranial implants. Headpost and connector-chamber implants are used to allow head stabilization and to house connectors of chronically implanted electrodes, respectively.
New Method We present long-lasting, modular, cement-free headpost implants made of titanium that consist of two pieces: a baseplate and a top-part. The baseplate is implanted first, covered by muscle and skin and allowed to heal and osseointegrate for several weeks to months. The percutaneous part is added in a second, brief surgery. Using a punch tool, a perfectly round skin cut is achieved providing a tight fit around the implant without any sutures. We describe the design, planning and production of manually bent and CNC-milled baseplates. We also developed a remote headposting technique that increases handling safety. Finally, we present a modular, footless connector chamber that is implanted in a similar two-step approach and achieves a minimized footprint on the skull.
Results Twelve monkeys were successfully implanted with a headpost and one with the connector chamber. To date, we report no implant failure, great headpost stability and implant condition, in four cases even more than 9 years post-implantation.
Comparison with Existing Methods The methods presented here build on several related previous methods and provide additional refinements to further increase implant longevity and handling safety.
Conclusions Optimized implants can remain stable and healthy for at least 9 years and thereby exceed the typical experiment durations. This minimizes implant-related complications and corrective surgeries and thereby significantly improves animal welfare.
Highlights
Long-lasting titanium implants for non-human primates
Refined implantation techniques that reduce post-operative complications
Minimized, footless connector chamber to house connectors of chronic arrays
Headpost implants so far without failure and with longevity > 9 years
Competing Interest Statement
P.F. has a patent on thin-film electrodes (US20170181707A1) and is beneficiary of a respective license contract with Blackrock Microsystems LLC (Salt Lake City, UT). P.F. is member of the Advisory Board of CorTec GmbH (Freiburg, Germany). The authors declare no further competing interests.
Footnotes
