Chronic skull-anchored percutaneous implants in non-human primates.

Three groups of chronic, skull-anchored, percutaneous implants differing in materials, design and surgical procedures used for implantation, were tested in macaque monkeys in conjunction with studies of an inner ear stimulation device. Implants from the first two groups in which high-speed drilling methods and stainless steel materials were used, showed a high percentage of failures during the first 3 months after implantation of the percutaneous connector. Implants in the third group, in which measures were taken to preserve living bone tissue, all survived for greater than 7 months. Probable factors relating to implant survival are care of the bone during surgery, postsurgical mechanical trauma, materials and other details of the surgical procedure.