Tribological Behavior of DLC Coated Spinal Disk Implants

INTRODUCTION: Based on good experiences gained in many mechanical applications, diamondlike carbon coatings (DLC) are regarded as a prime candidate for protective coatings on implants. However, the body environment imposes new challenges to the layer design and requires new research into possible layer failure mechanisms. METHODS: DLC-coated and uncoated polished ball-on-socket type implants were subjected to wear tests in a newly developed test setup simulating the appropriate body motions corresponding to in-vivo action. Data gathered included mass loss, friction coefficient, and surface roughness. The development of defects was monitored by optical microscopy, SEM/EDX, FIB cross cuts and profilometry. Additional dependencies on operational parameters (load, frequency of motion, lubricant medium) were investigated. Further data was acquired with a conventional cylinder-on-flat setup using coated samples running in synovial testing fluid (Thermo Scientific Hyclone ® ).