After a few years, many hip and knee joints have to be replaced. Much more complex are intervertebral disc implants, which cannot easily be replaced after their “expiry date” and which up to now have had to be reinforced in most cases. This restricts the patient’s freedom of movement considerably. Researchers at Empa have now succeeded in coating mobile intervertebral disc implants so that they show no wear and will now last for a lifetime.

Read: Joint Implants Without an Expiration Date

The simulator, which tested the Empa joint implants for five years.

Kerstin Thorwarth, one of the researchers, with the coated joint implants and the simulator.

Three intervertebral disc implants. On the right is the uncoated implant, in the middle is the DLC-coated implant with the unsatisfactory bonding agent and the corresponding corrosion, and on the left is the stable DLC-coated implant optimized by Empa.

A cross-section of a coated intervertebral disc implant under a scanning electron microscope (Philips XL30 ESEM–FEG). The metal in the implant is cobalt-chromium-molybdenum (CoCrMo), the coating is DLC and the bonding agent in between is made of tantalum. Small defects can be detected after 101 million cycles, but they are stable and do not continue to grow.