Zimmer Biomet faulty artificial knee

[Alistair_Heaton]

https://uk.yahoo.com/news/faulty-knee-replacements-given-more-180000101.html

Years ago, I did some FEA on an artificial hip which I found very interesting.

Anyone know what the issue with these are? Don't really understand the bioengineering stuff.

 

[TugboatEng]

It says the glue fails.

Tissues are typically glued or repaired with cyanoacrylate or methacrylate resins. These are subject to degradation by hydrolysis.

Here is a whole lot of information on bone glue:

https://www.sciencedirect.com/science/article/pii/S014374962030110X

 

[Alistair_Heaton]

similar issues with the hip.

but it was more the bone splintering green stick.

And as for titanimum being none reactive in the body... The amount of grey sludge round them when they took them out.

 

[TugboatEng]

It looks like aseptic loosening is also an issue with stainless steel implants. It doesn't seem that crevice corrosion was considered.

https://www.sciencedirect.com/science/article/abs/pii/S0142961297002081

One of our captains had one of the cobalt chrome implants. He long struggled with the side effects from cobalt poisoning which eventually led to his death.

Titanium is great for corrosion resistance and toxicity but has terrible wear resistance. The gray sludge was likely titanium particles from erosion. Coatings are key to getting long life from titanium.

 

[Alistair_Heaton]

This was 25 years ago now for me.

It was quite interesting very 3d, nonlinear geom, none linear materials, contact. The 2 months of experimental work on the tensile tester with pig bones then hand over to the proper Bio's for the next phase was good. Also did a vertebrae fusion yoke but that was easy comparted to the hip.