Metal Orthopaedic Implants and Magnetic Fields

Yes.

From: MRI Safety and precautions (Magnetic Resonance Imaging)

In regard to prostheses, non ferromagnetic materials with no electrical activity (titanium and its alloys, nitinol, tantalum, etc.) carry no particular risks in relation to magnetic field. For low magnetic prostheses (orthopedic material), a delay of 6 to 8 weeks after implantation is advised to avoid displacing the material.
Heart valves are generally MR compatible.
In all cases, it is advisable to check the MR compatibility of the material (see http://www.mrisafety.com/), particularly when operating in high fields: some devices carry no risks at 1.5 T but can be dangerous at a higher field.

I'd say they were justified, but wonder why they let it get to the point of an interview before disclosing the risks.

Congratulations on getting the interview!

That sounds overly picky, but it might depend on the specific alloys of the implants, the strength of magnets used in the motors, and how close they would get to your knee.

I long time ago a former coworker told me about a guy he worked with at another job who had several permanent metal pins in one hand from a old car accident he was in.

The guy worked at the company for a number of years without any problems right up until the day he transfered over to another area of the fabrication department where he started running the induction heating machine. He worked well there for one day until he had his hand too close to the induction heating coil when it cycled on and he ended up with a partially cooked a finger , from the inside out, before he had time to even realize where the heat came from!

If they use induction heating or other high powered alternating current magentic field systems in any of the process work there is more than enough reason to refuse you an interview. They could cook your knee right out from under you so to speek.

"Magentic" = light purple?

You lost me on that one.

I have several bits of surgical steel in me, they are all circular in shape. A 2.6MW induction coil had no effect what so ever.

I am referring to these types of induction heater systems.

http://en.wikipedia.org/wiki/Induction_heating

I have seen a few safety videos over the years of people operating them who got too close one time while on and got second and third degree burns from their rings and watches within a second or two.

One picture I saw in college was a guy with near perfect face of a Quarter branded right into his leg from the change in his pocket being inductively heated from mishandling one of the large hand held units. The lesson being don't pull the trigger while scratching your , um 'you know what' with the power coil.

If someone told me that it could heat a nail to red hot in two seconds I would believe it would also heat a stainless steel pin in someones finger bone just about as fast.

In a cyclotron room, however, there might be a risk of getting your knee plastered onto a pole face....

And maybe beware of scrapyard crane electromagnets.

Never bothered me until a lunatic crane driver dropped one of these on my foot.

The ground was soft so my foot sank in to it, I just limped for a while afterwards.

Is that why I can't walk by a scrap yard without being dragged through the gate?

Bazzer.

But is it not made out of Titanium, and i thought Titanium was not magnetic...

You've not been keeping up.

Induction heating - Wikipedia, the free encyclopedia

A friend's wife was telling me yesterday about a strange effect they witnessed. My friend had a hip replacement some years ago and underwent some serious involvement with a magnetic resonance machine shortly afterward. for a while afterward when he walked close to their car it either locked or unlocked ..... or perhaps she was the butt of a practical joke .....

I cannot think of any mechanism which could produce this behaviour, but then again......

Whatever you do, don't go for a job at CERN.

Yes: that's a bloke stood on the little platform at the bottom.

Thanks- belatedly- for all the replies. I've been digging around, and I've got a copy of the X-ray, and a letter from the hospital consultant saying that the implants are MRI-safe stainless steel, and he was surprised that it was considered a risk. The interview was arranged by an agency who assure me that they'll fight my corner -yeah, right- but ultimately, I'll just have to cast my nets in another direction.