Replacing arthritic joints with metal ones?

I was thinking. Why can’t they just replace arthritic joints with metal ball socktes or hinges? Wouldn’t that relieve all of the pain associated with arthritis? I understand it would be an expensive and traumatic procedure, but for people who have joints that have almost fused together it seems like a viable option. It seems like joints would be very easy to create and implement. Couldn’t they just saw off the knobby ends of the bone and put metal ends there?

If this is something that is already very popular then forgive me for asking, I am talking more along the lines of someone getting all thier joints replaced.

Errrr, never heard of hip replacements?? Actually I’m doing a PhD in this area so…
Metal hips- you can have problems with allergies particularly if you use stainless steel which contains nickel.
The biggest problem is stress shielding. The metal is stronger than the surrounding bone. This makes the bone think it’s no longer needed and is reabsorbed into the body.
That answer your question Stinkpalm?

They do this with several joints. There was a wonderful/awful exhibit on this at the Boston Museum of Science a few years ago. It was very graphic, which you can either find fascinating or disgusting. They showed a knee replacement in all its glory.

The problems, as I understand it, are:

1.) It’s very difficult to construct a mechanical joint that will exactly duplicate the operation of an organic one. Most joints aren’t simple hinges or ball-and-socket.

2.) Although folks have gone on to be very athletic with replaced joints, skiing with artificial hips or knees, apparently doctors have to keep wartning them that their new structures aren’t as strong as the old ones, and they have to take more care. (I think there’s practically a rule that anything you screw around with will end up inherently weaker, but I have nothing to back that up). Suffice it to say that metal ainb’t bone. It has different expansion coefficients, different strength, and the body (as noted above) will react to it differently.
So if you’re severaly suffering, get a new joint. But I suspect that If It Ain’t Broke, Don’t Fix It is a philosophy to live by. The Six Million Dollar Man probably spent a lot of time in the Shop. Look how big the support structure was for Ghost in the Shell.

I’m working on how to fix 'em in better…
Mostly they stay in just fine, even if you do sports, but people tend to move around too early. This makes them work loose. Wear on the joint can be a problem, depends how well the the implant was put in.
I can (and have) written essays on this!
Knees and shoulders are particularly difficult to reconstruct.

Need cites? I have an entire drawer full!

I have an artificial hip. So does carniverous plant.
I have trouble with it when I get chilled.
It doesn’t work just like original equipment.It would be easy to dislocate.So I am very careful.
My other hip isn’t normal anymore.
I also have bad shoulders. The “Fix” for them is replacement.
I’m putting it off until it is absolutely necessary.
I’ve been told that artificial joints only last 15 years. I want mine to last as long as possible.
Rejection of the joints and infection are problems I’ll have to deal with the rest of my life. The fix for infection is removal of the joint ,cure the infection, and maybe replacement and try again.It took one guy a whole year to be put back together.Thats hospital stay.

It just isn’t something you can take lightly.

Mrs. Kunilou had a knee replacement.

After 8 months of rehab, she’s still having nerve problems in that leg.

She’s also been told 15 years is the life expectancy for the joint. Based on her life expectancy, that means she might need TWO additional replacements.

Definitely not something you do until its absolutely necessary.

Although hips and knees seem to be the most commonly replaced joints, I’ve seen ankle and elbow replacements and I once did some neat work on finger joints. Instead of metal, the finger joint “knuckle” is one of several types of special plastic. This link goes to some of the ones we played around with.

With fingers, you can take someone with severe arthitis (the L-shaped hand look you can see in people like James Coburn in Maverick), and give them back finger mobility. Of course, the implants seem to have a relatively short life (10 years or so), but that’s 10 years of using your hands without pain.

Yep, 15 years is about it. There are some fancier hip replacements that last longer, but that requires a much bigger operation and mostly go in younger patients. Rejection is an unlikey problem. IIRC (I can look it up if you like) about 1% have to be replaced due to infection and almost all are in the first year.