Hip Science: Better Bone Implants

ke4roh writes "Space, medicine, and invention often cross paths. In this case, the invention is a new artificial hip. Scientists are researching ways to manufacture strong and porous ceramics with the benefit of microgravity - subtracting the effects of convection and settling from their experiment. In the end, they hope to offer a permanent artificial hip - much more user-friendly than today's models that come unglued and require replacement after only 5-10 years of use. It's just one more way space research helps to make life better on Earth."

Comments

Karma Sacrifice

[nocomment]

That's pretty hip stuff

Oh come on someone had to say it!!

Transplant bones

[Urox]

Why can't they use transplant bones? Other pieces of body are transplanted (veins, skin, internal organs).

That way, you'd automatically get the porousness and strength of real bone. And the old bone would be able to grow to the new bone which was stated as one of the obstacles.

Yes But

[4of12]

I know they're trying to reduce the effect of buoyant (natural) convection by going into the microgravity environment. And, pure density-driven convection due to the differences in density of air and molten ceramic will also be minimized in space.

But if there are temperature gradients in the molten ceramic, they might still have to contend with molten bubbles migrating due to thermocapillary (Marangoni) convection. The surface tension of the air/liquid interface is generally a function of temperature.

Good luck to them, anyway.

recipe for bankrupcy

[u19925]

1) Develop a new hip transplant.

2) Get sued when some transplants fail

3) Get (nearly) bankrupt.

One of the problem of hip transplant is:

[pruneau]

That the fucking surgeon just do not give a damn !

I've been working into a plant that made those hip prosthesis. One of the problem with the current model is that they used high-density polyethylene (plastic) against stainless steel. Of course the friction factor will be very good, but eventually, even the stainless still will wear out. The human body is quite both a fragile and hostile environmment for non-living parts.

Over the course of years, the various mechanical part in friction with eachother will eventually wear each other out.

But instead of allowing the transplant to have replaceable parts (like part of car breaks, for example) the surgeons wanted to have something that would have to be wholly replaced. Just imaging the result of having the whole ten-year-settled femur implant to be replaced by a new one, and you'll get the picture.

Maybe this has changed nowadays...

Re:One of the problem of hip transplant is:

[balloonhead]

Current hip transplants are the best tools for the job. In an ideal world, they would be better, but at the end of the day it is not even remotely financially feasible to make them better.

At the moment, most artificial hips are hemiarthroplasties (the end of the thigh bone is broken and needs replaced, the pelvic part if the joint is intact - you might get one of these if you break your thigh bone (femur) close to the joint. The rest are total hip replacements (THRs) where, more likely from severe arthritis, both parts of the joint surface need replacing. There are a variety of different types, but the best results are generally from metal on plastic or less often metal on metal joints.

These joints survive for, give or take, 10 years. Usually, 8-15 years, but with heavy wear or bad luck (this includes fat people) it can be less. Some last over 20 years. These are the hips which were put in 8-20 years ago - we won't know if the current crop are better for 8-20 years.

There are many problems in developing better hip transplants, but the surgeon's thoughts are not really one of them. They simply want the best tool for the job - they don't make the prostheses, they just put them in. A re-do hip op is much harder than the orginal, and so it's in their own interests to not have to replace them. The companies that make the hips spend years on R&D, and at great expense - if they get it wrong, it may be years before a problem is found, and if they are held liable, then that's a lot of payola. It's very hard to reproduce how a hip behaves in a person without putting it in a person, and what you are suggesting would make this even more complicated. More parts increases the chances of infection (probably the artificial hip's worst enemy) and is not a better solution just because your local car dealer does it.

At the end of the day, most people who have a hip transplant of either sort are likely to be very elderly - given that the 6-month mortality of a little old lady who breaks her hip is around 50% (yes, half will die within 6 months (almost all die within six months if it is not fixed with an operation)), and of the other 50%, the vast majority will die of other causes before the hip joint fails, you can see why they are the best tools for the job.

The problems are really with younger patients - one of the reasons why surgeons often delay THR in young people with severe arthritis - they do not want to operate three or four times on the same hip, each becoming more technically difficult, in this person's lifetime. It is preferable to wait as long as possible, as symptoms and disability allow, to reduce the number of operations they will need. Havine complicated, expensive multi-part hips as you suggest might be a better idea for some of these, but they are a minority, developing these magical implants would cost an absolute fortune, and no manufacturer has come up with something so far that would work. If you have any suggestions, then feel free to approach one and show them your ideas, but the likelihood is that someone has already tried and abandoned it for one reason or another, be it cost or complications.

Blaming the surgeon though, is a bit narrow minded and ignorant. Some surgeons might not give a damn, but all surgeons use the same tools, which are produced by a few manufacturers. I very much doubt that none of them give a damn about their patients, especially seeing as they have relatives (or themselves) that might need a new hip one day.

Can and Cant do this

[spineboy]

This is and isn't done for many diferent reasons

Bone is a living substance as well as the cartilage covering at the ends of the bone, and thus it is immunogenic. Donated bone (usually ground up donorcyclists) is often used in people in a variety of states. I order to not generate an immunogenic response it must be processed and this processing kills the cells (freezing/chemical, etc). Bone is continually being reformed - ie dissolved and rebuilt up by various cells in the body. If you plate a donated piece of bone into a body the living bone typically only grows 2 to 3 millimeters! into the donated bone, resulting in a piece of dead bone attached to a piece of living bone. Dead bone is sometimes "dissolved" by various cells in the body (unpredicatable response) and is often a source for infection (bad) and can fracture easily.
Don't forget that joint tolerances are approximately in the millimeter range and donated osteoarticular allografts( donated joints) are often not able to be precisely matched with the remaining joint surface and thus are subject to arthritis too.
All in all gross bone donations are usually only used in very rare tumor cases. It is much easier and much more predicatable to use artificial joints (total arthroplasties). The complication rate is significantly! much lower as well. Donated bone is typially only used as "spackle" to fill in some small defects.
In case you haven't guesed, this is what I do for a living.