Hip Science: Better Bone Implants 27
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."
Karma Sacrifice (Score:4, Funny)
Oh come on someone had to say it!!
Transplant bones (Score:3, Interesting)
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.
Can and Cant do this (Score:4, Interesting)
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.
New hip for grandma today, Cyborgs tomarrow. (Score:2, Funny)
Imagine it now: full contact bingo/shuffleboard/canasta is once again possible!
Now grandpa can PROVE to us that he used to walk uphill to school--in the snow, with no shoes--for 20 miles!
Uncle Leroy can _finally_ show us the move that won him the '93 Limbo tournament--which coincidentally broke the hip in the first place!
Oh the joy of old age and technology combined.
And, if we apply Moore's Law to this, I should be able to have a full endoskeleton that will increase my strength 1000 times by the time I'm 45. Combined with the fact that computers/technology will be getting smaller at the same rate, I will be able to have a Beowulf cluster of computers inside myself--which in turn will be connected over a wireless network (called "The Grid" by the kids of the day.) that will connect every person on the planet.
We will be walking, living, breathing, and thinking Beowulf clusters. And that will be the true end of these stupid "Imagine a Beowulf cluster of those!" posts in Slashdot!
Yes But (Score:4, Informative)
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.
Re:Yes But (Score:2, Insightful)
recipe for bankrupcy (Score:3, Interesting)
2) Get sued when some transplants fail
3) Get (nearly) bankrupt [hipimplantlaw.com].
Cost? (Score:2, Insightful)
One of the problem of hip transplant is: (Score:3, Interesting)
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: (Score:4, Interesting)
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.
Thank you for the answer... (Score:1)
My reaction had been driven by some experience I had more than ten years ago, trying to implement traceability for for various chirurgical implants, and especially hip ones.
At that time, (it was in France, btw.), I really had the chance to talk to people all along the delivery and manufacturing chain, and I was under the impression I wrote in my message. However, it might be because of the local market and conditions, and also of the currrent legislation.
I obviously have been a bit too rash about explaining my opinion, and if I shocked you, please accept my apologies. I have personnaly be subject to surgery, and I'm happy with the job my surgeon did.
One of the problem with implants and of course all kind of deep surgery is obviously the fact that it is at a confluent of emotionnal/political/technical/money issues. Which is of course the worse mix you can dream of.
But now I'm an engineer, and even if you cannot open a patient like you unscrew your car parts, I still do believe better solutions exists, but that they encountered roadblocks that had nothign to do with their adequateness with the problem.
Re:Thank you for the answer... (Score:2)
Most of the surgeons I have come across have been remarkably concerned about their patients - far more so than you would imagine. As I already said, it is quite possible that hips could be better, the problem is that developing them, for the tiny minority that need 'changeable' hips, would be prohibitively expensive. But add up coming up with an idea, and implementing it in enough people to give evidence that it's better (as you can see from the comment above, this might take 8-20+ years to prove), it is something most profit-oriented companies would rather not think about. The current lot do their job admirably, and beating them would be expensive, if not unfeasible. The 8-20 years R&D, and several, possibly litiginous, human subjects, are the problem. If they make a mistake with a prototype, the 50 or so people that they need (they might get away with 10-20) to prove their implant is better will have to be compensated if it is significantly worse. If it is no better, it's all wasted time and money. Animal studies would take just as long and are not directly comparible, the main problem is that human studies = liability.
Having some experience in the field, I would far rather be an engineer than a surgeon. These days, eveyone hates doctors.
I don't know how things compare in France - I imagine that they end up quite similar. The surgeons do a combination of what is best for the patient and what is practical (theatre time, available beds etc.). The companies that make the hips are marketing a product - maximise profit is their mantra. Neither are infallible, and while there are (more rarely than the media would like us think) unethical surgeons, big business and hospital management are far more likely to be the corner-cutting cost-cutters than the surgeon.
Re: Car parts (Score:1)
Re: Car parts (Score:1)
To mister allmonkey:-) there is a difference between the parts of your body and the parts of your car.
Car part does not tend to repair themselves, or more accurtely, the rest of the car does not try to repair something broken.
I would be interested in buying some clone of me though, where is the factory you are talking about ?
My friend's cat (Score:1)
Thanks PR guy (Score:1)
Re:Thanks PR guy (Score:1)
What good is space manufacturing? (Score:2)
Bo Jackson? (Score:2)
Back in 1992, Bo Jackson had a total hip replacement, and then played another two years of Major League Baseball.
Does anyone know how his hip is holding out? I couldn't find any recent information on him (everything seems to stop in 1994 when he left baseball)
It's 10 years later... I think he's due for a new hip.
Wore his out in 1.5 years (Score:2)
Total hips aren't made for running around/playing tenis, let alone pro ball.
He got what was coming to him for abusing his total hip that way - it only lasted a year, as opposed to 10-12 years in most people..
Try 8-14 years (Score:2)
Re:Bo Jackson? (Score:1)
AVN a reason to keep looking for better prostheses (Score:2, Informative)
AVN is a result of the human body's Architect and Prime Contractor making the entire blood supply for the head of the femur a single, badly oriented blood vessel. If the vessel becomes blocked or narrowed, the top of the femur loses its circulation and dies, and the cartilage necessary to keep the natural joint working can't be repaired. Within a short time, dead bone is grinding against living cartilage in the pelvic socket, which wears out quickly and painfully, or the head of the femur breaks, and dead, can't heal. This happens every year to a single digit percentage of the population, about evenly distributed between men and women. Smoking and some other personal health issues, including race and heredity, have been statistically linked to AVN, but no studies of which I'm aware have firmly established a causal relationship between health behaviors, environtmental factors, heredity and AVN. Accidental breakage is a another reason hip replacement surgery is performed, especially if the femoral head is severly damaged, and is unlikely to be able to heal.
100 years ago, and even today in medically underserved areas, hip joint failures, and the resulting loss of locomotion, resultant infections, and stress cause(d) high rates of subsequent mortality, within a few months, as other posters have mentioned. The various forms of hip prostheses are thus literally life saving devices, not just ways for little old ladies to enjoy a few more Arthur Murray dance lessons. It is hard for healthy people to appreciate just how debilitating and life threatening the loss of mobility is, but I assure you, it is a very, very real threat to life, within weeks, from many mortality paths.
The literature quotes the common "life span" of THR (total hip replacement) type prostheses at an average of 10 to 12 years. I have one that was originally installed in 1994, and the other which was a revision done in 1999, due to involvement in a tripping type accident. The joint replaced in 1994 appears sound in follow up X-rays, which look to predict failure by picking up very small particles in the extra cellular fluid, or in the joint parts themselves, near the joint movement surfaces, indicating that significant spalling wear is present. But the far more usual cause of failure is actually failure of the cement or bone that hold the joint parts in place. The usual indication of such failure is pain, caused by small fractures and infection of the bone surrounding the implants, or excessive movement of the implant parts in the bone cavities of the pelvis and femur made during surgery. In my case, and that of thousands of other THR patients of recent years, the former practice of cementing the replacement parts to living bone has changed to having the surfaces of the parts present a rough surface, to which living bone, which is accurately "machined" during surgery using jigs and a reaming toolset provided by the joint manufacturer, to achieve very close tolerance fit of the artifical hip parts to the living bone remaining. Under such close tolerances, and with immediate physical therapy, new bone will actually grow into the the implant surfaces, and be superior in overall life to the cemented versions. This remains an on-going investigation where ceramic surfaces show real promise.
Many designs of hip prostheses are easily damaged by torque moments and shock loads presented to the joint during common situations such as minor stumbles, or kicking or pushing small but dense objects. Learning to respect the hardware, and being very careful about shoes, walking surfaces, and instantaneous loads is all part of having the mobility the artifical joints provide. With care, most activities can be managed, and don't "wear out" the joints, but activities that put deformative shock loads into the plastic or metal "cup" parts surrounding the "ball" surface of the femur replacement portion of a THR are really, really bad ideas, and can result in premature or even instaneouses failures. This is more often due to crush and fracture failures of the supporting bone tissues, but in my case, I actually sheared a 3/8 inch diameter stainless steel "rod" forming the offset for the "head" of the femoral replacement part. There may have been some prior contributing damage to the joint part from surgical insertion damage, or in vitro degradation, but it is hard to know since the removed parts are hard to analyse, may suffer additional damage in extraction, and are often changed by years of immersion in the fluids of the living body.
If I live to a normal age for a man of my background, I'll face the surgeon another 4 to 6 times for revisions, so I'd like to see a "permanent" THR developed, as would thousands of others. Advanced materials leading to a substantially stronger, longer lived joint, are the most desirable course, and probably, the most likely. I applaud the folks involved in this, and I am grateful to the American taxpayers, and to NASA for time and space aboard shuttle missions, to do the early science that might lead to such materials.