Slashdot Mirror
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."
That's pretty hip stuff
Oh come on someone had to say it!!
/* oops I accidentally made a comment, sorry */
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.
"Would you rather have a playstation addicted dork wearing a star wars t-shirt?"
I can't wait until they make hips that will make grandma bigger, better, faster, stronger.
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!
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.
"Provided by the management for your protection."
2) Get sued when some transplants fail
3) Get (nearly) bankrupt.
Clearly the cost of producing a ceramic hip in space would be prohibitive (ballpark: ~$1 million). Then what technology could possibly produce such a micro-gravity environment at sufficient scale on earth to effect manufacture cost-effectively? I suspect it's not as easy as floating a frog.
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...
[Pruneau
That'll look great next to my wife's tits!
;-)
oh, that kind of bone
You see all these things (well, not really all that many) that have been developed aboard the space shuttle and stuff. Tempurpedic matresses come to mind, also aerogeles and other things that they say only form in a microgravity environment. Once they've developed these things in space, how do they manufacure them the same way here on earth?
"Sic Semper Tyrannosaurus Rex."
Most hip replacements only last 5-10 years, and that's usually for little old ladies who don't do much in the way of stenuous activity.
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.
"Tomorrow's forecast: a few sprinkles of genius with a chance of doom!" - Stewie Griffin
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.
..........FULL STOP.
He did what you're not supposed to do and has had at least 2 revisions(other surgeries, each more extensive) in about three years.
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..
..........FULL STOP.
If you're over 55, a total hip will have over 95% survivorship at 10-12 years post-op.
..........FULL STOP.
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.
[Pruneau
Bo Jackson, and many other middle aged people, including myself, lose their hip joints to AVN (avascular necrosis) or accident. At 42, I had crippling pain in both legs, so intense that a ten step walk down the hall to the bathroom was eventually an impossible journey.
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.
My friend's cat had the ball of her femur ( the part that sticks into the hip socket ) busted off by a BIG BAD BABY. The vet did something where he made a sling for it with the muscle and now the cat jumps and frolicks and plays happily and pain free. I wonder if they do that wit people?
Eat at Joe's.
I hate car parts that were never meant to come off, like clips that were made to be clipped but always break if you try to unclip them. I get really ticked off when I find 'disposable' crap like this on my vehicles. Yet people are built that way.. I tell ya the factory just want's to sell more people, they don't care if ya an fix it when it breaks...
Eat at Joe's.
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 ?
[Pruneau