Re: Why was THR developed before resurfacing?

[Guest guest]

Hi ,

From what I can gather surgeons have long looked for something that would

work in a hip joint ........... early work did have something like our

current Resurface prothesis but as I understand it the materials beat

them.............

The hip joint is interesting...... and it had to be a bit of a challenge to

get something to stay affixed with that sideways operation/rotation

friction........... Looking at it logically you either get it affixed onto

the actual femur head or you take it one step further down and affix it into

the femur itself........... which is the basic differences between the THR

and Resurface............. The alloys and other materials available seem to

have been the major determinants of how the ingeneous minds went about

figuring this out............. We have seen THR's go through a range of

materials trying to get it right with a range of problems constantly popping

up with ceramics shattering, plastics shedding, metals wearing

etc........... and that's without the femur bone hassles of it not always

appreciating a shaft of metal down its insides permanently........... so it

splits or moves itself away from the metal and so the prothesis

loosens..........

And because these brilliant minds rarely give up as the materials improved

the guys went back to the drawing board fretting about how to get it to work

as a Resurface instead of needing to cut off the femur.............. You

will see looking at the Resurface devices now available they are all still

dabbling with thinking of ways it may work better - I see one has little

fins around the insides, mine has a pin instead........... The Resurface

device still runs into the femur head bone objecting, developing AVN

etc.......... (Thankfully it seems not with as much enthusiam as the inner

bone areas)........... and there is a degree of skill needed in getting it

on just right and not hitting it with too much enthusiam with the hammer

when putting it on.............. which is where my OS says most failures are

born.

Edith LBHR Dr L Walter Syd Aust 8/02

> Out of curiosity, why was THR developed before resurfacing? It would

> seem that resurfacing would have been the logical choice since it is

> less radical that THR. Was it because of lack of metal-on-metal

> applicances as exist today? Or because of ???

>

> Thanks, Norrod

>

>

>

>

>

>

[Guest guest]

Edith,

A most fascinating post...

K. r/BHR De Smet Feb 3rd, 04

> Hi ,

>

> From what I can gather surgeons have long looked for something that would

> work in a hip joint ........... early work did have something like our

> current Resurface prothesis but as I understand it the materials beat

> them.............

>

> The hip joint is interesting...... and it had to be a bit of a challenge to

> get something to stay affixed with that sideways operation/rotation

> friction........... Looking at it logically you either get it affixed onto

> the actual femur head or you take it one step further down and affix it into

> the femur itself........... which is the basic differences between the THR

> and Resurface............. The alloys and other materials available seem to

> have been the major determinants of how the ingeneous minds went about

> figuring this out............. We have seen THR's go through a range of

> materials trying to get it right with a range of problems constantly popping

> up with ceramics shattering, plastics shedding, metals wearing

> etc........... and that's without the femur bone hassles of it not always

> appreciating a shaft of metal down its insides permanently........... so it

> splits or moves itself away from the metal and so the prothesis

> loosens..........

>

> And because these brilliant minds rarely give up as the materials improved

> the guys went back to the drawing board fretting about how to get it to work

> as a Resurface instead of needing to cut off the femur.............. You

> will see looking at the Resurface devices now available they are all still

> dabbling with thinking of ways it may work better - I see one has little

> fins around the insides, mine has a pin instead........... The Resurface

> device still runs into the femur head bone objecting, developing AVN

> etc.......... (Thankfully it seems not with as much enthusiam as the inner

> bone areas)........... and there is a degree of skill needed in getting it

> on just right and not hitting it with too much enthusiam with the hammer

> when putting it on.............. which is where my OS says most failures are

> born.

>

> Edith LBHR Dr L Walter Syd Aust 8/02

>

>

[Guest guest]

Just because I read it someplace and thought it was interesting.

>>

>> From what I can gather surgeons have long looked for something that

would

>> work in a hip joint ........... early work did have something like our

>> current Resurface prothesis but as I understand it the materials beat

>> them.............

>>

The first THR was done in Germany in the 1920's and used a glass ball. It

worked for a bit, but the ball itself fractured fairly shortly after

implant.

As Edith so well pointed out, it is materials that drives this. A BHR or

other resurfacing device is really simple -- just a chunk of metal, but

that belies its sophistication. Getting something that is non-toxic (there

are only about half a dozen metals out there that won't kill you) was the

first challenge. The next hurdle is getting an alloy that is really hard.

Finally, the ability to mill it to the tolerance levels needed are of quite

recent vintage. I seem to recall reading that making one of these implants

requires weeks if not months of work.

-- jeff

rBHR Aug. 1, 2001

Mr. McMinn

==================

" You know you've achieved perfection in design, not

when you have nothing more to add, but when you

have nothing more to take away. "

-- Antoine de Saint-Exupéry (1900-1944)

French aviator, writer