As I mentioned in this article, as soon as I saw Theodore Gray's prosthetic hip joint, I had to get one of my own. (Theodore's is one of the samples for his Periodic Table Table; he's pretty sure it belongs in the cobalt collection.)
And here mine is. I bought it on eBay; it cost me a total of $AU23.38 including delivery.
I've only got the hip part, not the corresponding socket part - which in this case would have been polyethylene, I think. But this is the interesting part, if you ask me. Mine even has a couple of nifty holes in the shaft, instead of the less elegant solid shaft of Theodore's. As I mentioned in that article, I find it makes a very acceptable ray gun.
I think it's probably made from a cobalt chrome molybdenum alloy. It's very slightly magnetic; you can't tell if you're just holding even a rare-earth magnet in one hand and the hip in the other, but when I hung a magnet from a string, I could get it to stick to the implant very slightly.
I'm not sure what company made it. There's a logo on the side like an R with a line around it, like so:
If you recognise that, drop me a line.
After the logo, there's "52-0346 46mm" (46mm is the diameter of the ball on the end), then "CC" on the next line. Further down the shaft there's a serial number, T00991004.
I'll have to buff all that stuff off before I try to pass the implant off as alien technology.
(See also: My bone chisel!)
UPDATE: One or another of my readers can reasonably be expected to know absolutely anything, so I now know exactly what this prosthesis is.
Take it away, Charles the anaesthetist:
Your prosthesis is an Austin Moore Hemiarthroplasty prosthesis [yep; now that I've got that string to search for, I instantly found it], used to replace the femoral head in cases of subcapital fracture (fairly high) of the neck of femur where the fracture site is high enough to probably affect the blood supply to the femoral head, leading to necrosis. Because of this you can't just screw the fracture together (search DHS, CHS, or IMHS).
Neck of Femur fracture (NOF) is an old person's fracture, as such not a great load is expected on the hip, in terms of use and duration, thus the acetabular side (socket) is left as is (which is why the head is so large: total hip replacment prostheses have a much smaller head diameter).
An Austin Moore is uncemented, too: you ream to size and bang it in. There are cemented hemiarthroplasties that are a sort of half way position (more stable and durable, less loosening) between this and a THR (total hip replacement), but cementing a prosthesis in this patient population has a high intraoperative morbidity and mortality itself.
There is a very high mortality post NOF: not due solely to the fracture, but due to the clinical situation of these patients. If a younger person happened to NOF themselves, you might pin it first if you thought the head had any chance of survival, but if not, a THR is better.
The "R" is Richards, an orthopaedic company since absorbed into Smith and Nephew, along with others.
I used to have a Austin Moore as a gear shifter in my Kingswood wagon: it fit nicely in the hand!
6 October 2008 at 10:37 am
Maybe you need to have a search through the Australian Register of Therapeutic Goods, Devices section?
[Oh, good idea! I haven't found any likely leads there, though; no R-logoed companies making hips that I can see. My hip is presumably pretty far from being a current product, to have shown up cheap on eBay; I think this one was a surgeon's display model or something, and perhaps got sold off when he retired. You'd think there might still have been other products from the same company on the list, though, but I wasn't able to find any. -Dan]
[I bet there's someone who works at the TGA who looks at that page fifty times a day, and now cannot escape recurring dreams about Anusol. -Dan]
6 October 2008 at 11:11 am
"Gee you guys are so unhip it's a wonder your bums don't fall off" - Zaphod.
I can see your work room in the reflection - but no naked Dan... ;)
6 October 2008 at 11:49 am
"I can see your work room in the reflection - but no naked Dan… ;)"
He's clearly triggered it remotely, or else it's on a timer - there's a large-camera-on-a-tripod there, and Dan's off to one side in all his unclothed glory.
6 October 2008 at 2:27 pm
Why?
I can understand the bone chisel, what with it being stupidly sharp and all, but... what do you do with a hip joint?
6 October 2008 at 4:09 pm
I'm a bit confused as to how a hip ends up on ebay.
If it's new, did the patient just buy it and decide it was the wrong size (like a pair of pants)? Do people have a pile of surgical implants that they are just waiting to offload on the next 99c listing day?
6 October 2008 at 5:40 pm
Whats the thing hanging off the side of your Camera, looks like a radar detector. I do like the raygun idea though.
6 October 2008 at 8:50 pm
@5 - see http://www.theodoregray.com/periodicTable/Elements/022/index.html#sample4
tl;dr - its been taken out of its sterile packaging in the operating room but hasn't been used.
6 October 2008 at 10:54 pm
Maybe you could ask the seller?
7 October 2008 at 1:04 pm
Isn't magnetism in a permanent implant a bad thing? In so much that the patient can never have a MRI? It would not do to have your hip replacement ripped from your body and adhere to the side of the torus.
7 October 2008 at 1:26 pm
Yes, but the metal this implant's made from is so close to non-magnetic that even an MRI magnet would only tug on it with a force of a few ounces, at the very most.
7 October 2008 at 5:37 pm
My girlfriend's daughter was hit by a truck 4 years ago. The impact did little else besides shatter her right arm almost completely; she had an unusual "Floating elbow" -the joint was disconnected from both sides due to breakages. At any rate, she has recovered 95% use (the most anyone can hope to after such catastrophic injury) and has two added benefits... (beyond a decent settlement) 1: her arm is now nigh-unbreakable due to its bone structure largely being cored with titanium and high-carbon steel, 2: she has a nice little card stating that the bearer has medical implants of a ferromagnetic nature and will always set off metal detection equipment. I have no idea what would happen if she were to be MRI'd. Fortunately though if she doesn't need it her biggest complaint is joint pain from atmospheric pressure changes. Which some of us have any way.