Arthroscopic knee surgery tool design and materials selection

A number of years ago I was consulting for a division of Johnson & Johnson, when arthroscopic knee surgery was big. When I was your age, I had a torn cartilage in my left knee — I matched it a few years ago with one in my right knee. If I wanted to get an operation to repair that cartilage in the late 1960s when it happened to me, they would have to lay your whole knee open to get in there, and you would be in a cast for six months, on crutches for a year. I decided I could live with the torn cartilage. I can hear it click. Even today, if I get my head down there near my knee and move my knee back and forth, I can hear the cartilage click. I can even feel it sometimes.

Stiffness scales as cube of diameter; slender surgical tools lose stiffness rapidly. Tom proposed single-crystal sapphire (60 Msi stiffness, ~2× steel) and color-coded ruby variants to a medical company; not adopted.

One of you was working on micro-catheters? I should have brought my micro-catheter stainless steel piece. Does anyone have a parent or grandparent that has a stent in their heart? How do they get it in? They take one of the arteries in your leg, and they go in with this long stainless steel Teflon-coated tube or wire, and they're taking flash x-rays so they can see. They put a little bit of barium on the tip so they can see exactly where it is in your arteries. They're taking x-ray movies while they're doing this. This has been a great boon for the radiology doctors putting stents in. It used to be the surgeon did open-heart surgery. Now these guys do this much less invasive stuff. The first one they put in is a guide wire, and then they use that like a little trolley wire to bring other things in, and they eventually put the stent in.