Subject: RE: Haley is a dumbassHmmmm... if she keeps it up, even her implants will need replacing. And - I got it right - titanium is the way to go!
Implant Construction The metal parts of the implant are made of titanium- or cobalt/chromium-based alloys. The plastic parts are made of ultrahigh-density polyethylene. All together, the components weigh between 15 and 20 ounces, depending on the size selected. The construction materials used must meet several criteria: - They must be biocompatible; that is, they can function in the body without creating either a local or a systemic rejection response.
- Their mechanical properties must be able to duplicate the structures they are intended to replace; for example, they are strong enough to take weightbearing loads, flexible enough to bear stress without breaking and able to move smoothly against each other as required.
- They must be able to retain their strength and shape for a long time. The chance of a knee replacement lasting 15 to 20 years is about 95 percent.
To date, man-made joints have not solved the problem of wear. Every time bone rubs against bone, or metal rubs against plastic, the friction creates microscopic particulate debris. Just as wear in the natural joint contributed to the need for a replacement joint, wear in the prostheses may eventually require a second (revision) surgery. |