Materials “Those higher levels weren’t planned for and weren’t in
the original fi ling data, so even though they haven’t been linked to any health problems, they’re an unexpected outcome, and the FDA is asking questions. So orthopedics
companies are trying to get away from cobalt chrome for such applications. “Instead of a metal-on-metal wear surface, companies typi-
Designed for production
The Arcam Q10 represents the 3rd generation EBM technology. It is a manufacturing equipment specifically designed for cost-efficient production of components with high complexity and fine detail, such as orthopedic implants.
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• Latest generation EB gun • Closed powder handling
cally will have a HDPE—high-density polyethylene wear surface, which simulates cartilage. In an actual hip joint, the bone is covered with carti- lage, which when lubricated with synovial fl uid is essentially friction-free. Inside the orthopedic joint, a biocompatible metal is coated with HDPE to mimic the cartilage role. But HDPE too can abrade, and in this case, the wear debris—inert polyethylene particles—builds up behind the metal, and as the body attempts to clean up these wear particles it can trigger an autoimmune reaction which causes resorption of bone tissue—a con- dition called osteolysis. The bone pulls away from the metal joint that had been screwed into it, and the joint can start to become loose. That’s usually why some patients need revision surgery—and why people who are, say, 65 years old may elect to put off having replacement surgery, in order to not need to replace the joint at age 75.
“Some hospitals are looking at reclaim and reuse, and considering investing in metal versions ... and reuse instead of disposables.”
www.arcam.com See us at RAPID Booth #821 80
ManufacturingEngineeringMedia.com | May 2013
“So the hunt has been on for a better wear surface. Enter ceramics. Ceramics are super-hard and are great wear surfaces. They don’t abrade so you don’t have the wear debris issues. There have been two issues with ceramics, however. The fi rst is that if the clearance isn’t completely and totally perfect, you end up with ceramic squeaking against
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