Tag Archives: orthopaedic

No match for nature? The amazing properties of bone

boneThere are some things that nature just gets right. Take bone, for example. This typically has an elastic modulus similar to concrete, but is 10 times stronger in compression and around 50 times stronger in tension. It has a compressive strength similar to stainless steel, but is three times lighter. Not only that, but as a living tissue, it can adapt to meet property requirements. Bones in the legs, such as the femur and tibia, are typically much stronger than bones found in the arm, for example. And its properties aren’t fixed: the graph below shows how bones change in behavior with age, as explored within Granta’s Human Biological Materials database. What’s more, bones adapt depending on external conditions – a constant challenge in space as bones weaken if they are not loaded (as happens in zero-gravity). Continue reading

Poly(methyl methacrylate): a biocompatible acrylic

medicalDiscovered in 1877 and patented in 1933, PMMA, or acrylic, is often used as a lighter, more shatter-resistant alternative to glass. It is easy to process and make, resulting in a low cost versatile material used for everything from windows in aquariums, to protecting the audience from stray pucks in ice hockey rinks, and even in shoes.

What is interesting about PMMA, though, is its biocompatibility. Despite being formed by polymerizing Methyl Methacrylate, an irritant, and possibly a carcinogen, PMMA is extremely biocompatible, resistant to long exposure to temperatures, chemistry and cell action of human tissue. Continue reading