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Thursday, July 12, 2012

Young's Modulus and some Physics and how We apply in Orthopaedics. Medical Students' Stuff!

Orthopaedics is a branch of medicine and surgery where the bones, joints and their ailments are diagnosed and treated. Correction of Deformity in Children is the literal meaning of the word "Ortho Paedics".



To correct the deformities due to fractures and other diseases and subsequently to prevent deformities primarily in fractures. we have to use materials other than the bone and the natural tissues.

One of the common materials used in this area are metals. There are various metals used namely Stainless Steel, Titanium, Cobalt Chrome, Plastics, Ceramics, Naturally available Gypsum and so on.

To understand how we choose different material and metal in this instance, one needs to be familiar with some physics.

This is where Young's Modulus of Elasticity which is what in Physics in Schools come to use.




If you pull any material with sufficient force, the material will elongate. This is easily understandable in a material like Elastic Rubber Band. The material will revert back to its normal length when the force is removed.

This property is true to a structure like Stainless Steel, Titanium, Cobalt Chrome etc. It is true to the bone as well.

We then to use a material which will have high strength but elasticity close to the bone. The measurement of elasticity is calculated by Young's Modulus. The high strength is denoted in the graph as the point where it is indicated "the material breaks"

This is where titanium scores over Stainless Steel in fracture fixation or joint replacements. Its modulus of elasticity is closer to bone than stainless steel, though stainless steel is very good indeed and the most commonly used metal in fracture fixation. Cobalt Chrome is commonly used in joint replacements as the wear is better.

Now what is Wear? here we are talking about the surface wear or the wear of the material's surface.

Wear is the damage by friction, shear or compressive force. you can scratch the stainless steel or plastic more easily than cobalt chrome. Hence you need a substance such as cobalt chrome for joint replacements where there is movement between two surfaces.

What is even better in joint replacement? considering the wear

we all have ceramic ware in our kitchen and dining room and we are often proud that it is there with us for a long time and not lose its shine. Yes we do use ceramic in joint replacements due to its surface hardness and resistance to wear. They are expensive like our domestic products compared to stainless steel.

Like our domestic ceramic cup, they were prone for breaking, however improvement in the manufacturing of these ceramic materials has made it unbreakable in joint replacments.

Now we do have these technologies available in a country like India and for use in a city like Trichy and the technology is helping us to provide a better care though at a price!

Now next time please do take time to talk to the Orthopaedic Surgeon treating you or someone known to you about the technology which goes behind.

Please watch the space as i would take time to more articles on the science in Medicine as the practice of medicine is considered to have Art and Science Component.


May be we can dwell into the art component which makes it human sometime in the future. Otherwise you wont have humans as doctors, rather you would be going to a robot doctor. May be we will and may not have a choice either in 2050 perhaps!!!!!!!!!!!!1



Warm Regards

Chockalingam