I saw a TV report about the latest research on spinal fusions. Japanese scientists are using an old formula from Boeing Company to find out how much stress is put on the tissues after the operation. I must have missed the reason why that would work. Can you explain it?

Engineers are able to use math to calculate the stresses on aircraft parts like wings and tires. Aircraft tires are made of elastic materials that also slide much like discs in the spine. Both tires and discs are subject to large strains. They must hold up without damage.

Aircraft companies like Boeing must make sure the tires can handle the loading and unloading during take off and landing. Mathematical models developed by aircraft engineers work quite well for measuring strain on the tire-shaped disc in the spine.

They take into account the shape, strain inside and out, forces of energy, and loading and unloading related to the spinal discs. The same methods that look at the properties of tires can be used to determine the dynamic deformations of discs.