I am reading introductory physics, and there is a chapter on equilibrium. In the chapter, the author mentions how devices can exploit distribution of forces to help those that are physically ill, via walking canes or crutches. But, the author doesn't really say how, and I'm curious.

I have no reference to check if my explanation is true or not, but I was wondering if this was the correct logic (forgive me if the explanations are atrocious, I'm working with an introductory book):

Assuming someone has two legs, when they use a cane, their weight is distributed along their two feet, putting more pressure on the knees and ankles then if they had a third body (cane) or fourth body (crutch) to transmit their body weight along. A rigid cane/crtuch provides this extra body to increase the distribution of weight, putting less pressure on joints, tendons, etc.

Then I thought about hunchbacks or people with back problems. These people slouch or curve their backs heavily, and isn't their center of gravity shifted away from its normal position around the hips? Weak people do not have strong enough bodies to deal with the gravitational forces, and I would assume canes and crutches would transmit this gravitational force through the cane as to prevent this force from causing a torque/leading them to fall over.

Finally, assuming someone's hands are strong enough, don't crutches or canes give them an opportunity to use their upper body strength and push down on the ground so that the force of the ground pushing back up on them is higher?

Again, sorry if these explanations sound novice or silly. I'm just trying to understand mechanics a little better.


I agree with your explanations. Just an afterthought, have you considered how much extra strength it requires to balance without a cane. Walking with a cane makes balancing easier taking stress away from the legs which would otherwise compensate for missteps.

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    $\begingroup$ As only an agreement and an afterthought, this should have been posted as a comment rather than an answer. $\endgroup$ – Asher Jul 12 '15 at 21:42
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    $\begingroup$ Alex, thanks for the insight. That is a better perspective from the medical standpoint of view, and something that is simpler to grasp. $\endgroup$ – Tyreke Davis Jul 12 '15 at 23:13

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