Crutches can be tiring to use and also cumbersome to carry around.
The main purpose of a crutch is to support a person’s leg if it is injured; so that they can lean their body on the crutch instead of the leg when walking.
I think a better solution would involve the injured person not having to walk differently to how they normally would. This means that they will not have to carry a crutch and lean on it, which also means that they will always have both arms free.
If a tougher and lighter material was used to make a crutch then its size could be reduced, and it might even be able to be hidden under trousers. A material such as carbon fibre could be used and create a thin frame around the injured leg. The frame can then extend further down the leg than the foot, and so the foot will never have to touch the ground.
The main problem would to be finding a place to attach the crutch. The thigh is a possibility but might have to be quite tight and so could be uncomfortable for long periods of time. The hip is another possibility but would mean that it would have to be quite a bit larger.
Of course, carbon fibre crutches will be a lot more expensive than existing ones, however if there is a comfortable place for it to be held on the body and it can be discrete, then it could be worth it.
As always, if you think you have a solution or if you have a problem you like me to try to solve then please feel free to comment it.