Any pole that reduces impact force in this way will also be wasting
energy. Yes, you might be less injury prone, but at the same time you
will go slower. There is no need to buy stiff poles with a spring tip
to reduce inury. Just buy some cheap fiberglass poles that are super
flexy and you'll get the same thing. The physical way to reduce
injury would be to increase the time of the impact force of the pole
hitting the ground. The spring in the tip would do that, yes. But so
would the pole flexing (in the shaft).

I admit that I have never used these tips, however I have tried
trekking poles with a spring in them and the same thing happens.
Maybe less injury, definitely energy lost.

mg
www.bendbikensport.com