Taking Weight Off Back Injuries
For back injuries, we attach the crutch to the leg by velcro bands and a hook to the belt secures the gizmo from slipping down. Now, you just walk normally but put your weight on the crutch that's not picked up during walking. Thus, your weight is shifted from one leg to the other while walking and is never fully placed on your lower vertebra. There is no grinding force in your armpit as is the case with standard crutches.
For a foot injury, the "forward arrest" at the articulation is bolted to the thigh rod thus immobilizing the articulation feature for one leg. You can have one foot always off the ground.
I can also imagine a belt being secured around the waste so that body weight can be transferred to the hips instead of the spine for back injuries. There are standard "button type" length adjustment settings in the aluminum tubes (same as above crutch). Here, you would just walk around normally but with a gait like the inhabitants of Goony Island in the old Popeye cartoon. Not too comfortable but better than some options.
In any case, you won't be running up stairs or doing a marathon.