The iWALK crutch has a thigh circumference range with a maximum (at top of the groin) of 28.00" (71.0cm), and a minimum of 15.50" (39.5cm).
If your upper thigh is larger than 28 inches, unfortunately, the iWALK likely won't work for you. We have seen some people use it at 29", however, at that point it makes it hard to put the straps on and off and the range of vertical alignment adjustment is reduced.
You can see all the requirements for use by viewing the article here.