We have many below knee amputees using shinfin fins around the world and we get great feedback. It depends on the person of course but many below knee amputees can pretty much get back to swimming as normal with shinfin fins, finding them very beneficial. Good hip movement helps and shinfin fins help to develop this too.
Fitting the fin on your lower leg stump is probably the best position if you can, because your knee joint helps to control the angle of the fin a bit more. 15 cm (6 inch) stumps should be enough for this (there are ways of adapting the fit to shorter stumps). Alternatively, you can fit the fin on your thigh with the straps just above your knee (as for above knee amputees). We have below knee amputee customers doing both. It depends on your body flexibility and joint movements as to which is best for you. You can experiment with this, and also with the angle of the fins around your legs.
The fins give extra kick power, encourage and stabilise a streamlined body position, and lift legs horizontal to reduce drag (even for slow kicking and gliding). The fins can be worn in different positions on each leg. The idea is to balance the down kick of one leg with the upkick of the other. The fins will also help get more power from the arm strokes because the left leg kicking down diagonally balances the force of the right arm pull, and vice versa. You can experiment with the height and angle of the fins around your legs to optimise your stroke.
The shinfin fins will help to lift your legs to a horizontal streamlined swimming position (on your front or on your back), even if you don’t kick. If you then kick a little bit, the shinfin fins will guide you towards the correct swimming kick. The shinfin fins do this because they have a natural flex that matches a good kicking style for freestyle, backstroke or fly. They encourage you to use the large muscles in your thighs, buttocks and torso and so help to build muscle tone in these areas. (Foot flippers are quite different as they require much more knee bend, and strain your feet, ankles and calf muscles).