Answer from Dr Merkl:
With regular training, it is often possible to achieve amazing success in rehabilitation. There are companies that specialise in helping with minor and major limitations (e.g. stiff leg, lack of ambidexterity, impaired sense of balance, etc.). For example, these companies offer crank arm shorteners, dead centre overwinders and eccentric cranks. Some of these are inconspicuous components that restore your ability to train on the ergometer. Under certain conditions, these aids are also covered by health insurance or other cost bearers. The best-known suppliers are Dreisin in Achern, Hoening in Leonberg, Hase in Bochum and Wulfhorst in Gütersloh.