Children prosthetics are a lot harder to build.  Building prosthetics for kids is similar to making them for adults but on a much smaller scale.  Everything from the limb itself to the motor that make it move are smaller making putting the prosthetic together a more tedious task.  Also as children grow they will need new prosthetics often.  This can be very time consuming for both the family and the prosthetist. Prosthetics take about a month to make and between 3-5 visits to the doctor for fitting before the limb is ready.  Also they have to go to therapy to learn how to use the prosthetic.  Can you imagine having to do this once or twice a year.