Animal experiments reveal that stability may be achieved in small metaphyses also by "small-fragment" screws if applied correctly. Although the bone fixation of lag screws is greater than that of positioning screws the latter still make internal fixation stable enough for early mobilization. With continuing bone healing there is decreasing screw stability though it is not lost completely. The forces exerted by the screws on bone or plate, respectively, therefore seem to provide enough stability for the osteosynthesis on the operating day as well as for the entire duration of the healing. If the screws ever come loose it is usually due to faulty operating technique.