The importance of the biology and the care for the soft tissues and bone during internal fixation of the fracture, as the fourth AO principle, had been stressed. A conventional AO compression plate pressed against the bone surface interferes with the cortical blood flow and induces structural changes underneath the plate. Low contact dynamic contact plate(LC- DCP) could reduce the area of contact between plate and bone undercuts. Locking head screws, the Point Contact Fixator (PC Fix), and the Less Invasive Stabilisation System (LISS) had the next evolution.The so- called internal fixator can be considered as an external fixator, which has been approximated very close to the bone, however, without actually touching or compressing bone. This feature prevents any additional damage to bone vascularity. The stability of the internal fixator depends on the angular stability of the screw- plate combination. The new LISS and Locking Compression Plate( LCP) offer new options and challenges in modern operative fracture care. These implants are ideal for the MIPO (minimally invasive (percutaneous) plate osteosynthesis) and appear to have a considerably better purchase in osteoporotic bone. Nevertheless, it must be stated that these new plates and screws do not solve all problems, either as they too demand a very careful planning of every procedure, which includes a re- thinking of the classical AO principles, especially when addressing meta- and diaphyseal fractures.