Ankle participates in static of feet, and in the dynamics of walking. Thus it has a load of pressure and tension. Tibial and fibular maleolus forms "fork" into which fits talus with the associated calcaneus. The integrity of the "fork" is important for the stability and thus the function of the ankle. Fractures of the distal tibia and fibula are 25-38% of all fractures of the physis. They occur most often between eight and fifteen years of age, more frequently in boys. The children's ligaments were stronger than epiphyseal cartilage, so that injuries to the adult caused ligament damage in children leading to fractures of the physis. Approximately 4% of ankle fractures affect physis. Fracture one of the ends of "forks" with detachment leads to its proliferation and instability. Fracture of tibial maleolus is intrarticular fracture and requires anatomical reposition and osteosynthesis of fragments to maintain the position obtained by reduction. Healing should be completed without growth abnormality or signs of arthritis. For operative treatment of tibial maleolus fractures in children (especially younger) the method of choice is osteosynthesis with Kirschner pins. They do not cause growth failure when passed through the growth plates. Kirschner pins osteosynthesis is not stable and requires additional plaster immobilization. In the immobilization on osteosynthetised fracture site worked forces of pressure and dynamic loading. The nature of the child is not to rest, on the contrary as soon as there is no control relies on the immobilized leg, stretches muscles normally due to itching under the cast. This notion of stability of osteosynthesis into the problem of "resistance". Taking into account the rules of mechanics, it is to assume that if we added a third Kirschner wire crossing the wires we get more stability. To prove it we carried out the experiment on the models of the lower end of the tibia of the company "Sawbones" which are normally carried out exercises on AO courses. Each model was cut so that it mimics a fracture of the medial maleolus, Kirschner wires 1.8 mm thick have been introduced, in various combinations of the number and position. Prepared models were tested in laboratory on a simulation machine (tension and pressure). These results are in the form of graphs to show the stability of the model.