Intramedullary osteosynthesis is used to treat complex fractures of tubular bones. This is a type of surgical intervention, which involves the introduction of a metal rod into the bone marrow. The operation is quite difficult to perform, but the effectiveness of its use is much higher than the application of plaster dressings or the use of other methods of treatment. Osteosynthesis is prescribed in specific cases, and not for any type of fractures, so it is important to know when intervention is appropriate.