In treating fractures, osteosynthesis is of particular importance for a good outcome of the treatment. Depending on the location and type of the fracture, stability is achieved by immobilization, external fixation, intramedular fixation, compression plates or locking plates. Nowadays, fractures are mostly cured by open repositioning or internal fixing, which requires locking plates. The strong connection between the bolt and the plate results from a specially designed screw head and a hole in the plate. The polyaxiality of screws ensures greater biomechanical stability of the bone-plate-screw system, resulting in preservation of biological bone integrity, faster healing and consequently fewer postoperative complications. This paper examines the functionality of the new proposed locking system and the existing system which is already used in surgical practice. Computer simulation experiments under static and cyclic loads were also performed for four cases of changing the angles of the screw axis with respect to the axis of the screw hole in the plate. The results of the computer simulations carried out by applying the finite element method show that stresses in the case when the screw is under axial load are slightly higher than in the case of the control locking system. The results of bending tests show that stresses in the screw are greater in the control locking system and stresses in the plate are greater in the new locking system. The displacements are greater in the screw in both cases. The results of the cyclic tests carried out by bending the screws locked in the plate show that there are no statistically significant differences in the displacements between the new and the control locking system. The results of the static push-out test show that in the case when the screw is locked perpendicularly to the plate, the maximum force leading to the release of the strong connection between the screw head and the screw in the plate is statistically higher in the control locking system.