Functional reliability of means of fixation for complex pelvic fractures. Part 3. Experimental studies under cyclic loads

Fixation of fragments of human pelvic bones by standard and new means of osteosynthesis, in addition to clinical indicators, should have sufficiently high mechanical characteristics. In particular, the “bone with a fracture - osteosynthesis system” system must be sufficiently strong, rigid and stable during long-term treatment, which may be accompanied by certain physiological loads. Today, in traumatology and orthopedics, two methods of fixation are used to fix complex fractures of the pelvic bones caused by high-velocity wounding projectiles: parallel insertion of spongy screws (osteosynthesis of the posterior pelvic ring) and stabilization with a rod apparatus of external fixation and fixation by means of reinforced with application of extramedullary reconstructive plate (osteosynthesis of the anterior pelvic ring). The anterior pelvis is stabilized more often because this technique is simpler, does not require much time and high qualification of the surgeon. However, this method of fixation does not provide sufficient stability of the connection of the pelvic ring bone fragments. This work is devoted to the study of the processes of occurrence and development of mutual displacements of fracture points of pelvic bones under the action of long-term cyclic loads. Experimental studies were carried out under the action of bending cyclic loads, which are close to physiological ones. Calculated creep deformations and irreversible displacements of fracture points. The stiffness characteristics of pelvic fracture fixation systems were studied.