EXPERIMENTAL STUDY OF OSTEOSYNTHESIS STABILITY OF THE DISTAL PART OF THE HUMERUS

Abstract

Unresolved issue is improving of the osteosynthesis of extraarticular fractures of the distal humerus. Search for a simplified method of biological fixation, which assumes, with low trauma, to ensure the stable fixation of fragments and movements in the elbow joint in the early postoperative period. Objective.To carry out a comparative analysis of the bone fragments displacement of the distal humerus in extra-articular fractures, stabilized by extraosseous and transosseous osteosynthesis. Methods. Biomechanical study of the distal humerus model was made. Transosseous osteosynthesis was modeled using the author’s external fixation apparatus (EFA). For comparison, we chose an osteosynthesis with a Y-shaped plate. The humeral models were loaded with an interval and a stepwise increased in the load for compression along the axis, flexion in a parallel plane, as well as perpendicular to the fixing elements of the plate and EFA. The magnitude of the load gradually increased from 0 to 250 N with a step of 50 N. The magnitude of the forces at which, due to the action of various loads, a displacement at the level of the fracture appeared. Results. The analysis of experimental studies showed that the rod apparatus and the plate provide the same stability of fixation of the fragments of the humerus under conditions of axial compression load (p > 0.05). Under the influence of bending loads of more than 100 N in a plane parallel to the fixing elements, the plate had a slight advantage (10 %). A significantly better result (p < 0.01) was obtained when an external device was used under the action of bending loads in a plane perpendicular to the fixing elements. Conclusions. In the case of fractures of the distal humerus, the transosseous osteosynthesis using the proposed external fixation rod device ensures the stability of the fragments under all loading options. It is quite reliable and can be recommended for use in clinical practice.