THE INVESTIGATION OF STRENGTH OF FIXATION WITH VARIOUS TYPES OF OSTEOSYNTHESIS OF THE PROXIMAL HUMERUS IN EXPERIMENTAL AND CLINICAL RESEARCH

In fractures of proximal humerus, stable fixation of osteoporotic bone fragments poses a significant problem, and wide surgical approach causes damage to blood supply of the humeral head, and to synovial bursae of the shoulder and tendons. These problems cause further permanent unfavourable changes in the shoulder. The least invasive surgical treatment is the percutaneous multi-plane fixation with a bundle of Kirschner wires monitored with fluoroscopy. Stability of these fixations and fixations by tension band, screws and Rush pins were examined in anatomical specimens of porcine humeri and in clinical evaluation. Experimental research concerned the primary stabilisation of various types of Kirschner wires inserted to the proximal part of a porcine humerus, later pulled out using a tensile testing machine, and fixations of 2-part fractures of a porcine proximal humerus fixed with Kirschner wires (various types), tension band, screws and Rush pins. The fixed bones were next torn apart with the same tensile testing machine to examine the strength of the junction. One type of Kirschner wires was designed by us. This type provided the maximum initial strength in the bone and maximum fixation strength, and was next used in surgical treatment of 21 proximal humerus fractures estimated as 2- and 3-part fractures in Neer classification. Follow-up covered a period from 18 months to 10 years. Results were estimated with Neer criteria. Reference comparison group was 50 patients, treated with different methods. Most of the very good and good results (86%) were obtained by fixation with the Kirschner wires of our design. These wires were threaded all over the part which entered the bone.