In vitro biomechanical testing of the 3.5 mm LCP in torsion: a comparison of unicortical locking to bicortical nonlocking screws placed nearest the fracture gap

Static and dynamic examination of a locking plate in various setups for the stabilization of bone shaft fractures, including periprosthetic

Introduction: Hip and knee arthroplasty, formerly known as the “gold standard” in the treatment of articular cartilage damage, after a period of being highly popular, are changing the way they are perceived over time due to their related complications. The number of complications is directly proportional to the number of prostheses placed. This is the case of numerus arthroplasty surgeries, also involving other joints. Since there is no tissue compatibility between the metal prosthesis and the bone tissue, the former represents a negative biological element that hinders the healing of the fracture. Objective of the study: The study aims at addressing the following questions: 1. What is the elasticity of the fixation with a locking plate depending on the number of screws in both fragments, in the case of interfractural diastasis?, 2. What is the elasticity of the fixation with a locking plate depending on the number of screws in both fragments, in the case of fracture-on-fracture compression? 3. What is the difference in elasticity of the fixation using the cable system on a fracture with prosthesis?, 4. Determining the influence of different stabilization setups with the locking plate screws on the spacing of the fracture on the static and dynamic experimental model, 5. Is it possible to achieve elasticity of the stabilization stimulating bone union in a plate-based fixation, and when? Material and methods: The study was performed in the research laboratory of ChM. The subject of the study was the ChM 5.0 ChLP straight narrow compression locking plate with limited contact L-238, holes-15. The plate was mounted using ChM 3.5 locking screws: 5.0 ChLP 3.5 x 18T self-tapping screw and 5.0 ChLP 3.5 x 36T self-tapping screw. The test was carried out under static and dynamic conditions. Results and Conclusions: 1. The elasticity of the fixation with a locking plate at the interfractural diastasis is inversely proportional to the number of screws (plate deflection), 2. The elasticity of the fixation with a locking plate at the fracture-on-fracture compression is inversely proportional to the number of screws (fracture-on-fracture compression), 3. Application of the “cable system” on the fracture with prosthesis and the derotation screw optimizes the elasticity of the fixation and seems to be an optimal solution (in periprosthetic fractures), 4. Studies on the experimental static and dynamic model demonstrated that placing screws in all the openings of the plate is a restrained/clinically useless fixation. 5. The elasticity of the stabilization stimulating bone union can be obtained in the plate fixation supported by the "cable system".