Effect of Fracture Gap on Biomechanical Stability of Compression Bone-Plate Fixation System after Bone Fracture Augmentation

PURPOSE: The goal of this study using the biomechanical test was to evaluate the mechanical stability of the bone-plate fixation system according to changes of the fracture gap sizes and widths. MATERIALS AND METHODS: For mechanical test, four types with different fracture models simulating the clinical situations were constructed depending on the gap size (FGS, mm) and the gap width (FGW, %) at the fracture site: 0 mm/0%, 1 mm/100%, 4 mm/100%, 4 mm/50%. For analyzing the effects of fracture gap on the biomechanical stability of the bone-plate fixation system, 4-point bending test was performed under all same conditions. RESULTS: It was found that the fracture gap sizes of 1 and 4 mm decreased mechanical stiffness by about 50~60% or more. Furthermore, even without fracture gap size, 50% or more fracture gap width considerably decreased mechanical stiffness and suggested the possibility of plate damage through strain results. CONCLUSION: Our findings suggested that at least 50% contact of the fracture faces in a fracture surgery would be maintained to increase the mechanical stability of the bone-plate fixation system.

A Finite Element Analysis of Biomechanical Stability of Compression Plate Fixation System in according to Existing of Fracture Gap after Bone Fracture Augmentation

PURPOSE: This study using the finite element analysis (FEA) focused on evaluating the biomechanical stability of the LC-DCP in accordance with existing of the fracture gap at the facture site after bone fracture augmentation. MATERIALS AND METHODS: For FEM analysis, total eleven types with different fracture models considering clinical fracture cases were constructed according to the fracture gap sizes (0, 1, 4 mm)/widths (0, 25, 50, 75, 100%). Limited contact dynamic compression plate (LC-DCP) fixation system was used in this FEM analysis, and three types of load were applied to the bone-plate fixation system: compressive, torsional, bending load. RESULTS: The results in FEM analysis showed that the 1, 4 mm fracture gap sizes and 75% or more fracture gap widths increased considerably the peak von Mises stress (PVMS) both the plate and the screw under all loading conditions. PVMS were concentrated on the center of the LC-DCP bone-plate, and around the necks of screws. CONCLUSION: Based on the our findings, we recommend at least 50% contact of the fracture faces in a fracture surgery using the compression bone-plate system. Moreover, if x-ray observation after surgery finds 100% fracture gap or 50% or more fracture gap width, supplementary measures to improve biomechanical stability must be taken, such as restriction of walking of the patient or plastering.

The Comparison of LC-DCP versus LCP Fixation in the Plate Augmentation for the Nonunion of Femur Shaft Fractures after Intramedullary Nail Fixation

PURPOSE: The purpose of this study was to evaluate the efficacy of the surgical treatment through the comparison of LC-DCP (Limited Contact-Dynamic Compression Plate) versus LCP (Locking Compression Plate) fixation in the plate augmentation for the nonunion of femur shaft fractures after intramedullary nail fixation. MATERIALS AND METHODS: Twenty-four patients with the nonunion of femur shaft fractures after intramedullary nail fixation who underwent plate augmentation were evaluated from Mar. 2001 to Sept. 2005. The group with LC-DCP augmentation was done bicortical screw fixation and the group with LCP was done monocortical fixation. RESULTS: There was one case of nail breakage in LC-DCP group, but sound bony union were achieved uneventfully in all the cases of both group. LCP fixation was slightly superior to LC-DCP fixation in view of the bony union time, operating time, postoperative Hb down, amount of postoperative transfusion, but there was no statistical difference (p>0.05). CONCLUSION: We got the satisfactory results after monocortical LCP augmentation as well as bicortical LC-DCP fixation and have concluded that monocortical LCP fixation was an effective treatment option for nonunion of femur shaft fracture occurred after Intrmedullary nail fixation.

Comparison of LC-DCP versus LCP for Internal Fixation of Humeral Shaft Fractures in Elderly Patient

PURPOSE: To compare outcomes of humeral shaft fractures fixed with locking compression plate and those fixed with dynamic compression plate in elderly patients. MATERIALS AND METHODS: Nineteen consecutive elderly patients with a fracture of the humeral diaphysis were evaluated retrospectively. Ten patients had been fixed with LC-DCP, and nine had been fixed with LCP. Radiological and clinical results were compared and comparison of implants was done. RESULTS: Loosening of the plate occurred in one case each from the LCP group and the LC-DCP group. The rest of the patients achieved union uneventfully without any complications. Union rate, clinical score and hardware were not significantly different between the two groups. One patient who developed loosening in the LC DCP underwent reoperation whereas one patient with loosening in the LCP was successfully managed conservatively. CONCLUSION: Principle of fracture fixation was more important than plate selection in humeral shaft fracture of elderly patient.