Introduction: Intertrochanteric fractures of the femur are a prevalent occurrence among elderly individuals afflicted with osteoporosis. Nevertheless, there exists a notable paucity of research endeavors focused on the comparative analysis of the femo...
Introduction: Intertrochanteric fractures of the femur are a prevalent occurrence among elderly individuals afflicted with osteoporosis. Nevertheless, there exists a notable paucity of research endeavors focused on the comparative analysis of the femoral neck angle and the optimal lag screw placement for the treatment of these fractures. Consequently, the principal aim of this investigation was to undertake a biomechanical assessment, utilizing two distinct femoral neck angles and varying lag screw positions in intramedullary nailing, with the ultimate goal of ascertaining the most stable fixation configuration.
Methods: Within the confines of this study, an unstable A2.2 intertrochanteric fracture, characterized by a 2mm interfragmentary gap, was meticulously replicated using artificial femurs as a consistent model. Four discrete fracture-fixation models were devised, predicated on the placement of lag screws either in the central or lower region of the femoral neck. These models were implemented using intramedullary nails featuring femoral neck angles of 125° and 130°, thereby constituting Groups 1, 2, 3, and 4, respectively. Each specimen underwent a series of four mechanical assessments while assuming a one-legged stance with a 25° frontal plane adduction angle and maintaining a neutral position in the sagittal plane. Mechanical evaluations were executed in a sequential fashion, commencing with a preload phase (100N, 20N/min), followed by dynamic loading (75-750N, 10,000 cycles, 2Hz), and culminating with static loading (10mm/min). Fracture strength and stiffness were determined at the juncture where a 10mm vertical deformation was observed. The movement of lag screws before and after dynamic loading was quantified through X- ray imaging. Furthermore, rotational alterations in the femoral head along the X (Rotation), Y (Varus collapse), and Z (Retroversion collapse) axes were assessed. For this purpose, markers were affixed to the femoral head, and their three-dimensional coordinates were recorded employing a Microscribe M (Revware Inc., USA).
Results: The outcomes of static compression testing unveiled that Group 2 exhibited the highest fracture strength (1350±64N) and stiffness (188±15N/mm) in contrast to Group 1 (1312±100N, 170±3N/mm), Group 3 (1316±98N, 173±2N/mm), and Group 4 (1327±92N, 183±7N/mm). Furthermore, the displacement of lag screws, assessed via X-ray imaging both pre- and post-testing, demonstrated the least amount of movement within Group 2 (0.54±0.11mm) when juxtaposed with Group 1 (0.64±0.11mm), Group 3 (0.62±0.11mm), and Group 4 (0.56±0.07mm). Conversely, rotational changes about the X, Y, and Z axes were most pronounced within Group 2, with respective values of 1.72±0.09°, 2.25±0.27°, and 0.58±0.21°, in contrast to Group 1 (1.42±0.19°, 1.94±0.41°, 0.51±0.12°), Group 3 (1.33±0.17°, 1.94±0.25°, 0.49±0.15°), and Group 4 (1.66±0.18°, 1.97±0.44°, 0.58±0.14°).
Conclusion: The findings of this study underscore the superiority of employing intramedullary nails with a femoral neck angle of 125° in conjunction with lag screws positioned in the lower region of the femoral neck (Group 2), resulting in enhanced fracture strength and stiffness when compared to other configurations. Nevertheless, it is imperative to note that the placement of lag screws in the lower region was associated with a significantly greater rotational change, amounting to approximately 30%. Therefore, future investigations are warranted to explore strategies for mitigating rotational changes in such instances.