Available online 6 December 2022

Author links open overlay panelABSTRACT

Distal femoral fractures are fractures associated with high rates of morbidity and mortality, affecting to three different groups of individuals: younger people suffering high-energy trauma, elderly people with fragile bones and people with periprosthetic fractures around previous total knee arthroplasty. They have been classically treated with conventional plates and intramedullary nails and more recently with locked plates that have increased their indications to more types of fractures. The main objective of the present work is the biomechanical study, by means of finite element simulation, of the stability achieved in the osteosynthesis of femoral fractures in zones 4 and 5 of Wiss, by using locked plates with different plate lengths and different screw configurations, and analysing the effect of screw proximity to the fracture site. A three dimensional (3D) finite element model of the femur from 55-year-old male donor was developed, and then a stability analysis was performed for the fixation provided by Osteosynthesis System LOQTEC® Lateral Distal Femur Plate in two different fracture zones corresponding to the zones 4 and 5 according to the Wiss fracture classification. The study was focused on the immediately post-operative stage, without any biological healing process. The obtained results show that more stable osteosyntheses were obtained by using shorter plates. In the cases of longer plates, it results more convenient disposing screws in a way that the upper ones are closer to fracture site. The obtained results can support surgeons to understand the biomechanics of fracture stability, and then to guide them towards the more appropriate osteosynthesis depending on the fracture type and location.

Section snippetsINTRODUCTION

Distal femoral fractures are fractures associated with high rates of morbidity and mortality. Although they can occur in young patients due to a high-energy trauma, currently 85% of patients are elderly, mainly women with osteoporotic bone [1], which entails an increase in the therapeutic complexity that these fractures always present. They have been classically treated with conventional plates and intramedullary nails and more recently with locked plates that increase their indications to more

Modeling of the femur and plates

The 3D geometrical model of the femur was developed using a replica of a healthy femur from 55-years-old male a donor. The geometry was obtained by means of 3D Laser Scanner Roland® PICZA (Irvine, California), using the same methodology of previous studies [15, 16]. The geometrical model of the plate was created in NX I-Deas software [17] using the real implant (Osteosynthesis System LOQTEC® Lateral Distal Femur Plate [18]) as reference. The plate thickness is 6 mm, and its length has been

RESULTS

The FE simulations allowed obtaining the biomechanical behavior of the different osteosyntheses, and then mobility and stress results for the different cases could be analyzed. The results that characterize the biomechanical behavior of the osteosyntheses are the maximum global displacement at the femoral head, the relative displacement between upper and lower fragments, decomposed into the axial displacement, following the anatomical axis of the femur, and the rotational angle, the maximum von

DISCUSSION

Despite clinical evidence about the influence of material, plate length and number and disposition of screws on the mechanical behavior of femoral fractures osteosyntheses, no consensus was achieved among surgeons, and consequently more biomechanical studies are necessary, in order to help surgeons to find the most appropriate osteosynthesis depending on the fracture type and location and patient conditions.

That is why in this work a biomechanical study about osteosynthesis of femoral fractures

Declarations of interest

none

Acknowledgements

This research has been partially financed by The SECOT Foundation (Research Project: “Estudio comparativo clínico y biomecánico de distintos tipos de osteosíntesis en el tratamiento de fracturas distales del fémur”) and by the Government of Spain, Ministry of Economy and Competitiveness (Research Project: DPI2016-77745-R).

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