A computational analysis of a novel therapeutic approach combining an advanced medicinal therapeutic device and a fracture fixation assembly for the treatment of osteoporotic fractures: Effects of physiological loading, interface conditions, and fracture

Risk of internal fixation treatment in intertrochanteric fracture based on different lateral femoral wall thickness: finite element analysis

OBJECTIVE

The thickness of the lateral femoral wall, which is an important indicator for evaluating the stability and integrity of intertrochanteric fractures, has been widely studied in recent years. However, as a typical representative of internal fixation treatment, there are few reports on the biomechanical comparison between PFNA and DHS + CS. This study focused primarily on the biomechanical effects of different lateral femoral wall thicknesses on two types of internal fixation through finite element analysis.

METHODS

We randomly recruited a healthy adult and collected his femoral CT data to establish a model of femoral intertrochanteric fracture with different lateral femoral wall thicknesses. Following PFNA and DHS + CS fixation, femoral models were simulated, and variations in stress and displacement of the internal fixation and femoral head were recorded under the same physiological load.

RESULTS

First, finite element mechanical analysis revealed that the stress and displacement of the internal fixation and femoral head were lower in the femoral model after PFNA fixation than in the DHS + CS model. Second, as the outer wall thickness decreased, the stress and deformation endured by both types of internal fixation gradually increased.

CONCLUSIONS

Finite element analysis determined that PFNA exhibits significantly better biomechanical stability than DHS + CS when subjected to varying lateral femoral wall thicknesses. Moreover, lateral femoral wall thickness substantially affects the stability of the two internal fixation biomechanical environments. When the thickness of the lateral femoral wall is too small, we do not recommend using extramedullary fixation because there is a significant risk of internal fixation fracture.

Finite element analysis of vertebroplasty in the osteoporotic T11-L1 vertebral body: Effects of bone cement formulation

Vertebral compression fractures are one of the most severe clinical consequences of osteoporosis and the most common fragility fracture afflicting 570 and 1070 out of 100,000 men and women worldwide, respectively. Vertebroplasty (VP), a minimally invasive surgical procedure that involves the percutaneous injection of bone cement, is one of the most efficacious methods to stabilise osteoporotic vertebral compression fractures. However, postoperative fracture has been observed in up to 30% of patients following VP. Therefore, this study aims to investigate the effect of different injectable bone cement formulations on the stress distribution within the vertebrae and intervertebral discs due to VP and consequently recommend the optimal cement formulation. To achieve this, a 3D finite element (FE) model of the T11-L1 vertebral body was developed from computed tomography scan data of the spine. Osteoporotic bone was modeled by reducing the Young's modulus by 20% in the cortical bone and 74% in cancellous bone. The FE model was subjected to different physiological movements, such as extension, flexion, bending, and compression. The osteoporotic model caused a reduction in the average von Mises stress compared with the normal model in the T12 cancellous bone and an increment in the average von Mises stress value at the T12 cortical bone. The effects of VP using different formulations of a novel injectable bone cement were modeled by replacing a region of T12 cancellous bone with the materials. Due to the injection of the bone cement at the T12 vertebra, the average von Mises stresses on cancellous bone increased and slightly decreased on the cortical bone under all loading conditions. The novel class of bone cements investigated herein demonstrated an effective restoration of stress distribution to physiological levels within treated vertebrae, which could offer a potential superior alternative for VP surgery as their anti-osteoclastogenic properties could further enhance the appeal of their fracture treatment and may contribute to improved patient recovery and long-term well-being.