Assessment of fracture risk in proximal tibia with tumorous bone defects by a finite element method

Abstract

There has not been a satisfying method to predict the fracture risk in tumorous bone lesions. To tackle this challenge, we used a finite element method to assess the fracture risk in the proximal tibia (pT) when the size and location of the tumorous defects are varied in bone. Towards this end, the circular cortical defects, mimicking the tumorous lesions by forming cortical window defects, with a diameter (Ф) of 20, 30, 40, or 50 mm, are structured on the anteromedial, lateral, posterior wall of pT, which is located 5, 15, and 25 mm below articular margin, respectively. We found that under walking conditions, the Von Mises Stress of each defective tibia model was larger than that of the intact tibia model and also showed a positive linear correlation with the sizes of the defects. A notable fracture risk was not observed until the defect was Ф30 mm or larger. When the defect emerged, the anteromedial wall resisted fracture risk more than the rest of wall. Our results show that the size and location of the bone tumors are important factors affecting the fracture risk of pT. Our findings will be beneficial to clinicians when deciding what treatment to use for pT lesions.

Post-operative fracture risk assessment following tumor curettage in the distal femur: a hybrid in vitro and in silico biomechanical approach

“…By considering θ equals to 0° and 90° in Eqs. (4) and (5), respectively, the stress at damage initiation and energy for damage evolution for tension and shear were obtained. Elastic stiffness (MPa/mm) was derived by dividing stress at damage initiation to the corresponding displacements (δ 0 ), which are 0.07 mm in tension, and 0.082 mm in shear 39 .…”

“…In the past few years, biomechanical approaches using FEA or rigidity analyses have been employed to improve the accuracy in predicting fracture risk in patients with a bone tumour and to decide on the most appropriate reconstruction method following tumour curettage 5,11,12,[17][18][19] . Li et al utilized a patient-specific linear QCT-based FEA method to compare the stiffness and stress distribution in a distal femur with a bone defect (which was left empty) with the femora filled with bone cement and augmented with an internal fixation device following GCT curettage 18 .…”

“…Li et al utilized a patient-specific linear QCT-based FEA method to compare the stiffness and stress distribution in a distal femur with a bone defect (which was left empty) with the femora filled with bone cement and augmented with an internal fixation device following GCT curettage 18 . In 2017, a biomechanical fracture risk criterion for tibia defects, in line with defect size and based on stress distribution, was introduced using linear FEA on homogeneous models of bones 5 . In 2018, an ad hoc CT-based FEA on a retrospective cohort of 45 patients with metastatic bone disease in the femur showed that 39% of patients who were referred by Mirels' criteria (commonly used clinical criteria for predicting pathologic fracture risk in patients with a bone tumour) and underwent prophylactic stabilization may not have needed surgery 11 .…”

“…Recently, numerical methods using linear finite element (FE) models and structural rigidity analyses were used to predict failure loads of human distal femora following curettage and cementation 19 . Although several studies have investigated the fracture risk of a bone affected by a tumour, most concentrated on improving the accuracy of predicting pathologic fracture, but not the post-operative fracture risk 5,11,12,17 . Moreover, most of these studies suffer from low accuracy due to a lack of consideration of non-linear effects 5,[18][19][20] , or ignoring non-homogeneous bone material properties 5 , or the lack of validation of FEA results with experimental or clinical data 5,18 .…”

“…Although several studies have investigated the fracture risk of a bone affected by a tumour, most concentrated on improving the accuracy of predicting pathologic fracture, but not the post-operative fracture risk 5,11,12,17 . Moreover, most of these studies suffer from low accuracy due to a lack of consideration of non-linear effects 5,[18][19][20] , or ignoring non-homogeneous bone material properties 5 , or the lack of validation of FEA results with experimental or clinical data 5,18 . Therefore, there remains a great need for an accurate and validated biomechanical study on post-operative fracture risk assessment, particularly for defects in the epiphyseal region of the distal femur, the most vulnerable site for primary bone tumours, such as GCTs 6 .…”