Patient-specific computed tomography-based finite element analysis: a new tool to assess fracture risk in benign bone lesions of the femur

Background: Most benign active and latent lesions of proximal femur do not predispose a patient to a pathologic fracture. Nonetheless, there is a tendency to perform internal fixation due to the lack of accurate clinical tools that may reliably confirm low risk of pathologic fracture. As many as 30% of these surgeries may be unnecessary. A patient-specific CT-based finite element analysis may quantify bone strength and risk of fracture under normal weight-bearing conditions. Methods: The clinical relevance of such finite element analysis was investigated in a retrospective study on a cohort of 17 patients. Finite element analysis results (high risk = indication for surgery, low or moderate risk = follow-up) were compared to actual clinical decisions (surgery vs follow-up). All patients predicted by the finite element analysis as high risk underwent internal fixation and had good outcomes (n = 6). Findings: Four of the 11 low- and moderate-risk finite element analysis patients (36%) were operated immediately, and seven (64%) were either operated after a delay of at least 6 months or were never operated. None sustained a pathologic fracture. Patients who were predicted as low fracture risk by finite element analysis remained fracture-free for a minimal period of 6 months. Prediction of high risk of pathologic fracture by finite element analysis was in complete agreement with the conventional clinical evaluation. Interpretation: We consider finite element analysis a promising decision support system for the management of patients with benign tumors of femur, and that it may reliably endorse the decision to withhold surgery for patients at low fracture-risk.