Florieke Eggermont1, Gerco van der Wal2, Paulien Westhoff3, Arjonne Laar4, Marianne de Jong5, Tom Rozema6, Herman M Kroon7, Onarisa Ayu2, Loes Derikx4, Sander Dijkstra2, Nico Verdonschot8, Yvette van der Linden9, Esther Tanck4. 1. Orthopaedic Research Laboratory, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, the Netherlands. Electronic address: Florieke.Eggermont@radboudumc.nl. 2. Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, the Netherlands. 3. Department of Radiation Oncology, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, the Netherlands. 4. Orthopaedic Research Laboratory, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, the Netherlands. 5. Radiotherapeutic Institute Friesland, Leeuwarden, the Netherlands. 6. Bernard Verbeeten Institute, Tilburg, the Netherlands. 7. Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands. 8. Orthopaedic Research Laboratory, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, the Netherlands; Laboratory of Biomechanical Engineering, University of Twente, Enschede, the Netherlands. 9. Department of Radiotherapy, Leiden University Medical Center, Leiden, the Netherlands.
Abstract
PURPOSE: To determine whether patient-specific finite element (FE) computer models are better at assessing fracture risk for femoral bone metastases compared to clinical assessments based on axial cortical involvement on conventional radiographs, as described in current clinical guidelines. METHODS: Forty-five patients with 50 femoral bone metastases, who were treated with palliative radiotherapy for pain, were included (64% single fraction (8Gy), 36% multiple fractions (5 or 6x4Gy)) and were followed for six months to determine whether they developed a pathological femoral fracture. All plain radiographs available within a two month period prior to radiotherapy were obtained. Patient-specific FE models were constructed based on the geometry and bone density obtained from the baseline quantitative CT scans used for radiotherapy planning. Femoral failure loads normalized for body weight (BW) were calculated. Patients with a failure load of 7.5 x BW or lower were identified as having high fracture risk, whereas patients with a failure load higher than 7.5 x BW were classified as low fracture risk. Experienced assessors measured axial cortical involvement on conventional radiographs. Following clinical guidelines, patients with lesions larger than 30mm were identified as having a high fracture risk. FE predictions were compared to clinical assessments by means of diagnostic accuracy values (sensitivity, specificity and positive (PPV) and negative predictive values (NPV)). RESULTS: Seven femurs (14%) fractured during follow-up. Median time to fracture was 8 weeks. FE models were better at assessing fracture risk in comparison to axial cortical involvement (sensitivity 100% vs. 86%, specificity 74% vs. 42%, PPV 39% vs. 19%, and NPV 100% vs. 95%, for the FE computer model vs. axial cortical involvement, respectively). CONCLUSIONS: Patient-specific FE computer models improve fracture risk assessments of femoral bone metastases in advanced cancer patients compared to clinical assessments based on axial cortical involvement, which is currently used in clinical guidelines.
PURPOSE: To determine whether patient-specific finite element (FE) computer models are better at assessing fracture risk for femoral bone metastases compared to clinical assessments based on axial cortical involvement on conventional radiographs, as described in current clinical guidelines. METHODS: Forty-five patients with 50 femoral bone metastases, who were treated with palliative radiotherapy for pain, were included (64% single fraction (8Gy), 36% multiple fractions (5 or 6x4Gy)) and were followed for six months to determine whether they developed a pathological femoral fracture. All plain radiographs available within a two month period prior to radiotherapy were obtained. Patient-specific FE models were constructed based on the geometry and bone density obtained from the baseline quantitative CT scans used for radiotherapy planning. Femoral failure loads normalized for body weight (BW) were calculated. Patients with a failure load of 7.5 x BW or lower were identified as having high fracture risk, whereas patients with a failure load higher than 7.5 x BW were classified as low fracture risk. Experienced assessors measured axial cortical involvement on conventional radiographs. Following clinical guidelines, patients with lesions larger than 30mm were identified as having a high fracture risk. FE predictions were compared to clinical assessments by means of diagnostic accuracy values (sensitivity, specificity and positive (PPV) and negative predictive values (NPV)). RESULTS: Seven femurs (14%) fractured during follow-up. Median time to fracture was 8 weeks. FE models were better at assessing fracture risk in comparison to axial cortical involvement (sensitivity 100% vs. 86%, specificity 74% vs. 42%, PPV 39% vs. 19%, and NPV 100% vs. 95%, for the FE computer model vs. axial cortical involvement, respectively). CONCLUSIONS:Patient-specific FE computer models improve fracture risk assessments of femoral bone metastases in advanced cancerpatients compared to clinical assessments based on axial cortical involvement, which is currently used in clinical guidelines.
Authors: Ali Ataei; Florieke Eggermont; Milan Baars; Yvette van der Linden; Jacky de Rooy; Nico Verdonschot; Esther Tanck Journal: Int J Comput Assist Radiol Surg Date: 2021-07-15 Impact factor: 2.924