title: Prediction of pathological fracture of the femoral shaft with an osteolytic lesion using a computed tomography-based nonlinear three-dimensional finite element method.
abstract: BACKGROUND
  Physicians radiologically estimate the reduction in bone strength based on the size or location of bone tumors. The goal of this study was to clarify the relationship between the size or location of a bony defect and its mechanical strength using a computed tomography-based three-dimensional finite element method.
  
  
  METHODS
  Computed tomography data of the right femur from two volunteers (one healthy male and one female patient with primary osteoporosis) were used for the present study. A spherical defect of various sizes and locations at the level of the isthmus of the femoral shaft was created on the three-dimensional finite element models to simulate the osteolytic bone tumor. We classified these defects into three types: inner erosion, cortical disruption, and outer erosion. Two types of mechanical testing were performed: axial compression and torsion.
  
  
  RESULTS
  In the axial compression testing of the healthy male subject, the correlation coefficients between the defect rate and the failure load in the cortical disruption type, inner erosion type, and outer erosion type were -0.916, -0.358, and -0.106, respectively. In the torsion testing, they were -0.8744, -0.9001, and -0.8907, respectively. In the axial compression testing of the osteoporotic female subject, the correlation coefficients in the cortical disruption type, inner erosion type, and outer erosion type were -0.754, -0.621, and -0.158, respectively. In the torsion testing, they were -0.9199, -0.5098, and -0.8363, respectively. In both tests, the defect rate of the cortex increased and the bone strength decreased, especially in the cortical disruption type.
  
  
  CONCLUSIONS
  The results of the present study demonstrate that osteolytic bone tumors can weaken the bone strength, particularly when perforation of the cortex occurs via tumor invasion. These results may be useful for risk assessment of pathological fractures due to primary and metastatic osteolytic bone tumors in clinical practice.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Chiba
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan. Electronic address: yu-mori@med.tohoku.ac.jp.
authors.forename: Yu
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Department of Orthopaedic Surgery, Sendai City Hospital, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sano
authors.affiliation: Department of Orthopaedic Surgery, Tohoku Kosai Hospital, Japan.
authors.forename: Koshi
authors.initials: K
authors.lastname: Kishimoto
authors.affiliation: Department of Orthopaedic Surgery, Tohoku Kosai Hospital, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Hatori
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Nakajo Orthopaedic Clinic, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakajo
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryomachi, Aoba-ku, Sendai 980-8574, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005260:Female; D005264:Femoral Fractures / Q000209:etiology*; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010024:Osteoporosis / Q000150:complications / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing