The prediction of pathologic fracture in patients with metastatic cancer

Abstract

PATHOLOGICAL FRACTURES RESULTING FROM NEOPLASMS WITHIN THE FEMUR ARE DISASTROUS TO ALL PARTIES INVOLVED AND IN MANY CASES COULD BE AVOIDED GIVEN EARLY DETECTION AND PREDICTIVE VALIDITY WITH RESPECT TO THE EXTENT OF THE LESION. IN PARTICULAR, PATHOLOGICAL FRACTURES OCCUR IN THE SUB- AND INTERTROCHANTERIC REGIONS OF THE FEMUR AS THESE ARE REGIONS OF UNIQUE STRESS CONCENTRATIONS AND FREQUENT SITES OF METASTASES. APPLICATION OF FINITE ELEMENT MODELING HAS PROVIDED GREATER UNDERSTANDING OF LOAD TRANSMISSION AND SHEAR PROPERTIES THROUGHOUT THE FEMUR (REFERENCES 5 AND 17). OONISHI AND HASEGAWA (1982) USED A TWO-DIMENSIONAL FINITE ELEMENT ANALYSIS TO INVESTIGATE DIFFERENT STRESS PROPERTIES OF CORTICAL AND CANCELLOUS BONE REGIONS OF THE FEMUR, INTUITIVELY, BECAUSE THE FEMUR IS ASYMMETRICAL AND CURVED IN EACH PLANAR AXIS ONE WOULD EXPECT A THREE-DIMENSIONAL MODEL TO BE MORE GENERALIZABLE TO A REAL-WORLD SITUATION. CROWNINSHIELD (1980) DEVELOPED A USEFUL 3-D MODEL TO RESOLVE GEOMETRICAL PROBLEMS INCURRED WITH TOTAL HIP RECONSTRUCTION. WITH THIS MODEL, AS ANY FINITE ELEMENT ANALYSIS, A GREATER NUMBER OF NODAL POINTS AND ELEMENTS YIELDS A MORE ACCURATE RESOLUTION OF LOAD STRESS/DISPLACEMENTS. THE PRESENT STUDY UTILIZED THESE AND OTHER FACTORS IN SIMULATING A FEMUR PRESENTING METASTATIC LESIONS OF THE SUB- AND INTERTROCHANTERIC REGIONS. REMOVAL OF ELEMENTS IN THESE AREAS ALONG WITH THEIR INHERENT STIFFNESS/SUPPORT PROPERTIES TO THE MODEL THUS SIMULATED THE EFFECT OF NON-SUPPORTIVE TUMOR WITHIN OTHERWISE HEALTHY BONE.