Skeletal Mechanical Stresses Can be Accurately Modelled by Computers

Journal of Biomechanics, the most prestigious journal in biomechanical research, published on 12 April 2007 the electronic preprint of a paper entitled: “Schileo E, Taddei F, Malandrino A, Cristofolini L, Viceconti M. Subject-specific finite element models can accurately predict strain levels in long bones. J Biomech. 2007 Apr 12; [Epub ahead of print]”.

In this study the computational Biomechanics group lead by Fulvia Taddei at the Medical Technology Lab of the Rizzoli Orthopaedic Institute in Bologna, Italy, reports about an extensive validation study of the so-called subject-specific finite element analysis. This method makes possible the creation of computer models capable of predicting the mechanical stresses in any region of the skeleton of a given patient, starting only from a Computed Tomography exam of that subject.

In the study eight cadaver bones instrumented with dozen of sensors and subjected to multiple physiological loading conditions were used by the Experimental Biomechanics group lead by Luca Cristofolini to determine the mechanical stresses in the region of the proximal femur, consider one of the most difficult to model accurately.

Then the eight cadaver bones were examined with a standard clinical CT procedure; the eight computer models generated from these data were used to predict the mechanical stresses in the same loading conditions, and the predictions were then compared to the measured values. The study confirmed that the method developed at the Medical Technology Lab has accuracy better than 10%, which twice more accurate than any other previously published study.

This level of accuracy makes possible the introduction of these subject-specific predictive models in the clinical practice, in applications such as the prediction of the risk of fracture in osteoporotic patients, the preoperative planning of complex skeletal reconstructions in paediatric oncology or in traumatology, or the retrospective investigation of joint arthoplasties that failed in relation to biomechanical factors.