Laurence Solovei, Dominique Ambard, Robin Chastant, Charles Marty-Ané, Simon Le Floch, Jean-Philippe Berthet
Institution : Service de chirurgie thoracique et vasculaire, CHU de Montpellier
Objectives : Thoracic osteosynthesis implants commonly used in reconstructive surgery are rib-fixation device, made of titanium or titanium alloys. Severe complications have been reported following these surgeries when implants fracture occurs. The evolution of our surgical practice requires detailed understanding of the local constraint conditions due to respiratory movements.
Methods : Displacements of tags, related to the fixation area of the rib implants, were studied by stereocorrelation first on the skin and then directly on the rib on patients in the operating room. The measures were done with six degrees of freedom: linear displacements x y z and rotations phy, psi and theta.
Results : Six patients were included. The displacements of the tags , according to x, y and z are small, respectively 0.43 mm ±0.04, 1.36 ±0.06 mm and 2.66 mm ±0.13. The amplitudes of displacement are correlated with respiratory volumes. An increase of 4 mL/kg amplifies the movements by an average factor of 1.6.
Conclusion : Numeric simulation of implants and constraints confirmed the phenomenon of fatigue failure for titanium and identify the flexion on y axis and lateral compression as the main mechanical stresses.