ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

direction at knee extension, placing it in a position where it becomes “wedged” between
the femur and tibia during knee flexion. Contact pressures on the medial side
intercondylar imminence increase with removal of the ACL (Fig. 6), indicating that the
geometric constraint of the imminence is taking more load in the absence of the
ligament constraint. The flexion angle for the three natural simulations did not change.
The magnitude of the muscle forces did change slightly for muscles crossing the knee,
but the patterns of the muscles forces did not change with increasing ACL deficiency.
a.) b.) c.)
Figure 5: Tibia plateau during forward dynamics simulation of the natural model at
maximum flexion for the intact ACL (a.), partial ACL transection (b.), and full ACL
transection(c.). The black arrows point to subluxation of the lateral meniscus.
Figure 6: Predicted contact pressures on the medial tibia plateau during
forward dynamics simulation of the natural model at maximum flexion for the
intact ACL (a.), partial ACL transection (b.), and full ACL transection (c.).
5. REFERENCES
a.) b.) c.)
[1] B. J. Fregly, T. F. Besier, D. G. Lloyd, S. L. Delp, S. A. Banks, M. G. Pandy, and D.
D. D'Lima, "Grand challenge competition to predict in vivo knee loads," Journal
of Orthopaedic Research, vol. In Press, 2012.
[2] A. Erdemir, S. McLean, W. Herzog, and A. J. van den Bogert, "Model-based
estimation of muscle forces exerted during movements," Clin Biomech (Bristol,
Avon), vol. 22, pp. 131-54, Feb 2007.
[3] T. M. Guess, H. Liu, S. Bhashyam, and G. Thiagarajan, "A multibody knee model
with discrete cartilage prediction of tibio-femoral contact mechanics," Comput
Methods Biomech Biomed Engin, Oct 4 2011.
[4] T. M. Guess, G. Thiagarajan, M. Kia, and M. Mishra, "A subject specific multibody
model of the knee with menisci," Med Eng Phys, vol. 32, pp. 505-15, Jun 2010.
[5] I. Lifemodeler, LifeMOD Manual, 2010.