Alterations to the subchondral bone architecture during osteoarthritis: bone adaptation vs endochondral bone formation  L.G.E. Cox, C.C. van Donkelaar, B. van Rietbergen, P.J. Emans, K. Ito  Osteoarthritis and Cartilage  Volume 21, Issue 2, Pages 331-338 (February 2013) DOI: 10.1016/j.joca.2012.10.013 Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

Fig. 1 Simulated bone structures. (a) Baseline simulation. (b) Adaptation to high loading conditions. (c) Endochondral ossification. (d) Endochondral ossification combined with high loading conditions. Osteoarthritis and Cartilage 2013 21, 331-338DOI: (10.1016/j.joca.2012.10.013) Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

Fig. 2 Bone structural parameters as determined for the final structures of each simulation. (a) For both high load simulations bone volume fraction increased, while for endochondral ossification alone it decreased compared to baseline. (b) For both endochondral ossification simulations, trabecular number increased, while for high load alone, trabecular number decreased compared to baseline. (c) For both endochondral ossification simulations, trabecular thickness decreased, while for high load alone, trabecular thickness increased compared to baseline. (d) For both high load simulations trabecular separation decreased, while for endochondral ossification alone it increased compared to baseline. Osteoarthritis and Cartilage 2013 21, 331-338DOI: (10.1016/j.joca.2012.10.013) Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

Fig. 3 Bone structural parameters determined in osteochondral plugs with increasing OA severity. P-values were determined using one-way ANOVA with a Bonferroni post-hoc test. (a) Bone volume fraction is highest for ICRS grade 4 samples. (b) Trabecular number is highest for ICRS grade 4 samples. (c) Trabecular thickness is highest for ICRS grade 4 samples. (d) Trabecular separation is lowest for ICRS grade 4 samples. Osteoarthritis and Cartilage 2013 21, 331-338DOI: (10.1016/j.joca.2012.10.013) Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions

Fig. 4 Osteochondral plugs with different ICRS grades. At a short distance from the bone–cartilage interface, a second subchondral plate seems to be present (first and second subchondral plate indicated with yellow dotted line). Osteoarthritis and Cartilage 2013 21, 331-338DOI: (10.1016/j.joca.2012.10.013) Copyright © 2012 Osteoarthritis Research Society International Terms and Conditions