Trabecular bone strain changes associated with cartilage defects in the proximal and distal tibia.

Intraarticular fractures with cartilage defects can lead to post-traumatic arthritis (PTA). The purpose of this study was to determine how cartilage defects affect load transmission through subchondral trabecular bone in human cadaveric knees and ankles to further understand the pathomechanics of PTA. We created full-thickness cartilage defects in the meniscectomized proximal tibia and distal tibia and measured changes in trabecular bone strain using Texture Correlation. Texture Correlation compares high quality digital images made from contact radiographs of unloaded samples to images of the same sample under load to measure trabecular bone strain. Cartilage defects caused trabecular bone strain to decrease in the proximal tibia and increase in the distal tibia. The column of bone directly beneath the defect in the tibial plateau had the most significant reduction in strain. In the distal tibia, strain near the jointline and in the anterior third had the most significant increases in strain. The distal tibia had greater strain changes with small defects. The clinical course of intraarticular fractures of the proximal and distal tibia are markedly different. We postulate that disturbances in load transmission through the subchondral bone caused by cartilage defects may be important mechanical determinants of PTA.