Demonstration of subchondral bone density patterns by three-dimensional CT osteoabsorptiometry as a noninvasive method for in vivo assessment of individual long-term stresses in joints.

Since the work of Pauwels and his successors, it has been possible to use the distribution of subchondral bone density within a joint surface as a metric parameter that can reflect the principal long-term stress acting upon a joint. However, the x-ray densitometry method he employed cannot be applied to living people. A procedure was therefore developed whereby CT osteoabsorptiometry (CT OAM), based on the use of computed tomography, allows the distribution pattern of the density to be demonstrated in living subjects. This method has now been further developed, so that the form of the individual joint surfaces can be included by means of a three-dimensional reconstruction program. This method is presented here. In addition, selected representative examples of various joints from normal people, athletes, and patients are used to demonstrate the use of CT OAM. In these examples from living subjects, regularly occurring, reproducible distribution patterns of subchondral bone density can be recorded, reflecting changes in mechanical stresses on a joint (increased stress, reduced stress, and disorders of joint mechanics). CT osteoabsorptiometry is demonstrated as a suitable noninvasive technique for investigating the individual long-term stresses (loading history) acting on a living joint.