The association between velocity of the center of closest proximity on subchondral bones and osteoarthritis progression.

Altered surface interactions following joint instability may apply novel, damaging loads to articular cartilage. This study measured the velocity of the centers of closest proximity on subchondral bone surfaces on the femur and tibia during running in normal and unstable canine stifle (knee) joints. The purpose was to explore the relationship between the velocity of the centers of closest proximity on subchondral bones and the severity of cartilage damage. Dynamic biplane radiography was used to acquire serial knee kinematics [5 control, 18 cranial cruciate ligament (CCL) deficient] during treadmill running over 2 years. Custom software calculated the difference between the rate at which the center of closest proximity on the femur translated relative to the femur bone surface and the rate at which the center of closest proximity on the tibia translated relative to the tibia bone surface. Comparisons were made between dogs that developed minor versus major medial compartment cartilage damage over 2 years. Major damage dogs showed a significantly greater increase in the difference between femur and tibia medial compartment closest proximity point velocity from the instant of paw strike to peak velocity difference at 2, 4, and 6 months after CCL transaction. This implies increased tangential forces associated with the velocity of the compressed cartilage region during joint movement (plowing) may be a mechanism that initiates osteoarthritis (OA) development and drives OA progression. In the future, articulating surface velocity measurements may be useful to identify patients at risk for long-term OA due to joint instability.