Early regional adaptation of periarticular bone mineral density after anterior cruciate ligament injury

The present study measured early-stage adaptation of bone mineral (BMD) in the periarticular cancellous bone of the canine knee (stifle) joint after a nterior cruciate Ligament (ACL) transection (ACLX). Regional changes in BMD in the tibia and femur were analyzed by using quantitative computed tomogr aphy (qCT) at 3 wk and 12 wk after unilateral ACLX to determine whether the re were focal points for BMD changes and whether these changes occurred ear ly after the induced knee injury. BMD decreased rapidly after ACLX, and the more pronounced response was in the femur. In the 3-wk group, there were d ecreases in BMD in the tibia and the femur, and these changes were signific ant in the posterior-medial region of the femur, which showed a decrease of BMD in the ACLX limb (-0.048 +/- 0.011 g/cm(3)). In the 12-wk group, all r egions in the tibia and femur exhibited significant decreases in BMD, and t he average decrease was greatest in the posterior-medial region of the femu r (-0.142 +/- 0.021 g/cm3). The regions of pronounced periarticular cancell ous BMD adaptation corresponded to observed focal cartilage defects. Early decreases in BMD in the injured knee may be related to altered loading and kinematics in the knee and may be an important link in the pathogenesis of posttraumatic osteoarthritis.