Early morphometric and anisotropic change in periarticular cancellous bone in a model of experimental knee osteoarthritis quantified using microcomputed tomography

Objective. To quantify early stage microstructural changes of periarticular cancellous bone in a canine anterior cruciate ligament transection model for experimental osteoarthritis. Design. Unilateral transection of the anterior cruciate ligament was performed in 10 animals, Bone structure changes were quantified in five animals at 3-week post-transection and five animals at 12-week post-transection. An additional two non-operated animals were used as controls. Background. Changes in trabecular architecture of the periarticular cancellous bone in early stage post-traumatic osteoarthritis is not well understood. Previous studies have found alterations in bone mineral density in experimental osteoarthritis suggesting adaptation of the trabecular structure. Early change of the periarticular bone following a ligament injury may contribute to the longterm development of osteoarthritis. Methods. Bone cores from the medial condyles of the femoral and tibial pairs were scanned with a three-dimensional microtomographic system. Structural indices were quantified including bone volume ratio, bone surface ratio, trabecular thickness, trabecular separation, trabecular number, as well as structural anisotropy determined by the mean-intercept-length method. Results. Significant structural changes were observed at 3-week post-transection, and were more prominent at 12-week post-transection. These changes were accompanied by decreasing anisotropy. Conclusions. Periarticular cancellous bone microstructure is significantly altered in experimental osteoarthritis. These changes occurred as early as 3-week post-transection, and were large at 12-week post-transection.