| The purpose of this study was to develop a model of post-traumatic osteoarthritis in the palmar metacarpal condyle and to evaluate the timing of the early events following impact trauma on subchondral bone and articular cartilage.;In each of 12 skeletally mature horses, an impact injury was created on the palmar metacarpal condyle of one randomly chosen limb, under arthroscopic and fluoroscopic guidance. A low to moderate level of forced exercise was instituted; and horses were evaluated clinically via lameness examinations, synovial fluid analysis, and radiographs. Macroscopic examination, micro-computed tomography, and sample collection were performed following euthanasia at one month (3 horses), 4 months (4 horses), and 8-10 months (5 horses) after impact injury.;There was variability in impact-lesion location, depth, and area on macroscopic inspection; histologic evaluation revealed more consistent cartilage defects due to impact injury. Cartilage degeneration, in terms of color and clarity, was observed in impacted joints. The mean sulfated glycosaminoglycan (sGAG) concentration from cartilage at the impact site was significantly lower than for a similar site in control limbs. Higher concentrations of cartilage oligomeric matrix protein (COMP) were observed in synovial fluid from impacted joints. Bone viability, as evaluated by the Alamar blue assay, was significantly decreased in impact specimens versus control specimens one month after impact injury.;This impact injury model caused lesions consistent with mild focal osteoarthritis in the palmar metacarpophalangeal joint, involving cartilage more than subchondral bone. Further development is required to create a reliable and consistent model of naturally occurring post-traumatic osteoarthritis at this site. |
