Aso K, et al. - Researchers assessed two groups of medial tibial plateau (N=31 per group) to classify the osteochondral pathologies specifically linked to symptomatic human knee osteoarthritis (OA). They observed similar Mankin score, subchondral bone density, and subchondral CD68-immunoreactive macrophage infiltration between the groups. They noted a higher nerve growth factor in osteochondral channels and osteoclast densities in subchondral bone in symptomatic vs asymptomatic chondropathy groups. They observed an association of subchondral pathology with symptomatic knee OA, independent of chondropathy and synovitis. They concluded that osteoclast density and elevated NGF expression in osteochondral channels are key characteristics associated with bone pain in OA.