Can you explain chondropenia to me? I've been told this is what I now have in my knee after a serious soccer injury.

Chondropenia refers to changes in the articular cartilage of the joint. The articular cartilage is the smooth cartilage over the bone. This smooth surface is what allows the joint to slide and glide easily.

Microtrauma to the cartilage in athletes from high-impact loads can cause loss volume and stiffness of the articular cartilage. This is what is referred to as chondropenia. Lesions or defects in the cartilage make the surface uneven. Pressure on the area can cause further damage.

If other soft tissues in the joint occur at the same time, joint instability can occur. For example ligament tears or meniscal injury lead to further progression of the chondropenic cascade. The final result may be osteoarthritis (OA). Treatment to repair or replace the cartilage defect is advised to avoid this outcome.